Optimization of reactor fueling regime after pre-term withdrawal of failed fuel assembly

A simple reactor model with a heat release field fully leveled in the radial direction and linear reactivity dercease with power generation growth is considered. Thus, the reactor refueling patterns are considered to differ slightly from the patterns, where all assemblies are in the reactor for n0 intervals between refuelings. For such a model the next factor is shown. If a part of fuel is recharged in the stationary condition in n intervals differing from n0, it is not economically profitable, except that case when n0 > √2nopt (nopt is the optimal number of rechargings during a fuel cycle). Small deviations of a part of charged fuel channels from 1/n0 at linear approximation have no affect on the efficiency. If a failured fuel assembly is recharged ahead of shedule, then the assemblies operating less than n0 intervals should not be withdrawn in the recharged conditions after accident. The damage caused by the fact that an assembly operated by i intervals less is approximately proportional to (i/n0)2. This denendence is accurate within the limit n0 → ∞