Office for Nuclear Regulation

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Heysham 1 - Corrosion Management Inspection

Executive summary

Purpose of Intervention

The purpose of this intervention was to conduct an inspection to establish the adequacy of arrangements implemented under the site corrosion management programme. The work was carried out as part of the Office for Nuclear Regulation (ONR) planned intervention task sheet TS027 - “Management of Corrosion - Concealed and Buried Systems” and task sheet TS023 - “Management of Storage Tanks and Vessels”.

I carried out this inspection accompanied by the ONR Heysham 1 site inspector and two additional Structural Integrity Inspectors. The inspection took place on 20 & 21 June 2017 and involved discussions with a number of EDF Energy Nuclear Generation Limited’s (NGL) employees responsible for the operation and safety of the plant. A targeted plant walk down of the systems selected for sampling was also undertaken.

 Interventions Carried Out by ONR

The first part of the inspection reviewed the revised procedures for managing corrosion under insulation on pipework at Heysham 1 in response to a number of actions raised during a previous site intervention conducted in October 2016 against the requirements of licence condition (LC) 28 (examination, maintenance, inspection and testing).

The second part of the inspection reviewed the adequacy of the licensee’s arrangements for managing plant material condition of buried pipework and storage tanks that are important for safety, against the requirements of LC 28.

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

With respect to the first part of the inspection,  I judge that Heysham 1 has demonstrated adequate progress has been made with respect to the inspection and remediation of corrosion defects that require ‘immediate’ consideration (Category 1 defects) on those systems judged to be most vulnerable to corrosion (CV1 systems).

However, in my opinion insufficient evidence was provided to demonstrate that there is an adequate forward action plan in place to prioritise, and record the reasoning for, the selected remediation strategy with respect to corrosion defects of a lower category.  This particularly applies to defects that the licensee has identified requires ‘prompt’ consideration (Category 2 defects) on those systems with safety significance.  My concerns on this matter are related to the potential for the existing arrangements to not fully account for this category of defects, which if they are not evaluated and sentenced within an appropriate time frame, could degrade further to a point where immediate attention is required and the opportunity to take pro-active action is missed.

I am therefore not satisfied that Heysham 1 has provided sufficient evidence to close actions raised in my previous visit in October 2016 and monitored via ONR issue number 4840. I remain concerned that the site is not yet able to demonstrate that the threat posed by corrosion under insulation on pipework is being adequately managed.  I note that the site has recently made changes to improve the effectiveness of the corrosion management team, but these were not fully embedded or effective at the time of our visit.  

With respect to the second part of the inspection on management of buried pipework and storage tanks important for safety, I am broadly satisfied that the licensee has adequate arrangements in place for managing examination, inspection maintenance and testing. My inspection has identified a number of areas for improvement, however I am satisfied that the licensee is already taking the necessary steps to address my concerns through the implementation of revised processes and procedures to improve their understanding of plant material condition as part of the fleetwide corrosion management programme.

Conclusion of Intervention

Heysham 1 falls short of where I would have expected them to be at this stage following our previous visits and in comparison with the progress made by the rest of the fleet.  Although Heysham 1 could demonstrate that for those systems sampled, significant corrosion requiring immediate attention on the most vulnerable systems was being adequately managed, they were unable to show that they are fully taking ownership of the challenges posed to station from corrosion. I remain concerned that the site is not yet able to demonstrate that the threat posed by the corrosion under insulation on pipework is being adequately managed.

I judge that the progress of the corrosion management programme in terms of corrosion under insulation on pipework conforms to an AMBER rating against the ONR guidance on inspection ratings on the basis of this intervention.  In accordance with this guidance, the application of an AMBER inspection rating requires ONR to seek improvement from the licensee, and the recommendations below set out the way forward

In terms of the second part of the intervention I judge that the arrangements demonstrated by the licensee for the management of buried pipework and tanks at Heysham 1 against the requirements of LC28 currently conform to a GREEN rating with no formal action necessary.


I propose the following recommendations as a result of this intervention:

Recommendation 1: ONR should seek improvement from the licensee through the issue of a formal enforcement letter to the Heysham 1 Site Director, requesting a response to the following issues within 3 months:

Heysham 1 should explain how they intend to improve their process for prioritising, sentencing and remediating corrosion under insulation on pipework, and show how these decisions are recorded.

Heysham 1 should explain how they will develop a forward action plan to progress the remediation of both historic and ongoing Category 2 defects on systems with safety significance in a timely manner.

Heysham 1 should explain how they will ensure effective and sustainable oversight of the corrosion management process and should implement a process for ensuring that staff changes involving key members of the Corrosion Management Program are managed with minimal impact to the inspection or remediation programme.

Recommendation 2: ONR should conduct a return visit to Heysham 1 site within six months of this intervention to review the effectiveness of the revised corrosion management programme strategy and organisational changes.

Recommendation 3: The licensee's Central Technical Organisation should be asked to explain why their oversight of the corrosion management programme at Heysham 1 was not fully effective in ensuring that the site had progressed adequately, and how they will learn the lessons from this.

Recommendation 4: The current ONR issue number 4840 should be held open at the current level and updated to reflect this intervention to include an action for ONR to review the progress of the CV1 and 2 system inspections to confirm that they are completed within a timely manner.

I judge the proposed recommendations are appropriate from a safety perspective on the basis that the licensee has demonstrated they are adequately managing the most significant defects identified on the most vulnerable systems. I judge the proposed timeframe for a conducting a return visit to review the progress of the revised corrosion strategy to be acceptable to enable the new organisational and procedural changes to be fully embedded.