An overview of molten salt reactor research experiments at NRG PALLAS

• Published in: Nuclear engineering and design Vol. 442; p. 114241
• Main Authors: de Visser – Týnová, Eva, Hania, Ralph, Laot, Mathilde, Kottrup, Konstantin, Naziris, Frideriki, Uitslag-Doolaard, Heleen, Visser, Dirk, Zwijsen, Kevin
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.10.2025
• Subjects: Irradiation; Molten salt; Nuclear waste; Post-irradiation examination; Radiolysis; Structural materials; Irradiation; Radiolysis; Structural materials; Post-irradiation examination; Nuclear waste; Molten salt
• ISSN: 0029-5493
• DOI: 10.1016/j.nucengdes.2025.114241

•NRG PALLAS conducts a comprehensive research program on MSR related materials.•Irradiation experiment of MSR fuel salt has been realized in the HFR, including PIE.•Irradiation experiment of nickel-based alloys has been done, PIE is ongoing.•New irradiation experiments on MSR fuel salt and materials are being prepared. NRG PALLAS conducts a comprehensive research program on molten salt reactor related materials, including both molten salts and structural materials. After decades of low activity on the subject, a new irradiation experiment of molten fluoride fuel salt has been realized in the HFR in Petten, including post-irradiation examination of the salt and its interaction with graphite. In addition, an irradiation experiment of nickel-based alloys foreseen to be used for structural and/or piping use in MSR systems for their high resistance to corrosion and temperature has been performed to study the effects of helium production on its mechanical and physical properties, as well as gamma irradiation of fuel salt samples to investigate radiolytic gas production; the latter was identified as a risk during the preparation of molten salt irradiations, and becoming relevant in cases where radioactive salt cools down to near room temperature, such as salt spills or during storage of spent fuel. Two additional irradiation experiments are in preparation: a molten salt capsule irradiation to study the in-pile corrosion rate of Hastelloy N depending on salt chemistry and the characterization of the behaviour and migration of fission products; and a structural materials irradiation to assess mechanical performance, focussing on in-pile measurement of creep behaviour. Finally, suitable methods for handling new types of radioactive waste are being set up to allow the disposal of these materials in the Dutch waste repository. This paper gives an overview of the experiments, the post-irradiation examinations and a description of planned work.