Executive summary
Date(s) of inspection
- June 2026
Aim of inspection
ONR nuclear safeguards inspectors will conduct an accountancy focussed compliance inspection on the moves of QNM between the Dounreay Exotics Storage Facility (QS40) into the Waste Treatment Complex (QS14). The purpose of this inspection is to seek evidence in support of Sellafield Ltd.’s compliance with the Nuclear Safeguards (EU Exit) Regulations 2019 (NSR19).
Utilising the principles detailed in the ONR Risk Informed Targeted Engagement (RITE) policy, the transfer of material between QS40 and QS14 has been targeted as material has not been moved via this material flow for approximately six years so assurance is being sought of effective and efficient nuclear material tracking, control and reporting.
Subject(s) of inspection
- NSR19 Reg06 - Accountancy and control of qualifying nuclear material - Rating: Green
- NSR19 Reg11 - Accounting records - Rating: Green
Key findings, inspector's opinions and reasons for judgement made
ONR targeted this intervention informed by the principles set out in the ONR Risk Informed Targeted Engagement (RITE) policy for the following reasons:
- In April 2025, ONR received notification from Sellafield Limited that it would commence the movement of Qualifying Nuclear Material (QNM) out of QS40 Dounreay Exotics Storage Facility (DESF) ultimately into QS14.15 (Waste Treatment Facility (WTC)) before the end of the calendar year as part of the Residues to Wastes Project.
- Regulatory intelligence gathered from the assessment of nuclear material accountancy reports submitted by Sellafield Ltd under NSR19 Regulations 12 (1)(2) and 14 confirmed that material movements commenced in November 2025 after a period of stasis in the QS40 Material Balance Area (MBA). This MBA has typically remained static for some time; this activity represents the first major exports from this facility.
- The Residues to Waste project is a part of the wider Plutonium Disposition Strategy for the UK, allowing some small Pu residues to be processed to waste, therefore reducing the overall stockpile to go through SRP, which is under construction, and a future plutonium Disposal Plant. This identifies the project as a high-priority activity involving strategically important material.
ONR targeted this area to gain assurance that Sellafield Limited have appropriate and adequate Nuclear Material Accountancy and Control for Safeguards (NMACS) arrangements in place to enable accurate and timely statutory Nuclear Material Accounting (NMA) reporting.
This intervention sought evidence that the declared accountancy reports for the Sellafield Limited QNM flow between QS40 and QS14.15 are traceable and accurate to underpinning operating and accounting records. ONR sought evidence that arrangements for NMACS as described in the Basic Technical Characteristics (BTCs) for QS40 and QS14.15 and the Accountancy and Control Plans (ACPs) for QS40, QS14.15 and Sellafield site were appropriate and being adequately implemented by those with NMACS responsibilities for the MBAs.
To inform my judgements on the adequacy of the arrangements and implementation of NMACS, I utilised the Safeguards Technical Assessment Guidance (TAG) [SG-TAST-GD-001 – Issue 4], the Safeguards Technical Inspection Guidance (TIG) [SG-INSP-GD-001 – Issue 4], the Safeguards Nuclear Material Accountancy Technical Assessment Guide (TAG) [SG-TAST-GD-002, Issue 3] and safeguards expectations as described in the ONR guidance for Nuclear Material Accountancy, Control and Safeguards (ONMACS) [ONR-SAF-FW-001 – Issue 6].
I held discussions with Sellafield Ltd staff with responsibilities for NMACS, reviewed relevant operating and local instructions, and conducted a verification of source documentation used for NMACS, which underpinned the accountancy reports declared by Sellafield Ltd. under the Nuclear Safeguards (EU Exit) Regulations 2019 (2019) Regulation 14.
I noted a shortfall against NSR19 Regulation 6 as QNM values observed on the Plutonium Contaminated Material (PCM) Drum Filling Sheets differed to those reported in monthly Inventory Change Reports. I have raised a Regulatory Issue [RI-13111] for Sellafield Limited to address this shortfall.
Based on the sampled evidence during the intervention, I judge that there were no significant shortfalls identified during this intervention. Sellafield Ltd are adequately implementing their arrangements in line with the ONMACS Fundamental Safeguards Expectations (FSEs) 7, 8 and 9, and maintaining an appropriate system of accountancy and control for qualifying nuclear material in accordance with NSR19 Regulations 6, 9, 10, 11, 12 and 14, with the exception of the Regulatory Issue raised. Based on the evidence presented, I judge that a GREEN rating is appropriate for this intervention.
Conclusion
Based on the sampled evidence, I judge that there were no significant shortfalls identified during this intervention. A single minor shortfall was noted, and I have raised RI-13111 to address this.
Sellafield Limited are adequately implementing their arrangements in line with regulatory expectations FSE 7, 8 and 9 and maintaining an appropriate system of accountancy and control for qualifying nuclear material in accordance with NSR19 Regulations 6, 9, 10, 11, 12 and 14. I judge that a rating of GREEN is appropriate for this intervention.