The primary focus of this intervention was a planned system based inspection (SBI) of the EDF Energy Nuclear Generation Ltd (EDF NGL) Hartlepool (HRA) power station reactor post trip logic (RPTL) system, which was undertaken as part of the HRA integrated intervention strategy (IIS) plan.
The nominated Office for Nuclear Regulation (ONR) HRA site inspector, an ONR control and instrumentation (C&I) inspector and an ONR operational inspector undertook a SBI of the HRA RPTL system in order to judge whether it was able to fulfil its safety duties (safety functional requirements) in line with the safety case.
The RPTL system automatically start-ups / shut-downs essential plant in a defined sequence following a reactor trip in order to control post-trip temperature transients and ensure adequate decay heat removal.
Through sampling of associated operating and maintenance documentation, a plant walkdown and discussions with relevant HRA staff we examined the performance of the RPTL system against the following Licence Conditions (LCs), which are applicable provisions of the Energy Act 2013:
It should be noted that the RPTL system does not contain radioactive material; therefore, LC 34 (leakage and escape of radioactive material and radioactive waste) was not considered as part of this inspection.
The intervention was performed in line with ONR's guidance requirements (as described in our technical inspection guides) in the areas inspected.
During the week of the SBI, the nominated ONR HRA site inspector also undertook follow-up enquiries in regard to two ONR reportable events and met with Independent Nuclear Assurance (INA) staff.
The key findings of our SBI of the RPTL system are:
Pass / fail criteria were not stated on the checksheets;
‘As found condition’ entries were not made in most cases, (no descriptive entries were provided);
The test equipment used was not always recorded.
We also noted that the plant maintenance policy (PMP) did not list two RPTL system tests, which were listed in the maintenance schedule (MS) and EDF NGL’s asset management system (AMS).
We raised a L4 RI to capture the above issues. However, it should be noted that we did not consider the issues to present an immediate risk to nuclear safety. We will track their progress to resolution, as part of normal regulatory business.
We found that each of the sampled maintenance tasks had been completed in line with the periodicity specified in the MS.
We, therefore, judged that the RPTL system was being adequately examined, inspected, maintained and tested. We, therefore, judged the IIS rating for LC 28 to be Green (No formal action).
From the evidence sampled during this SBI against LCs 10, 23, 24, 27 and 28, we judged that the RPTL system was able to fulfil its safety duties (safety functional requirements) in line with the safety case.
There are no findings from this intervention that could significantly undermine nuclear safety at HRA. At present, no additional regulatory action is needed over and above the planned interventions at HRA, as set out in the HRA IIS, which will continue as planned.