Consequences of the use of MOX fuel in light water reactors

Currently, French nuclear safety authorities stipulate that no more than one third of the nuclear fuel used in LWRs should be MOX and that the plutonium contents of this fuel should not exceed more than about 7.5% and impose more stringent operating characteristics for MOX fuel than for uranium fuel. It is not only the MOX fabrication plants that become storage sites for a raw material which can be used for the fabrication of nuclear weapons but also the sites of the reactors in which MOX fuel is used. The management of MOX fuel implies protective measures similar to those employed for separated plutonium. The Ministries for Industry and the Environment of the second Juppé Government requested an official internal evaluation of the economic and ecological consequences of different options for the management of spent fuel and radioactive waste. The first version of the report did not convince the staff of the new Minister of the Environment; a further report has been requested from the authors; this new report should be available over the next few months.

MOX and Fissile Material Management

Following denuclearisation treaties between the USA and the Russian Federation, large quantities of fissile material will have to be disposed of, so as to reduce or eliminate nuclear proliferation risks. Different solutions have been proposed for weapons grade plutonium, of which vitrification together with high-level radioactive waste and production of MOX fuel for standard reactors. Both solutions are being studied in the USA. France is participating in projects for the construction of a plant for the conversion of weapons grade plutonium (from a metallic alloy to oxide) and for a demonstration MOX fuel fabrication plant located in the Russian Federation.

Conclusion

A critical situation has been reached in France in the management of plutonium. On the one hand, stockpiles of separated plutonium are increasing. On the other hand, the national utility, EDF, has been endeavouring to burn more and more plutonium in order to decrease plutonium stockpiles; the utility has however been confronted with safety and security requirements which jeopardize cost efficiency. The fact that EDF has attributed a zero monetary value to its plutonium stocks speaks for itself. Plutonium has for a long time been a source of concern rather than a source of energy. There seems to be no logic in spending a lot of money to produce plutonium while generating very large quantities of radioactive effluents (the La Hague plants discharge 8,000 times more radioactivity to the environment than a standard French reactor !) and stocks of a highly toxic and proliferating material having a zero monetary value.

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