Executive summary
Date(s) of inspection:
Aim of inspection
System based inspections (SBIs) are an essential element of ONR’s overall intervention on a nuclear site, and consist of a series of inspections which are intended to establish that the basic elements of a site/facility safety case (as implemented in Safety Systems, Structures and Components (SSCs)) are fit for purpose, and that they will fulfil their safety functional requirements.
The aim of this SBI was to determine whether the SSCs associated with CO2:
- storage;
- distribution;
- processing, and;
- blowdown,
adequately fulfil their safety duties (safety functional requirements), in line with claims made within the safety case; and to consider the adequacy of implementation of the licensee’s arrangements.
Subject(s) of inspection
- LC 10 - Training - Rating: GREEN
- LC 23 - Operating rules - Rating: GREEN
- LC 24 - Operating instructions - Rating: GREEN
- LC 27 - Safety mechanisms, devices and circuits - Rating: GREEN
- LC 28 - Examination, inspection, maintenance and testing - Rating: GREEN
- LC 34 - Leakage and escape of radioactive material and radioactive waste - Rating: GREEN
- Overall Inspection Rating - Rating: GREEN
Key findings, inspector's opinions and reasons for judgement made
I sampled a selection of training records and processes for Suitably Qualified Experienced Persons which provided confidence that EDF Nuclear Generation Limited have implemented adequate arrangements for suitable training for those who have responsibility for operations which affect nuclear safety
I identified a discrepancy between a CO2 system surveillance requirement and the associated consumables stock check sheet, however EDF Nuclear Generation Limited demonstrated the appropriate behaviours by immediately raising a condition report to correct this, therefore I do not consider this to be a regulatory issue. Furthermore I consider that EDF Nuclear generation Limited have adequately demonstrated that the CO2 system is operated in accordance with the operating rules as defined in the safety case.
From the sample of operating instructions, I identified an ambiguity in a Plant Item Operating Instruction. Again, EDF Nuclear Generation Limited demonstrated adequate behaviours by taking immediate action to correct the ambiguity. Hence, I am content that EDF Nuclear Generation Limited are adequately operating the plant in accordance with written instructions.
I noted that each of the sampled Work Order Cards was adequately annotated, signed and completed within the inspection period specified within the plant maintenance schedule.
I therefore judge that the examination, maintenance, inspection and testing activates on the CO2 system are bring adequately completed in accordance with schemes laid down in writing.
During the plant walkdown, I observed:
- a large number of defect tags on the system following 3rd party plant walkdown. I consider the number of defect tags could lead to an increased risk, given the system's role in supporting upcoming defueling activities, hence I judge that a Level 4 regulatory issue is appropriate (RI-11339)
Outside of the scope of the walkdown, de-aerator pipework was observed vibrating. No formal enforcement action required.
Conclusion
Site Licence Condition 10 - Training - ONR Inspection Rating - Green
I am content that the arrangements for Licence Condition 10 are adequate and implemented appropriately in line with the licencee’s arrangements. Based on the evidence sampled during this inspection, I consider that an inspection rating of Green (no formal action) is appropriate for Licence Condition 10.
Site Licence Condition 23 - Operating Rules - ONR Inspection Rating - Green
From the evidence sampled, it is my opinion that a clear line of sign is evident from living safety case documents to Tech Specs, and that the site surveillance requirements are being appropriately observed. Therefore, I consider an inspection rating of Green (no formal action) is appropriate for Licence Condition 23.
Site Licence Condition 24 - Operating Instructions - ONR Inspection Rating - Green
From the information sampled, I consider compliance with Licence Condition 24 to be adequate, and judge that a rating of Green (No formal action) is appropriate.
Site Licence Condition 27 - Safety Mechanism Devices and Circuits - ONR Inspection Rating - Green
Although EDF NGL follow in-house, fleet-wide arrangements for compliance with Licence Condition 27, from the sampled evidence I am confident that EDF NGL have an adequate process for identifying Safety Mechanisms Devices and Circuits, therefore green rating (no formal action) is appropriate for Licence Condition 27.
Site Licence Condition 28 - Examination, Inspection, Maintenance and Testing - ONR Inspection Rating - Green
From the evidence sampled, maintenance activates on the CO2 system are bring adequately completed in accordance with schemes laid down in writing. Therefore I judge a rating of Green (no formal action) to be appropriate for Licence Condition 28
Site Licence Condition 34 - Leakage and Escape of Radioactive Material and Radioactive Waste - ONR Inspection Rating - Green
From the information sampled, I consider compliance with Licence Condition 34 to be adequate, and judge that a rating of Green (No formal action) is appropriate.