- Site: Heysham 1
- IR number: 19-193
- Date: March 2020
- LC numbers: 10, 23, 24, 27, 28
Executive summary
Purpose of Intervention
The purpose of this intervention was to undertake a multi-disciplinary system based inspection (SBI) at EDF Nuclear Generation Limited’s (NGL’s) Heysham 1 power station in line with the relevant site inspection plan. The inspection was led by myself, a fault studies inspector. I was supported by a further fault studies inspector, a fuel and core inspector, a control and instrumentation inspector, and the nominated site inspector (partial). The aim of this SBI was to confirm that the safety case functional requirements have been adequately implemented in the HY1 back end fuel route facilities, including the associated operating instructions and maintenance schedule.
Interventions carried out by ONR
The system based inspection of the fuel route (back end) was conducted against compliance with the following licence conditions (LCs):
- LC 10: Training
- LC 23: Operating rules
- LC 24: Operating instructions
- LC 27: Safety mechanisms, devices and circuits
- LC 28: Examination, inspection, maintenance, and testing
The Heysham 1 arrangements for monitoring the health of the fuel route systems were examined. A plant walk-down of key areas associated with the fuel route was conducted. This included the additional fuel storage facility (AFSF), the irradiated fuel dismantling facility (IFDF), and the fuel ponds and flasks areas (P&F). Inspections were conducted, on a sample basis, of the implementation of arrangements against each of the above licence conditions.
In addition to the safety inspectors, an ONR safeguards inspector also attended. This was to afford ONR safeguards an opportunity to understand HY1’s back end fuel route arrangements from a safeguards perspective. The safeguards inspector focussed on implementation of components 6 and 7 of NGL’s nuclear material accountancy and control (NMAC) system, as defined in Schedule 2 of The Nuclear Safeguards (EU Exit) Regulations 2019. As the safeguards activities were not part of the formal SBI, further detail of these aspects is reported separately in CM Ref. 2020/85566.
The intervention was performed in line with ONR's guidance requirements (as described in our technical inspection guides) in the areas inspected.
Explanation of judgement if safety system not judged to be adequate
Based on the sample, I judged that for some plant areas, the compliance with licence condition 28 was not adequate. This was principally due to the failure to perform equipment reliability reviews for all fuel route facilities, and examples of individuals’ acceptance of readings which are outside of specification, during plant surveillance activities. As such an amber rating has been assigned for LC 28.
The operating rules arising from safety cases for the fuel route systems had been identified by EDF NGL, and were adequately implemented in the plant operating instructions and other documentation listed on the administrative control sheets.
Key findings, inspector's opinions and reasons for judgements made
From the intervention conducted, I summarise the following judgements for each of the licence conditions inspected:
- LC 10 (Training) – I examined the training records of a number of individuals associated with the fuel route, including a systems engineer and a fuel route technical support engineer. I found that individuals who were in the process of being trained were working within their limited range of authorisations. From sampling activities as detailed within fuel route quality plans, I observed that staff were suitably qualified and experienced. No significant shortfalls were identified. I therefore assigned a rating of Green (no formal action) for LC 10 compliance.
- LC 23 (Operating Rules) – I examined a sample of administrative control sheets (ACS) relevant to the fuel route (back end). The link between the safety case and the ACS for the AFSF, IFDF and P&F facilities was satisfactory. The ACS demonstrates identification of the limits and conditions of operation (LCO) from the safety case and links to the implementation of the LCOs in station and plant operating instructions (SOI and POI). I assigned a rating of Green (no formal action) for LC 23 compliance.
- LC 24 (Operating Instructions) – I sampled a number of SOI and POI, associated with key fuel route controls or post-fault actions, as identified on the related ACS. I confirmed safety case requirements were captured in the relevant OIs, and sampled quality plans to check that these instructions were being followed. I assigned a rating of Green (no formal action) for LC 24 compliance.
- LC 27 (Safety Mechanisms, Devices and Circuits) – Based on the areas sampled in our inspection relating to LC23. LC24 and LC28, we were satisfied that suitable and sufficient safety mechanisms, devices and circuits are connected and in working order to meet the requirements of the safety case and identified operating limits and conditions. I therefore assigned a rating of Green (no formal action) for LC 27 compliance.
- LC 28 (Examination, Inspection, Maintenance and Testing) – A number of the key fuel route (back end) systems had not been subject to an equipment reliability review, which represents a shortfall in implementation of LC28 arrangements for ageing and obsolescence management. In addition, operators were found to be accepting measurements that fell outside of the specified range during plant surveillance. Whilst it is possible that this behaviour could lead to significant consequences, it is likely that due to the shift rotation a member of staff or a plant alarm would report the failure. I therefore assigned a rating of Amber (seek improvement) for LC 28 compliance.
The following observations were raised with the station during the inspection:
- Some SOIs and POIs (e.g. SOI 08/09/450) do not fully capture the safety case requirements identified in the relevant ACS (e.g. HYA/7801), which appears to indicate a failing of the review and update process. NGL should consider whether post-fault SOIs and POIs should be subject to periodic review.
- A mixed position on safety case ownership at Heysham 1 was observed. The systems engineers had limited familiarity with the ACS related to their facilities, and also had very little awareness of the safety case health review (SCHR) process or outcomes. To improve safety case ownership, I suggested:
- A change to the ACS format to indicate the Barnwood fuel route systems support group engineer had approved its contents with the final sign off given by the appropriate station-based fuel route group system engineer.
- The SCHR reports be circulated to the individual station-based systems engineers and not just the fuel route group head.
Conclusion of intervention
From the sample inspected, it is judged that compliance against LC 10, 23, 24 and 27, met the required standard; therefore a 'Green' rating was given for these licence conditions. It is judged that compliance against LC 28 did not meet the required standard; therefore an ‘Amber’ rating was given for this licence condition. Following application of ONR’s enforcement management model, an enforcement decision record was completed (ONR-EDR-19-051), resulting in the decision to raise a new L3 Regulatory Issue #7983 and send an enforcement letter to the licensee. The EDR noted that it was unlikely that ageing related failures would result in significant or serious consequences, due to there being other mechanisms in place to identify ageing plant and due to the redundancy and diversity implemented in the safety measures. It was therefore considered not to be proportionate to take more stringent enforcement action at this point in time.
The back-end fuel route systems are in-general judged to meet the safety case requirements; however there is a significant shortfall associated with LC 28 compliance, which should be addressed in an appropriate time frame by satisfactory resolution of RI #7983.