Office for Nuclear Regulation

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Sellafield - Essential Operations Inspection of MSSS Emergency Preparedness for Installation of the SEP Machines - Follow Up

Executive summary

Purpose of intervention

The current ONR regulatory strategy for Sellafield Ltd (SL) is focussed on stimulating, facilitating and expediting hazard and risk reduction.  ONR has a number of planned interventions in place to ensure hazard and risk reduction activities are delivered safely.

There are also a number of supporting functions at site that play a key role in delivery of hazard and risk reduction.  These would not normally warrant attention from ONR on the basis of their low off-site consequence, but ONR is keen that such functions have sufficient reliability and resilience such that they do not have the potential to prevent hazard and risk reduction at the earliest possible opportunity.

The intervention reported in this record is one of a series of ‘essential operations inspections’ designed to provide ONR with confidence that such functions can adequately facilitate sustained hazard and risk reduction. 

Interventions Carried Out by ONR

This inspection was a follow-up to an essential operations inspection undertaken during July 2015.  Similarly to the previous inspection, it focussed specifically on SL’s capability to respond to possible loss of containment events that may arise from the installation and inactive commissioning of the Silo Emptying Plant (SEP) machines in the Magnox Swarf Storage Silo (MSSS); in particular on the potential impact to sustained retrievals operations and therefore continued hazard and risk reduction.  I sought to gain practical confirmation that the learning points identified during July had been addressed by SL.

The inspection was undertaken at the Sellafield site on 10 September 2015.  I was supported by the ONR Project Inspector and the Environment Agency Inspector for the MSSS facility. 

Explanation of Judgement if Safety System Not Judged to be Adequate

This was not a system based inspection.

Key Findings, Inspector's Opinions and Reasons for Judgements Made

I was encouraged to note that SL has considered and addressed the learning points identified during the July inspection.

I judge that SL’s investigation into the incomplete training records identified during the July inspection has been thorough and completed in a timely manner, resulting in implementation of an improved process.

Further confidence was gained in SL’s emergency response capability via observation of an evaluated training exercise, during which I was able to observe use of the test wall/rig that is used to simulate leaks resultant from a loss of containment.  I judge that the training appeared useful to all involved, however I requested that SL consider whether further realism should be introduced into future exercises.

Based on my concerns regarding the potential impact of contradictory emergency response information, SL committed to consider consistency and compatibility with the ‘Severe Accident Management Strategy for Loss of Containment’ as part of the ‘Emergency Guidance Instruction for Response to a Breach of Silo’ review later this year.

Learning points were discussed with SL, however I judge that they have insignificant impact on nuclear safety and so no regulatory issues or actions have been raised. 

Conclusion of Intervention

From the evidence sampled, I have gained further confidence and judge that SL’s emergency response capability in the event of a loss of containment from MSSS during the installation and inactive commissioning of the SEP machines is adequate and proportionate to the risks identified in the safety case.  I judge that the capability is suitable and sufficient to support sustained retrievals operations, and therefore facilitate continued hazard and risk reduction.