부산대학교 도서관

Decay heat residuals of spent nuclear fuel (SNF), i.e., the differences between calculations and measurements, were obtained previously for various spent fuel assemblies (SFA) using the Polaris module ofthe SCALE code system. In this paper, we compare decay heat residuals to their uncertainties, focusing onfour PWRs and four BWRs. Uncertainties in nuclear data and model inputs are propagated stochasticallythrough calculations using the SCALE/Sampler super-sequence. Total uncertainties could not explain theresiduals of two SFAs measured at GE-Morris. The combined z-scores for all SFAs measured at the Clabfacility could explain the resulting deviations. Nuclear-data-related uncertainties contribute more in thehigh burnup SFAs. Design and operational uncertainties tend to contribute more to the total uncertainties. Assembly burnup is a relevant variable as it correlates significantly with the SNF decay heat. Additionally, burnup uncertainty is a major contributor to decay heat uncertainty, and assumptionsrelating to these uncertainties are crucial. Propagation of nuclear data and design and operational uncertainties shows that the analyzed assemblies respond similarly with high correlation. The calculateddecay heats are highly correlated in the PWRs and BWRs, whereas lower correlations were observedbetween decay heats of SFAs that differ in their burnups