Overview of fuel management analysis methodology

One issue that has been raised with regard to the acceptance of the burnup credit concept for cask design has been the accuracy of the methods utilized to determine the isotopic composition of spent fuel. In other words, how well can a utility determine the isotopic content, and therefore the reactivity, of a fuel assembly that has been exposed for three or four cycles in an operating power reactor? This issue is of importance in determining the safety margin requirements for the design of a burnup-credit cask. The objectives of this paper are to: (1) review the typical features of core analysis methodologies used by utility engineers for keeping track of the nuclear characteristics of individual fuel assemblies throughout their exposure lifetime, using the Electric Power Research Institute (EPRI) sponsored analysis package, ARMP-02 as an example, (2) summarize the validation that such a methodology is subjected to, and (3) demonstrate the accuracy of utility spent fuel isotopics and reactivity predictions