Office for Nuclear Regulation

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Dungeness B - LC22 planned inspection

Executive summary

Purpose of Intervention

The purpose of this intervention was to undertake a Licence Condition (LC) 22 (Modifications) compliance inspection at EdF Energy Nuclear Generation Limited (NGL) Dungeness B (DNB) Power Station in line with the Reactor 22 2018 ONR Outage Inspection Plan. The intervention was to review the boiler and new nitrogen plant invasive modifications taking place on Reactor 22 during the outage and also on Reactor 21 while shut down during the co-incident planned double reactor outage.

Interventions Carried Out by ONR

As part of this intervention I, the outage project inspector and project inspector for Dungeness B boiler and new nitrogen plant modifications, carried out a planned compliance inspection against LC22 (Modifications) in accordance with the corresponding ONR Outage Inspection Plan.  

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

Not applicable: no safety system inspection was undertaken during this intervention.

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

My planned intervention against LC22 from sampling the boiler and nitrogen plant invasive modifications carried out to date are summarised below:

Boiler Modifications

I was provided with an update of the current progress with boiler modifications on Reactor 22 and Reactor 21. All the invasive boiler modifications are planned to be carried out on Reactor 22, apart from Boiler Overfeed Protection System (BOPS) on three remaining circuits. I was informed that this was due to access limitations during the planned outage. Some boiler modifications had been carried out on Reactor 21, out of a limited number of planned invasive boiler modifications, due to the short duration of the planned double reactor outage.  However, due to the extended shutdown periods, NGL planned to carry out further modifications, which I supported. I encouraged NGL to maximise the number of modifications in the time available.

I enquired regarding the Intelligent Customer and Quality Control arrangements used when engaging with the supply chain for new equipment. The Intelligent Customer engagement via the Architect Engineer I judged to be adequate, however Quality Control requirements appeared to be lacking. Given the Condition Reports raised because of new equipment faults, NGL were seeking an investigation report from the supply chain, which should address direct fault causes. However, NGL were not pursuing an investigation to establish extent of condition or establish root causes and associated corrective actions.

I inspected, by sampling, the NGL proposed quality plans and Work Order Cards for the installation of the boiler modifications, the configuration control arrangements to ensure compliance with the requirements of the safety case and proposed revised Plant Item Operating Instructions. I judged that the arrangements were adequate. I also carried out a plant tour reviewing some of the on-going work locations, all of which appeared to be adequate.

Based on my inspection I have judged that the Dungeness B arrangements meet the requirements of LC22 and I have therefore rated this inspection as Green, no further regulatory action required. I raised one observation relating to lack of NGL investigation to identify root causes and appropriate corrective actions associated with problems encountered with the supply chain.

New Nitrogen Plant Modifications.

I was informed that the invasive new nitrogen plant pipework connections into the existing nitrogen injection pipework had been completed.

I inspected the new pipework valve operating platform on Reactor 21 and was provided with photographs of below ground pipework connections. I also inspected the project’s completed plant installation quality assurance arrangements. From the samples inspected, I found the completed quality plans etc to be adequate and completed in full.

Based on my inspection I have judged that the Dungeness B arrangements meet the requirements of LC22 and I have therefore rated this inspection as Green, with no further regulatory action required.

Conclusion of Intervention

Overall, I consider that the arrangements and their associated implementation for invasive boiler and new nitrogen plant modifications under LC22 meet legal requirements and have therefore rated this inspection as Green. I raised one observation relating to lack of NGL investigation to identify root causes and appropriate corrective actions associated with problems encountered with the supply chain for boiler modifications.

There are no findings from this inspection that could significantly undermine nuclear safety nor require a change to the planned interventions and inspections of Dungeness B.