Nuclear heating measurements for fusion and fission relevant materials in the JSI TRIGA reactor

• Published in: Fusion engineering and design 2022-06, Vol.179, p.113136, Article 113136
• Main Authors: Carcreff, Hubert, Radulović, Vladimir, Fourmentel, Damien, Ambrožič, Klemen, Destouches, Christophe, Snoj, Luka, Thiollay, Nicolas
• Format: Article
• Language: English
• Subjects: Aluminum; Calorimetry; Differential calorimeter; Eurofer; Heating; Materials testing; Nuclear fission; Nuclear fusion; Nuclear heating; Nuclear reactors; Perturbation; Reactor cores; Research facilities; TRIGA; Tungsten
• ISSN: 0920-3796; 1873-7196
• DOI: 10.1016/j.fusengdes.2022.113136

•The experiment allowed nuclear heating measurements in two materials widely used in fusion: tungsten and Eurofer. The results show that, depending on the nature of the material (atomic number), the differences in nuclear heating are not negligible and must be taken into account in the design of mechanical parts subjected to high photon flux. The knowledge of nuclear heating inside nuclear (fission or fusion) reactor is essential for safe reactor operation, to know and meet limits expressed in terms of cooling requirements, and it represents critical input information for the design of any experimental irradiation device. In the framework of a research collaboration project between the Atomic and Alternative Energy Commission (CEA) in France, and the Jožef Stefan Institute (JSI) in Slovenia, a new project was launched in 2018 with the objective to measure the total heating rates in different materials of interest inside the JSI TRIGA Mark II reactor using the calorimetry technique. Three standard materials, graphite, aluminum and tungsten, and a fusion-relevant material, Eurofer-97, have been selected. The design of the calorimeters to host the four selected material samples is based on the CALMOS and CARMEN differential calorimeters, previously developed at the CEA, which were used to perform nuclear heating measurements in the OSIRIS material testing reactor (MTR) at the Saclay research center. The design of these specific calorimeters, and the dimensioning of the material samples located within, necessitated preliminary particle transport calculations using the MCNP V6.1 Monte Carlo code in order to estimate the expected heating levels in the experimental Central Channel of the core, and to avoid excessive perturbation of the measured radiation field. On the other hand, a parametric study was carried out using the COMSOL multiphysics code, to evaluate the expected temperature differences that could be measured using calorimeters designed specifically for low heating rates in the JSI TRIGA reactor core. A dedicated measurement campaign took place in July 2021 in which heating measurements were carried out at 100 kW reactor power and at nominal reactor power - 250 kW. This paper presents the design and preparation of the calorimeters, their preliminary calibration, the measurements carried out and the analysis of the obtained experimental results.