On Tuesday 7 October, Dounreay Site Restoration Limited (DSRL) notified SEPA about a small fire that had occurred in the sodium tank farm at the Prototype Fast Reactor facility and was subsequently extinguished by the on-site fire brigade. Sodium, which is tritium contaminated, is being removed as part of site decommissioning.
SEPA has investigated the circumstances surrounding the decommissioning work being undertaken in the sodium tank at the time and, having looked at the highest estimate of the amount of tritium released, and environmental monitoring results, we consider the environmental impact to be very low. We are confident that there has been no risk to the public or the environment as a result of any potential release. It is important to note that any such release is unplanned, and therefore, unauthorised. As such, these releases are not monitored and so we have based our assessment of environmental impact on a worst case release of tritium.
Although the environmental impact of the discharge is considered to be very low, SEPA’s investigation identified numerous failings in the arrangements in place for controlling radioactive gaseous waste during such work. As a result we have issued a Notice of Variation to include the requirement for DSRL to undertake a range of improvements within its authorisation for the disposal of radioactive waste. These improvements relate to the design and testing of temporary containment and ventilation systems and to the management and supervision of decommissioning activities. DSRL are required to complete the various improvements between 1 March 2015 and 1 June 2015.