Caesium and iodine release from spent mixed oxide fuels under repository relevant conditions: Initial leaching results

Christian Schreinemachers; Gregory Leinders; Thierry Mennecart; Christelle Cachoir; Karel Lemmens; Marc Verwerft; Felix Brandt; Guido Deissmann; Giuseppe Modolo; Dirk Bosbach

doi:10.1557/s43580-022-00220-7

Caesium and iodine release from spent mixed oxide fuels under repository relevant conditions: Initial leaching results

MRS Adv. 2022;7(5-6):100-104. doi: 10.1557/s43580-022-00220-7. Epub 2022 Feb 9.

Affiliations

¹ Forschungszentrum Jülich GmbH, Institute of Energy and Climate Research, IEK-6: Nuclear Waste Management and Reactor Safety, 52425 Jülich, Germany.
² Belgian Nuclear Research Centre (SCK CEN), Institute for Nuclear Materials Science, Boeretang 200, 2400 Mol, Belgium.
³ Belgian Nuclear Research Centre (SCK CEN), Institute for Environment, Health and Safety, Boeretang 200, 2400 Mol, Belgium.

Abstract

Autoclave leaching experiments are conducted on three well-characterised, irradiated, and cladded mixed oxide fuel-rod segments with burnups ranging from 29 GWd/t_HM to 52 GWd/t_HM to investigate the instant release fraction of fission gases and long-lived fission products and to assess the long-term fuel matrix corrosion. The segments are exposed to bicarbonate solutions as reference groundwater at neutral pH and a synthetic young cementitious water at pH 13.5 under reducing atmosphere (4 vol% H₂ in Ar at 40 bar pressure), since 2018. The initial leaching results for the fission products caesium and iodine as representative elements of the instant release fraction were found to depend on the leachate composition as well as on the fuel burnup.