Experimental validation of reaction rate distributions in an SCWR-Like fuel lattice at Proteus - 049

High resolution gamma-ray spectroscopy experiments were performed on 61 pins of an SCWR-like fuel lattice at the PROTEUS zero-power research reactor at the Paul Scherrer Institut in Switzerland. The derived reaction rates were compared to calculated results from full-core Monte Carlo simulations with MCNPX. Reaction rates (captures in 238U and total fissions in 235U and 238U) were measured and mapped pin-wise on the lattice. Ratios of calculated to experimental values (C/E's) were assessed for both reaction rates. These C/E's show excellent agreement between the calculations and the measurements. In the case of neutron captures in 238U all experimental results agree within 2σ while for the total fissions only 5 (out of 61) values are outside the 2σ confidence interval. For the 238U capture rate, the 1σ level in the comparisons corresponds to an uncertainty of ±2.5%, while for the total fission rate the 1s level is below ±1%. To determine the reproducibility of these results, the measurements were performed twice, once in 2006 and again in 2009. The agreement between these two measurement sets is better than 1%. (authors)