A statement on incidents at nuclear installations in Britain which meet Ministerial reporting criteria is reported to the Secretary of State for Trade and Industry and the Secretary of State for Scotland and is published every quarter by the Health and Safety Executive.
For the period 1 October 2005 to 31 December 2005 there was 1 incident at a nuclear licensed installation that met the reporting criteria.
On 4 December 2005, British Nuclear Group Sellafield Ltd, (BNGSL), the licensee, detected high levels of radiation in some outcell areas of the Highly Active Liquor Evaporation and Storage (HALES) facility. This occurred during a routine operation to sample highly active liquor.
The operation was stopped. Operators evacuated the building safely and quickly in accordance with instructions. Controlled re-entries into the building were then carried out to define the scope of the problem and put in place appropriate contingency controls and recovery plans.
There was no loss of primary containment and no environmental effects were found inside or external to the building. Restrictions were placed on the use of an adjacent building because of high background radiation levels but were later removed on successful completion of the recovery plans.
Three operators carried out the sampling operation. They received radiation doses, which were elevated though well within legal limits.
The source of the high radiation was traced to a small diameter wash line feeding the sampling plant. The line has since been cleared, restoring normal operating conditions except to local areas where some access restrictions remain.
HSE's NII has conducted a preliminary investigation and BNGSL is conducting its own internal investigation. The root cause of the incident has not yet been established but on the basis of its own investigation, BNGSL has already recognised the need to improve its approach to learning from experience in HALES. NII will await completion of BNGSL's investigation before deciding whether enforcement action is warranted.
NIl will seek engineered improvements to ensure the safety of future sampling operations.
Single copies of statements are available free from the Health and Safety Executive, Nuclear Directorate, Division 4a, Building 4 NG1, Redgrave Court, Merton Road, Bootle, L20 7HS,