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Mixed Oxide Fuel, or MOX Fuel, Advantages and Disadvantages

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wrecked_edsel:
The concerns about MOX are real, and do we really want to deal with the aftermath of it ie... higher dose rates, higher contamination levels, alpha contamination ? The chances of an accident copuld be increased by the use of MOX fuel. Are todays reactors able to handle the MOX type fuels. Let's hear some other opinions.

Marco:
Here in Europe we use MOX elements since ten years or more. At our plant we don't know any problems regarding MOX fuel. What are the increased possibilities of an accident that you mentioned ? In our MOX elements is Plutonium from Sovjet atomic weapons contained, so we do a kind of disarmament with the help of commercial use of nuclear power.
Doesn't use US plants MOX fuel ?

Kernwerker:
Hmm? well here in Germany we have been using MOX fuel assemblies for some time now. Except for some minor RP measurements i.e a bit higher neutron and gamma doserates compaired to "conventional" fuel assemblies and some alpha contamination precautions ( we never experienced any). Well we really never had any probs

HydroDave63:
Edsel, the fuels engineers will tell you it is just as safe, etc. The real problem I see with MOX fuel, aside from the greatly increased alpha levels (what plant has NEVER had fuel flea problems/broken pins ?) is the shifted neutron spectrum. There will be more Pu-239 buildup at EOC, which can produce a positive moderator temp. coefficient. In a PWR you have the ability to change boration if there are surprises in the flux profile change from the Pu-239 buildup, but less room to maneuver CEAs at a BWR. I'd love to see the analysis done for a BWR 100% load rejection at End of Core, and prove that the void coefficient with a MOX core would NOT violate adequate shutdown margin requirements. Color me skeptical.

Kernwerker:

--- Quote from: HydroDave63 on Oct 16, 2004, 01:28 ---Edsel, the fuels engineers will tell you it is just as safe, etc. The real problem I see with MOX fuel, aside from the greatly increased alpha levels (what plant has NEVER had fuel flea problems/broken pins ?) is the shifted neutron spectrum. There will be more Pu-239 buildup at EOC, which can produce a positive moderator temp. coefficient. In a PWR you have the ability to change boration if there are surprises in the flux profile change from the Pu-239 buildup, but less room to maneuver CEAs at a BWR. I'd love to see the analysis done for a BWR 100% load rejection at End of Core, and prove that the void coefficient with a MOX core would NOT violate adequate shutdown margin requirements. Color me skeptical.



--- End quote ---
Hmm a Pu-239 buildup? Well that would mean that we would have a higer resonance absortion peaks. But wouldnt the fuel temperature coefficient or doppler coefficient be the main reason for a buildup. What i mean doesnt the doppler coefficient have much greater effect then the the moderator coefficient? I mean since this effect is also called the prompt temperature coefficient meaning higher reactor power emmediately causes higher fuel temperature. Not sure if i said it right please correct me if i am wrong here

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