Study on Intra-Fuel Assembly Reshuffling Options in PWR In-core Fuel Management - 14137

The cycle energy production for the fuel could be maximized with the selection of the advanced low-leakage longer cycle loading patterns and/or through the use of higher discharged burnup of the light water reactor above the currently licensed value. In addition to those measures, the preliminary study is initiated to search for an alternative way to enhance efficient use of nuclear fuel. That is the fuel pin reshuffling option within PWR fuel assembly (FA) with the expectation of more economic and safety benefits. First of all, simplest calculation procedure is proposed by which, the isotopic compositions of each pin of burnt FA could be predicted and then the results were verified. There are two scenarios under consideration. The improvement on the uniform flux spatial distribution and neutron economy was investigated by reshuffling the existing fuel pins within some uneven, once-burnt FAs. As a result, when treating 8 FAs, the operating time could be somewhat increased for few minutes by keeping enough safety margins. Secondly, feasibility of reduction of fresh fuel loading and discharged FAs was examined under the situation that some available spent fuels pins that could still carry enough reactivity and mechanically assured, could be reused by combining with other twice-burnt fuel pins. Reduction of 4 FAs loading did not show any failures to meet the targeted parameters from the standpoint of safety despite loss of 14 EFPDs for operation at reference plant full rated power. (authors)