- Site: Dungeness B
- IR number: 22-018
- Date: May 2022
- LC numbers: 10, 23, 28
Purpose of Intervention
The purpose of this intervention was to sample EDF Energy Nuclear Generation Limited’s (NGL’s) progress with their Chemistry Improvement Plan (CIP) workstreams at Dungeness B (DNB). These were raised in response to ONR’s License Condition (LC) 15 (4) Direction, served in response to the DNB feedwater chemistry event in May 2021. Recognising a number of workstreams remained in progress at the time of the intervention, ONR chemistry specialists, the chemistry and chemical engineering professional lead and the nominated site inspector sought to gain confidence in the direction of travel and identify any outstanding work necessary to enable future warm-up activities.
Interventions Carried Out by ONR
The intervention sought to sample improvements made through the DNB CIP. This included a review of workstreams relevant to people, processes, and plant. LC compliance was therefore sampled for LC 10 (Training), LC 23 (Operating Rules) and LC 28 (Examination, Maintenance, Inspection & Testing (EMIT)). While not rated, discussions of chemistry technical governance requirements and personnel resilience for end of generation activities were also held. For the purposes of brevity, the views of all inspectors contributing to this inspection are referred to as “I” throughout this report.
Explanation of Judgement if Safety System Not Judged to be Adequate
Key Findings, Inspector’s Opinions and Reasons for Judgements Made
LC 10 – Training
I sampled progress of training enhancements for the chemistry and operations functions. I observed enhanced essential training requirements for chemistry personnel, to enable capacity to provide leadership, advocacy of chemistry importance and robust challenge when required. I consider this to represent a potential fleet improvement and have shared this with NGL’s chief chemist.
For operators, I observed pilot training to reinforce the importance of chemistry control necessary to ensure safe operations. I noted further improvements however with regard to visibility of Technical Specifications (TS), Station Operating Instructions (SOI) and explicitly informing operators as to the cumulative and irreversible nature of chemical degradation (including expectations to act upon entry to action levels). Further, I highlighted that DNB should consider broader just-in-time training requirements ahead of future warm-up activities.
Based on my sample, I judge a rating of GREEN is warranted for LC 10. I have updated Regulatory Issue (RI) 8952 to capture progress and identify required outstanding activities to enable safe warm-up activities.
LC23 – Operating Rules
I sampled progress with updated Technical Governance relevant to off-load feedwater chemistry control (BEOM/004), TS, SOIs and Action on Receipt of Alarms (AORAs). While visible progress was noted in TS and SOI, I identified further areas of improvement within SOIs. This included consistency with technical governance, links to TS and aspects open to interpretation. AORAs did not appear to have been reviewed. I therefore identified a need for systematic review of AORAs to ensure these were consistent with technical governance and made effective links to SOIs. I also observed a long-standing BEOM/004 reheater dispensation, with reference to previous BEOM/004 versions and no current reheater preservation strategy.
Based on my sample, I judge a rating of GREEN is therefore warranted for LC23. I have however updated RI 8457 to track reheater preservation strategy progress and updated RI 8952 to capture progress and identify required outstanding activities to enable safe warm-up activities.
LC28 – EIMT
I sampled metrics used to identify plant condition and availability, including the new Chemistry Risk Indicator (CRI) and the System Health Indicator Performance (SHIP). While I acknowledged the CRI strengthened ability to identify plant availability relevant to chemistry control, I observed inconsistencies in approach across systems. Related to SHIP, I reiterated challenges regarding insensitivity of overarching metrics to physical condition and potential incomplete picture being presented to DNB management. I recognise this is a fleet tool however, and have raised this for the attention of ONR’s corporate inspector.
I observed visible improvement in the condition of the Water Treatment Plant (WTP) and improvements to Central Control Room (CCR) feedwater hydrazine indications. Conversely however, I observed degraded condition within the nitrogen blanketing system including corroded valves and severely corroded pipework supports. I highlighted that DNB should seek to complete key remediation work on the nitrogen blanketing system prior to planned warm-up activities.
Based on my sample, I judge a rating of GREEN is therefore warranted for LC 28. I have updated RI 8952 to capture progress and identify required outstanding activities to enable safe warm-up activities.
Conclusion of Intervention
In summary, I am content that DNB is adequately progressing the CIP workstreams sampled. I have identified however that work remains in progress, and identified a number of outstanding items. I have therefore updated RI 8952 to reflect aspects which I judge to be significant enablers for future warm-up activities.