Talk:MOX fuel

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--Alex 13:14, 24 July 2006 (UTC)


"MOX appeared during the 1960s in research centers and was tested by the US, but they rejected it because it was dangerous and not cost-effective."

The citation given does not really support this statement and appears to me not to make much sense anyway because it states that a high price of uranium is making MOX not cost effective (which is the wrong way round). Also, the cited article clearly has a political agenda (which is not proof they are talking nonsense but does make them suspect).

This section could do with a clear source, and also a clear indication of what the danger is: is it proliferation (people might extract the plutonium to make bombs) or the less forgiving nature of the fuel (which should be safe enough when used in reactors that were actually able to obtain a license to burn the stuff)? Man with two legs 20:36, 31 August 2006 (UTC)

MOX is dangerous because the plutonium in it speeds up the nuclear chain reaction in a nuclear power reactor :
  • Uranium-235 nuclear reaction : U-235 + neutron = fission fragments + 2.52 neutrons + 180 MeV
  • Plutonium-239 nuclear reaction : Pu-239 + neutron = fission fragments + 2.95 neutrons + 200 MeV.
I'm searching a more relevant article about danger and cost of MOX.--Enr-v 13:28, 1 September 2006 (UTC)
Are you sure it is that that leads to danger, and not the lower proportion of delayed neutrons (U: 0.6%, Pu: 0.2%) and consequent risk of prompt criticallity? Either way, the danger should be eliminated as part of the licencing process. Man with two legs 14:53, 1 September 2006 (UTC)
i'm sure of one thing : licensing process have no effect on nuclear physics. --Enr-v 17:38, 1 September 2006 (UTC)
But it DOES affect whether dangerous things are, or are not, allowed to go ahead. A nuclear reactor using any fuel is entirely safe or incredibly dangerous depending on the detailed design. A reactor that is perfectly safe with pure uranium may, or may not, be dangerous with MOX, which is why there is an exhaustive licencing process. Man with two legs 09:15, 4 September 2006 (UTC)
Licensing process does not affect dangerousity, it is just a relativ scaling of dangerousity, and it is a way for deciding what is alowed and what is not in some countries, like the US or France (other countries like Austria consider nuclear energy illegal). With nuclear physics (lower proportion of delayed neutrons, or faster nuclear chain reaction, it depends on the model taken into account), it is proved that it is more dangerous to use plutonium or MOX than pure uranium. Enr-v
This is nonsense for a number of reasons:
  • There is a fundamental safety difference between a reactor that can blow up and one which physically cannot
  • Delayed neutrons are fundamental to nuclear safety. Without them, all existing nuclear reactors would blow up. They are quite a different matter from the number of neutrons produced per fission
  • The fact that Austria is against nuclear energy proves only that they disagree with the French
Man with two legs 16:26, 4 September 2006 (UTC)
You are right, just don't forget that :
  • All nuclear reactors can physically blow up, if they are not properly controlled. See nuclear meltdown
  • Delayed neutrons are part of a model that is not considered in the equations above.
  • Austria, like many other antinuclear countries, disagree also with the american NRC.--Enr-v 16:45, 4 September 2006 (UTC)
Meltdown is not the same as blowing up. Three Mile Island suffered a meltdown and nobody was killed. Chernobyl went prompt critical and blew up, and many people were killed. Man with two legs 17:47, 4 September 2006 (UTC)
thank you for the terminological information, i have mixed up the 2 different things (my english is just at intermediate level). indeed it is not the same, but anyway i'm not convinced those licensing processes (US, France, ...) can prevent a plant from blowing up, because russia had also its own licensing process at the time of Chernobyl. However I can understand that the risk of blowing up is extremly lower for new pressurized water reactors than for old RBMK. --Enr-v 20:23, 4 September 2006 (UTC)

The sentence discussed above has since disappeared from the article Man with two legs 11:06, 4 September 2006 (UTC)

I'm still searching a more relevant article about danger and cost of MOX. I will put the sentence back as soon as i find it.--Enr-v 13:28, 4 September 2006 (UTC)
Clearly anything reliable you do find on this should be included. Man with two legs 16:32, 4 September 2006 (UTC)

Plutonium 240, 241[edit]

It says:

Pu-240 is a neutron poison...

I question if this is correct. Pu-240 has a critical mass of 40kg according to the article on critical mass, lower than U-235. Either it is very reluctant to fission with slow neutrons, or it is not a nuclear poison. Does anyone know for sure? Man with two legs 17:18, 30 November 2006 (UTC)

Pu-240 does not have an extremely high thermal neutron capture cross section [1] (only slightly more than Pu-239's cross section for capture without fission) but it does have a very low thermal neutron cross section for fission. It is not fissile, though "neutron poison" is an exaggeration.

However, Pu-241 appears to have an even higher cross section than Pu-239! (35% higher total, same 75% chance of fission) So decay to Am-241 is reducing the quality of the remaining Pu, not improving it as the article currently says.

In general it seems that the nuclides with odd numbers of neutrons are fissionable with thermal neutrons, and the nuclides with even numbers of neutrons are not. --JWB 14:55, 5 May 2007 (UTC)

Thanks for clearing that up. Man with two legs 11:57, 8 May 2007 (UTC)

Proliferation risk?[edit]

There is a comment in the introduction that MOX fuel is a proliferation risk. If the plutonium therein is not weapons grade, then I don't see how it can be. I have put a [citation needed] tag on it for the time being. Thoughts, anyone?

Man with two legs (talk) 15:05, 4 September 2008 (UTC)

The distinction of weapons grade and not for plutonium is less significant that for uranium. Reactor grade plutonium can still make a bomb, though maybe less powerful from pre-detonation problems and less convenient to store safely. MOX fuel can be chemically processed to extract the plutonium fairly easily if you can evade IAEA monitoring of MOX fuel. Don't have a ref immediately to hand other than [2], but will look out for one in my reading. See also discussion in 2006 North Korean nuclear test which had a pre-detonation problem. Rwendland (talk) 15:54, 4 September 2008 (UTC)
In the article the reference is to the proliferation risk of using MOX as a method for disposition of plutonium - the concern was that it would normalize the civil use of plutonium. That is, creating a MOX economy would create demand to separate more plutonium to meet demand. But most concluded that the benefit exceeded the risk. NPguy (talk) 03:36, 6 September 2008 (UTC)
I added two refs. The NIRS one avers that if the U.S. uses MOX, then other countries will not restrain themselves from following in the footsteps of such peace-threatening nations as France, the UK, India and Japan. Simesa (talk) 04:47, 6 September 2008 (UTC)
That ref is highly POV and unreliable as, like most anti-nuclear sites, it can't distinguish legitimate concerns from urban legends. The logo of that site (a strangled cooling tower) suggests that it is anti-nuclear on principle rather than from reason. It would be much better to find one that is not obviously POV if such exists. It is not wise to accept that avoiding proliferation is why the US does not reprocess fuel just because that site says so. How can we be certain it is not just to save money?
I have not deleted the reference because it shows correctly that some people are concerned about proliferaton. What I can't tell at this stage is whether any sensible people are concerned about it.
By the way, suggesting that countries will make their decisions on whether to use MOX fuel based on moral leadership by the US is over-optimistic. The world does not work like that and never will. Governments will always do what they think is best for themselves.
Man with two legs (talk) 08:00, 6 September 2008 (UTC)

Source of U.S. Ban on Reprocessing[edit]

I moved my entries to nuclear reprocessing. Simesa (talk) 05:15, 6 September 2008 (UTC)


There is no reason to include Thorium in an article about mixed OXIDE uranium fuel. We don't mention coal or petroleum in this article either. Please don't readd it. (talk) 14:59, 2 August 2009 (UTC)

Nobody is likely to mistake coal or petroleum for nuclear fuel. However the fuel with thorium oxide and plutonium oxide is a mixed oxide nuclear fuel. If the term is restricted to uranium oxide and plutonium oxide (sources?) this needs to be explained. --JWB (talk) 15:27, 2 August 2009 (UTC)

" Q: What is mixed oxide fuel?

A: Mixed oxide fuel is a mixture of uranium oxide with plutonium oxide. It can be safely used in commercial nuclear reactors, and has been successfully used as a fuel source in Europe for more than 20 years. In the U.S., the National Academy of Sciences has studied mixed oxide technology and recommends the process as a preferred means of safely disposing of surplus plutonium. "

source: (talk) 17:02, 2 August 2009 (UTC) Great. So the article should have the explanation that the industry definition (or at least one common usage) is this non-obvious one. --JWB (talk) 17:53, 2 August 2009 (UTC)

The industry term is the only reason this phrase exists. Mixed oxide is not a scientific term. MOX term used by the project spearheaded by Areva and the US Department of Energy. You can read more about it at The use of mixed oxide to describe Thorium Oxide - Plutonium Oxide is a neologism that you invented and does not need to be explained in a wikipedia article about MOX. (talk) 18:17, 2 August 2009 (UTC)

The phrasing did not say that the MOX name applies to fuels containing thorium oxide - it said that it did *not* apply.

The purpose of the article is to explain. If you already know all the specifics like this jargon usage of "MOX", you do not need to read the article in the first place. --JWB (talk) 18:41, 2 August 2009 (UTC)

Nobody is going to make the mistake that it does apply to other oxides (titanium dioxide for instance :)) because the first paragraph states "Mixed oxide, or MOX fuel, is a blend of oxides of plutonium and natural uranium, reprocessed uranium, or depleted uranium which behaves similarly (though not identically) to the low enriched uranium feed for which most nuclear reactors were designed. MOX fuel is an alternative to low enriched uranium (LEU) fuel used in the light water reactors that predominate nuclear power generation." There is no need to mention a competing technology in the second paragraph of this article. If you want to add a section for competing technologies at the bottom of the article you are free to do so. (talk) 18:51, 2 August 2009 (UTC)

Ok, this has led me to do a little research. It turns out the statement that MOX does not refer to Th/Pu fuels is false - there are abundant references to "Thorium MOX":

So "MOX" is used in the literature both to refer to a specific uranium-plutonium composition and as a generic term; the former derived from the latter by synecdoche, specifically Totum pro parte. --JWB (talk) 02:14, 3 August 2009 (UTC)

This is english speaking wikipedia, which makes use of secondary sources from english speaking countries. You may be able to find references to Thorium-MOX or TMOX if you look for sources in non english speaking countries, but as you probably gathered after looking for your sources nobody refers to thorium fuel sources as only "MOX fuel" without further qualification. There are two possibilities. We can move this article to Mox Project and make the current article a subsection on the fuel used for the Mox Project, or you can let the article stay as it is.

Onto the second subject, just to make clear because I've been seeing something promoted a lot on the internet recently. Have you ever been compensated by Thorium Power Ltd either directly or indirectly, where compensation includes cash; free or restricted stock of common or preferred equity shares of OTCBB:THPW; services; or favorable treatment by this corporation? Are you knowingly invested in OTCBB:THPW using personal or a 3rd party's funds?

I am not employed by the US Government(DOE,NNSA), Areva, or Shaw Industries. I have never received anything from these corporations and have never invested in their stock. I have no Conflict of Interest other than making sure wikipedia is as accurate as possible. (talk) 02:47, 3 August 2009 (UTC)

I am not employed or compensated by anyone in or related to the nuclear industry. If you take even a casual look at my edits you will see I am not pushing thorium or any particular technology.

We are not restricted to the "two possibilities" you mention. We can simply describe the actual situation and document "mixed oxide" as a term with the obvious, generic meaning, and a conventional, more specific meaning. This is a situation similar to many other terms.

The idea of disqualifying sources published in good English by Europeans, Japanese or Indians is new to me, and particularly bizarre since you are citing Areva which is a European company. If you are not simply making this up please give a policy link. Most work on MOX has been outside the native English speaking countries and if you disqualify this there is not much left. --JWB (talk) 18:25, 4 August 2009 (UTC)

Sorry about not following the guidelines that discourage anonmynity but this is my first time posting on wiki. At any rate, I just wanted to add that I am doing my thesis on thorium fuel cycles and, therefore, have seen many talks on the subject. Although it sometimes is a point of confusion (that needs further clarification), MOX is used to describe other mixed oxide fuels. I this is insufficient evidence but I'd advise the editors of this page to consider broadening the definition. (talk) 19:28, 25 May 2011 (UTC)SomeNukeStudent

Change in notation[edit]

An editor recently changed all the instances of isotope names to the Nuclide2 template, which shows the atomic number and atomic mass number is preceding subscript and subscript before the element symbol. This is standard notation in the specialist technical literature, but seems inappropriate for a popular encyclopedia article since it is unfamiliar to most readers. I propose to revert to notation that uses either the element name or the element symbol followed by the atomic mass number, e.g. plutonium-239 or Pu-239. Comments? NPguy (talk) 15:43, 19 March 2011 (UTC)

This same discussion was also started at Talk:Thorium_fuel_cycle#Change_in_notation - let's keep the discussion there to avoid duplication.     SkyLined (talk) 21:49, 27 March 2011 (UTC)

Inadequate source citations[edit]

This is an important article about a subject with important implications. Therefore, the lack of citations to enable verification of the article's statements is disappointing. Also, direct quotations or attributing statements to a particular person or organization require pinpoint citations to the source. If this is not corrected within 30 days, I will delete unsourced material.—Finell 02:35, 26 March 2011 (UTC)

Lacks discussion of added risk in case of nuclear meltdown[edit]

As we are learning from the Fuchishma plant, in the case of core meltdown, all fuels do not pose the same risk. MOX, because of its plutonium, is much more dangerous. This is certainly an important consideration when evaluating which fuel to use, and needs prominent inclusion in the article. —Preceding unsigned comment added by (talk) 16:34, 1 April 2011 (UTC)

It's not that simple. The greatest immediate hazard from a reactor accident is from fission products (particularly iodine-131 and cesium-137). Plutonium can be dangerous if absorbed into the body, but is much less likely to be released than these volatile fission products, and also less likely to be absorbed than these isotopes of chemicals that that become concentrated in the food chain. Fresh MOX fuel is more hazardous than fresh low-enriched uranium fuel, but nowhere near as hazardous as irradiated LEU fuel. And over time as LEU fuel is used it generates plutonium - never as much as fresh MOX fuel, but an appreciable amount nonetheless.
There is an aspect of MOX fuel that reduces operational safety margins in a reactor: the smaller fraction of delayed neutrons. It is the delayed neutrons that make the chain reaction controllable. But in practice the most significant safety risks come from the possible lost of backup power to pump cooling water, as happened in Fukushima Dai-ichi, Japan. This accident had nothing to do with the type of fuel used, and so far I have seen no indication that the presence of MOX fuel has increased the resulting hazards appreciably. NPguy (talk) 02:33, 2 April 2011 (UTC)
Here's a source: Mariah Blake (April 7, 2011). "The Trouble with MOX; Why is the U.S. intent on imitating one of Fukushima’s scariest flaws?". The New Republic.  . -- John Broughton (♫♫) 13:41, 12 April 2011 (UTC)
Not being a subscriber I can't read the whole article, but the lead describes the added risk of using MOX in reactors not designed for MOX as "marginal." MOX was not a cause of the Fukushima disaster and I've seen no indication yet that it increased the resulting harm. NPguy (talk) 01:28, 13 April 2011 (UTC)

Who is still actively reprocessing MOX?[edit]

"Reprocessing of commercial nuclear fuel to make MOX is done in the United Kingdom and France" says the article. Citation needed, says I. might have been the source, but although it claims to have been updated in 2012, it appears not to have noticed that the closure of UK reprocessing at Sellafield was announced in 2011, as seen in Wikipedia article on Sellafield. — Preceding unsigned comment added by (talk) 10:25, 25 January 2013 (UTC)

Just France. France is producing MOX fuel for its own reactors and for other countries that send their spent fuel to La Hague for reprocessing. France's customers have included Japan, Belgium, and Germany, but Switzerland may be the only one left. The United Kingdom has a MOX plant that never reached full-scale operation, after MOX fabricated for Japan failed quality control tests. Japan has not yet completed its own MOX plant. The United States is also building a MOX plant for disposition of excess plutonium from weapons. NPguy (talk) 02:44, 26 January 2013 (UTC)

The UK govt still expects to get back into MOX production in due course, even though the last plant hardly worked: "An indicative DECC timeline, should the government continue with the idea, sees procurement start in 2015, construction from 2019 and operation from 2025. MOX fuel use in civilian reactors could start as soon as 2029."[3] The UK has 100+ tonnes of expensively produced civilian Pu, and now has the problem of getting rid of this now zero-valued material somehow. It currently considers MOX fuel is the least-worst way of doing this: "The cost of continuing to store plutonium at Dounreay until 2075 and Sellafield until 2120, in line with the previous policy, would be about GBP 8 billion ($12.5 billion), ... immobilising and disposing the plutonium would cost GBP 5-7 billion, depending on the technology. In contrast, building and operating a new MOX facility would cost GBP 5-6 billion." Just shows how badly mistaken the UK reprocessing policy was, pushed for decades by the UK nuclear establishment in the hope fast reactors were the future! Rwendland (talk) 16:56, 26 January 2013 (UTC)

nice summary of the state of Japan's MOX plans and the amount of money spent, also much needed perspective on what it may be good for and what not (notably the argument that it diverts much needed funds from renewables):

Fukushima reactor 3[edit]

This reactor has Mox and is in meltdown. SaintAviator (talk) 02:02, 29 December 2013 (UTC)

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