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Springfields Works - Inspection ID: 52900

Executive summary

Date(s) of inspection: July 2024

Aim of inspection

The aim of the inspection was to consider Springfield's implemented measures to prevent, control and mitigate fire and explosion hazards affecting both nuclear safety and life safety. This included reviewing Springfield's examination of fires through their safety case documentation as well as building fire risk assessments and arrangements for compliance with the Regulatory Reform (Fire Safety) Order. With respect to explosion hazards, the inspection considered risks associated with nuclear safety and conventional health & safety focussing on compliance with the Dangerous Substances & Explosive Atmospheres Regulations (DSEAR).
 
Systems relevant to Major Accident Hazard (MAH) scenarios associated with hydrogen were also inspected as part of findings identified during Springfield's COMAH 2023 Safety Report - 5 year review (PR-01235). 

Subject(s) of inspection

  • COMAH - Control of Major Accident Hazards Regulations 2015 - Rating: GREEN
  • LC10 - Training - Rating: GREEN
  • LC23 - Operating rules - Rating: AMBER
  • LC24 - Operating instructions - Rating: GREEN
  • LC27 - Safety mechanisms, devices and circuits - Rating: GREEN
  • LC28 - Examination, inspection, maintenance and testing - Rating: GREEN
  • Regulatory Reform (Fire Safety) Order 2005 - Rating: GREEN

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

This inspection was a themed inspection to assess Springfield Fuels Ltd (SFL) arrangements to support fire and explosion safety. The inspection also sampled the implementation of those arrangements on site. Specifically the inspection covered:

Life Fire Safety (LFS) and compliance with the Regulatory Reform (Fire Safety) Order (RRFSO)

Internal Hazards (Fire & Explosion) and compliance with the following license conditions:

  • LC10 – Training
  • LC23 – Operating Rules
  • LC24 – Operating Instructions
  • LC27 – Safety Mechanisms, Devices and Circuits
  • LC28 – Examination, Inspection, Maintenance and Testing
  • Compliance with the Dangerous Substances & Explosive Atmospheres Regulations (DSEAR)
  • Compliance with the Control of Major Accident Hazards (COMAH) regulations and follow-up of actions defined in the 5-Yearly COMAH review conclusions record – captured in WIRED Permissioning Record – PR01235.

The inspection was carried out in line with relevant Technical Inspection Guides (TIGs) such as NS-INSP-GD-073 Issue 2 – The Regulation of Life Fire Safety Provision on GB Nuclear Sites. The inspection consisted of examination of the licensee’s arrangements covering the above topics, meetings to assess the implementation and management of each topic at a site level and walkdowns of the Oxides Fuels Complex (OFC), Enriched Uranium Residues Recovery Plant (EURPP), Hydrogen Compound and Administration Block facilities.

This intervention was undertaken by three inspectors from the Office for Nuclear Regulation’s (ONR) Nuclear Internal Hazards & Site Safety (NIHSS) specialism, one inspector from the Chemistry and Chemical Engineering specialism and the Springfield site’s Nominated Site Inspector.

Several findings were noted during the inspection:

  • It was noted that inspectors were allowed to enter the hydrogen storage compound, which has a Zone 1 hazardous area, without changing to anti-static clothing and footwear as identified in the site standard (SSI 734). Additionally, it was noted that the calculation of hydrogen event frequency contained a probability of hydrogen ignition factor of 0.1. This is not aligned with relevant good practice. Additionally a factor of 0.1 is applied for the frequency of hydrogen deflagration vs a jet fire. This is not supported by the geometry of the hydrogen compound. A level 4 regulatory issue has been raised to address these shortfalls against the DSEAR and the implications for Occupied Building Risk Assessment (OBRA).
  • It was noted that there were some examples, within OFC, where Springfields were unable to demonstrate adequate control of combustibles despite the building having some known vulnerabilities to fire. A level 4 regulatory issue has been raised to address this shortfall.
  • The current nuclear fire safety assessment for OFC considers fire on an individual Fault Sequence Group (FSG) basis and only considers the potential impact of SSCs which support the individual fault. A holistic view of fire which considers the potential impact of fire spread on SSCs which potentially support multiple FSGs is not covered. Additionally, the process for compliance with operating assumptions (the lowest tier of safety case operating rules) lacked clarity leading to inconsistent application in areas sampled. Given the buildings known vulnerability to fire a Level 3 regulatory issue has been raised to address this shortfall.
  • It was noted that Springfields do not currently have formal emergency guidance identifying the strategy and actions required to deal with a potential leak of hydrogen at the site compound. This is not aligned with Schedule 4 of L111 (The guide to The Control of Major Accident Hazards Regulations 2015). A level 4 regulatory issue has been raised to address this shortfall.

Conclusion

The Internal Hazards and Fire Safety specialist inspector has provided the following judgement.

The following points which form my overall judgement are based on the facts established as part of the inspection, discussions with the nominated site inspectors and my own judgement on the presentations and information provided by the licensee:

  • SFL have SQEP resource to assess internal hazards and fire safety and have an established process in place for developing nuclear fire safety assessments and supporting HAZANs.
  • The life fire safety condition of buildings is assessed through both fire risk assessment and supporting conventional fire safety assessments where required. Conventional fire safety assessments for OFC were found to be broadly adequate.
  • No specific operating rules are derived with respect to fire safety however, claims are made on the FADS within OFC and implicit claims are made on the compartmentation installed within the building. Recent projects have been undertaken to improve the standard of both.
  • The OFC facility has known vulnerabilities to fire and does not meet current fire safety relevant good practice.
  • The FADS system within OFC appeared to be appropriate for the risk within the building and a suitable maintenance regime is in place. Compartmentation has been supported by a recent survey and the facility is in the process of replacing fire doors throughout. Examples of both were observed during the facility walkdown.
  • The nuclear fire safety assessment considers fault sequence groups at an individual level only and does not consider fire holistically. Given the buildings known vulnerabilities to fire this presents a potential gap within the safety case as the totality of potential consequences is not fully understood.

With regards to the above facts, I consider that the site is complying with licence conditions (LCs) 24, 27 & 28 within the context of internal hazards. However, I judge that the nuclear fire safety case is not fully complete and this represents a shortfall against LC 23 – Operating Instructions with respect to the adequacy of the safety case LC23(1). I therefore judge that an ONR inspection rating of (GREEN) is appropriate for each license condition inspected with the exception of LC23 which I rate as (AMBER).

With respect to the life fire safety portion of the inspection despite some minor shortfalls observed which will be followed up through a Level 4 Regulatory issue, I consider that the site complies with the requirements of the Regulatory Reform (Fire Safety Order) 2005. I consider that an ONR Inspection Rating of (GREEN) is appropriate.

The Chemical Engineering specialist inspector has provided the following judgement.

I consider that the licensee is adequately implementing the requirements of the DSEAR, based upon my sampling and the evidence presented by the duty holder. I therefore judge that, an ONR inspection rating of adequate (GREEN) is appropriate for this intervention.  Nevertheless, I consider the raising of one level 4 regulatory issue and an additional action within a level 3 regulatory issue linked to LC23 compliance as appropriate. One will be focussed on the improvements to DSEAR and the other on the duty holder showing compliance with the Operating Assumptions identified in the safety case.

The COMAH specialist inspector has provided the following judgement

I consider that the licensee is adequately implementing the requirements for emergency planning, relating to  the COMAH Regulations 2015. I therefore judge that, an ONR inspection rating of adequate (GREEN) is appropriate for this intervention. However, a level 4 issue will be raised to ensure a formalised guidance is developed and evaluated on a periodic basis, in accordance with Schedule 4 of L111 (The guide to The Control of Major Accident Hazards Regulations 2015).