The 0E2 benchmarks for PWR UO₂ decay heat: an analysis from the NEA WPNCS

This paper presents the work performed in the subgroup 16 of the Working Party for Nuclear Criticality Safety (WPNCS) of the OECD Nuclear Energy Agency. The main goal was to define two decay heat benchmarks for Spent Nuclear Fuel (one pincell and one assembly), perform calculations and compare and analyze the results in light of existing calorimetric measurements. The selected case is the PWR UO 2 assembly 0E2, irradiated at the Ringhals-3 reactor and measured at the Clab facility in Sweden. In total, 21 institutes worldwide participated to the exercise, leading to 55 calculated results (named C ). It was found that the measured decay heat values ( E ) can be satisfactorily reproduced with two-dimensional assembly calculations, leading to an average C / E value of 0.99, with an uncertainty (or one standard deviation) of ±0.01.