Validating a simplified water-activation transport model using time-resolved reactor-pulse neutron measurements at KATANA

KATANA is a water activation facility at the Jožef Stefan Institute TRIGA Mark II reactor in Ljubljana, Slovenia, developed to study water activation processes relevant for future fusion systems such as ITER. In this work, we validated a simplified activation-transport model of the KATANA loop using time-resolved neutron measurements during reactor pulse operation. A finite volume of water in the KATANA loop was irradiated during reactor pulses, and the subsequent decay of was tracked with a 3 He detector. For each reactor pulse two distinct activation peaks were observed, corresponding to successive passages of activated water, and showed excellent agreement with model predictions. The measurements enabled to determine loop parameters in particular the effective loop volume, which gave excellent agreement with the direct measurements. The presented validation provides a solid foundation for future experimental campaigns at the KATANA water activation facility, aimed at performing integral cross-section measurements of the reaction and advancing studies of activation phenomena relevant to fusion applications.