Construction of a gas-mixing and analysis facility for fission gas release and analysis studies.

The formation of fission gases in the fuel during operation and their rate of release to the grain boundaries and hence to the plenum is a major feature that can limit the linear power rating of the fuel and the duration of a reactor’s continuous operation. Much attention has been given to investigating the mechanisms of fission gas accumulation in the fuel matrix and its gradual collection into bubbles, both within the grains and at grain boundaries and how to maximize its retention in the fuel matrix. Considerable work has been done at JRC-ITU and elsewhere looking at the mechanisms and irradiated fuel history effects on fission gas retention/release from the fuel. The current concern for commercial reactors is particularly about fission gas behaviour for MOX or high burn-up UO2 under operating power transients. Gradual accumulation in the rod free volume would increase the internal rod pressure and may ultimately induce cladding rupture. In extreme cases, such as power transients or accident conditions, sudden fission gas release can result in multiple rods failure and release of fission gas and other volatile fission products to the primary water circuit, forcing reactor shut down. This paper will look at the construction and preliminary testing at JRC-ITU of a gas-mixing facility and its analytical devices (mass spectrometer, cold traps and gamma spectrometers) along with its connection to a high temperature furnace in view of new campaigns to assess fission gas behaviour during off-normal conditions from commercial or innovative nuclear fuels.

FONTANA Ernesto;  BOTTOMLEY Paul;  RONDINELLA Vincenzo; 

2017-01-11

SCK CEN

JRC96618

http://science.sckcen.be/en/Events/HOTLAB-2015-20150927-20151001-b5e94ad823a6e411b9ec00155d010700,    https://publications.jrc.ec.europa.eu/repository/handle/JRC96618,