Automatic or semiautomatic planning of Boiling Water Reactor core loading and operation

An automatic process for designing reload and control rod patterns for boiling water reactors has been developed. Starting from a good initial guess, the computer code CORFU suggests improvements in the patterns, which are then tested by a core simulator. The results of the simulation provide feedback to CORFU for the next iteration. A semiautomatic application of the method is, however, often more powerful, i.e. if the obtained solution does not yet fulfil all requirements after some 10 - 100 loading patterns have been tried, then the user should consider modifying the inputs in some suitable way. The code tries to maintain high end of cycle reactivity while improving the linear heat generation rates, the critical power ratios and the shutdown margins through fuel bundle moves that increase the burnup at locations where problems have arisen. Control rod patterns are chosen to yield the correct keff for a favourable power distribution in the core