Nuclear Reactor Types

OK, we’ve got a bit of an ongoing discussion of Nuclear Power and various Nuclear Reactor designs Some of it is spread over the Japan Nuke disaster pages and some of it on the USA radiation exposure page (both natural from Uranium and on the wind from Japan – even though that is an almost unmeasurable amount here in the USA).

That sent me off looking at what were the definitions of the different nuclear reactor types…

The first thing I realized was that there are dozens of different designs. Just sorting out the “Alphabet Soup” was a PITA. The second thing I realized was that with very few reactors built in any given year, there would be precious few of these that were the same; both in the macro design and in the ‘revision’ details. Some designs have never been built. Some are widely built, with variations. A few places have a couple of standardized designs so they may even have built the same thing more than once (such as the GE Mark I reactors in Japan, but even there one of them is fueled with MOX fuel so is a slightly different configuration).

Sometimes I wonder how much better and safer things would be if we actually standardized a bit. At other times I think about what would have happened if we standardized on a bad design…

With that in mind, I’m going to document here, mostly for my own reference, some of the different reactor types in the world. A lot of this will just be links to Wiki articles (or better ones if I’ve found one or if folks post a link) so that when I run into some particular alphabet soup of PHWR or BONUS I can hit this link and remind myself that it’s a Pressurized Heavy Water Reactor or a “Boiling Nuclear Superheater (BONUS) Reactor Facility”…

Lists of Lists

There is a nice Wiki that purports to list all the reactors of the world. It lists the type, so you can get a clue as to where they might actually have the same design. Places outside the USA look to have done a much better job of “standardize and simplify your life”. There is one heck of a lot of these guys pretty much all over the planet:

List of nuclear reactors is an annotated list of all the nuclear reactors of the world, sorted by country. This list excludes nuclear marine propulsion reactors, except those at land installations, and excludes reactors that never achieved criticality.

For folks wondering what nuclear accidents might be connected with any given location, here are the Wiki lists of various accidents so you can play “mix and match”:

This article lists notable civilian accidents involving radioactive materials or involving ionizing radiation from artificial sources such as x-ray tubes and particle accelerators. Accidents related to nuclear power that involve fissile materials are listed at List of civilian nuclear accidents. Military accidents are listed at List of military nuclear accidents.

This article lists notable civilian accidents involving fissile nuclear material or nuclear reactors. Civilian incidents not serious enough to be accidents are listed at List of civilian nuclear incidents. Military accidents are listed at List of military nuclear accidents. Civil radiation accidents not involving fissile material are listed at List of civilian radiation accidents. For a general discussion of both civilian and military accidents, see Nuclear and radiation accidents.

This article lists notable military accidents involving nuclear material. Civilian accidents are listed at List of civilian nuclear accidents. For a general discussion of both civilian and military accidents, see nuclear and radiation accidents.
See also: Lists of nuclear disasters and radioactive incidents

FWIW they seem to glory in making long and repeated lists of things that have gone wrong. The same things are on the “rollup lists” as in the detail by type lists. Events where even a single person is injured are given grave weight… even though for decades the standard practice in Organic Chem Lab was to wash the labware with Benzene ( I know, I did it…) and only later was Benzene found to be a carcinogen and maybe that was why the organic chemists were dropping like flies with cancers… buy you don’t find much attention paid to that on the Wiki… from:

Many students were exposed to benzene in school and university courses while performing laboratory experiments with little or no ventilation in many cases. This very dangerous practice has been almost totally eliminated.

I guess it would be too much trouble to “dwell” on every single college campus world wide that had an organic chem lab and the millions of students who washed their labware by hand in benzene… (It was used to assure removal of organics and dryness). I guess the millions exposed every year to this “known carcinogen” are less important than a couple of folks working on nuclear weapons who got killed in plutonium accidents (the top item in the list was a nuclear core accident that fried a couple of folks).

Benzene exposure has serious health effects. The American Petroleum Institute (API) stated in 1948 that “it is generally considered that the only absolutely safe concentration for benzene is zero.” The US Department of Health and Human Services (DHHS) classifies benzene as a human carcinogen. Long-term exposure to excessive levels of benzene in the air causes leukemia, a potentially fatal cancer of the blood-forming organs, in susceptible individuals. In particular, Acute myeloid leukemia or acute non-lymphocytic leukaemia (AML & ANLL) is not disputed to be caused by benzene. IARC rated benzene as “known to be carcinogenic to humans” (Group 1).

If you think I’ve got a chip on my shoulder about Benzene, “damn straight”. I love organic chem, but the “discovery” of it being nasty happened while I was in school. I noticed a “hazard” sign on a door about “benzene in use” and enquired… they were doing research into the damage it did to rats and other poor critters. Then went to my lab and washed my labware in benzene “as instructed”… you would have thought the two groups would talk to each other… The risks to the general population from chemicals and Genetically Modified Organisms are so much more huge than anything nuclear as to make ones head spin; but folks focus on radiation. Go figure…

This is not a hypothetical, btw. For much of the time up until the 1980s gasoline had high levels of benzene and other aromatics in it. High Octane was often from high benzene… My first college roommate died from leukemia, in his late 40s, of the type caused by benzene. His Dad owned a gas station and as a kid he worked in it. Often cleaning parts. In gasoline… I helped my Dad work on our cars, and we, too, cleaned parts in gasoline, just not as many or as often. It was common all over the farm country to do that as gasoline was a cheap and available solvent. So where is the railing against this widespread destruction of lives from splattering that carcinogen all over? What’s that I hear? Silence? Oh, better to scream and shout about nearly undetectable I-131 in California…

At any rate, back to nukes…

Special Mention

Reactor B

Goes to the first large scale “production” reactor. We used it to make Plutonium for bombs. It is a straight forward no frills and little safety reactor. Pile of carbon, uranium metal, water cooling. Reactor B. (Each one got a letter. This one is preserved, the others are not).

The B Reactor at the Hanford Site, near Richland, Washington, USA, was the first large scale nuclear reactor ever built. The project was commissioned to produce plutonium-239 by nuclear fission as part of the Manhattan Project, the United States nuclear weapons development program during World War II. The B reactor was fueled with metallic natural uranium, graphite moderated, and water cooled. It has been designated a U.S. National Historic Landmark since August 19, 2008.


These were exploring boiling water and what it does to fuel.

The BORAX Experiments were boiling water reactor experiments done at the National Reactor Testing Station, now the Idaho National Laboratory.

This series of tests began with the BORAX-I nuclear reactor, which proved Samuel Untermyer II’s 1952 theory that a reactor using direct boiling of water would be practical, rather than unstable, because of the bubble formation in the core. Subsequently the reactor was used for power excursion tests which showed that rapid conversion of water to steam would safely control the reaction. The final, deliberately destructive test in 1954 produced an unexpectedly large power excursion that “instead of the melting of a few fuel plates, the test melted a major fraction of the entire core.” However, this core meltdown and release of nuclear fuel and fission products provided additional useful data to improve mathematical models. The tests proved key safety principles of the design of modern nuclear power reactors. Design power of BORAX-I was 1.4 megawatts thermal. The BORAX-I design was a precursor to the SL-1 plant, which was sited nearby and began operations in 1958. The principles discovered in the BORAX-I experiments helped scientists understand the issues which contributed to the fatal accident at SL-1 in 1961.

Built in 1954, the BORAX-II reactor proved the principles of pressurized water reactors, with a design output of 6 MW(t).

BORAX-II, modified into BORAX-III with the addition of a turbine, proved that turbine contamination would not be a problem. It was linked to the local power grid and for about an hour on July 17, 1955, it provided 2,000 kW to power nearby Arco, Idaho (500 kW), the BORAX test facility (500 kW), and partially powered the National Reactor Testing Station (now the Idaho National Laboratory) (1,000 kW). Thus Arco became the first city solely powered by nuclear energy. The reactor continued to be used for tests until 1956.

BORAX-IV, built in 1956, explored the thorium fuel cycle and uranium-233 fuel with a power of 20 MW thermal. This experiment utilized fuel plates that were purposely full of defects in order to explore long-term plant operation with damaged fuel plates. Radioactive gasses were released into the atmosphere.

BORAX-V continued the work on boiling water reactor designs, including the use of a superheater. It operated from 1962 to 1964

Can you imagine what folks would say today if you proposed “destructively testing a core to meltdown”?

Also of note is that they were exploring the use of Thorium as early as 1956.


Almost as interesting as making a reactor under the bleachers in an abandoned gym:

Chicago Pile-1 (CP-1) was the world’s first artificial nuclear reactor. CP-1 was built on a rackets court, under the abandoned west stands of the original Alonzo Stagg Field stadium, at the University of Chicago. The first artificial, self-sustaining, nuclear chain reaction was initiated within CP-1, on December 2, 1942. The site was designated a National Historic Landmark in 1965 and was added to the newly created National Register of Historic Places a little over a year later. The site was named a Chicago Landmark in 1971. It is one of the four Chicago Registered Historic Places from the original October 15, 1966, National Register of Historic Places list.
The reactor was a pile of uranium and graphite blocks, assembled under the supervision of the renowned Italian physicist Enrico Fermi, in collaboration with Leo Szilard, discoverer of the chain reaction. It contained a critical mass of fissile material, together with control rods, and was built as a part of the Manhattan Project by the University of Chicago Metallurgical Laboratory. The shape of the pile was intended to be roughly spherical, but as work proceeded Fermi calculated that critical mass could be achieved without finishing the entire pile as planned.

A labor strike prevented construction of the pile at the Argonne National Laboratory, so Fermi and his associates Martin Whittaker and Walter Zinn set about building the pile (the term “nuclear reactor” was not used until 1952) in a rackets court under the abandoned west stands of the university’s Stagg Field. The pile consisted of uranium pellets as a neutron-producing “core”, separated from one another by graphite blocks to slow the neutrons. Fermi himself described the apparatus as “a crude pile of black bricks and wooden timbers.” The controls consisted of cadmium-coated rods that absorbed neutrons. Withdrawing the rods would increase neutron activity in the pile, leading to a self-sustaining chain reaction. Re-inserting the rods would dampen the reaction.

I can just hear someone shouting at a Grad Student “Hey, go shove those rods further into that pile, will you? The neutron flux over here is getting a bit high.” (The life of a Grad Student is not always the best ;-)

Nuclear Rockets

OK, I’m mostly just going to give a link to the wiki. I only mention them in passing as they are just bizarre. Many of the typical design constraints are removed as “in space, no one cares”… it already has lethal levels of radioactivity. Like this “liquid core” design. Worried about a core melt? Heck no, we call it a design feature!:

Dramatically greater improvements are theoretically possible by mixing the nuclear fuel into the working fluid, and allowing the reaction to take place in the liquid mixture itself. This is the basis of the so-called liquid-core engine, which can operate at higher temperatures beyond the melting point of the nuclear fuel. In this case the maximum temperature is whatever the container wall (typically a neutron reflector of some sort) can withstand, while actively cooled by the hydrogen. It is expected that the liquid-core design can deliver performance on the order of 1300 to 1500 seconds (12.8–14.8 kN·s/kg).
An alternative liquid-core design, the nuclear salt-water rocket has been proposed by Robert Zubrin. In this design, the working fluid is water, which serves as neutron moderator as well. The nuclear fuel is not retained, drastically simplifying the design. However, by its very design, the rocket would discharge massive quantities of extremely radioactive waste and could only be safely operated well outside the Earth’s atmosphere and perhaps even entirely outside earth’s magnetosphere.

Way to “think outside the sphere” guys! ;-)

And for another reason to hate Nixon, the space rocket that could have been:

NERVA is an acronym for Nuclear Engine for Rocket Vehicle Application, a joint program of the U.S. Atomic Energy Commission and NASA managed by the Space Nuclear Propulsion Office (SNPO) until both the program and the office ended at the end of 1972.

NERVA demonstrated that nuclear thermal rocket engines were a feasible and reliable tool for space exploration, and at the end of 1968 SNPO certified that the latest NERVA engine, the NRX/XE, met the requirements for a manned Mars mission. Although NERVA engines were built and tested as much as possible with flight-certified components and the engine was deemed ready for integration into a spacecraft, much of the U.S. space program was cancelled by the Nixon Administration before a manned visit to Mars could take place.

NERVA was considered by the AEC, SNPO and NASA to be a highly successful program; it met or exceeded its program goals. Its principal objective was to “establish a technology base for nuclear rocket engine systems to be utilized in the design and development of propulsion systems for space mission application”. Virtually all space mission plans that use nuclear thermal rockets use derivative designs from the NERVA NRX or Pewee.

(NRX being a Canadian research facility).

Not surprisingly, the Russians made one also. It, too, was tested.

RD-0410 (РД-0410, GRAU index: 11B91) was a Soviet nuclear thermal rocket engine developed from 1965 through the 1980s using liquid hydrogen propellant. The engine was ground-tested at the Semipalatinsk Test Site, and its use was incorporated in the Kurchatov Mars 1994 manned mission proposal.

Research and Small Scale Reactors

In some ways these are the most interesting. Something you could “build in your own back yard” ;-)

I’m especially fond of the swimming pool type, as it looks a whole lot like some nuclear fuel stuck in a swimming pool. The top is left open (as the water absorbs the radiation) and you can actually look down into the running core. Designed mostly for teaching purposes and research, so you can “fool around with it” while it is live. I could easily see this being the approach taken by a ‘bad guy’ to make ‘boom stuff’ on a very slow very patient basis. You can also take a neutron feed out of them via a pipe through the water. Plumbing neutrons, what a concept… but very useful for a lot of medical and research purposes. Everyone needs a neutron faucet in their lab ;-)


Designed with the leadership of Freeman Dyson. What more could you ask for? Training, Research, Isotopes, General Atomics.

TRIGA is a class of small nuclear reactor designed and manufactured by General Atomics. The design team for TRIGA was led by the physicist Freeman Dyson.

TRIGA is the acronym of Training, Research, Isotopes, General Atomics.

TRIGA is a pool-type reactor that can be installed without a containment building, and is designed for use by scientific institutions and universities for purposes such as undergraduate and graduate education, private commercial research, non-destructive testing and isotope production.

The TRIGA reactor uses uranium zirconium hydride (UZrH) fuel, which has a large, prompt negative thermal coefficient of reactivity, meaning that as the temperature of the core increases, the reactivity rapidly decreases. It is thus highly unlikely, though not impossible for a nuclear meltdown to occur.


The TRIGA was developed to be a reactor that, in the words of Frederic de Hoffmann, head of General Atomics, was designed to be “safe even in the hands of a young graduate student.” Edward Teller headed a group of young nuclear physicists in San Diego in the summer of 1956 to design a reactor which could not, by its design, suffer from a meltdown. The design was largely the suggestion of Freeman Dyson. The prototype for the TRIGA nuclear reactor (TRIGA Mark I) was commissioned on 3 May 1958 in San Diego and operated until shut down in 1997. It has been designated as a nuclear historic landmark by the American Nuclear Society.

Even a “Nuclear Historic Landmark”… Didn’t even know there was such a thing… I’ll have to visit it next time I’m down that way…

Looking into a TRIGA as it glows ;-)

Looking into a TRIGA as it glows ;-)

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The water between “you” and the “glow” is all that is needed to stop the radiation.


The SLOWPOKE (acronym for Safe Low-Power Kritical Experiment) is a low-energy, pool-type nuclear research reactor designed by Atomic Energy of Canada Limited (AECL) in the late 1960s. John W. Hilborn (now retired from AECL) is the scientist most closely associated with its design. It is beryllium-reflected with a very low critical mass but provides neutron fluxes higher than available from a small particle accelerator or other radioactive sources.

It is interesting in how it uses beryllium as a neutron reflector to make it work. Much like a bomb, it uses highly enriched uranium. Since it is low temperature, the fuel cladding is aluminum. (That is fairly transparent to neutrons. See: for a list of neutron cross sections). I like the way it is licensed for “unattended”. Talk about “walk away safe”!

The SLOWPOKE-2 uses 93% (originally) enriched uranium in the form of 28% uranium-aluminum alloy with aluminum cladding. The core is an assembly of about 300 fuel pins, only 22 cm diameter and 23 cm high, surrounded by a fixed beryllium annulus and a bottom beryllium slab. Criticality is maintained by adding beryllium plates in a tray on top of the core. The reactor core sits in a pool of regular light-water, 2.5 m diameter by 6 m deep, which provides cooling via natural convection. In addition to passive cooling, the reactor has a high degree of inherent safety; that is, it can regulate itself through passive, natural means, such as the chain reaction slowing down if the water heats up or forms bubbles. These characteristics are so dominant, in fact, that the SLOWPOKE-2 reactor is licensed to operate unattended overnight (but monitored remotely). Most SLOWPOKES are rated at a nominal 20 kW, although operation at higher power for shorter durations is possible.

Then there is the “miniature” knock-off of it:

The Chinese built Miniature Neutron Source reactor (MNSR) is a small and compact research reactor copied from a Canadian SLOWPOKE reactor design.

The MNSR is tank-in-pool type, with highly enriched fuel (~ 90% U235 ). The tank is immersed in a large pool, and the core is, in turn, immersed in the tank. The maximum nominal power is ~ 30 kW, the power being removed by natural convection. The central core is formed of about 347 fuel rods, with 4 tie rods and 3 dummy elements distributed on a total of ten circles, each consisting of a number of fuel rods ranging between 6 and 62. A thick beryllium reflector (~ 10 cm) surrounds the core radially.

China operates two MNSRs and has supplied Ghana, Iran, Pakistan, Nigeria and Syria with reactors of this type as well as the enriched uranium to fuel them. These transfers have raised serious concerns about China’s commitment to nuclear nonproliferation as the Chinese Government has not committed itself to requiring full-scope safeguards in countries receiving its nuclear-related exports and thus might be contributing to nuclear proliferation.

So, 90% enriched nuclear fuel sent to: Ghana, Iran, Pakistan, Nigeria and Syria.

What could possibly go wrong…

Power Reactors

The two most common types of power reactors are the PWR and BWR, near as I can tell. That is: Pressurized Water Reactor and Boiling Water Reactor, both usually types of LWR or Light Water Reactor as opposed to HWR Heavy Water Reactor, though my favorites are HWR types. The first one has a high pressure water loop that is used to heat the working water that boils and spins the turbine. The second one just boils that water directly in the reactor.


I must lead this section with my favorite reactor design. The CANDU. This Canadian design is, IMHO, just stellar. The US designs of the era are compromised by the US Government’s demand for ever more proliferation resistance, even if that meant kludgy designs. The CANDU was made to use natural uranium (so no first step enrichment needed to be in the nuclear business) and have active refueling while on line (so easier and in many ways safer operation as the whole core does not need to be shut down and opened). It is also flexible enough in the use of moderator and absorber plates that the fuel used is highly flexible. From U to MOX (mixed oxide with U and Pu) to Thorium. The rumors that folks used CANDU to make “boom stuff” look to be wrong. Evidence points to them using “research reactors” instead (and it would be easier in many ways to do that, though slower). At any rate, here’s the CANDU:

The CANada Deuterium Uranium reactor is a Canadian-invented, pressurized heavy water reactor. The acronym refers to its deuterium-oxide (heavy water) moderator and its use of (originally, natural) uranium fuel. CANDU reactors were first developed in the late 1950s and 1960s by a partnership between Atomic Energy of Canada Limited (AECL), the Hydro-Electric Power Commission of Ontario (now Ontario Power Generation), Canadian General Electric (now GE Canada), and other companies. All current power reactors in Canada are of the CANDU type. The reactor is also marketed abroad.

CANDU Schematic

CANDU Schematic

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The magenta stuff (2) is the heavy water bucket. Fuel bundles (1) are loaded sideways in the yellow pipes (10 “pressure tubes”) and cooling water, that is heavy water in the original design, but light water in a newer variant, flows over them. Just elegant.

Since heavy water is less efficient at slowing neutrons, CANDU needs a larger moderator to fuel ratio and a larger core for the same power output. Although a calandria-based core is cheaper to build, its size increases cost for standard features like the containment building. The next generation Advanced CANDU Reactor (ACR) mitigates these disadvantages by having light water coolant and using a more compact core with less moderator. Generally nuclear plant construction and operations are ~65% of overall lifetime cost; for CANDU costs are dominated by construction even more. Fueling CANDU is cheaper than other reactors, costing only ~10% of the total, so the overall price per kWh electricity is comparable.

and then there is this interesting variation:

In parallel with the classic CANDU design, experimental variants were being developed. WR-1, located at the AECL’s Whiteshell Laboratories in Pinawa, Manitoba, used vertical pressure tubes and organic oil as the primary coolant. The oil used has a higher boiling point than water, allowing the reactor to operate at higher temperatures and lower pressures than a conventional reactor. WR-1 operated successfully for many years, and promised a significantly higher efficiency than water-cooled versions. Gentilly-1, near Trois-Rivières, Quebec, was also an experimental version of CANDU, using a boiling light-water coolant and vertical pressure tubes, but was not considered successful and closed after seven years of fitful operation.

This is part of why I think there is ‘room to play’ in the moderator selection and an alternative to heavy water could be made.

At any rate, the CANDU served as the model on which India has made many “CANDU derivatives” as it is very flexible about fuel choice, and India is up to their eyeballs in Thorium:

CANDU Fuel Cycles

CANDU Fuel Cycles

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Were I building a nuclear program, I’d start from the CANDU and I’d use a research pool reactor to make the SNM for any “boom stuff” ‘research’, just like India did. Smart cookies those Indians…

For details on the variations of the CANDU, hit the wiki link. For Indian activities, see:

The CANDU is part of a class of Pressurized Heavy Water Reactors PHWR:

Russian VVER

The Russians had a fairly standardized PWR that you find all over the place.

The VVER (From Russian: Водо-водяной энергетический реактор; transliterates as Vodo-Vodyanoi Energetichesky Reactor; Water-Water Energetic Reactor) is a series of pressurised water reactors (PWRs) originally developed by the Soviet Union, and now Russia. Power output ranges from 440 MWe to 1200 MWe with the latest Russian development of the design. VVER power stations are used by Armenia, Bulgaria, China, Czech Republic, Finland, former East Germany, Hungary, India, Iran, Slovakia, Ukraine, and the Russian Federation.

It looks to me like a pretty safe design and has the usual Russian “straight forward and effective” ethos to it.

European Pressurized Reactor EPR

A Gen3 design from Europe (basically France). Looks to me like a mostly modest evolutionary design advance. Bigger. More safety systems. Made to run MOX from the get-go so has excess control rod capacity.

The main design objectives of the generation III EPR design are increased safety while providing enhanced economic competitiveness through improvements to previous PWR designs scaled up to an electrical power output of around 1650 MWe (net) with thermal power 4500 MWt. The reactor can use 5% enriched uranium oxide fuel, optionally with up to 50% mixed uranium plutonium oxide fuel. The EPR is the evolutionary descendant of the Framatome N4 and Siemens Power Generation Division KONVOI reactors.


The AP1000 is a Westinghouse GEN3+ design. It is “passively safe” but only after some action starts the process by blowing some explosive valves… which is an interesting view of “passive” ;-) (Sorry, but I can’t resist… “Honest, I’m a passivist! I only blew them up so I could remain at peace!” ;-) Or maybe “It is designed to be passively safe by exploding.”? I know, explosives are your friend in an emergency ‘cut a hole’ kind of way…)

Power reactors of this general type continue to produce heat from radioactive decay products even after the main reaction is shut down, so it’s necessary to remove this heat to avoid meltdown of the reactor core and possible escape into the containment or, very unlikely, beyond the containment. In this design Westinghouse’s Passive Core Cooling System (PCCS) uses less than twenty explosively operated and DC operated valves which must operate within the first 30 minutes. This is designed to happen even if the reactor operators take no action. The electrical system required for initiating the passive systems doesn’t rely on external or diesel power and the valves don’t rely on hydraulic or compressed air systems.

If the active process to turn on the passive system works the design is intended to passively remove heat for 72 hours, after which the PCS gravity drain water tank must be topped up for as long as cooling is required.

Nice design, even if I never would have thought to include explosives in a reactor…

AP600 Passive Cooling Containment

AP600 Passive Cooling Containment

The AP1000 is a bigger version of the AP600.

There is an odd China Connection. Looks like China has embraced these, but in exchange for “property rights”…

Construction plans

The Chinese units will be the first to be built.

The Sanmen Nuclear Power Plant in Zhejiang will have six units. Site construction for the first two began in February 2008; operation is scheduled for 2013–15.
The Haiyang Nuclear Power Plant in Shandong also has six units planned. Site construction for the first two began in July 2008; operation is scheduled for 2014–15.

The first four AP1000s built are to an earlier revision of the design without a strengthened containment structure to provide improved protection against an air crash.

China has officially adopted the AP1000 as a standard for inland nuclear projects. The National Development and Reform Commission (NDRC) has already approved several nuclear projects, including the Dafan plant in Hubei province, Taohuajiang in Hunan, and Pengze in Jiangxi. The NDRC is studying additional projects in Anhui, Jilin and Gansu provinces. China wants to have 100 units under construction and operating by 2020, according to Aris Candris, Westinghouse’s CEO.

CAP1400 development

In 2008 and 2009 Westinghouse made agreements to work with the State Nuclear Power Technology Corporation (SNPTC) and other institutes to develop a larger design, probably of 1400 MWe capacity, possibly followed by a 1700 MWe design. China will own the intellectual property rights for these larger designs. Exporting the new larger units may be possible with Westinghouse’s cooperation.

In December 2009, a Chinese joint venture was set up to build an initial CAP1400 near the HTR-10 Shidaowan site. Construction is expected to start in 2013, operating in 2017.

Unless they were very careful in their contracts, Westinghouse will have given away the store to China with that intellectual property transfer. If it’s a “maybe someday” you can export, they are toast. If it’s a “you have exclusive on any export” then they’ve got a deal…

So, 100 Nukes in 9 years. Somehow I think that Uranium Mine is looking better every day…

Ship Reactors

There are a bunch of these, and I’m not going to list them all. This is already ‘way too long’ and information is often sketchy anyway. But I just love this one:

Presently mothballed. But you just gotta love a ship whose whole purpose is to be a ‘drive up nuke power station’. And built in a recycled Liberty Ship to boot!

The reactor was built for the US Army by Martin Marietta under a $17,000,000 contract (August 1961), with construction starting in 1963. The reactor was built on the Sturgis, a converted liberty ship formerly known as SS Charles H. Cugle. The original ship propulsion system was removed,and a single-loop pressurized water reactor, in a 350 ton containment vessel, was installed, using low enriched uranium (4% to 7% 235U) as fuel. After testing at Fort Belvoir for five months starting in January 1967, the “Sturgis” was towed to the Panama Canal Zone. The reactor supplied 10 MW (13,000 hp) electricity to the Panama Canal Zone from October 1968 to 1975.
The plant replaced power from a hydroelectric plant, allowing lake water to instead be used to fill locks of the Panama Canal. The plant was retired from service in 1975 since the Army reactor program had been discontinued, and, as a unique prototype, operation cost for the unit was high. It operated at an effective annual capacity factor of 0.56 over nine years.

The barge was towed to the United States in early 1977, suffering some storm damage during the tow. Fuel was removed from the reactor and the plant put into SAFSTOR (safe storage), with decontamination and physical barriers to prevent release of radioactivity. The Sturgis is now moored in the James River outside Fort Eustis, VA and is part of the James River Reserve Fleet.

The Russians want to have one also:

but it isn’t real yet..

Though they have a couple in ice breakers:

The KLT-40 reactor is a nuclear fission reactor used in pairs to power Arktika-class icebreakers and singly to power the Soviet merchant ship Sevmorput and all Taymyr-class icebreakers. It is a pressurized water reactor (PWR), using 90% enriched uranium-235 fuel to produce 135 MW of thermal power and 32MW to 35MW electical power.

The KLT-40S variant is used in the Russian floating nuclear power station.

so their ‘floating power station’ is just an icebreaker without the icebreaker parts…

BWR Types

It looks to me like these pretty much derive from BORAX via GE in the USA and Japan.

The boiling water reactor (BWR) is a type of light water nuclear reactor used for the generation of electrical power. It is the second most common type of electricity-generating nuclear reactor after the pressurized water reactor (PWR), also a type of light water nuclear reactor. The BWR was developed by the Idaho National Laboratory and General Electric in the mid-1950s. The main present manufacturer is GE Hitachi Nuclear Energy, which specializes in the design and construction of this type of reactor.

This is the kind that is presently “having issues” in Japan.

These then sprouted the variants of ABWR and SBWR or Advanced Boiling Water Reactor and Simplified Boling Water Reactor (one wonders if they just want to try all variations of complexity to see what really works well…)

The SBWR was never built and looks mostly like the first ‘thought experiment’ in the passive features that led to the ABWR.

The Simplified Boiling Water Reactor was submitted to the United States Nuclear Regulatory Commission, however, it was withdrawn prior to approval; still, the concept remained intriguing to General Electric’s designers, and served as the basis of future developments.

ABWRs have been built in Japan and Taiwan. The Wiki spends a fair amount of time talking about the ESBWR variation from GE-Hitachi, but isn’t very clear as to what makes an ABWR an ESBWR and vice versa.. though the ESBWR wiki implies it is the use of convection instead of pumps to keep things cool. That would have been useful in Japan… At any rate, there is a very technical discussion of the ESBWR reactor on the ABWR page, and hardly any on the ESBWR page…

The reactor formally known as Economic Simplified Boiling Water Reactor (ESBWR) is a passively safe generation III+ reactor based on the advanced boiling water reactor (ABWR). Both are designs by GE Hitachi Nuclear Energy, and are based on previous BWR designs.

The ESBWR uses natural circulation with no recirculation pumps or their associated piping, thereby greatly increasing design integrity and reducing overall costs.

The passively safe characteristics are mainly based on isolation condensers, which are heat exchangers that take steam from the vessel (isolation condensers, IC) or the containment (passive containment cooling system, PCCS), condense the steam, transfer the heat to a water pool, and introduce the water into the vessel again.

This is also based on the gravity driven cooling system (GDCS), which are pools above the vessel. When very low water level is detected in the reactor, the depressurization system opens several very large valves to reduce vessel pressure and finally to allow these GDCS pools to re-flood the vessel.

All of the safety systems operate without using pumps, thereby further increasing design safety reliability and reducing costs.

The core is made shorter than conventional BWR plants to reduce the pressure drop over the fuel, thereby enabling natural circulation. There are 1132 bundles and the thermal power is 4500 MWth. The nominal summertime output is rated at 1575-1600 MWe, yielding an overall plant efficiency of 35%.

In the case of an accident, the ESBWR can remain stabilized for 72 hours without any operator action. Below the vessel, there is a piping structure which allows for cooling of the core during a very severe accident. These pipes divide the molten core and cool it with water flowing through the piping.


Of course, no discussion of BWR types would be complete without a nod to the “Graphite moderated BWR” that “blew up” in Chernobyl. The RBMK.

RBMK is an initialism for the Russian reaktor bolshoy moshchnosti kanalniy (Russian: Реактор Большой Мощности Канальный) which means “High Power Channel-type Reactor”, and describes a class of graphite-moderated nuclear power reactor which was built in the Soviet Union. The RBMK reactors are a type of boiling water reactors developed by the Soviet Union. The RBMK reactor was the type involved in the Chernobyl disaster. In 2010, there were at least 11 RBMK reactors operating in Russia, but there are no plans to build new RBMK type reactors (the RBMK technology was developed in the 1950s and is now considered obsolete) and there is international pressure to close those that remain.
Using light water for cooling and graphite for moderation, it is possible to use natural uranium for fuel. Thus, a large power reactor (RBMK reactors at the Ignalina Nuclear Power Plant in Lithuania were rated at 1500 MWe each, a very large size for the time and even for today) can be built that requires no separated isotopes, such as enriched uranium or heavy water.

It is a very straight forward design that actually works pretty well, as long as you don’t go to “odd” and “experimental” power regimens to “see what happens”… (They were testing odd edge cases when they found out what happens…)

The basic problem is the “positive void coefficient” that is illegal in US reactors. That, and the control rods had a carbon tip on them that initally raised reactivity prior to then lowering it. A bad idea when you are “on the edge” and want “Less power NOW!!”.

In RBMKs, generation of steam in the coolant water would then in practice create a void, a bubble that does not absorb neutrons; the reduction in moderation by light water is irrelevant, as graphite is still moderating the neutrons, enabling them to be absorbed more easily to continue the reaction. This event would dramatically alter the balance of neutron production, causing a runaway condition in which more and more neutrons are produced, and their density grows exponentially fast. Such a condition is called a positive void coefficient, and it is particularly high for RBMK reactors.

Some Thorium Bits & Pebble Beds & Gas Cooling

In addition to the flexible CANDU, there have been other Thorium reactors over the years. Thorium in reactors is not a new concept, just some folks are talking about it again.

The THTR-300 was a thorium high-temperature nuclear reactor rated at 300 MW electric (THTR-300). The German state of North Rhine Westphalia, in the Federal Republic of Germany, and Hochtemperatur-Kernkraftwerk GmbH (HKG) financed the THTR-300’s construction. Operations started on the plant in Hamm-Uentrop, Germany in 1983, and it was shut down September 1, 1989. The THTR was synchronized to the grid for the first time in 1985 and started full power operation in February 1987. Whereas the AVR was an experimental pebble bed high-temperature reactor (HTR) used to develop the pebble fuel, the THTR-300 served as a prototype HTR to use the TRISO pebble fuel. The THTR-300 cost €2.05 billion and was predicted to cost an additional €425 million until December 2009 in decommissioning and other associated costs

Ah, Germany. Make a stellar machine, hook it to the grid. Then demolish it. … Never mind that the pebble bed HTR design doesn’t have melt downs and is about as safe as a granite rock… Probably because the experimental reactor that preceded it (and had a variety of experimental things done with it, including operators whacking on a stuck ‘pebble’ until they damaged it) had some issues with fuel and Cs-137 contamination inside the pressure vessel.

It was 15MWe, 46 MWt, and was used to develop and test a wide variety of fuels and machinery over its lifetime. Its Helium outlet temperature was 950°C, but fuel temperature instabilities occurred during operation with locally far too high temperatures. As a consequence the whole reactor vessel became heavily contaminated by Cs-137 and Sr-90.

But the design lives on in China:

HTR-10 is a 10 MWt prototype pebble bed reactor at Tsinghua University in China. Construction began in 2000 and it achieved first criticality in January 2003.

In 2005, China announced its intention to scale up HTR-10 for commercial power generation. The first two 250-MWt High Temperature Reactor-Pebblebed Modules (HTR-PM) will be installed at the Shidaowan plant in Shandong Province and together drive a steam turbine generating 200 MWe. Construction is scheduled to begin in 2009 and commissioning in 2013.

HTR-10 is basically a replica of the German Arbeitsgemeinschaft Versuchsreaktor (AVR). Like AVR, HTR-10 and HTR-PM are intended to be fundamentally safer, cheaper and more efficient than other nuclear reactor designs. Outlet temperature ranges between 700 C to 950 C, which allows these reactors to generate hydrogen as a byproduct efficiently, thus supplying inexpensive and non-polluting fuel for fuel cell powered vehicles.

Though it is a bit unclear if they will use a U or Th based fuel in the “pebbles”.

A general introduction to Pebble Bed designs is here:

The pebble bed reactor (PBR) is a graphite-moderated, gas-cooled, nuclear reactor. It is a type of very high temperature reactor (VHTR), one of the six classes of nuclear reactors in the Generation IV initiative. Like other VHTR designs, the PBR uses TRISO fuel particles, which allows for high outlet temperatures and passive safety.

The base of the PBR’s design is the spherical fuel elements called pebbles. These tennis ball-sized pebbles are made of pyrolytic graphite (which acts as the moderator), and they contain thousands of micro fuel particles called TRISO particles. These TRISO fuel particles consist of a fissile material (such as 235U) surrounded by a coated ceramic layer of silicon carbide for structural integrity and fission product containment. In the PBR, thousands of pebbles are amassed to create a reactor core, and are cooled by an inert or semi-inert gas such as helium, nitrogen or carbon dioxide.

Which is all well and good but they ought to pay a bit of homage to the previous HTGR designs that led them to the Pebble Bed:

and the much more successful British designed Advanced Gas Cooled Reactor AGR:

where many are still in service (despite a complex build process that limited acceptance). 14 reactors at 7 sites in the UK per the chart in the link.

These were an improved form of the original Magnox gas cooled design. It uses CO2 as the moderator and coolant, in addition to a base load of moderation from graphite. The name comes from the fuel cladding that is a magnesium aluminum alloy. MAGnesium Non-OXidizing.

Magnox reactors are pressurised, carbon dioxide cooled, graphite moderated reactors using natural uranium (i.e. unenriched) as fuel and magnox alloy as fuel cladding. Boron-steel control rods were used. The design was continuously refined, and very few units are identical. Early reactors have steel pressure vessels, while later units (Oldbury and Wylfa) are of prestressed concrete; some are cylindrical in design, but most are spherical. Working pressure varies from 6.9 to 19.35 bar for the steel pressure vessels, and the two prestressed concrete designs operated at 24.8 and 27 bar. No British construction company at the time was large enough to build all the power stations, so various competing consortia were involved, adding to the differences between the stations; for example nearly every power station used a different design of Magnox fuel element.

On-load refuelling was considered to be an economically essential part of the design for the civilian Magnox power stations, to maximise power station availability by eliminating refuelling downtime. This was particularly important for Magnox as the unenriched fuel had a low burn up, requiring more frequent changes of fuel than enriched uranium reactors. However the complicated refuelling equipment proved to be less reliable than the reactor systems, and perhaps not advantageous overall.

This also let them be used to make weapons grade plutonium, and several reactors were used for both power and Pu production purposes. Many are still in use today. Britain sold one each to Italy and Japan, while North Korea made their own copy (gee, I wonder why…):

The term magnox may also loosely refer to:
=Three North Korean reactors, all based on the declassified blueprints of the Calder Hall Magnox reactors:
– A small 5 MWe experimental reactor at Yongbyon, operated from 1986 to 1994, and restarted in 2003. Plutonium from this reactor’s spent fuel has been used in the North Korea nuclear weapons program.
– A 50 MWe reactor, also at Yongbyon, whose construction commenced in 1985 but was never finished in accord with the 1994 U.S.-North Korea Agreed Framework.
– A 200 MWe reactor at Taechon, construction of which also halted in 1994.

Nine UNGG power reactors built in France, all now shut down. These were carbon dioxide-cooled, graphite reactors with natural uranium metal fuel, very similar in design and purpose to the British Magnox reactors except that the fuel cladding was magnesium-zirconium alloy.

Here is the link for the French UNGG types:

Breeder Reactors & Related Fast Reactors

These make more fuel than they use up, by turning stuff than can be fissioned into stuff that fissions on its own (fissionable into fissile). This lets you use all that U-238 and Thorium all over the place… To some extent, every reactor does some “fuel breeding”, the key bit is that the ratio here is “over unity”. You get out more than you put in, not just making some extra long the way. But it really is a semi-artificial divide, as with design variation you can make most reactor physical types into over unity core types.

The write up in the Wiki is pretty good:

The UK, USA, USSR, Japan, France, India, and Germany all have, or had, breeder reactor programs. You can read about a sodium spill / fire in Japan here:

While this was widely reported as a “nuclear accident” it was in a non-nuclear part of the coolant loop and no radioactive materials were involved.

And the UK breeder reactors here:

along with a nuclear submarine prototype reactor. This link talks about their heavy water reactor:

It was optimised for high neutron flux for testing materials and was sent to several countries including: Germany, Australia, and Denmark.

Here you get the EBR Experimental Breeder Reactor and the IFR Integral Fast Reactor.

both cooled with liquid metal (sodium) though there are other liquid metal cooled types:

using any of mercury, lead, sodium, sodium/potassium alloy, and lead bismuth alloy for cooling. I’ll leave that alphabet soup in the links as there are not a lot of these in the world right now. (Soviet submarines use some of them, though not as breeders… at least, not that I can tell ;-)

Some Soviet designed reactors were “multiple use” like this one that made electricity, steam for a desalinizer, and Plutonium too:

The BN-350 was a sodium-cooled fast reactor nuclear power plant located at Aktau (formerly known as Shevchenko from 1964-1992), Kazakhstan, situated on the shore of the Caspian Sea. Construction of the BN-350 Fast breeder reactor began in 1964, and the plant first produced electricity in 1973. In addition to providing power for the city (150 MWe), BN-350 was also used for producing plutonium and for desalination to supply fresh water (120,000 m³ fresh water/day) to the city.

The project lifetime of the reactor officially finished in 1993, and in June 1994, the reactor was forced to shut down because of a lack of funds to buy fuel. By 1995, the plant’s operating license had expired. The facility continued to operate far below capacity until reactor operations ceased in 1999, when plutonium-bearing spent fuel stopped being produced.

There are several BN-xxx types, so “follow the links” if you want to know more…

A proposed “new and advanced” design is the from the new “Gen 4” proposals.

Related to it are the GCR Gas Cooled Reactor

a proposed helium cooled reactor and the related HTGCR (though not always a breeder)

Then there is the lead cooled fast reactor or LFR whose major “issue” is that lead is so damned heavy…

Yet overall the reactor can be fairly light, so it has been used in some Soviet submarines. (Think “ballast” ;-) See the link for details. Oddly, down in the bottom of the page, it mentions a US reactor that used quartz as a neutron reflector. Didn’t know it was… but that has interesting potentials… The Hyperion Power Module is the proposal using this method. It’s an interesting beast, even if only theoretical at the moment.)

There are all variations on a theme. Fast neutrons. But with different variations on what thing is used for heat transport out of the core (you need things that do not moderate the neutrons much or at all and are neutron transparent, yet still transport heat OK and can be moved about.)

There is a list of “Fast Reactors” at the bottom of this link:

So I’m not going to list them all here.

But one of interest is this little reactor in Japan. It is reputed to run hot enough to produce hydrogen. That would be very useful for making synthetic gasoline and Diesel (as well as the largely hypothetical ‘hydrogen economy’).

The high temperature test reactor (HTTR) is a graphite-moderated gas-cooled research reactor in Oarai, Ibaraki, Japan operated by the Japan Atomic Energy Agency. It uses long hexagonal fuel assemblies, unlike the competing pebble bed reactor designs.

HTTR first reached its full design power of 30 MW (thermal) in 1999. Other tests have shown that the core can reach temperatures sufficient for hydrogen production.

Technical details

The primary coolant is helium gas at a pressure of about 4 MPa, the inlet temperature of 395 °C, and the outlet temperature of 850/950 °C. The fuel is uranium oxide (enriched to an average of about 6%).

There are also the Very High Temperature Reactors that have an outlet temp of up to 1000 C and are the reactor I usually talk about in the context of making nuclear “process heat” for cheap “Coal To Liquids” facilities.

That includes a liquid salt cooled variation as well, the LS-HTGCR

The molten salt cooled variant, the LS-VHTR, similar to the advanced high temperature reactor (AHTR) design, uses a liquid fluoride salt for cooling in a pebble core. It shares many features with a standard VHTR design, but uses molten salt as a coolant instead of helium. The pebble fuel floats in the salt, and thus pebbles are injected into the coolant flow to be carried to the bottom of the pebble bed, and are removed from the top of the bed for recirculation. The LS-VHTR has many attractive features, including: the ability to work at high temperatures (the boiling point of most molten salts being considered are >1,400°C), low pressure operation, high power density, better electric conversion efficiency than a helium-cooled VHTR operating at similar conditions, passive safety systems, and better retention of fission products in case an accident occurred.

Then there is the Extreme case:

The Ultra High Temperature Reactor Experiment (UHTREX) was an experimental gas cooled nuclear reactor experiment starting in 1959 and lasting about 12 years. UHTREX was located at Los Alamos Scientific Laboratory. The reactor first achieved full power in 1969. The purpose of the experiment was to test the advantages of using a simple fuel vs the disadvantages of a contaminated cooling loop. With the over all goal of finding ways to reduce the cost of nuclear power. The UHTREX concept came as a direct spin off from technology developed by the earlier ROVER project.
The UHTREX core was composed of a vertical hollow rotating cylinder (turret) constructed of solid graphite. The cylinder was 70 in. OD x 23 in. ID x 39 in. high. The core had 312 fuel channels. The channels were equally spaced radially around the core at 15 degree intervals arranged in 13 separate layers of 24 channels each. Each channel held up to 4 fuel elements and extended completely through to the inside of the cylinder. The core could be refueled remotely while at full power [4]. Refueling involved rotating the core to the channel containing the element requiring replacement and pushing in a new element. The used element would be pushed out into the center and fall to the base of the reactor to be collected. At full power the reactor used up 1 to 6 fuel elements per day depending on enrichment and porosity of the fuel element. It produced 3MW of thermal energy.
The UHTREX used un-clad porous carbon extruded fuel elements each shaped like a long hollow cylinder. The fuel elements were manufactured by vacuum impregnating the porous carbon cylinders with aqueous uranyl nitrate solution then air drying and baking them in a furnace ultimately producing a uranium oxide coating tightly held in a porous graphite matrix. This fuel was expected to be substantially less expensive to manufacture than other types of fuel at the time. The primary advantages of this type of fuel was that the porosity of the pellet in addition to the high temperatures achievable would allow most of the poisons created by the fission products to migrate out of the fuel. The poisons would then be carried away by the coolant stream for eventual filtering out and removal. This allows a higher percentage of fuel to be burned up before the pellet needed replacement (up to 50%)

A very strange design…

And if you are beginning to get the feeling that there are more reactor types than running reactors, well, there ARE a lot of “proposed and never built” types… so it’s a “race condition” of sorts…

That leads to “what to do with exactly 1.0 ratio?”. This design is sometimes called “Breed and Burn” as it has a traveling wave of activity, with a breeding blanket area, a residual burnup area, and an active burn area. It’s a hypothetical so far:

TWR or Traveling Wave Reactor.

Traveling-wave reactors were first proposed in the 1950s and have been studied intermittently since. The concept of a reactor that could breed its own fuel inside the reactor core was initially proposed and studied in 1958 by Saveli Feinberg, who called it a “breed-and-burn” reactor. Michael Driscoll published further research on the concept in 1979, as did Lev Feoktistov in 1988, Edward Teller/Lowell Wood in 1995, Hugo van Dam in 2000, and Hiroshi Sekimoto in 2001.

No TWR has yet been constructed, but in 2006, Intellectual Ventures launched a subsidiary named TerraPower, LLC to model and commercialize a practical engineering embodiment of such a reactor, which has since come to be called a traveling-wave reactor. TerraPower has developed TWR designs for low- to medium-power (300-MWe) and large power (~1000-MWe) application. Bill Gates featured TerraPower in his 2010 TED talk.

So, with Bill Gates behind it, if it crashes and the core burns will we have a blue radiation glow in the “Blue Screen Of Death”? ;-)

Metal Reactors

As most of these are used on nuclear submarines and related military shipping, it’s a bit hard to get details on them ;-) The ones I’ve read about use metal plates for the reaction and have plate shaped neutron reflectors. By changing the relative locations and / or angles of the plates you can rapidly make a lot more, or less, power. As everything is metal, getting the residual heat out happens pretty fast and they can be “made quiet” quickly.


This one is of particular interest in that it uses U-233 bread from Thorium.

Reactors using straight metal are very small and can often be rapidly shifted from high to low power (so are seen in submarines). They also typically use highly enriched fuel that is subject to relatively easy conversion into “boom stuff” so are typically only seen in the hands of folks who already have nuclear bombs…

KAMINI (Kalpakkam Mini reactor) is a research reactor at Indira Gandhi Center for Atomic Research in Kalpakkam, India. Its first criticality was on October 29, 1996. It produces 30 kW of thermal energy at full power.

KAMINI is light water cooled and moderated, and fueled with uranium-233 metal produced by the irradiation of thorium in other reactors.

KAMINI was the first reactor in the world designed specifically to use uranium-233 fuel. Use of the large thorium reserves to produce nuclear fuel is a key strategy of India’s nuclear energy program.

Look closely at that size. 30 KILO Watts. That’s about what a Toyota Land Cruiser does… It’s easy to get in the habit of seeing “Mega W” everywhere and forget some things can be made very small…

It is of note that a couple of the first nuclear bombs the USA ever made used U-233 (that is about as good as plutonium for making bombs, in terms of neutron cross section) and that India has set off at least one bomb made with U-233 just to find out if they could. (They did a bunch of nuke tests in “one go” as they knew they would be vilified for it, so figured “do ’em all at once then get it over” and tested everything they could think of at once. Even a bomb made with “reactor grade Pu”.. yes, it can be done, despite what you see commonly repeated…)

See “Teapot – MET” here:

MET stands either for “Military Effects Test” or “Military Effects Tower” (according to Frank Shelton). This was a LASL test of a composite U-233/plutonium bomb core (the first test by the U.S. to use U-233) in a Mk 7 HE assembly. The 30 inch diameter spherical implosion system weighed 800 lb.

The primary purpose was to evaluate the destructive effects of nuclear explosions for military purposes. For this reason, the DOD specified that a device must be used that had a yield calibrated to within +/- 10%, and the Buster Easy device design was selected (this test gave 31 kt and used a plutonium/U-235 core). LASL weapon designers however decided to conduct a weapon design experiment with this shot, and unbeknownst to the test effect personnel substituted the untried U-233 core. The predicted yield was 33 kt. The actual 22 kt was 33% below this, seriously compromising the data collected.

Pokharan-II refers to test explosions of five nuclear devices, three on 11 May and two on 13 May 1998, conducted by India at the Pokhran test range. These nuclear tests resulted in a variety of sanctions against India by a number of major states, and were followed by nuclear testing under the codename Chagai-I on May 28th and Chagai-II on May 30, by its neighboring and arch-rival country Pakistan.
Shakti V

A 0.2 kt experimental device that used U-233, an isotope of uranium not found in nature and produced in India’s fast breeder reactors that consume Thorium. This device too was used to collect data.

At 0.2 kt one could classify it as a squib or “fizzle”, but as the purpose was to gather data, it was a success. Mix in some gadolinium as a stray neutron absorber and you are likely “good to go”…


Argentina has a nuclear reactor program. They’ve made a 8 with odd acronyms: NUR (Algeria), RA-6, RA-8, RP-0 (Peru), RP-10 (Peru), ETRR-2 (Egypt), CAREM and OPEL (which is in Australia). For details see:

CAREM is interesting:

The reactor was first developed as a request of the Argentine Navy to power the TR-1700 submarine of German design. In 1984 it was presented publicly for the first time during a IAEA conference in Peru. For political reasons the project was halted but was relaunched by the 2006 Argentine nuclear reactivation plan.

A 25 MWe, light water version of CAREM is currently being built near Bariloche for testing purposes and a second one of 200 MWe is planned to be installed in Formosa Province.

While OPEL is a pool type research reactor:

Open-pool Australian lightwater reactor

OPAL (Open Pool Australian Lightwater reactor) is a 20 megawatt (MW) pool-type nuclear research reactor that was officially opened on the 20th of April 2007 at the Australian Nuclear Science and Technology Organisation (ANSTO) Research Establishment at Lucas Heights, located in South Sydney, Australia.

The main reactor uses are:
Irradiation of target materials to produce radioisotopes for medical and industrial applications
Research in the field of material science using neutron beams and its sophisticated suite of experimental equipment
Analysis of minerals and samples using the neutron activation technique and the delay neutron activation technique
Irradiation of Silicon ingots in order to dope them with phosphorus and produce the basic material used in the manufacturing of semiconductor devices

In Conclusion

There are a lot more acronyms and a lot more reactors. I’d originally thought I’d make an exhaustive list. Then I got exhausted first… So this is a ‘crib note’ only. I may add one or two over time if I run into something particularly interesting, or not.

I think it does an OK job of getting the flavor of variety in the field. Frankly, it looks to me like in the ’60s and ’70s a bunch of Nuclear Engineers were pumped out of our colleges and then they found not much to do after everything came to a screeching halt… so they busied themselves with creating new reactor types as they worked on decommissioning plans or Yet More Government Forms…

At any rate, the basic formula seems to be:

1) Pick a fuel: U (natural), U (low enriched), U (high enriched – actually a spectrum), Pure U-235 or U-233, Pu, Th (breeder required or in mixed fuel bundles), or blends of the above as in MOX.

2) Pick a fuel chemistry: Metal, Oxide, Nitride, Complex (such as the Pebbles and those UZrH and even UF forms)

3) Pick a moderator: Carbon, Heavy Water, Light Water, CO2, None (Fast reactors – metals, helium), other.

4) Pick a reactor layout and specs for same (CANDU, BWR, PWR, GCR, etc.) based on temperatures and radiation levels expected, also based on design goals such as cool temps and neutrons for research vs 1500 MWe power. Fiddle with the details based on what you find interesting. Fiddle some more to assure desired traits like negative power coefficient and / or rapid quench.

5) Pick materials that let you do all those things well, safely, and relatively cheaply.

6) Add safety features.

7) Integrate and adjust.

8) Let your heirs wait for government approval.

At least, that’s the way it looks to me. Part of what I find facinating is just how many ways those basic ‘pick points’ can be mixed and matched and still have a reactor that works. That is even without getting into the really exotic ones like the Actinide Burners. (That link gets an interesting 28 page PDF).

At the end of the day, nuclear power is all around us, from the stars to the sun to the natural reactors that formed in Africa and even down to the day to day nuclear changes from isotope decay in our own bodies. It is, in essence, natural, and perhaps needed to power the geology of Earth and the liquid iron core that lets life survive. That it is also highly lethal if not controlled and limited is an interesting contrast.

The basic problem is not “how to make a reactor?”. That just happens all on it’s own. The basic problem is “how to make one I can control and use safely?” And while I’m pretty sure I know how to make one of those that would work and fit in my yard, using no enrichment at all, I think I’d rather have my garden…

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About E.M.Smith

A technical managerial sort interested in things from Stonehenge to computer science. My present "hot buttons' are the mythology of Climate Change and ancient metrology; but things change...
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37 Responses to Nuclear Reactor Types

  1. George says:

    My favorite BWR is the Westinghouse AP1000. They did away with a huge amount of complexity of BWRs:

    * 50% fewer safety-related valves
    * 80% less safety-related piping
    * 85% less control cable
    * 35% fewer pumps
    * 45% less seismic building volume

  2. Level_Head says:

    I’d guess that a completely separate post would be appropriate for pyroprocessing and other spent-fuel handling and reuse processes.

    The space propulsion also has a “whole ‘nother” area–the Project Orion concept, involving the detonation of a large number of very small nuclear weapons.

    With that, we could stack every rocket ever launched on a giant plate, and lift them all to orbit in one go — fuel and all. The solar system would officially be open for business.

    And if micro-fusion bombs could be put together that did not use dirty fission bombs as starter kits, it might just be possible to launch such a thing from Earth’s surface.

    It would be impressive to see! A nuclear weapon — fusion or fission — going off every second, for the minutes it would take to get to orbit. Probably not good to look directly at.

    ===|==============/ Level Head

  3. paulID says:

    Come on up to Idaho in the summer we have a nuclear historic landmark and the first town in the world powered by atomic energy. :)

  4. E.M.Smith says:


    Just for you, I’ve added a section on the AP100. Complete with a picture.

    Kind of surprising that China is getting property rights to a larger version of it…

    We also get a peak at the political leanings of Arnold Gunderson:

    In April 2010, Arnold Gundersen, a nuclear engineer commissioned by several anti-nuclear groups, released a report which explored a hazard associated with the possible rusting through of the containment structure steel liner.

    So when he rails against nukes we ought to remember who is paying him…

  5. boballab says:


    Remember the famous quote attributed to Stalin: One death is a tragedy, a million a statistic.

    Also it’s amazing that between all the scaremongering and your reactor search you didn’t have this little factoid:

    Idaho Falls, the National Reactor Testing Station and the Idaho National Laboratory, since there is something like 50 different types of reactors there and it at NRTS is where the only nuclear fatalities have happened on American soil. Even Wiki has it listed so I’m mystified how the scaremongers missed it:

    On January 3, 1961, the only fatal nuclear reactor accident in the U.S. occurred at the NRTS. An experimental reactor called SL-1 (Stationary Low-Power Plant Number 1) was destroyed when a control rod was pulled too far out of the reactor, leading to core meltdown and a steam explosion. The reactor vessel jumped up 9 feet 1 inch (2.77 m).[53] The concussion and blast killed all three military enlisted personnel working on the reactor. Due to the extensive radioactive isotope contamination, all three had to be buried in lead coffins. The events are the subject of two books, one published in 2003, Idaho Falls: The untold story of America’s first nuclear accident,[54] and another, Atomic America: How a Deadly Explosion and a Feared Admiral Changed the Course of Nuclear History, published in 2009.[53]

    I learned about this accident when a Prototype Training Unit Windsor Locks. The military members killed were US Army and it was caused by one of the operators going against safety regs and hand pulling a control rod. That individual got pinned to the roof of the containment building like a butterfly in a showcase, by that rod:

    The force of the explosion was so severe that one body had to be removed from the ceiling, where it was pinned by a control rod ejected from the reactor.,_Idaho#Idaho_Falls

    And here is my favorite little piece of Nuclear History S1C:

    The S1C reactor was a prototype naval reactor designed for the United States Navy to provide electricity generation and propulsion on warships. The S1C designation stands for:

    S = Submarine platform
    1 = First generation core designed by the contractor
    C = Combustion Engineering (C-E) was the contracted designer

    This nuclear reactor was built in Windsor, Connecticut as a prototype for the experimental USS Tullibee (SSN-597) submarine, though that boat was in fact powered by a S2C reactor. The propulsion plant was unusual in that the steam turbines powered an electric motor, rather than a set of reduction gears. The USS Tullibee was an early advanced-design, fast-attack submarine constructed by Electric Boat and commissioned in 1960.

    Throughout the Cold War, the S1C Prototype nuclear submarine propulsion plant at the Windsor Site supported the submarines and surface ships of the Navy’s nuclear fleet by testing new equipment and training Naval propulsion plant operators. S1C was the prototype for the USS Tullibee. The S1C Prototype was operated at the Windsor Site from 1959 until 1993. During that time, over 14,000 Naval operators were trained there, including Admiral Kirkland H. Donald early in his career.

  6. George says:

    Valves operated by pyrotechnics are very well tested in the space program and have proved very reliable. They are often used by satellites and space probes. It would seem that they require no operator intervention in order to operate.

    A more detailed brochure than the web site is here:

    Click to access AP1000_brochure.pdf

    Westinghouse Electric, by the way, is owned by Toshiba.

  7. George says:

    The SL-1 casualties were actually injuries from the explosion. Radiation exposure was minimal outside the site.

    We have had boiler explosions (which is basically what this was) kill far more people than the SL-1 did.

    Hey, remember that entire ship load of ammonium nitrate blew up in Texas City? 581 people killed. That’s more than Chernobyl.

    Actually, boiler explosions on riverboats on the Mississippi were a major problem. Sometimes dozens of people would be killed by them.

  8. E.M.Smith says:

    Uh, George, you are “way low” on riverboats…

    The SS Sultana was a Mississippi River steamboat paddlewheeler destroyed in an explosion on April 27, 1865. This resulted in the greatest maritime disaster in United States history. An estimated 1,800 of the 2,400 passengers were killed when three of the ship’s four boilers exploded and the Sultana sank near Memphis. This disaster received somewhat diminished attention, as it took place soon after the assassination of President Abraham Lincoln and during the closing weeks of the Civil War.

    So, um, I think you meant to say “sometimes a thousand”…

    And the SL-1 was still a nuclear accident, even if it was “nuclear powered steam” ;-)

    I’d love to use the Westinghouse / Toshiba brochure, but the Wiki is not a copyright problem, so folks will have to hit the link for the “good stuff”.

    Yeah, explosive bolts and pyrotecnic valves are ‘well proven’ in aerospace. The comment was more about my limited “vision” than a comment on the technology. I didn’t realize that I lived inside that part of the box until I saw someone standing on the otherside and looking happy ;-)


    I had to “cut” somewhere or I’d have spent days on it and it would be too long to read… so I decided not to explore the USN program and “related”. From the story you posted, looks like that was “a cut too soon”…

  9. George says:

    I suppose what I meant to point out is that the injuries were due to a steam explosion and those have killed (apparently) thousands of people with all sorts of different fuel sources.

    We have not ever seen in this country a commercial nuclear reactor event that would cause any significant area to be uninhabitable. And due to the designs of these plants, we aren’t likely to, either. This would be less of a concern if we would build more modern plants and retire the old ones.

    The SL-1 event is a good study because that was in a building that was not even in a containment building. It was in a regular old ordinary building. Even then, no significant amount of radiation left the premises. In that case, because many of the control rods had not been “buttoned up” and were ejected by the explosion, it probably improved the situation because it allowed all the water to be ejected from the reactor. There can not be a critical reaction without water. Without water to slow the neutrons, you will not get fission and all of the water was either ejected immediately or quickly boiled off and was not contained in the reactor vessel.

    It actually isn’t all that hard to make a facility that can contain an accident. It is probably easier to build that than it is to build a pesticide plant. Heck, I have seen more evacuations from around oil refineries and railroad accidents than I have from nuclear events.

  10. boballab says:


    But, but these are NUCLEAR deaths, those others were ordinary deaths so don’t count.

    What is amazing is that the Wiki article actually states it was the explosion that killed the 3:

    All three men succumbed to injuries from physical trauma (not the radiation).[7]

    And for everyone else there is an old government documentary that was for internal use back in the 60’s that can now be seen on Youtube:

  11. George says:

    Yes, it is a known fact that if you die with even a speck of radiation on you, then you are 8.32 times deader than you would have otherwise been.

  12. No mention about the DIRECT CONVERSION of radioactivity into ELECTRICITY. In the 1950’s the french magazine “Science et Vie” published the blue prints of a reactor which obtained electricity directly from radiation. As I remember it resembled a radio vacuum tube, round shaped, with a depolarizing grid.
    BTW, the following principle, found accidentaly by me, back in 1963 could be applied for improving some processes:

  13. John Silver says:

    Why are the reactors always built above ground?

  14. George says:

    They aren’t. But most commercial reactors are. They are build above ground for maintenance reasons. Also, you don’t want to contaminate ground water.

    But I see no gain from building one under ground. You still need vents, access to cooling water, etc. Building it underground would increase assembly costs for little/no real gain.

    Also, it is much easier to seismically isolate a building that is above ground than one that is below ground. It was pretty expensive to isolate those missile silos. But hey, those silos would make great reactor containment for molten salt or metal reactors where you don’t need lots of cooling water.

  15. GregO says:


    Haven’t had time to read and digest everything here (doggone day gig!) but wanted to take a quick second and say Thanks for all you work here. Great post!

  16. E.M.Smith says:

    @John Silver:

    Becuase it’s a lot of work to dig a big hole. Then you get to try keeping ground water out of the basement…

    Easier, cleaner, safer, and more manageable to put it above ground. I’d put the “spent pool fuel” below grade, though, so you could just dump water on the surface and have it run in, in an accidental loss of cooling water case…


    Thanks! Nice to know someone likes it!

    This one was a ‘bit of a bear’ as the more I looked, the more I found more… Even as it is, I’ve left out dozens of interesting bits (that you can get to from links and / or short searches).

    It really is like every single reactor is a custom job…

    There are themes, though. Russians started with “graphite and water” while GE started with “boiling water and fuel enrichment” while it looks like others took the Pressurized water and enrichment route. Then England has this CO2 moderator / coolent with graphite approach. Kind of like that one… and Canada is just unique.

    After that, things kind of diffuse into the variations we see now.

    I dodged the “metal reactors” mostly as they are largely military and I decided to do a ‘cut off’ at military stuff for a variety of reasons (one being not a lot is public and what is may be suspect…) but gave a sketch of them.

    There is also a whole lot of “historical” reactors left out.

    Frankly, I think you could do an entire book on “reactors of the world”…

    Hmmm… he does a “Bing! Search”:

    Now seems like a good week to revisit this set of 105 reactor wall charts, uploaded by the University of New Mexico. The dates next to each chart relate to the issue of Nuclear Engineering International magazine in which they first appeared. Ronald Knief, a nuclear engineer from Sandia National Laboratories, assembled the image collection.

    then has a link to more:

    which leads to the link for downloading the PDFs at:

    with thumbnails and download clickers…

    (I can hear hard drives filling up now all over the place ;-)

    Wall Charts of reactors of the world… who knew?…

  17. George says:

    One form of reactor that I am not the least bit fond of is the “pebble bed” reactor.

    Imagine a graphite pool ball impregnated with little flecks of nuclear fuel and covered with a silicon carbide shell. They are designed so that it is impossible to melt down because they just can’t possibly get hot enough because the geometry. You can only pack so much fuel into so much space.

    The problem is the nuclear waste. The spent fuel from those “pebbles” is impossible to recover so they must be thrown away whole. It is a great waste of fuel as only about 5% of the potential energy can be extracted from these fuel elements. They are “use once, throw away” fuel elements.

  18. Ken McMurtrie says:

    Magnificent effort EM!

  19. E.M.Smith says:

    @Ken McMurtrie:

    Glad you like it 8-)


    I thought there was some way to recover the fuel? (Though I can’t think of how I’d approach graphite and silicon carbide without a fire… and thats “not a good thing”… )

    If it really is “one and done” and no alternative, that’s pretty crappy…

    Hmmm… a BING! search landed me on this interesting page about an “advanced Pebble” reactor floating the pebbles in molten salt…

    His testbed lab units use analogue fluids, including water and oils, and synthetic pebbles made from a nylon-like material. The model core of the reactor stood about 2 metres tall, and I asked what the power output of a full-sized 4 m tall (2 m wide) reactor core unit would be. Try 400+ MWe. Wow…

    I have to think there would be some increadible stresses at that power density…

    In the early days of VHTR technology, a crush-burn-leach process was proposed to reprocess VHTR fuel. This process produced large quantities of carbon dioxide that needed to be trapped. A new head-end process consistent with the UREX+ separation technologies has been identified and demonstrated at the proof-of-principle level for TRISO fuel in the past few years. The process flow consists of separation of the compacts from the graphite block, disposal of the graphite block as lowlevel waste, grinding and jet-milling of the compact components (matrix, coatings, fuel kernels) into a fine powder to support chemical separation, and leaching, to dissolve the TRU for aqueous separation or a novel electrochemical process termed METROX for the pyroprocessing separation. The project will develop a full flowsheet for TRISO recycling using both aqueous and non-aqueous reprocessing, particularly as it pertains to spent DB-TRISO fuel. The process of crushing the ceramic coatings and exposing the spent-fuel kernels to dissolving agents will be brought up to today’s standards of low secondary waste streams and process losses. The project will study the crush-leach flowsheet to minimize waste, establish and test a laboratory filtering system, and study the suitability of the fuel solution for liquid separation. Lab-scale tests of the equipment for separation of the solid coating and compact material from the fuel solutions will be performed.

    So looks like someone is working out a theoretical / lab prototype way to do recycle…

  20. Level_Head says:


    Also it’s amazing that between all the scaremongering and your reactor search you didn’t have this little factoid:

    The SL-1 accident was indeed referenced and linked in one of these nuclear threads. I read the after-action and cleanup reports with interest.

    Most intriguing to me was the immediate handling. The building had apparently completely contanied the blast, though the inside was highly radioactive (with about 10% of the fuel spattered around). So they opened the building, so that they could get a crane in to fetch out that last body and look around with remote cameras.

    They don’t say this, but I expect that almost all of the outside radiation was from that opening.

    By the way, as you note, these were the first nuclear reactor fatalities in the US, though they did not die directly from radiation. (The sudden “excursion” of the reactor was impressive!) But a few of the people working on the first bomb development died from radiation poisoning during the process.

    And there was the whole “Radium Girl” story that predated the nuclear industry by decades, and permanently changed employment law.

    ===|==============/ Level Head

  21. George says:

    They did not die from radiation, they died from what was, in effect, a boiler explosion. If you have a boiler explosion from excessive steam from a nuclear heat source, it is apparently a world crises, particularly if it kills three people. But a boiler explosion from a coal source that kills thousands is apparently no big deal.

    The difference is ignorance. Ignorance breeds fear. We know and have empirical evidence that supports the notion that you can spew fission products into the open air and it doesn’t kill people though it isn’t a good idea.

    Our irresponsible news media has people literally terrified of Fukushima for absolutely no reason. We have people running around spewing nonsense such as “there is no such thing as a *safe* level of radiation” when the radiation levels they are talking about is less than the amount that already naturally exists inside their own body … by several orders of magnitude!

    You have people frightened of a 1/1000 of a banana dose now because of irresponsible reporting and agenda-based reporting.

    Let me give a clue here:

    If we were to go on a massive nuclear electric program and eliminate all of our coal power plants, our environment would be LESS radioactive than it is now. The air would also have less heavy metals and sulfur dioxide. We could recycle the fuel on site and eliminate the spent fuel disposal problem with currently existing technology. There is no need to subsidize the development of any new technology, we can put it into practice today if we chose to.

    But there is a problem with it. If you make so much electricity that it becomes cheap again, and eliminate any shortage of energy and remove any need for “conservation” and can go back to incandescent bulbs and electric heat, the bureaucracy loses a major control lever over the masses. When they lose a control lever, they lose the ability to curry favor by allocating resources. So the idea is to create a scarcity of energy and then curry favor (or exact punishment) through the allocation of resources or the lack thereof.

    We have right now the means to make electricity ridiculously inexpensive to the point where utilities would be BEGGING you to use more of it. So they must create these artificial barriers in order to maintain control. One key is to make sure people fear nuclear power, don’t want fossil power, and then waste what money we do have on “rainbow power”.

    How many windmills does it take to power a steel mill 24×7? The answer is “it can’t be done”.

  22. Level_Head says:

    In a sense, it’s rather country-specific as well. as industry-specific.

    In the US, the year that we lost those miners near Buckhannon, WV, the US had a total of less than 30 fatalities in coal mining accidents. China later admitted some 6,600 fatalities in coal mining during the same year — with estimates ranging much higher. This figure was reported in US News and World Report as an aside (bragging about how much China’s safety record had improved from earlier, even grimmer statistics) to how wonderful China’s new military-controlled research initiatives were.

    The China numbers were ignored by US media in favor of how horrible the US coal mining practices are and that they must be stopped.

    How long would James Hansen last protesting the coal mining in China? It would serve him right to try, perhaps.

    ===|==============/ Level Head

  23. boballab says:

    If you really want to read up on bad handling of ionizing radiation look up the term Shoe fitting Fluoroscope:

    Shoe-fitting fluoroscopes, also Pedoscopes, were X-ray fluoroscope machines installed in shoe stores from the 1920s until about the 1960s in the United States (by which time they were prohibited), and into the mid-1970s in the United Kingdom.[1] In the UK, they were known as Pedoscopes, after the company based in St. Albans that manufactured them.[2] Fluoroscopes were also used in shoe stores in continental Europe.

    A fluoroscope was a metal construction approximately 4 feet (1.2 m) high in the shape of an upside-down tea cup, with steps for a child to ascend. The child would then place his or her feet in the opening provided and while remaining in a standing position, look through a viewing porthole at the top of the fluoroscope down at the x-ray view of the feet and shoes. Two other viewing portholes on either side enabled the parent and a sales assistant to observe the child’s toes being wiggled to show how much room for the toes there was inside the shoe. The bones of the feet were clearly visible, as was the outline of the shoe, including the stitching around the edges. The exposure time would have been around 15 seconds.

    Or read this paper from 1950:

    It will be noted that there was a range from 12 to 107 r per minute, with an average of 38.4 r per minute. Although no tests were made with a customer’s foot in the apparatus, these values give a conservative approximation of the range of radiation to which skin and tissue may be subjected. It is of interest here to point out that several shoe salesmen volunteered the information that they frequently placed their hands within the fitting opening to demonstrate to parents and customers the nature of the fit or to place the foot in a more favorable position for viewing while another salesman operated the machine. It would be interesting to determine the actual exposure per customer and the amount of time during which shoe salesmen are subjected to stray radiation during the course of the day. In this study no such measurements were possible except for casual observations which indicated that there was little inclination to be satisfied with a single timed exposure. Some of the machines were set for five seconds and others for 20 to 30 seconds, but these times were frequently found to be insufficient for customer satisfaction. The possibilities for multiple exposure to the direct beam are obvious when one considers the frequency with which some patrons may go from store to store, at each of which there may be several fittings.

    Click to access califmed00247-0028.pdf

    Yep for over 40 years in the US and the UK we placed our feet into an unshielded X-ray beam just to fit shoes without fear, but we are so afraid of the same radiation when it is inside a steel alloy container which itself sits inside a concrete building that could withstand a direct hit from most bombs and rockets.

  24. E.M.Smith says:


    I remember one of those shoe machines. I was about 4? and wanted to see my feet. Dad said “no” as he didn’t trust them (and I think didn’t want to part with money at that store that was more expensive than the usual place…) Guess is Amish Mom’s distrust of technology paid off for me in some small way ;-)

    But what it illustrates is the same thing I always see:

    Folks who don’t “do the math” and “measure the meaning” have no clue what they are doing. In either direction. Both too accepting of real risks and too paranoid about non-risks.

    It really is “a numbers game” and if you don’t “count the cards” you will lose. One way or the other…

    Oh, I probably ought to have given some “honorable mention” to that kid who was making his own “neutron source” (a very small low power kind of reactor) via collecting Americium from smoke detectors. Clever kid…

    I’ve sporadically done “thought experiments” on making a reactor. I’m presently resisting the urge to do some “lab scale tests” using natural Uranium and some “interesting” moderators… but I’m pretty sure it would work… Maybe a bit of Americium instead… just for a ‘little test’ ;-)

    (One of the things I found facinating was that in the “pool type” research reactors they would “plumb” a neutron flow out to where they could play with it. Just “make a hole in the water” with a bit of pipe and the neutrons just flow along… Means all sorts of interesting things could be easily done, not the least of which is to put some U in the way for short periods of time and chemically extract bomb grade Pu – which is how Pakistan is speculated to have done it, IIRC… Anyway, the notion of “hot and cold running neutrons” just won’t leave me alone ;-)

  25. George says:

    The kid that played with that stuff was arrested for endangering his neighbors. Of course I am not really sure how much danger they were really in but I am sure the authorities plenty scared them.

    A neutron walks into a bar and orders a beer. The bartender sets the beer down and says, “For you, no charge!”

  26. Gary P Smith says:


  27. P.G. Sharrow says:

    Chiefio; if you really have to try it. Come up here. We have knowlagable people and 20 acres in the woods. Safety is very important for yourself and for others. pg

  28. Level_Head says:

    I see that Mr. Smith has entered just a single punctuation mark. I wondered about it at first, but finally realized:

    It’s done periodically. ;)

    I think it would be a nice feature to be on the comment list without having to do this; I don’t see a quick way at this point.

    On topic, sort of, or at least related to the shoe X-rays:

    Within the last several years, there’s been a surge in companies offering scans for profit — they’ll save your life, the ads say, and they encourage you to be scanned early and often. I wonder how much of a health issue the scans themselves are.

    The Mayo Clinic discusses them, including risks, here:

    The upshot:

    CT scans may slightly increase your risk for developing cancer, but this small risk is vastly outweighed by the crucial usefulness of the information obtained by CT scans.

    CT scans, like other X-ray imaging exams, involve a brief, targeted exposure to a small amount of ionizing radiation — which is used to create an image of your internal structures. Although CT scans expose you to more radiation than traditional X-ray exams do, they also provide much more detailed images, which allows your doctor to detect and precisely locate a vast array of medical conditions.

    Still, it’s a bad idea to request a CT scan unless you have symptoms that require one. No matter how small the risk, any exposure to radiation without a definite medical purpose just isn’t appropriate.

    This advises against the “gee, you should have one just because” approach in the advertisements, but without any sort of specifics to make an intelligent decision.

    ===|==============/ Level Head

  29. P.G. Sharrow says:

    Yes CT scanners are the newest GEE whiz medical toy and a great profit center. Everyone just must get a scan now and often!
    Yeah right!
    I’ll pass for now. pg

  30. George says:

    Pop about 600mg of alpha lipoic acid and scan away.

  31. E.M.Smith says:


    “Granny” just had another CT scan. She gets one or two about every 6 months for someting or other. This time she fell. Hit her head. Couple of stitches. But, into the scanner she goes! (Kaiser ownes it, so if it’s not running, why not? thinks the Doctor…) So at about 2 or 4 per year for about 5 years now that’s what dose?…

    Ah, well… it’s only radiation.

    She’s also the one that got a dose of I-131 for Grave’s Disease as they literally “nuked” her thyroid.

    IIRC she’s 86 and still going… Maybe raditation does prolong life ;-)

    (BTW, I’ll groan later…. much later…. I think.)

    One of the “interesting bits” of psychology winning over logic: Dogs have been trained to smell cancer cells. They can find it faster and earlier than a CT scan. Folks have to pay for this service themselves, though, as the mecical establishment can’t bring itself to accept dogs sniffing out cancer.

    (Cancer cells have an unbalanced metabolism so they have a different “nose” about the chemicals they dump…)

    Why have a dog and handler when you can get a Science Grant for a multi million dollar machine.

    @P.G. Sharrow:

    For now, it must remain a “thought experiment” as if I’m right, the world changes in ways I’d rather it not change. So better not to prove it right as such secrets never hold.

  32. George says:

    I was reading that rats can actually smell the difference between heavy water and regular water and if given both in in separate dishes, will avoid the heavy water. So there must be more to those chemical receptors than we are giving them credit for.

  33. David says:

    I found this to be an informative page on safety issues for LFTR technology as well as having excellent comments.

  34. Scarlet Pumpernickel says:
  35. George says:

    Actually, that is a pretty ridiculous number, too. I read one study where they attributed every single cancer death in the study region to Chernobyl. In truth today rates of cancer are in statistically changed from what they were before the incident.

    There was a significant increase in thyroid cancers, particularly in children who were under 5 years old when exposed. The increase in thyroid cancers seems to be for the most part limited to that group.

    As for leukemia, there is currently no significant change today from the rates before the incident:

    Childhood leukemia incidence has not changed in the decade since the accident. There is no significant change in the level of leukemia and related diseases in the contaminated (more than 555 kBq/m2) and noncontaminated territories of the three states (WH95). Other attempts through epidemiological studies have failed to establish a link between radiation exposure from the Chernobyl accident and the incidence of leukemia and other abnormalities. No epidemiological evidence of an increase in childhood leukemia around Chernobyl (Iv93, Iv 97), in Sweden (Hj94, To96), Germany (Mi97) or the rest of Europe (Pa92, Wi94) has been established. However, if the last OECD/NEA report recommended to be prudent, to withold final judgement, 6years later, no increased risk of leukemia related to ionising radiation has as yet been found among recovery operation workers. The probability of observing a significant increase of leukemias decreases with time, and the next five years will be conclusive.


    And this is also important to note:

    It can be stated that:

    Thirty-one people died in the course of the accident or soon after and another 134 were treated for the acute radiation syndrome. Forty-one of these patients received whole-body doses from external irradiation of less than 2.1 Gy, 2& between 6.5 and 16 Gy.
    Extensive accident-related health effects are apparent in the affected regions of the former Soviet Union, manifested as anxiety and stress, as well as diverse health effects not directly related to radiation exposure. Severe forms induce a feeling of apathy and despair often leading to withdrawal. In the rest of the world these individual effects were minimal.
    In the last decade, there has been a real and significant increase in childhood and, to a certain extent, adult carcinoma of the thyroid in contaminated regions of the former Soviet Union (Wi940) which should be attributed to the Chernobyl accident until proven otherwise.
    * In children, the thyroid cancers are:

    – largely papillary and particularly aggressive in nature often self presenting with local invasion and/or distant metastases;

    – more prevalent in children aged 0 to 5 years at the time of the accident, and in areas assessed to be the more heavily contaminated with 131I;

    – apparently characterised by a shorter latent period than expected; and

    – still increasing for children younger than 5 years in 1986.

    Iodine deficiency and screening, have almost certainly had an influence on observed risk factors can be said that the increase of thyroid cancers in children is clearly established to be linked to exposure of radioactive iodine isotopes releases. The number of these cancers is still increasing in adults. Conversely, no increase in leukaemia has been observed to date.

    No increase of congenital abnormalities, adverse pregnancy outcomes or any other radiation induced disease in the general population, either in the contaminated regions or in Western Europe, could be attributed to this exposure sixteen years after the accident. It is unlikely that surveillance of the general population will reveal any significant increase in the incidence of cancer but continued follow-up is necessary to allow planning of public health actions and to gain a better understanding of influencing factors.

    The present knowledge of the effects of protracted exposure to ionising radiations is limited, since the dose-assessments rely heavily on high-dose exposure. An increase in cancer rates was already observed before the Chernobyl accident in the affected areas and, moreover, a general increase in mortality has been reported in recent years in most areas of the former USSR.

    Among recovery operation workers, no increase of leukaemia has been identified more than sixteen years after the accident.

    So basically what they are saying is that cancer rates are higher for people who were under 5 years of age. Cancer rates were already increasing, though, before the incident and a couple of reasons were iodine deficiency in the population and increased screening was discovering more of them.

    In fact, I read a Canadian report that also attributed increased rates to increased screening, finding more cancers earlier.

    There is no significant change in leukemia or in other defects.

    A person who is already iodine deficient would be expected to readily take up radioactive iodine in the environment.

    The notion that chernobyl killed “millions” though is pure bull.

  36. George says:

    “In truth today rates of cancer are in statistically changed from what they were before the incident.”

    Meant to say:

    “In truth, rates of cancer today are statistically unchanged from what they were before the incident” but I will make the exception of thyroid cancer for individuals under 5 at the time of the incident the exception to that statement.

  37. conscious patrick says:

    please fellow engineers, i want updates and maintenance schedule for nuclear reactor,can somebody help me?.

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