Simplified activation calculations in SERPENT: the case of the GEMINI+ reactor

The GEMINI+ reactor is a small-size high temperature gas-cooled, graphite moderated block-type reactor (HTGR). Components like replaceable reflector (RR), permanent reflector (PR), and reactor pressure vessel (RPV) are irradiated over more than the single fuel cycle (550 days). The goal of activation calculations is to determine the specific activity of selected materials after defined irradiation time (up to 60 years) together with neutron fluxes and fluences. The above factors are important for irradiated graphite management (RR), decommissioning (PR, RPV), and fluence limits. The Monte Carlo code SERPENT (v2.1.31) was used for this purpose.

This work is part of the GEMINI+ project, funded by the European Union's Horizon 2020 programme. The activation calculations were carried out in cooperation with J.C. Kuijper (NUCLIC - Nuclear Innovation Consultancy, the Netherlands).