Office for Nuclear Regulation

SBI 26 - Reactor Post Trip Logic System

Executive summary

Purpose of Intervention

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.

Interventions Carried Out by ONR

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.

Explanation of Judgement if Safety System Not Judged to be Adequate

Not applicable.

Key Findings, Inspector's Opinions and Reasons for Judgements Made

The key findings of our SBI of the RPTL system are:

Conclusion of Intervention

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.