Office for Nuclear Regulation

This website uses non-intrusive cookies to improve your user experience. You can visit our cookie privacy page for more information.

Planned joint (with EA) licence compliance inspection covering LC35; Decommissioning – focussing on the preparations for Post Operational Clean Out (POCO) in the THORP Facility

Executive summary

Purpose of intervention

In accordance with the Office for Nuclear Regulation’s (ONR’s) Sellafield Strategy, each year ONR performs a series of planned compliance inspections of core licence conditions, targeting those facilities with the potential to give rise to off-site effects to the public.

This planned, core licence condition inspection was performed to assess Sellafield Ltd.’s (SL’s) compliance with Licence Condition (LC) 35 (Decommissioning) in the Thermal Oxide Reprocessing Plant (THORP).  LC35 requires the licensee to make and implement adequate arrangements for the decommissioning of any plant or process that may affect safety, and to make arrangements for the production and implementation of decommissioning programmes.

This inspection focused on the adequacy of THORP’s preparations for Post Operational Clean Out (POCO).  THORP will be SL’s first major plant to enter POCO when reprocessing operations are currently expected cease in 2018. POCO is a key enabler for safe plant decommissioning and is addressed within SL’s arrangements for compliance with LC35. 

Interventions Carried Out by ONR

A team comprising the THORP site inspector, a specialist inspector in nuclear liabilities regulation (ONR’s SL POCO lead) and a specialist inspector in operational inspection carried out a one day planned compliance inspection against LC 35 Decommissioning utilising the following ONR inspection guidance:

In addition, the THORP site inspector carried out a number of information sharing sessions with senior members of the THORP management team. These are not covered further in this Executive Summary.

Explanation of Judgement if Safety System Not Judged to be Adequate

N/A as this was not a safety systems inspection.

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

LC 35 Decommissioning

I noted that THORP is currently developing a systematic and structured approach to planning POCO tasks for those parts of the plant due to enter POCO at the end of reprocessing operations.  We recognise that the work is at a relatively early stage of development but we are broadly content with the approach being taken and the progress made to date. 

THORP is starting to implement the principles and strategies for POCO established at a site programme level.  It is my opinion that there is good recognition of the need to remove radioactive inventory and reduce risks to reach a defined “end-state” at the end of POCO preparations and to record the information needed to document the end-state achieved.  This will be of benefit in reducing the risks associated with future decommissioning of the plant.

We are encouraged by a number of aspects of the work reported to us during the inspection. These include the involvement of a representative from the Site Remediation and Waste Management Directorate (SRWM) to provide expertise and advice on decommissioning in the end-state definition process and the transition from POCO to subsequent Surveillance and Maintenance.  It is my opinion that the THORP team understands the importance of characterisation, knowledge management and asset care for both POCO and subsequent decommissioning phases.  Aspects of the design of THORP will be of benefit in facilitating POCO.  I recognise that SL has taken account of learning from experience and undertaken benchmarking both nationally and internationally in developing its strategy and plans for POCO.

Conclusion of Intervention

LC 35 Decommissioning – Preparations for POCO

Whilst the THORP POCO team was able to demonstrate commendable progress utilising a structured and systematic approach to POCO preparations, which potentially would merit an IIS rating of 2 (good), it has, as yet, not formally documented some of these processes. Consequently, on the basis of the evidence gathered and examined during the inspection we consider an IIS rating for LC35 of 3 (adequate) to be appropriate. I have not raised any Regulatory Issues as a result of this intervention.

Whilst we acknowledge that THORP is leading the development of some of the approaches to POCO at Sellafield and that some processes remain in development, we consider it important that THORP formally documents the processes when they are sufficiently mature, which we consider is currently the case. This will ensure that their learning is effectively collated and available for promulgation around the SL site and that future revisions and updates are effectively controlled.  

We consider SL’s proposal to change the site POCO programme’s role from owning and developing strategies to one of “oversight and support”, with POCO ownership of delivery      resting with the plants, represents a potential risk to successful, coordinated and coherent POCO across the site.  Consequently, we believe it is important that SL is able to appropriately demonstrate that the strategic, site level POCO roles and responsibilities are appropriately captured and resourced in order to ensure the effective implementation and coordination of POCO at a site level.  In particular, it is our opinion that it is particularly important that there is adequate integration of the planning and implementation of POCO between the reprocessing plants and those involved in downstream waste management to ensure that wastes arising during POCO are managed appropriately.