Office for Nuclear Regulation

System Based Inspection-C02 Processing and Gas Blowdown Systems

Executive summary

Purpose of Intervention

The purpose of this intervention was to undertake planned compliance inspection activities at EDF Nuclear Generation Limited’s (NGL’s) Heysham 2 (HYB) power station in line with the 2020/21 Heysham 2 integrated intervention strategy (IIS).

Interventions Carried Out by ONR

An ONR specialist Chemistry inspector, assisted by the ONR nominated site inspector performed a system based inspection (SBI) to confirm the implementation of safety claims made for the carbon dioxide processing and blowdown systems.  The SBI examined the licensee’s compliance with the following licence conditions (LCs):

Plant integrity was not examined in detail as there is a follow-up corrosion inspection later this month.

Explanation of Judgement if Safety System Not Judged to be Adequate

On the basis of the evidence sampled during this inspection, we judged that the CO2 Processing and Blowdown systems were adequate and met the requirements of the safety case.

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

I was satisfied that staff training records and profiles were in accordance with the requirements for the roles performed from an LC10 perspective. I noted however, despite the system engineer being new in role, no system handover was completed or planned. I have therefore raised a L4 issue in this regard.

With respect to LC23 and LC24, I identified appropriate operating rules and implementation of these as written instructions based on my sample.

I was satisfied that safety mechanisms examined within the sample were appropriately maintained and available to perform their safety functions. I considered the LC27 requirements that safety mechanisms, devices and circuits were available.

I sampled the examination, inspection, maintenance and testing (EIMT) regime of a wider sample of components judged to be important to nuclear safety. Overall, the LC 28 maintenance regime was judged to be meeting relevant good practice, I have however raised a couple of L4 regulatory issues for the site to consider the maintenance categorisation and additional inspection of some items of equipment.

From an LC34 perspective, the station had undertaken a self-assessment of their safeguards to prevent and detect radioactive leaks, this was in-line with normal business. This was examined and no significant issues were found in relation to LC34. 

The intervention was performed in line with ONR's guidance requirements (as described in our technical inspection guides) in the areas inspected.

Conclusion of Intervention

After considering the evidence examined during the inspections undertaken against LCs 10, 23, 24, 27 28, and 34, I considered that the CO2 Processing and Blowdown system meets the requirements of the safety case. A rating of green has been given against all licence conditions as no significant regulatory issues were found.

A number of observations, improvements and minor issues were identified, which were fed back to the licensee. The licensee accepted ONR’s findings.

There are no findings from this inspection that could significantly undermine nuclear safety and no change to the planned interventions and inspections of Heysham 2.