EXPERIMENTAL VALIDATION OF NUCLEAR REACTION DATA FOR INVENTORY SIMULATIONS ON MOLYBDENUM

Culham Centre for Fusion Energy, UKAEA, Culham Science centre, Abingdon, Oxfordshire, UK, OX14 3DB

mark.gilbert@ukaea.uk
lee.packer@ukaea.uk
thomas.stainer@ukaea.uk

Published online: 22 February 2021

Abstract

Molybdenum is being considered as a potential material for future nuclear fusion experiments and power plants. It has good thermo-mechanical properties and can be easily fabricated, making it attractive as an alternative first wall material to tungsten, which is the current leading candidate. Unfortunately, according to simulations, fusion-neutron irradiated Mo may become too activated during reactor operation to maintain the objective of fusion of avoiding the generation of long-term, higher-level radioactive waste.

However, these simulated predictions rely heavily on having high-quality, accurate nuclear reaction data. For example, reliable simulations of the radiological response of isotopically-tailored Mo would be required by reactor designers and eventually nuclear regulators to assess if it is a viable low-activation fusion solution (in comparison to pure Mo). In recent years, UKAEA has developed benchmarks to test and validate the FISPACT-II inventory code and the input international nuclear data libraries against experimental measurements. This paper presents nuclear code prediction comparisons to new data acquired from γ-spectroscopy measurements of Mo irradiated in the ASP 14 MeV facility at AWE in the UK.

Results demonstrate that FISPACT-II predictions for Mo are remarkably accurate; particularly for activity generated from the shorter-lived radionuclides explored by these laboratory experiments, such as ⁹¹Mo and ⁹⁷Nb, etc., and their metastable isomeric states.