EPJ Web of Conferences 253, 03005 (2021)
https://doi.org/10.1051/epjconf/202125303005

Long Term Neutron Activation in JET DD Operation

¹ Reactor Physics Department, Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia
² University of Ljubljana, Faculty of Mathematics and Physics, Jamova cesta 19, 1000 Ljubljana, Slovenia
³ Department of Fusion and Technologies of Nuclear Safety and Security, ENEA C. R. Frascati, via E. Fermi 45, 00044 Frascati (Roma), Italy
⁴ Department of Physics and Astronomy, Uppsala University, Box 516, SE-75120 Uppsala, Sweden
⁵ The Henryk Niewodniczanski Institute of Nuclear Physics (IFJ PAN), Polish Academy of Sciences, 31-342 Kraków, Poland
⁶ United Kingdom Atomic Energy Authority, Culham Centre for Fusion Energy, Culham Science Centre, Abingdon, Oxon OX14 3DB, UK
⁷ INRASTES, NCSR ‘Demokritos’ 153 10, Agia Paraskevi Attikis, Greece

andrej.zohar@ijs.si
^* See the author list of ‘Overview of JET results for optimising ITER operation’ by J. Mailloux et al. to be published in Nuclear Fusion Special issue: Overview and Summary Papers from the 28th Fusion Energy Conference (Nice, France, 10-15 May 2021)”

Published online: 19 November 2021

Abstract

In the 2019 C38 Deuterium-Deuterium campaign at JET several different ITER-relevant materials and dosimetry foils were irradiated in a specially designed long-term irradiation station located inside the vacuum vessel with the purpose of testing the activation of ITER materials by fusion neutrons. The samples were exposed to a neutron fluence of 1.9E14 n/cm² during JET discharges performed in the experimental campaign over a period of 5 months. Gamma ray spectroscopy measurements were performed on irradiated samples to determine the activation of different long-lived isotopes in the samples. Monte Carlo computational analysis was performed to support the experiment by using the measured neutron yield and irradiation time. In this paper we focus on the computational analysis of the dosimetry foils that are used in order to measure the local neutron energy spectrum and flux. The foils were chosen to cover different neutron energies: thus Yttrium and some of the Nickel and Cobalt reactions were used to determine the Deuterium-Tritium fusion fraction, while Scandium and Iron and some of the Nickel and Cobalt reactions were used for comparison of the computed activity with the experimental measurements. The obtained C/E values show a reasonably good agreement between calculated and measured activity, thus validating the computational methodology and providing the basis for the analysis of the ITER-relevant materials and future experiments performed at JET in the Deuterium-Tritium campaign.