Office for Nuclear Regulation

Invasive Installation of Westinghouse Integrated System for Centralised Operation (WISCO)

Executive summary

Purpose of Intervention

This intervention was carried out to determine the readiness of EDF Energy Nuclear Generation Ltd (EDF NGL) to undertake invasive installation of Westinghouse integrated system for centralised operation (WISCO) 2 hardware and software during the Sizewell B (SZB) refuelling outage (RO) 16. The intervention forms part of the Office for Nuclear Regulation’s (ONR)’s intervention strategy for the WISCO 2 project (CM9 Ref. 2018/380576).

Interventions Carried Out by ONR

The SZB WISCO comprises of the plant control system (PCS), distributed computer system (DCS) and high integrity control system (HICS) subsystems; all of which were installed when SZB was built in the 1990’s. The PCS and DCS subsystems support the majority of SZB’s category 2 and 3 controls, alarms, indications and data processing functions. The HICS supports SZB's category 1 control functions.

The objective of the WISCO-2 project is to replace the existing PCS and DCS subsystems’ hardware and software in order to address current and future obsolescence issues; whilst retaining their existing inputs, outputs, roles, functionality and performance.

It should be noted that the HICS or SZB’s reactor protection systems (RPS) (i.e. the primary protection system (PPS) and the secondary protection system (SPS)) are not being modified.

This readiness review was undertaken by two ONR control and instrumentation (C&I) nuclear safety inspectors and involved determining the readiness of EDF NGL to undertake the invasive installation of WISCO-2 PCS and DCS hardware and software during RO16. This entailed sampling associated testing, commissioning, maintenance, operating and training documentation, undertaking a plant walkdown and holding discussions with relevant stakeholders in relation to the following Licence Conditions (LCs), which are applicable provisions of the Energy Act 2013:

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 this readiness review are:

However, we did find the following issues, which resulted in us raising a level 3 regulatory issue (RI) (ONR RI Database (RID) number (no.) 7141):

We also identified a number of issues associated with installation activities, the testing of alarms, panel earthing, modification processes and the handling and storage of panels. As a result we raised a level 4 RI (ONR RID no. 7142) in order to enable these issues to be tracked through to resolution.

It is important to be noted that we do not consider the above issues to present an immediate risk to nuclear safety; but do require them to be addressed before invasive installation of the WISCO-2 hardware and software commences. It should be noted that these issues will be discussed during the above level 4 WISCO-2 meeting.

Conclusion of Intervention

This SZB WISCO-2 readiness review provided an early opportunity to inspect arrangements for the proposed installation during the R016 outage. We consider that the key stakeholders appear to be well integrated and that adequate nuclear safety oversight is being given to the project by EDF NGL Independent Nuclear Assurance (INA) and the Project Safety Review Group (PSRG).

Reasonable progress has been made with regard to developing and implementing training, T&C and O&M arrangements and issuing the associated documentation. However, at the time of our inspection, we did not consider that EDF NGL were ready for the invasive installation of WISCO-2 hardware and software during RO16. We decided to defer making a formal readiness judgement until a level 4 WISCO-2 meeting on the 25th April 2019. EDF NGL has confirmed to us that this date provides sufficient time to address the RIs we raised (ONR RID nos. 7141 and 7142). For this reason, we assigned a rating of GREEN for LC 10, 22 and 28.