Office for Nuclear Regulation

Sellafield – Inspection ID: 50558

Executive summary

Date(s) of inspection:

  • July 2023

Aim of inspection

The purpose of this inspection was to seek evidence in support of Sellafield Ltd.’s compliance with The Nuclear Safeguards (EU Exit) Regulations 2019 (NSR19). The purpose of an accountancy focussed inspection is to:

  • examine operating and accounting records to establish a correct set of data and to provide confidence to ONR that the operator has an adequate nuclear material accountancy and control system established
  • examine the specific arrangements and procedures in place for nuclear material accountancy as detailed in Section 5 of the ONR Safeguards Technical Inspection Guide SG-INSP-GD-001 Revision 3.

Subject(s) of inspection

  • FSE 6 Measurement Programme and Control – Rating: Green
  • FSE 7 Nuclear Material Tracking – Rating: Green
  • FSE 8 Data Processing and Control – Rating: Green
  • NSR19 Reg06 – Accountancy and control of qualifying nuclear material – Rating: Green
  • NSR19 Reg10 – Operating records – Rating: Green
  • NSR19 Reg11 – Accounting records – Rating: Green
  • NSR19 Reg12 – Accounting reports – Rating: Green
  • NSR19 Reg14 – Inventory change report – Rating: Green
  • NSR19 Reg20 – Weight units and categories of qualifying nuclear materials – Rating: Green

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

In accordance with the Office for Nuclear Regulation (ONR) Safeguards’ integrated intervention strategy 2023/24 for Sellafield Ltd, ONR Safeguards undertakes several of safeguards compliance inspections at the Sellafield site. An inspection was undertaken to assess Sellafield Ltd’s compliance with the requirements of the Nuclear Safeguards (EU Exit) Regulations 2019 (NSR19) in relation to nuclear material accountancy and control arrangements within MBA QS34 (THORP Product Store) being implemented in a manner, which is proportionate to, and appropriate for the qualifying nuclear facility.

The inspection comprised of discussions with Sellafield Ltd  staff, sampling and review of Sellafield Ltd operating, accounting records and other source documentation, and plant walkdowns to check implementation of arrangements. It was carried out in line with ONR’s guidance which can be found on ONR’s website (

I provided two pieces of regulatory advice relating to formally capturing the results of successful Store Map quality assurance checks conducted by the Sellafield Ltd. Nuclear Material Custodian, and the DAPs awareness of the QS34 Accountancy and Control Plan (ACP)

Based on the sampled evidence I judge Sellafield Ltd. is implementing appropriate and proportionate arrangements for nuclear material accountancy at QS34 and have met the requirements for nuclear material accountancy set out in NSR19, specifically, Regulations 6, 10, 11, 12(1,2),14 and 20. Noting ONR guidance on inspection ratings, I am providing a green rating for this inspection.


In line with the ONR Inspection Rating Guide, based on the sampled evidence during the course of the intervention at Sellafield Ltd, I consider a rating of green against the following as identified within the scope of inspection:

THORP Product Store (MBA QS34); NSR 19 regulations 6 (1-4) , 10 (1) , 11(1-4), 12, 14 , 20, Schedule 2 and ONMACSs FSEs 6, 7, 8, and 10.