Talk:Fast breeder reactor

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Contents 1 Move article 2 Transmutation and politics 3 Sodium, radiation and water 4 Other articles 5 Removed text 6 BWR risk and article name 7 Diagram 8 PFR 9 SuperPhenix Shutdown 10 How much fuel does a breeder produce? 11 Proliferation risks 12 LMFBR schematic

EGAD!! why no mention of the thorium cycle? there's no mention of it anywhere else on wikipedia ... nor could i find info on other nuclear cycles for that matter... Discussion of it would provide good insight as to how the reactor actually produces more nuclear fuel than it uses. Thanks in advance to whoever might write something on it!

I'm unsure of the date of this, but currently or now there is mention of teh Thorium cycle and breeding as a major object of the Indian nuclear programme. --Midgley 23:11, 21 January 2006 (UTC)

Shouldn't this be redirected to Fast Breeder Reactor? Rmhermen 01:33, Aug 21, 2003 (UTC)

It is a bit confusing saying that fast reactors use enriched fuel and then saying they've become obselete because enriched uranium is so widely available. I assume the enriched fuel is plutonium but it is not clearly spelt out.

Hmmm. I hope this issue has now been addressed in the new introduction. Andrewa 07:50, 28 Oct 2004 (UTC)

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This article compares fast breeder reactors (FBR) reactors to another type of reactor, PWR. But it doesn't say when PWR stands for, nor does it link to an explanatory article.

Fixed. Andrewa 07:50, 28 Oct 2004 (UTC)

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Removed text:Ā

One problem with FBRs for producing weapons is that they produce significant quantities certain heavy plutonium isotopes (especially 240Pu) which are useless in weapons, and which in fact may cause a premature, low-yield detonation, or even a failed detonation. These isotopes fission either easily, or spontaneously, and would "pre-ignite" a bomb before it was fully assembled, causing at most a puddle of molten, no-longer-critical metal, rather than a nuclear explosion.

That's got some true statements but it's generally barking up the wrong tree completely. Pu-240 contamination is certainly the main problem with using reprocessed reactor fuel for bombs, as described. But exactly the same problem occurs with PWR fuel. The main proliferation risk with FBR technology is that while the plute in the fuel is pretty useless for bombs, the stuff in the breeder blanket is pretty good, and if you have facilities to change the breeder blanket while on power it can be made as high-grade as you like without interupting the power generation activities. Andrewa 07:50, 28 Oct 2004 (UTC)

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Why was the Economics section removed? I thought it was balanced and informative, and asks an important question: why aren't these breeders a bigger part of the nuclear economy any more, especially since they would appear to solve many of the worst problems of high level waste disposal? --Mike Van Emmerik 21:56, 10 September 2005 (UTC)

It was just a vandal. Feel free to revert when you see interesting material deleted. --noösfractal 22:15, 10 September 2005 (UTC)

[edit] Move article

The article should be at Fast breeder reactor. Or it should be a section within Fast neutron reactor. Laurel Bush 14:57, 19 September 2005 (UTC).

The title should be 'Fast reactor'; it's a type of reactor that uses fast neutrons with highly-enriched fissile fuel. A 'Fast breeder reactor' is a modification, where the reactor is surrounded by fertile U-238 to create more plutonium fuel, the very fuel being burned in the fast reactor core. The article does not make this distinction clear. 82.40.252.131 14:43, 8 November 2006 (UTC)

[edit] Transmutation and politics

Removed from the end of "Associated reactor types": "The energy department later condemned the waste producing effects of these fuel reprocessing units, and accordingly shut down all Uranium plants that were deemed harmful to the environment." which was part of a vandalism by 24.97.156.194. At least, I assume it was part of the vandalism; it just reads silly to me. Surely breeder reactors consume long lived waste from ordinary reactors, and produce short lived waste, so even a politician couldn't use this reason to shut down breeders and not ordinary reactors. --Mike Van Emmerik 22:21, 18 October 2005 (UTC)

If they can assert (as some do) that nukes produce greenhouse gas, then they can assert anything. If they can shut down Barsebäck nuclear power plant on promises of not increasing greenhouse gas, then they can do anything. A diplomat's words must have no relationship to action, otherwise what sort of diplomacy is it? - Joseph Stalin. Politics, I'm afraid, has similar problems with the truth. Andrewa 17:20, 29 December 2005 (UTC)

[edit] Sodium, radiation and water

I took out this:-

", therefore 2 sodium loops are required to prevent the contamination of the turbine water with the sodium 24"

Na*24 AFAIK doesn't spit neutrons, [1] agrees (beta decay) so it will not poison a secondary water cooling loop - I think there are also other convincing reasons to not mix Na and water!

My reference was here [2] I amn't too hot on nuclear physics so am willing to accept what you say, however there is still a Na / Water heat exchanger so this doesnt account for having a second loop. I was interested in finding out why there was the double loop, and if it isnt to do with Na 24, It would be nice to include why it is as otherwise it looks like complexity for the sake of it.

Sodium + water = bad. Radioactive sodium + water = worse.

"Sodium reacts chemically with air, and especially with water, which is a safety drawback. To improve safety, a secondary sodium system acts as a buffer between the radioactive sodium in the primary system and the steam or water that is contained in the conventional Rankine-cycle power plant. If a sodium-water reaction occurs, it does not involve a radioactive release."

THE SODIUM-COOLED FAST REACTOR (SFR)

—wwoods 17:39, 17 December 2005 (UTC)

that makes excellent sense. Is the primary loop entirely within the reactor containment, whereas the secondary loop can take heat far enough away to be convenient? That would make another reason. Midgley 21:30, 17 December 2005 (UTC)

Apologies for my physics gaffes, maybe someone could condense the above coherently into the page? Any comments about the DFR schematic let me know Emoscopes 05:13, 18 December 2005 (UTC) Another question that perhaps deserves an explenation in the article, why is it that the coolant flows into the top of a FBR and out at the bottom?

Please Wikipedia: sign your posts on talk pages.

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Some very perceptive comments above! At least part of the motivation (perhaps most of it) for the secondary sodium loop is the need to contain the entire primary coolant within a biological shield. Thus, Dounreay Fast Reactor had a separate neutron shield, inside its biological shield. A sodium leak or fire (probably one implies the other) is going to be embarrassing and difficult whether the sodium contains the short-lived sodium radioisotope or not.

One of the things the Brits did at Dounreay was to do live testing of the results of a pressure tube failure in a sodium-water heat exchanger; The French licensed (and paid for) the technology the Brits developed, and used it at Phénix and Superphénix. Andrewa 20:36, 3 February 2006 (UTC)

[edit] Other articles

See Talk:Fast neutron reactor#Other articles. Andrewa 18:30, 29 December 2005 (UTC)

[edit] Removed text

After some soul-searching, I've removed the following section:

Carbon

A Plutonium cycle might reduce the Carbon emissions associated with preparation of fuel - Uranium refinement and enrichment from the lower grade ores which would be used in coming years requires considerable energy and diminishes the advantage fission power has over burning hydrocarbons in limiting greenhouse gas emission and consequent global warming.

Some of this is speculation, but it's entirely based on the false premise that nuclear power contributes to carbon emissions. It doesn't. Even before the development of the gas centrifuge, when significant power was required to drive gaseous diffusion enrichment plants, France managed to fuel all her power reactors, her nuclear submarines, run a weapons program, and export enriched uranium as well, all with a gaseous diffusion plant supplied by a four-unit PWR station. (And in fact the power requirements for the enrichment plant never reached two units, the rest was fed to the grid.)

Claiming that nuclear power requires burning of fossil fuel is an ingenious and sometimes successful political tactic, but it has no basis in fact. In some other parts of the world (notably the USA) enrichment plants are still powered by fossil fuel, but if these plants were to close the nuclear power industry would do very well without them. Andrewa 02:20, 30 December 2005 (UTC)

More removed text, from the section on Superphenix:

the liquid sodium cooling system proved largely unwieldy. Superphénix was also the focus point of various groups hostile to nuclear energy.

Come now! If the liquid sodium cooling system had really proved largely unwieldy, would the generation IV reactors, the BN-800 under construction, Monju, etc really be persisting with it? Certainly, it was 'bleeding edge' technology, and showed it. But it was remarkably successful.

As for being the focus point..., we should perhaps add like any other nuclear reactor. That's not really saying anything encyclopedic about Superphenix. Andrewa 01:51, 5 February 2006 (UTC)

[edit] BWR risk and article name

"It is generally agreed that—if designed incorrectly—the FBR poses a greater risk of proliferation of nuclear weapons than the PWR." What about boiling water reactors? Perhaps it should be changed to light water moderated reactors ("light" because the article says heavy water reactors may be able to be breeders).

Also, breeder reactor redirects here, but fast breeders are only one type of breeder reactor. Should a new article be started at breeder reactor, or should this article be modified and the article named changed (back) to "breeder reactor"? -- Kjkolb 07:04, 19 January 2006 (UTC)

Eeek! I've removed the if designed incorrectly. My guess is that it was added by someone who is pro nuclear power, as am I, but I can't imagine any justification for such a POV qualification. The FBR does have extra proliferation risk, owing to the fact that the probability of using a PWR (or BWR, you're quite right, it's just that PWRs are a bit more common) to provide bomb plute is near-zero (and the much-quoted non weapons grade test used plute from a magnox, not a PWR).

There's still some serious work required. POVs from both sides evident, and the result comes across to me as just plain confused. Andrewa 15:56, 3 February 2006 (UTC)

Move done.

I think the idea of a separate article at breeder reactor is an excellent one, as many people are probably unaware of the Indian direction and assume that all breeder reactors are FBRs, as this redir suggests. Andrewa 20:08, 3 February 2006 (UTC)

Perhaps Thermal breeder reactor? splitting from breeder reactor tot eh two with more or less discussion in common left at the junction page?Midgley 21:04, 3 February 2006 (UTC)

I think the first step is a high-level article at breeder reactor, to replace the current redir. Otherwise, we have a problem as to where this redir will point! Andrewa 21:15, 3 February 2006 (UTC)

Done. Andrewa 20:41, 4 February 2006 (UTC)

[edit] Diagram

I've ammended the DFR diagram as suggested, so that the coolant is NaK. One question that has puzzled me though, is why the reactor design appears to be "upside down", as in why is it that the coolant flows in through the top and the hot coolant leaves at the bottom? Other reactor designs iv'e looked at have the hot coolant leave the top of the reactor core. Is it that unusual? If it is, what is the reasoning, and should this be in the article? Emoscopes 11:39, 4 February 2006 (UTC)

[edit] PFR

I would also like to make a schematic diagram for the Dounreay PFR design. There are some good, if overly technical, schematics here http://www-frdb.iaea.org/react/pfr.html but they have posed me a couple of questions;

1. Do other users think I should go into the complexities of the multi-stage heat removal plant? Or should I concentrate on the reactor itself.
2. http://www-frdb.iaea.org/photos/pfr/cut_away.jpg this diagram shows what appears to be some rotating part of the core. From what I can make out from http://www-frdb.iaea.org/photos/pfr/discharg.jpg  ;
   1. when breeding has occured, the "charge machine" lifts the breeder subassembly out and into the rotor
   2. The rotor is cooled and then rotates in the core so that the breeder sub-assembly can be moved into a transfer flask
   3. This flask is then lifted out of the core and onto re-processing. Have I got this correct?
3. I am presuming that the coolant in this case is Na, not NaK

Emoscopes 20:21, 5 February 2006 (UTC)

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Some replies:

1. I'd concentrate on the core itself, and the online refuelling machinery. That's the interesting bit.

2. There are two rotating bits:

• The centre part of the top plate rotates, to locate the charge machine over any one of the assemblies in the core or surrounding breeder blanket. How the machine is moved radially is not obvious to me! There's some clever way of doing it that avoids the control rod mechanisms.
• There's a temporary storage for both spent and new fuel assemblies, labelled the "rotor". The innermost position of this rotor is accessible to the charge machine. Assemblies can be loaded into, and removed from, the rotor via the transfer tube. When unloaded, they were placed into a transfer flask, as you say. Both fuel and breeder assemblies are loaded and unloaded in this fashion. The transfer flask may or may not have been used for loading unirradiated assemblies; On a DIDO class reactor for example, a similar flask is used for loading unirradiated fuel, just because the most convenient way to manage the contamination is to always have a flask on top of the reactor when anything goes in or out, and for every element that goes in one comes out so the flask needs to be there anyway.

3. The coolant is sodium. NaK (pronounced "nack") is the normal name for sodium-potassium alloys, particularly those liquid at room temperature. But, I suggest calling sodium "sodium" rather than giving it its chemical symbol Na.

I'm not convinced that http://www-frdb.iaea.org/photos/pfr/cut_away.jpg is entirely accurate. At the time DFR and PFR were built, there was obsessive secrecy about these programs (one of several reasons that DMTR was built at all rather than doing the work at Harwell). So some of these diagrams probably weren't done at the time (perhaps some were); There were no schematics drawn or released for publicity at that time, only highly-classified construction drawings, most of which would have been shredded when the British FBR program was running down (that's how the public service used to work).

These may rather be drawings done by the decomissioning team, who are publicly and sorely lamenting the fact that the designers and builders (now all long retired) didn't leave them better documentation, and who have very limited physical access to the machinery described owing to residual radioactivity.

http://www-frdb.iaea.org/photos/pfr/core.jpg and http://www-frdb.iaea.org/photos/pfr/reactor.jpg both have an authentic government-draftsman-of-the-time look. The others look more recent to me, and IMO may contain some guesswork, particularly in the still-to-be-decomissioned active areas. And even when these areas are cleaned up, documenting what they cut up will not be the highest priority.

Hope this helps. Andrewa 23:15, 4 February 2006 (UTC)

[edit] SuperPhenix Shutdown

I was unabl;e to find a good source for the change made on March 23, 2006 -- [3] was as close as I got to one. Does anyone have a source as r to why the SuperPhenix was shut down? Simesa 03:23, 24 March 2006 (UTC)

Try the article on SuperPhoenix. It should be in the list at the bottom of this article. J.Ring 10 September 2006 (UTC)

[edit] How much fuel does a breeder produce?

It is always mentioned that the breeders are a potential source of fuel for other reactors. What is never said is how much other reactors a breeder can supply with fuel. 1? 10? 0.5? This information should in some way be included at least for one or two of breeders that have been in operation.

It depends what you mean. Breeder reactors would obviously not need fuel from other reactors, so the only reason to build breeder reactors with breeding ratios above 1.0 would be if you wanted to fuel a lot of conventional reactors using a single or a few breeder reactors with high breeding ratio. In this case a breeder reactor could probably produce fuel for roughly 1-2 other reactors of similar power rating. However, this figure would depend greatly on the design of the other reactor as the conventional reactors would also breed some fuel ( They are not called breeders as they can't breed as much fuel as they consume, but they still produce some). As an example, if the breeding ratios of the conventional reactors were as high as 0.5 (and this is not too far fetched a figure ) they would only need about half of their fuel consumption replaced, meaning 2-4 reactors could be fuelled by the fuel from a single breeder reactor.

Note however that improved breeding ratios do not increase the total amount of energy that can be extracted once a breeding ratio of 1.0 has been achieved. This is because reactors with breeding ratios above 1.0 can burn all the fertile material, so the amount of available fuel does not increase by increasing the breeding ratio above 1.0, it would just allow you to consume uranium quicker, producing the same total amount of energy over a shorter period of time. Once a breeding ratio of 1.0 has been achieved, the total amount of energy that could be extrated from a closed fuel cycle could extract roughly 100 times as much energy as a once-through fuel cycle (since there is roughly 100 times as much U-238 as U-235 ). If in addition U-233 was made from Th-232 in thermal breeder reactors, this would put the figure up to about 400 times as much. All in all this could easily satisfy current trends in electricity consumption for centuries or more. J.Ring 00:58, 10 September 2006 (UTC)

[edit] Proliferation risks

The article currently seems to suggest that the reason FBRs are generally considered a greater proliferation concern is due to on-load refuelling, but surely the main increase in proliferation risk is due to the need for a reprocessing plant, and not because some designs might be able to refuel on-load? After all, many thermal designs (Rhapsodie, RBMK, CANDU, magnox ), do refuel on load, and could very well be used to produce weapons grade plutonium if operated by a country with reprocessing technology. Furthermore, several FBR designs ( such as the LFR ) have very long refuelling times ( decades ) and would be very expensive to operate at short cycles as the liquid metal coolant would require continuous heating. Thus it appears to me that the main reason FBRs are more of a proliferation concern is not due to on-load refuelling, but rather because reprocessing would be necessary in order to utilise their ability to breed fissile material. I will try to clarify this in an NPOV way, but I think the entire section could do with a rewrite. J.Ring 23:03, 9 September 2006 (UTC)

It depends on how you're doing reprocessing. PUREX is a risk because it can produce pure uranium and plutonium. Pyroprocessing wouldn't be, because it sweeps all the actinides together, which'd be much harder for a bomb-maker to work with.

—wwoods 02:55, 10 September 2006 (UTC)

Surely it would still be useable to extract plutonium from low-burnup reactors tho? After all, the low burnup keeps the amount of Pu-240 low ( bellow 4-6% ), so I'd imagine the minor actinides would be pressent in even lower amounts if the reprocessing technology was copied and used to extract plutonium from a low-burnup thermal reactor. I.e pyroprocessing when applied to fast breeder fuel may not be a problem, but the pyroprocessing technology might potentially be used to reprocess fuel from other reactors with much lower concentrations of actinides in the spent fuel ( Tho I agree it would be a much lower risk than PUREX reprocessing). J.Ring 17:41, 10 September 2006 (UTC)

Surely not. Pyroprocessing gives you two batches of uranium, plutonium, minor actinides and some lanthanide fission products all mixed together. One of these batches contains mostly uranium, the other more of everything else, but none of the two can be considered "pure" in any conventional sense of the word. A bomb needs chemically pure Pu. This stuff is dirty, so isotopic composition doesn't matter at all. 88.73.236.212 17:04, 23 September 2006 (UTC)

[edit] LMFBR schematic

It appears to me that the "Loop Design" section of this schematic contradicts the text by having the primary loop extend outside the biological shielding. AfOrr 14:25, 2 December 2006 (UTC)