Method for reconstituting a partially burnt nuclear fuel assembly

摘要

A method of reconstituting a partially spent nuclear fuel assembly, the rods of which contain mixed uranium and plutonium oxide fuel, involves replacing th or each extracted rod with a new fuel-free rod comprising a mixt. of neutron-transparent material and a neutron absorbent material in proportions such that the average power output of the assembly, during one or more passages in the reactor, does not differ by more than 8% wrt. an unmodified assembly and the radial power factor variation of the assembly is max. 1%. Pref. the new rod consists of Hf and Zr, Ta and Nb, or Ti. The method does not use a replacement rod contg. Pu or other fissile material and only affects the reactivity and power (esp. the radial power factor) of the assembly in an acceptable manner irrespective of the location of the new rod in the assembly.