Office for Nuclear Regulation

Torness - Systems Based Inspection 22 – CO2 storage and distribution

Executive summary

Purpose of Intervention

The main purpose of this intervention was to conduct a system based inspection (SBI) of EDF Energy Nuclear Generation Ltd.’s (NGL) Torness Power Station (TOR) in relation to the CO2 storage and distribution system.

This intervention was undertaken as part of a series of planned interventions that are listed in the Torness Integrated Intervention Strategy 2018/2019. The inspections were undertaken by the ONR nominated site inspector and two ONR nuclear specialist inspectors for structural integrity, which for the purpose of this intervention report shall be referred to as “I”. 

Interventions Carried Out by ONR

I performed a safety case informed SBI of the CO2 storage and distribution system.  Through examination of these systems, compliance inspections were performed against the following Licence Conditions (LC):

The objective of the inspection was to determine whether the licensee’s arrangements were adequately implemented and in accordance with the systems’ safety case requirements.  These inspections were informed through the review of the station safety report (including supporting documents and references), discussion with station specialists, plant inspection and sampling of electronic documents and records.  During normal operations, the CO2 plant provides a supply of CO2 to the reactors, fuelling machine and various other facilities to maintain reactor pressure, facilitate fuel route operations and support other operations.  The safety function of the CO2 plant is to provide protection during various reactor faults, fuel route activities, for fire suppression and other safety features.

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

Explanation of Judgement if Safety System Not Judged to be Adequate

From the system based inspection, I judge that overall the CO2 storage and distribution system meets the requirements of the safety case.

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

Based on the areas sampled during this system based inspection, I consider that Torness has implemented suitable arrangements to ensure that the CO2 storage and distribution system is maintained and operated in accordance with the safety case and the station’s arrangements.

In summary, the outcome of the SBI of the system was as follows:

Conclusion of Intervention

After considering all the evidence examined during the sample inspection undertaken against LCs 23, 24, 27, 28 and 34  I judged that the requirements of the safety case have been adequately implemented at Torness, with a rating of ‘Green – no formal action’ assigned against licence conditions 23, 24, 27, 28 and 34.

There were no findings from this inspection that could significantly undermine nuclear safety.  However, during my inspection the following minor shortfall was identified: 

Entries within the maintenance schedule had been deleted for plant which NGL considered to be duplicated under PSSR inspections.  As a consequence, any future potential modifications to the PSSR maintenance tasks could lead to the inadvertent breach of the safety case since no direct link exists to the safety case.  I have therefore raised a Level 4 regulatory issue (7035) to address this shortfall and have requested for NGL to propose and implement the most appropriate method of ensuring all future maintenance activities are made in accordance to the safety case requirements for all nuclear safety related systems