KATANA - water activation facility at JSI TRIGA, Part II: First experiments

Water as a primary coolant will play an important role in the performance of fusion reactors, as after being irradiated and activated, it causes an ionising radiation field throughout the facility. In direct support of ITER, the KATANA irradiation facility, which utilises a closed-water activation loop and serves as a well-defined and stable high-energy γ and neutron source, was commissioned in 2024 at the TRIGA Mark II research reactor at the Jožef Stefan Institute in Slovenia. A series of first experiments using the KATANA irradiation facility were performed to determine the operational characteristics of the KATANA, i.e. characterisation of the neutron flux within the irradiation component, dose rate measurements, spectrum characterisation of the activated water, and response to a change in reactor power & flow rate. The KATANA facility demonstrated the desired operational characteristics in terms of high and stable water flow rates and high activity values of the observed isotopes 16 N, 17 N and 19 O, which is essential for minimising the experimental uncertainties. The first experiments performed at KATANA provided in-depth knowledge into the operation and capabilities of the facility and essential data to serve as a basis for further, more detailed/benchmark experiments.