Office for Nuclear Regulation

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

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 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.  As such, I sought to gain practical confirmation of the availability, reliability, maintenance and testing of SL’s emergency preparedness capability.

The inspection was undertaken at the Sellafield site from 29 – 30 July 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 continued hazard and risk reduction in their decision making processes.  In particular, given the intolerable and increasing risk from MSSS, ONR is supportive of the site strategic decision to continue retrievals following a loss of containment, provided that SL can demonstrate that the risk is As Low As Reasonably Practicable. 

It was clear that all key stakeholders were well informed of the available emergency response capability and that good communications and positive interfaces had been established and maintained. 

Confidence was gained in SL’s emergency response equipment capability, in terms of the quantity and range of equipment itself, the storage regime, maintenance, testing and the suite of associated documentation.  I was encouraged that although the safety case claims the likelihood of above ground leaks to be negligible, SL had considered the ‘what if’ scenarios and were exercising them in-location.

I judged that the development and implementation of the 5 year rolling plan of realistic exercise drills was an example of good practice.  In particular, it is valuable that the actual emergency response equipment is being used in terms of testing and increasing operator familiarisation.  I encouraged SL to share this plan more widely with key stakeholders, in particular because it would be useful to observe training drills as part of regulatory permissioning activities.

This inspection identified a number of learning points, which are described in the main body of this record.  These 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.  These learning points may be followed up during a further inspection planned for September 2015 in support of permissioning the installation and inactive commissioning of the SEP machines.

Conclusion of Intervention

From the evidence sampled, I 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.