Executive summary
Date(s) of inspection:
November 2025
Aim of inspection
ONR will seek to draw an independent and informed regulatory judgement that the nuclear material accountancy and control arrangements within the MBA QBS3, include adequate statistical analysis procedures, and that they meet the expectations as outlined in ONR guidance.
This will include seeking evidence that the uncertainty (sigma) in material unaccounted for (MUF) calculated by the operator is in line with a sigma MUF calculated by ONR.
ONR will conduct the intervention remotely and will hold discussions with relevant Springfields Fuels Limited personnel who have nuclear material accountancy and control responsibilities, as well as seeking accountancy records, and other relevant information.
ONR requests discussions with relevant staff, accountancy information, and provision of relevant NMAC&S arrangements prior to the intervention.
Subject(s) of inspection
- FSE 8 Data Processing and Control - Rating: AMBER
- FSE 9 Material Balance - Rating: AMBER
- NSR19 Reg03 - Declaration of basic technical characteristics - Rating: AMBER
- NSR19 Reg06 - Accountancy and control of qualifying nuclear material - Rating: AMBER
- NSR19 Reg10 - Operating records - Rating: AMBER
- NSR19 Reg11 - Accounting records - Rating: AMBER
- NSR19 Reg12 - Accounting reports - Rating: GREEN
- NSR19 Reg14 - Inventory change report - Rating: GREEN
- NSR19 Reg15 - Material balance report and physical inventory listing - Rating: GREEN
Key findings, inspector's opinions and reasons for judgement made
This intervention sought evidence that Springfields Fuels Limited (SFL)’s arrangements for Material Balance Evaluation (MBE) were compliant with legal requirements under The Nuclear Safeguards (EU Exit) Regulations 2019 (NSR19) and with ONR’s expectations pursuant to ONMACS and relevant international guidance; that the outcomes of MBEs performed by SFL were traceable to – and underpinned by – appropriate procedures, calculations, and source data; and that the Inventory Difference Action Levels (IDALs) calculated by SFL were statistically defensible.
To inform my judgements on the adequacy of the arrangements and outcomes of MBE, I utilised the Safeguards Technical Inspection Guidance (TIG) [SG-INSP-GD-001 – Issue 4]; safeguards expectations as described in the ONR guidance for Nuclear Material Accountancy, Control and Safeguards (ONMACS) [ONR-SAF-FW-001 – Issue 5]; the ONR Organisational culture guide for inspectors [NS-INSP-GD-070 – Issue 3.2]; and international relevant good practice, including the IAEA Safeguards Glossary 2022 Edition, the International Target Values for Measurement Uncertainties in Safeguarding Nuclear Materials 2022 (ITVs), and the Evaluation of measurement data — Guide to the expression of uncertainty in measurement JCGM 100:2008 (GUM).
I held discussions with SFL staff with responsibilities for MBE, reviewed relevant documents, and performed independent calculations against a sample of SFL’s MBE reports in order to make a judgement as to the sufficiency of SFL’s arrangements for MBE.
Based on the evidence I sampled during the course of the intervention, I judged there to be three significant shortfalls and four minor shortfalls against NSR19 Regulations 3, 6, 10, and 11, and/or against ONR’s expectations pursuant to ONR guidance and international relevant good practice. The significant shortfalls related to a lack of stratification for MBE, a lack of traceability to source data, and a lack of sufficient documentation of procedures for MBE. I therefore rated this intervention AMBER.
Conclusion
In examining the evidence above, I observed seven shortfalls - three of which were significant - against NSR19 Regs. 3, 6, 10, and 11; against ONR’s expectations pursuant to ONMACS; and against international relevant good practice. The shortfalls I observed were:
No stratification: I judge this shortfall to be a shortfall against NSR 19 Reg. 3.(1) and the associated requirements of NSR19 Schedule 1, Part 1, I-C. para. 26. I also judge this shortfall to be a significant shortfall against ONR’s expectations pursuant to international relevant good practice (IAEA Safeguards Glossary, 2022 Edition) and against ONR’s expectations pursuant to MACE 9.3 of ONMACS.
Lack of traceability to source data: I judge this shortfall to be a significant shortfall against NSR19 Reg. 11.(2) and ONR’s expectations pursuant to MACE 8.3, Para. 169.d) of ONMACS.
Lack of sufficient documentation: I judge this shortfall to be a significant shortfall against NSR19 Reg. 3.(1) and the associated requirements of NSR19 Schedule 1, Part 1, I-C. para. 26; NSR19 Reg. 10(d); and ONR’s expectations pursuant to MACE 9.3 of ONMACS.
Lack of justification for use of particular international standards for measurement uncertainties: I judge this shortfall to be a minor shortfall against NSR19 Reg 6(3) / Schedule 2 part 5, and ONR’s expectations pursuant to international relevant good practice in the IAEA Safeguards Glossary, 2022 Edition, Paragraph 5.36.
Unsuitable weigh scales used: I judge this shortfall to be a minor shortfall against NSR19 Reg 6(3) / Schedule 2 part 5; ONR’s expectations pursuant to MACE 6.3 of ONMACS; and international relevant good practice in the Guide to the expression of uncertainty in measurement.
Assessment of inventory differences: I judge this shortfall to be a minor shortfall against ONR’s expectations pursuant to NSR19 Reg. 3.(1) and the associated requirements of NSR19 Schedule 1, Part 1, I-C. para. 26; and ONR’s expectations pursuant to FSE 9, Para. 172 of ONMACS.
No follow-up at two sigma confidence level: I judge this shortfall to be a minor shortfall against ONR’s expectations pursuant to MACE 9.3, Para. 203 of ONMACS.
In examining the evidence above, I did not observe any shortfalls against NSR19 Regulations 12, 14, or 15.
The above shortfalls fall into two categories:
- Inadequate, insufficient, or incomplete procedures (Shortfalls 1, 2, 3, 5, and 7), and
- Inability to explain or justify:
- Statistical calculations and/or conclusions that lacked full procedural documentation (Shortfalls 1, 3, 6, and 7); and
- Atypical uses and/or types of measurements and/or uncertainties (Shortfalls 4 and 5).
I have raised a Level 4 Regulatory Issue (RI12868) to address the procedural shortfalls in the former category.
The shortfalls in the latter category are further evidence of the observed lack of safeguards SQEP from other recent inspections and shortfalls at SFL. Therefore, I have raised a single Level 3 Regulatory Issue (RI-12869) for SFL to address the shortfalls in the latter category.
Upon consideration of the ONR guidance on inspection ratings, I judge that a rating of AMBER (seek improvement) is appropriate for this intervention.