Fractional Isotope Release Comparisons Between X-Energy’s Mechanistic Source Term Code XSTERM and the AGR-1, AGR-2 and HFR Experiments

Abstract

Licensing activities for new reactor projects, such as the Xe-100 Small Modular Reactor, require that computer codes used in design and analysis calculations, such as the XSTERM Code Suite, are qualified in accordance with applicable standards. XSTERM calculates the mechanistic source term for the Xe-100 reactor, under normal operating conditions and during postulated accident scenarios. It can also be used in a standalone Experiment Mode, calculating the isotopic releases from individual (simulated) fuel elements during irradiation and subsequent furnace-heating for comparison to actual experiments such as the Advanced Gas-cooled Reactor (AGR) campaign and the High Flux Reactor (HFR) campaign.

As part of the code validation process, the irradiation and furnace-heating of selected experimental cases were simulated in XSTERM and the results for fractional isotopic releases were compared to those published in the open literature. This paper will discuss the background, methodology and overall code validation effort.