Talk:MOX fuel
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--Alex 13:14, 24 July 2006 (UTC)
[edit] History
- "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 :
- 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)
- This is nonsense for a number of reasons:
- 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)
- 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
- 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)
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)
[edit] Plutonium 240, 241
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)
