Office for Nuclear Regulation

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Sellafield - Essential Operations Inspection - Magnox Operating Programme

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.

Any facility or operation with potential for off-site consequence would attract ONR attention on a proportionate basis. However there are a number of supporting functions at the site that play a key role in delivery of hazard and risk reduction. These would not normally warrant prioritised attention from ONR, nonetheless 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 activities at the earliest opportunity.

The intervention reported in this record is one of a series of 'essential operations inspections' in accordance with ONR's Sellafield programme strategy. These interventions are designed to provide ONR with confidence that such supporting functions can safely and adequately facilitate sustained hazard and risk reduction activities.

This intervention sampled 3 areas: Magnox Encapsulation Plant (MEP), B211 Buffer Storage Tanks, and B303 Salt Evaporator Plant that support the Magnox Operating Programme (MOP), which is an ONR prioritised hazard and risk reduction activity on the Sellafield site. I sought to gain practical confirmation of the availability and reliability of these supporting functions to the MOP.

Interventions Carried Out by ONR

The inspection focused upon the MEP, B303 and B211 facilities resilience to provide a continuity of support to the MOP which is an ONR prioritised hazard and risk reduction activity. As such, discussion and inquiries sampled aspects pertaining to licence conditions LC25 "Operational Records", LC28 "Examination, inspection, maintenance and testing" and Safety Assessment Principle EDR.2 "Redundancy, diversity and segregation" as well as general assessment of supply chain resilience.

The inspection was undertaken at the Sellafield site on the 22nd March 2017 and comprised desktop based discussions and a facility inspection.

Explanation of Judgement if Safety System Not Judged to be Adequate

N/A - This was not a safety system inspection.

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

At the end of the inspection I provided the following summary of my key inspection observations and regulatory judgements:


The MEP process has sufficient capacity to process MOP swarf arisings.

Processes are being reviewed and opportunities for improvement have been identified including condition monitoring of the drum vibrator, changes to drum surface finish requirements and stillage construction technique.

System Health Reports (SHRs) have been drafted but not approved in accordance with internal governance arrangements. SHRs are key to demonstrating a systematic approach to understanding facility condition, monitoring process trends and where relevant identifying remedial or preventative actions. I consider it appropriate that ONR revisits MEP to confirm that SHRs are actively being utilised to assess plant condition and bring about plant improvements where required.

Reorder points and stock holdings for encapsulation powders should be reviewed to optimise availability. The licensee has agreed to undertake this review.

A number of plant indications and process controls within MEP are supported by instrument air. The licensee indicated that it is considering restoration of the local LP air compressor within the Waste Encapsulation Plant (WEP) facilities, thereby reducing reliance on site air. This restoration I consider to be a practical opportunity to improve process resilience and is thereby supported.


The licensee has scheduled two improvement programmes that are currently immature in their development; the reinstatement of B303 evaporator A and the reinstatement of design intent of the Wastwater pipeline. Both these programmes will improve process resilience and therefore I consider it appropriate for ONR to monitor progress to the implementation stage.

Maintenance of B211 tank ullage space to receive liquor from MOP at the B211 facility is important to maintaining a receipt capability, such that MOP processes remain unhindered and inspection of the plant control room confirmed available ullage space was available. The continued adequacy of the administration controls that maintain this capability will be reviewed during routine inspection follow up activities.

Conclusion of Intervention

The facilities are aged and towards the end of their operational phase. With the MOP coming to an end in 2020, the importance of understanding plant condition and implementing an appropriate EIMT regime dominate considerations in terms maintaining or improving process resilience. A key document in demonstrating this understanding is the facility System Health Report. In this respect MEP appears to lag other facilities at SL in the generation of SHRs. It is for this reason that I have raised a Regulatory Issue to monitor the management of the drafted MEP SHRs and the implementation of recommendations contained therein.

For both the MEP and B303/B211 facilities there was evidence of resilience considerations having been made such as the upgrading of steam services, and introducing real time plant condition monitoring to MEP drum vibration plant and the B211 roof structure. However there were a number of improvement plans that have been identified by the licensee, which will improve process resilience and reliability but were considered immature at the time of inspection. I consider it proportionate to monitor the licensee's progress in delivering these plans. This will be undertaken as actions under a Regulatory Issue.