Complex reactions occur between the compounds used for the treatment of spent fuel. They can lead, under certain conditions, to the formation of unstable compounds known as "red oils". At some point, there is a danger of thermal runaway and explosions like in the Savannah River reprocessing plant (USA) in 1953 and in the Tomsk-7 industrial complex (Russia) in 1993.
In 2017, IRSN will complete a research program to understand in depth the thermal runaway phenomena and the parameters leading to it. The research program aims to define appropriate operating procedures to prevent the phenomena. It also seeks to improve safety provisions used to control this type of risk.
Since its start in 2012, the program is also supported by Areva NC, the operator of the spent fuel reprocessing plants in La Hague in Normandy, and the public government-funded research organization CEA.
First results in the research program led to recommendations issued by IRSN during the safety review for the UP3 spent fuel reprocessing plant in La Hague (Report in French).
The Institute has requested that risk analysis be supplemented by taking into account accident situations associated with red oils. For its part, Areva proposed to improve the procedures in existing fission product concentration units as well as technical changes for future units.
IRSN also develops a simulation tool named “ALAMBIC” intended to model red oils phenomena. The parameters used in this tool will be validated with data obtained with the current research program.
Read more :
Read the technical note of IRSN about “Risks of explosion associated with "red oils" in reprocessing plants” (June 2008)