Link do spotkania w aplikacji Microsoft Teams: https://teams.microsoft.com/meet/356567535381819?p=LSbFmcoUw3Jl5MjNk1

Identyfikator spotkania: 356 567 535 381 819

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Abstract

The Joint European Torus (JET) was the largest operational tokamak capable of performing controlled deuterium–tritium (DT) fusion experiments and provided a unique environment for studying the activation of materials relevant to future fusion devices. The DT neutron spectrum at JET, characterized by a dominant 14.1 MeV peak, enabled experimental validation of activation predictions and inventory calculation methodologies required for the design and operation of ITER and future fusion power plants. Although the neutron fluences achieved at JET were significantly lower than those expected during ITER operation, they represent the highest DT neutron exposures obtained in a tokamak environment. During the final JET DT campaigns (DTE2 in 2021 and DTE3 in 2023), ITER-relevant materials and dosimetry foils were irradiated in the Long-Term Irradiation Station (LTIS), located close to the JET vacuum vessel. The DTE2 campaign included 68 material samples and 25 dosimetry foils irradiated during 2356 JET shots, corresponding to a total neutron yield of 8.67 × 1020 n, while the DTE3 campaign included 69 material samples and 20 dosimetry foils irradiated during 2925 JET shots, with a total neutron yield of 7.88 × 1020 n. After irradiation, selected samples were distributed to European fusion laboratories, including the Institute of Plasma Physics and Laser Microfusion (IPPLM), for high-resolution gamma-ray spectrometry measurements. This work presents activation measurements and inventory calculations for ITER-relevant materials irradiated during JET DT operations. The investigated specimens are representative of materials foreseen for ITER components, including stainless steels, EUROFER97, tungsten, Al-bronze and other structural materials, together with Ni, Ti and Fe dosimetry foils. Activities of neutron-induced radionuclides were determined by gamma-ray spectrometry at IPPLM and compared with predictions obtained using the FISPACT-II inventory code, based on neutron yields measured by the JET KN1 fission chambers and neutron spectra calculated with a high-fidelity MCNP model of the JET device. The calculated-to-experimental (C/E) ratios obtained for activation products from both the DTE2 and DTE3 campaigns demonstrate overall satisfactory agreement between simulations and measurements. A comparison of the two campaigns was performed to identify systematic deviations and assess the reproducibility of activation results. In addition, selected samples were analysed independently at IPPLM and the Institute of Nuclear Physics (IFJ), enabling an inter-laboratory comparison of measured activities and an assessment of measurement consistency. The combined analysis of the DTE2 and DTE3 activation data provides valuable insight into the reliability of activation prediction methodologies for fusion applications. The observed discrepancies for selected radionuclides indicate possible effects of unreported impurities, uncertainties in material characterization, or limitations in inventory simulations and nuclear data. These results contribute to improving activation assessment methodologies and increasing confidence in activation predictions required for ITER and future fusion power plants.