- Site: Heysham 2
- IR number: 21-134
- Date: December 2021
- LC numbers: 10, 23, 24, 27, 28
Executive summary
Purpose of Intervention
The main purpose of this intervention was to conduct a system-based inspection (SBI) at EDF Energy Nuclear Generation Ltd (NGL) Heysham 2 Power Station (hereafter known as ‘the licensee’) on the Auxiliary Cooling and Seawater System.
SBIs involve a sample into the safety case and supporting documentation with a view to assess the adequacy of the implementation of the licensee’s arrangements as part of licence condition compliance. These inspections are informed through the review of the station safety report (including supporting documents), discussion with station specialists, plant inspection and sampling of documents and records.
This inspection was undertaken as part of a series of planned interventions that are listed in the Heysham 2 Integrated Intervention Strategy (IIS) 2021/2022. The inspection was undertaken by two ONR Structural Integrity Specialist Inspectors. In addition, the Heysham 2 Site Inspector attended the close out meeting.
Interventions Carried Out by ONR
I performed a system-based inspection to assess the adequacy of the implementation of the licensee’s arrangements for the following licence conditions in relation to the auxiliary cooling and seawater system:
- LC10 (Training)
- LC23 (Operating Rules)
- LC24 (Operating Instructions)
- LC27 (Safety Mechanisms and Devices)
- LC28 (Examination, Inspection, Maintenance and Testing)
- LC34 (Leakage and Escape of Radioactive Material) (N/A)
- LC34 relating to leakage/escape of radioactive material and waste is deemed to be not applicable to the auxiliary cooling and seawater system and hence excluded from this SBI.
The objective of the inspection was to form an overall judgement as to whether the auxiliary cooling and seawater system adequately fulfils the requirements of the safety case.
There are a number of different systems that make up the auxiliary cooling and seawater system. The following systems were targeted for the inspection based upon their safety significance:
- Pressure Vessel Cooling System (PVCS)
- Diagrid Support Skirt Cooling System (DSSCS)
- Reactor Seawater (RSW) System
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 auxiliary cooling and seawater system fulfils the requirements of the safety case.
Key Findings, Inspector's Opinions and Reasons for Judgements Made
For LC10 (Training), the licensee has not adequately implemented their LC10 arrangements for the PVCS System Engineer’s training profile. I judged this to be relatively low risk due to the PVCS System Engineer having substantial experience. However, I am concerned that this could have occurred elsewhere, and if so, personnel with responsibility for operations which may affect safety, may not have received suitable training. Therefore, I have assigned an AMBER rating for LC10. The licensee’s training group stated that they would raise a condition report to address the specific issue around the PVCS System Engineer’s training profile, and place actions to ensure this is not an issue elsewhere. The ONR Heysham 2 Site Inspector will follow this up as necessary. For the remaining aspects sampled, the licensee has adequately implemented their LC10 arrangements.
For LC23 (Operating Rules), I am content that the licensee has adequately implemented their LC23 arrangements in relation to the PVCS and DSSCS. However, the licensee has not adequately implemented their LC23 arrangements for the RSW system in relation to chemistry control provided by Sodium Hypochlorite Dosing. This presents a long-term risk, however there is no immediate risk to nuclear safety. The ONR Chemistry Specialist Inspector will follow this up with a level 4 regulatory issue. For the remaining aspects sampled, I am content that the licensee has adequately implemented their LC23 arrangements. Therefore, I have assigned a GREEN rating for LC23.
For LC24 (Operating Instructions), I am content that the licensee has adequately implemented their LC24 arrangements in relation to the PVCS, DSSCS and RSW system and therefore I have assigned a GREEN rating for LC24.
For LC27 (Safety Mechanisms and Devices), I am content that the licensee has adequately implemented their LC27 arrangements in relation to the PVCS and RSW system (DSSCS was not sampled) and therefore I have assigned a GREEN rating for LC27.
For LC28 (Examination, Inspection, Maintenance and Testing), I am content that the licensee has adequately implemented their LC28 arrangements in relation to the PVCS, DSSCS and RSW system. Therefore, I have assigned a GREEN rating for LC28.