Office for Nuclear Regulation

Sellafield – Inspection ID: 50133

Executive summary

Date(s) of inspection:

  • September 2022

Aim of inspection

In accordance with the Office for Nuclear Regulation’s (ONR’s) Sellafield Strategy, each year ONR performs a series of planned compliance inspections of selected licence conditions, targeted at those facilities with significant importance to nuclear safety. One such inspection was performed to assess the Special Nuclear Materials (SNM) Value Stream’s compliance with Sellafield Limited’s corporate arrangements for Licence Condition (LC) 35 (Decommissioning).

The purpose of this intervention was for ONR to inspect the adequacy of implementation of the licensee’s formal arrangements for compliance with Licence Condition (LC) 35 (decommissioning) by the SNM Value Stream. This inspection covered both SNM North (N) and SNM South (S). The overall adequacy of the licensee’s formal arrangements has been considered separately in another ONR intervention.

Subject(s) of inspection

  • LC35 – Decommissioning – Rating – Green

Key findings, inspector’s opinions and reasons for judgement made

I saw evidence that SNM were implementing corporate arrangements for Planning, Preparing, and Delivering Post Operational Clean Out (POCO). Finishing Line 5 is due to enter POCO in 2023. For the first work package, I saw evidence that SNM had an adequate POCO delivery schedule, and were appropriately following the arrangements with regard to the POCO readiness self-assessment activities. Assurance was provided that the Sellafield Limited Nuclear Independent Oversight are being engaged, and that they were preparing to undertake a readiness review in-line with corporate arrangements.

Finishing Line 6 and the Sellafield Mixed Oxide Plant (MOX) are currently being subject to POCO. A Sellafield Limited  representative explained the process he was currently undertaking to review the Preliminary Decommissioning Plans for FL6 and SMP. This included reviewing the proposed end states, and checking that the revised timescales align with the plans for availability of strategic waste streams. I was content with the approach.

SNM now have an overarching POCO strategy that covers all facilities. Assurance was provided that SNM are planning POCO for the other areas on a prioritised basis which involves assessment by the relevant System Engineers.

I found that the Sellafield Limited personnel involved in the inspection demonstrated a sound knowledge of the corporate requirements for LC35. SNM explained that personnel resources remain a challenge for SNM POCO preparations.  A SNM Senior Operations Manager stated that he was undertaking a strategic review of SNM POCO to take account of operational constraints including resource.  This review was intended to ensure that resources were appropriately prioritised. He noted that a POCO lead for SNM(S) has been appointed and will join the team in January 2023. I found no evidence that the resource challenges were preventing SNM complying with the LC35 corporate arrangements.  However, this is an area where SNM need to remain vigilant.


On the basis of the evidence sampled at the time of the inspection, I judge that Sellafield Limited has adequately implemented its arrangements for LC35 in the SNM Value Stream. Noting the ONR guidance on inspection ratings, it is my opinion that an inspection rating of Green (no formal action) is appropriate.