EDF Energy Nuclear Generation Ltd’s (NGL’s) Dungeness B (DNB) nuclear power station’s two reactors have been in extended outage as a result of the station’s event recoveries regarding corrosion, steam main cracking and boiler tube safety case. During this period there has been a significant turnover of staff, there have been a number of significant events (including INES events and ONR Enforcement Letters) and the station is in Enhanced Regulatory Attention.
The purpose of the ONR readiness review is to build regulatory confidence in the Licensee’s ability to adequately conduct activities that will ensure safe operation of the reactors at power.
This Intervention Record (IR) covers an inspection of the Human and Organisational Capability (HOC) at DNB to assess the station’s readiness to return to service (RTS). The aim of this inspection was to determine, through sampling, the adequacy of both DNB’s return to service preparations and relevant aspects of the Enhanced Regulatory Attention issues.
This inspection was performed as part of an ONR Operating Facilities Division (OFD) initiative to inspect DNB’s readiness to return to service and follows the inspection conducted during the period 13th to 17th January 2020 (ONR-OFD-IR-19-148).
This intervention was carried out by Human Factors and Leadership and Management for Safety Inspectors over the period 4th to 6th February 2020, supported by ONR’s Nominated Site Inspector for DNB.
The intervention was performed in line with ONR's guidance requirements (as described in our technical inspection guides) in the areas inspected.
Not applicable, no system based inspection was undertaken.
We judge the generic human performance training to be of a suitable content and quality to meet the needs of raising awareness of the importance of the human impact on performance;
There is a clear auditable trail to demonstrate that Technical Specifications have been updated appropriately to reflect Engineering Changes and that training requirements have undergone due governance and been written to highlight clearly the relevant changes to operators.
Recent human performance (HU) events have been subject to NGL’s event investigation process and a Significant Adverse Condition Investigation (SACI) is being established.
There has been a clear focus on the development of, and support to, inexperienced personnel across all departments and this has had the additional consequence of increasing cross-functional co-operation and understanding between operations and maintenance. We noted a number of good practices in addressing the challenges of inexperienced personnel within the Maintenance and Operations Departments.
General RTS matters including match-fit plans and governance, oversight and assurance. We found that:
We considered, however, that the Licensee has several minor shortfalls in regulatory expectations for LC10, LC23 and LC7 and, to close these gaps, we intend to raise two Level 4 regulatory issues relating to:
Interventions ratings of Green, i.e. meets minimum legal requirements, were assigned against LCs7, 10, 12 and 23, with two Regulatory Issues being raised. A number of recommendations were also raised regarding completion of walk-down plans and oversight of the Station’s RTS preparations and decision making.
The positive mind-set apparent together with the eagerness for RTS must be translated not only through actions in match-fit programmes but sustained beyond RTS; the Station should focus on sustainability of its activities and initiatives and develop its plans for the post RTS period.
On the basis of the interventions carried out, no issues were identified that would prevent support of ONR’s overall approach in permissioning return to service. A joint ONR/INA follow-up inspection is being considered shortly before a return to service date, to ensure actions have been completed and circumstances have not significantly changed.