Office for Nuclear Regulation

System Based Inspection of PMF(S) Finishing Line 6  Glove Box Cabinet Extract and Process Vessel Ventilation System

Executive summary

Purpose of intervention

The Office for Nuclear Regulation (ONR) undertakes all regulatory interaction with the Sellafield site licensee (Sellafield Limited, SL) against a strategy defined by the ONR Sellafield Programme.  The inspection plan PP1 for the plutonium finishing and storage facilities (PF&S) details a strategic programme of regulatory inspections which includes a System Based Inspection (SBI) of the Plutonium Management Facility (South) (PMF(S)) Finishing Line 6 (FL6) Cabinet Extract and Vessel Vent system in April 2015.

FL6 is the plutonium finishing line that takes the plutonium-enriched nitric acid feedstock from THORP and produces pure powdered plutonium dioxide (PuO2) in cans for storage.

The purpose of this inspection was for ONR to look at the adequacy of implementation of the safety case SL has made for the glove box cabinet extract and process vessel ventilation system (CE&VV). This system is responsible for maintaining low pressures within the plant’s vessels and glove boxes in order to maintain the containment of the radioactive material.

Interventions Carried Out by ONR

We carried out a two-day, on-site team inspection, delivered by the ONR site inspector and two ONR mechanical specialist inspectors.

As part of this SBI, we used ONR guidance to examine SL’s compliance with the following licence conditions (LCs):

The inspection included a general discussion of the requirements set out for the CE&VV system in the facility safety case and relevant safety documentation, a plant walk down and individual discussions with relevant plant safety case and operational personnel.

In addition to the SBI we also held a meeting with PMF(N) to discuss the Finishing Line 3 (FL3) ventilation improvement projects. This was an unannounced intervention, i.e. the licensee was not informed of any agenda other than that we wished to discuss these projects.

Explanation of Judgement if Safety System Not Judged to be Adequate

This safety system was judged to be adequate.

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

The key findings of my inspection are:

Conclusion of Intervention

The PMF(S) FL6 CE&VV system is considered to meet the requirements of the safety case to a good standard.

Regulatory issues were raised in regard to a small number of minor issues.  These do not detract from the overall good quality of SL’s demonstration of compliance.