Report on S/U analyses in MYRRHA homogenized model v1.8 performed with the MCNP6.2 and SUMMON codes and the JEFF-3.3 library

Abstract

This report presents nuclear data sensitivity and uncertainty (S/U) analyses for several safety-related

reactor parameters (keff, βeff and reactivity coefficients) of the latest design (version 1.8) of the MYRRHA

facility. This work has been performed within the frame of task 5.1 of EU H2020 SANDA project using the

codes MCNP 6.2 and SUMMON, the JEFF-3.3 nuclear data library and an homogenized model of

MYRRHA version 1.8 supplied by SCK CEN. In this report, nominal values for these parameters,

integrated sensitivity coefficients (ISCs), sensitivity profiles for the major nuclear reactions with the highest

contributions to the uncertainty, the total uncertainty due to nuclear data and top reactions contributing to

the uncertainty are provided. As a conclusion, and although major contributors to the uncertainty depend

on the specific parameter, in general, the major reaction contributors are elastic and inelastic reactions in

fuel, coolant and structural materials. Nevertheless, given the slow convergence of sensitivity calculations

with these reactions, more detailed simulations will be required to fully understand these contributions.