Office for Nuclear Regulation

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The Thermal Oxide Reprocessing Plant (THORP) on Sellafield Ltd.'s nuclear licenced site at Sellafield, Cumbria

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 carried out to assess Sellafield Ltd.'s (SL's) compliance with licence condition (LC) 7 - incidents on the site, at the Thermal Oxide Reprocessing Plant (THORP) at Sellafield. LC 7 requires the licensee to "make and implement adequate arrangements for the notification, recording, investigation and reporting of such incidents occurring on the site..."

Interventions Carried Out by ONR

I carried out a one day licence compliance inspection against licence condition 7 utilising the following ONR inspection guidance:

In addition, I completed a one day inspection to confirm that SL had adequately implemented the required corrective actions in response to a formal regulatory letter issued to SL by ONR in October 2014 following an event where an Intermediate Bulk Container (IBC) containing the chemical formalin had been delivered (and accepted) in error into the minor reagents area at THORP - the "Formalin event". I also attended the Oxide Operating Strategy Regulatory (OOSRF) Forum. This is 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 7 Inspection

It is my opinion that there have been significant improvements made to the way in which the Performance Improvement process has been embedded into the THORP Operating Unit probably as a result of improved engagement between the Performance Improvement team and THORP operations.

It is my opinion that the quality of investigations and the resultant corrective actions has been inconsistent. SL has recently made changes to how it carries out its management level investigations (MIs - the middle level of investigation for more significant events) and the resultant actions, which I believe should result in improved quality and consistency.

I believe that Sellafield Ltd has produced high quality training materials to support its investigations, however, currently for its lowest category of investigations, basic cause investigations (BCIs); it does not make the completion of this training mandatory. I consider that completion of this training by all personnel who complete BCIs would ensure competence can be properly demonstrated and would improve the quality of BCIs.

I noted that the management oversight arrangements for performance improvement have been streamlined giving greater clarity of responsibilities. In addition, the THORP management team has set clear expectations regarding the management of investigations and resultant actions.

Consequently, it is my opinion that THORP's management of corrective actions and investigations has significantly improved, particularly the use of visual management tools, which has resulted in improvements to those key performance indicators applicable to performance improvement. I also believe that SL's trending capability is maturing, with higher quality more meaningful data being produced.

I was pleased to see that THORP Safety Representative participated in the LC 07 inspection.

The formalin event

It is my opinion that SL has adequately implemented the improvements required as a result of ONR's formal regulatory letter following this event.

Conclusion of Intervention

LC 7 Inspection

On the basis of the evidence gathered during the inspection, I judge that an IIS rating of GREEN (No formal action) to be appropriate for compliance against LC 7; Incidents on the site. This being due to that fact that I found SL to be compliant with its legal duties with only minor areas for further improvement being identified.

The formalin event

It is my opinion that ONR should close the formal Regulatory Issue raised to track SL's implementation of the required improvements to its processes for the importation of chemicals into THORP identified following the formalin event.