Office for Nuclear Regulation

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Sellafield – MRSP Regulatory Strategy Implementation

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.

The Magnox Reprocessing Separation Plant (MRSP) has an important role within the UK nuclear industry until circa 2020, as it supports a number of UK national risk and hazard reduction programmes, including the UK Magnox Operating Programme (UK MOP).  If the MRSP is not available to reprocess spent Magnox fuel, there would be significant knock-on effects on a number of other nuclear facilities which would result in safety and security issues.  Continued operation of the MRSP is fundamental to on-going risk and hazard reduction on the Sellafield site.

In June 2015 ONR issued an Improvement Notice (IN) in relation to LC24 ‘Operating Instruction’ breaches related to poor conduct of operations over the previous 14 months.  Since the IN was served there have been further conduct of operations related events reported at the MRSP. 

In July 2015 ONR approved a revised regulatory strategy for the MRSP which recognised the strategic importance of the plant, the age (and design) of the plant, and the conduct of operations related events that continue to occur. A key aspect of this strategy is to inspect parts of the reprocessing process targeting the area’s most important to nuclear safety.

This record reports the first of a set of interventions, currently planned to take place between October 2015 and March 2016, as part of the new approach to support the future implementation of the strategy.   

Interventions Carried Out by ONR

This inspection is the first of a set of interventions required to implement the MRSP regulatory strategy that has been approved by ONR in July. It was also identified to familiarise myself with the facility, its processes and people in preparation to support future inspections.

The sample of this particular inspection was focused on the primary separation cycle of the facility. The implementation of the Licensee’s arrangements for the following LCs was tested during the inspection:

The inspection was undertaken at the Sellafield site on 15 - 17 September 2015.

Explanation of Judgement if Safety System Not Judged to be Adequate

This was not a system based inspection, however the future inspections will be.

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

For the primary separation (PS1 & PS2) cycle of the Magnox Reprocessing Plant:

LC23:  I confirmed that the safety case specifies limits and conditions with respect to primary separation, and that these limits and conditions are specified in operating and alarm response instructions. I identified that the one of the operating rules sampled did not have a direct measurement; however the compliance activity identified suitable surrogate measures. The facility confirmed that review of both Operating Rules and Operating Assumptions had been identified to improve the clarity of the safety limits and conditions for the operators.  

I confirmed that a sample of operating assumptions in the safety case was captured in operating instructions. I identified that a couple of the operating assumptions reflected historic operational practices, through discussion with the facility I ensured that the nuclear safety intent of the operating assumptions were being met.

The facility recognised the issue and stated that the Operating Assumptions are statements of understanding on operational practice at the time and if they no longer reflect operational practice, then there will be scope for the OA’s to be reviewed, amended, or withdrawn from the safety case as appropriate.

Based on my sampling inspection, I identified procedural weaknesses which could affect clarity of the limits and conditions to operators; however I judged from my discussions with the facility that the nuclear safety intent was being met and well understood in primary separation cycle. The areas identified will be followed up in subsequent system based inspections.

LC24: I sampled a range of operating instructions, maintenance instructions and alarm response instructions associated with primary separation cycle.  I judged that the written instructions sampled were clear and did relate to ensuring compliance with the limits and conditions derived from the safety case.

The plant explained the current programme of work underway to improve instructions as a result of the Improvement Notice issued and SL own internal assurance programme, over the period of implementing the new regulatory strategy we should see improvements in instructions coming to fruition.

LC27: I sampled a number of key Safety Mechanisms (SMs) from the primary separation cycle.  Based on my sample, there are suitable and sufficient SMs for this system, they are being inspected and are reported in good working order.  When individual SMs were not available I confirmed appropriate substitution arrangements were in place, where evident in the clearance certificate and had clear responsibilities for enacting substitution arrangements.

LC28: I sampled the maintenance schedule, maintenance instructions and maintenance records for key components of the system and found a maintenance anomaly with an aspect of the sample. This related to clarity between the maintenance instruction and the actual maintenance being carried out. The facility were able to show that this particular SM was delivering its safety functionality and that if this failed then it would be revealed and could not lead to any cliff edge effects.

This sample highlighted previously identified issues with instructions and in this instance it was found to be ambiguous requiring clarification and confirmations from the facility. This will be followed up in subsequent inspections, and a judgement made on the best prioritisation of improvements for nuclear safety impact with the facility.

Conclusion of Intervention

From carrying out this inspection, I have identified with the facility a useable and effective framework for our future interventions. I have identified some procedural weaknesses which the facility have reacted positively to and with the facility I have determined the nuclear safety intent is being met consistently within the primary separation cycle sampled. The weaknesses identified from this and future inspections will need to be considered with the facility taking into consideration the totality of improvements currently being undertaken by the facility to confirm that the highest nuclear safety priority is being adequately addressed, this will be a key part of implementing the new regulatory strategy.