In the "hot room" of the spent fuel reprocessing plant a spent fuel assembly was being prepared for grinding and loading into the dissolver. During the chopping of the lower end plug an electric arc was formed at the place of installation of the "static" clamp of the fuel assembly jacket tube. Personnel stopped the chopping process and switched off the chopping machine.
The electrical arc caused local burning in the fuel assembly jacket tube and thermal damage to several fuel elements. As a result, the concentration of radioactive substances rose in the "hot room", leading to increased releases of radioactive aerosols into the atmosphere through the ventilation and filtration system (4.36% of the maximum permissible release for Cs 137).
There was no exposure of personnel, nor contamination of the plant's operational area or of the environment above authorized limits.
After an analysis of the causes of the event at the chopping machine corrective action was taken in order to preclude recurrence of such incidents.
Event date: Wed, 31-08-1994