Further update on the Thorp Feed Clarification Cell
British Nuclear Group has today published the full Board of Inquiry report into the fractured pipe in the Feed Clarification Cell in Thorp.
The incident, which we first reported nine weeks ago, has highlighted several areas where improvements are needed. These are comprehensively dealt with in the report. Barry Snelson, Managing Director at Sellafield said: “By their very nature Boards of Inquiry seek to get to the root cause of an incident. The report produced is written in a no-nonsense style, to ensure that we learn real lessons from whatever has happened. We will systematically address and resolve every issue raised in this report. There is no room for complacency in our industry and I will personally be ensuring that these recommendations are implemented in Thorp and across Sellafield.”
A CCTV camera inspection on 19 April identified that approximately 83m3 of liquor had escaped through a fracture in the pipe feeding one of the accountancy tanks into the secondary containment of a purpose built, thick walled concrete cell lined with stainless steel.
The secondary containment is specifically designed for failure of primary containment releasing liquid in quantities significantly greater than in this event. It is fitted with engineered systems to pump liquid from the cell floor back into primary containment tanks within the cell. The event caused no harm to any individuals and did not release any radioactivity to the environment.
The situation within the cell remains safe and secure and the recovery of all liquid back into primary containment was completed two weeks ago. We have successfully accounted for all of the material on the floor of the cell and have been able to focus our attention on finalising the best repair option and working to implement the recommendations of the Board of Inquiry report.
The repair options presented by the engineering team have been independently reviewed on behalf of the NDA. The review was supportive of our optioneering for repair, and dialogue with the NDA and regulators to select and act upon one option is continuing. We are confident that we have the capability to return Thorp to service.
Work to address the eighteen recommendations in the Board of Inquiry report has been given the highest priority and a dedicated project team under the supervision of a senior manager and ultimately accountable to Barry Snelson, Managing Director, Sellafield, has been established to quickly but methodically implement the recommendations.
Eleven of the recommendations principally address the issues relating to cell instrumentation (which would indicate a plant abnormality) and the operating practices within the plant. Most of these are applicable only to Thorp and will need to be progressed before the plant can be returned to normal service.
Four of the recommendations address metal fatigue assessments and design issues and are applicable across other parts of Sellafield. These will be completed as soon as possible but no later than the timescales indicated in the report, the longest of which is by the end of this year.
The project team has developed an integrated recovery plan which addresses the recommendations. Workstreams associated with this plan are complete. Good progress is being made against the individual recommendations.
As a result of the Inquiry’s findings, British Nuclear Group has instigated further reviews aimed at ensuring that the learning from this event is fully embedded across the organisation and that any wider implications are picked up and fully addressed.
British Nuclear Group Chief Executive Lawrie Haynes will chair a comprehensive review of safety at Sellafield to reaffirm confidence in the integrity of safety management and control and supervision of operations across the site. The review will include expert representation from across the BNFL Group including Paul Thomas, Director of Environment, Health, Safety and Quality and Director of Technology Sue Ion. Additionally, Sellafield Production Director John Clarke will chair a root and branch management review to examine in detail the performance of Sellafield’s management team in response to the entire event.
Alongside these reviews and the board of inquiry report published today, the Nuclear Installation Inspectorate has conducted its own review of the event and has concluded its preliminary investigations. As a result of the NII’s investigations, we have received two improvement notices, the first relating to leak detection equipment and the second to operating instructions relating to the use of this equipment and the response to alarms. The NII are progressing with further investigations which will continue for a number of weeks.