Kinetics parameters evaluation on the first core of the RSG GAS (MPR-30) using continuous energy Monte Carlo method

Abstract

The kinetics parameters, namely the effective delayed neutron fraction (βeff) and the generation time (Ʌ), of the first core of RSG GAS (MPR-30) multipurpose reactor were, for the first time, evaluated by using the recently released, continuous energy Monte Carlo code, MVP3, with latest nuclear data libraries (JENDL-4.0 and ENDF/B-VII.0). To check the accuracy and consistency of the MVP3 calculation results, independent MCNP-6.2 calculations with JENDL-4.0, ENDF/B-VII.0, and ENDF/B-VII.1 nuclear data libraries were also conducted. The calculated βeff was then used for re-evaluating the measured core excess reactivity and total control rod worth. The original βeff provided by the reactor vendor was 765 pcm, while the newly calculated βeff was found to be 738 pcm (MVP3, JENDL-4.0), i.e. the old value was approximately 4% larger. Using the newly calculated βeff, the first core excess reactivity and control rod worth were evaluated to be 8.16% Δk/k (11.054$; k = 1.08886) and 17.18% Δk/k, respectively. Using these new excess reactivity and control rod worth, the ratio of the calculation to the experiment results (MVP3, JENDL-4.0) of them were found to be 1.01 and 1.04, respectively. Other MVP3 calculation results using ENDF/B-VII.0 library, and the ones of MCNP-6.2 using JENDL-4.0, ENDF/B-VII.0, and ENDF/B-VII.1 libraries, showed very close values and consistent with the MVP3 (JENDL-4.0) results.