ENSURING THE SAFETY OF MOX FUEL TRANSPORT

All-Russian Project and Research Institute of Complex Energy Technology (VNIPIET) 

Principal Factors That Affect MOX Fuel Transport 

The application of the mixed uranium-plutonium fuel in power reactors requires assurance of safe transport of semifinished items, fuel elements, and fuel bundles (FB). To research various aspects of safety, it is necessary to take into account that the thermal and radiation characteristics and criticality parameters of MOX fuel are higher than the characteristics of fuel on a basis of uranium dioxide. 

Particularly, the minimum critical mass for Pu-239 is less than 1.5 times the appropriate parameter for U-235, whilst the critical masses for dry dioxides of the above isotopes differ from each other more than 3 times. Moreover, the mixed uranium-plutonium fuel is a powerful source of neutron and gamma radiation. 

Sources of radiation in fresh fuel are plutonium isotopes, products of decay of the plutonium isotopes, and impurities of products of fission in the regenerated plutonium. As a result, the gamma and neutron radiation dose on a surface of fresh fuel bundles generated by fuel from weapon plutonium exceeds by more than an order of magnitude the appropriate dose capacity for FB from uranium fuel. Moreover, capacity of dose on a surface of FB with regenerated plutonium exceeds on an order of magnitude the dose capacity for FB with weapons plutonium. 

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