Neutronic calculations for preliminary core design of SCW-SMR

Serpent 2 particle transport code is used to develop the pre-conceptual neutronic design of the Supercritical Water Cooled SMR. After initial criticality and burnup calculations, the starting core design of (Schulenberg and Otic, 2021) is improved using predetermined criteria, such as burnup cycle length and power distribution, while also considering operational safety. In order to achieve higher reserve reactivity, several modifications are considered, including the introduction of alternative structural materials and fuel assembly wall type, moderation improvement by adjustment of moderator temperature and fuel assembly gap width, and selection of a suitable enrichment map. As a result of the introduced modifications, the burnup cycle length is increased to 26 months and an acceptable core power distribution is achieved. The improved core design can be used for further investigations, such as coupled calculations using neutronic and thermal–hydraulic codes and examinations targeting reactivity control during burnup.