Office for Nuclear Regulation

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System Based Inspection 04 - Auxiliary Cooling System

Executive summary

Purpose of Intervention

The purpose of this intervention was to conduct a systems based inspection of EDF Energy Nuclear Generation Ltd’s (NGL) Hartlepool Power Station in relation to the auxiliary cooling systems.  This was undertaken as part of a series of planned interventions that are listed in the Hartlepool Integrated Intervention Strategy 2018/19.

Interventions Carried Out by ONR

Two ONR mechanical engineering specialist inspectors conducted the Systems Based Inspection of the Auxiliary Cooling System (ACS). 

System based inspections examine evidence to determine compliance against six key Licence Conditions:

These are selected to help determine whether the safety case requirements of the system concerned are adequately implemented.

Explanation of Judgement if Safety System Not Judged to be Adequate

As part of this intervention I performed a desktop review of the Licensee’s arrangements and associated documentation for the six License Conditions. I also performed a plant walkdown and had discussions with various System Engineers, Training Group Heads and Nuclear Safety Group personnel. I sampled a valve which is considered important to nuclear safety and is included in the technical specification, requiring a shiftly surveillance to confirm position.  Through my inspection I identified that this valve was not on the maintenance schedule and had a status of run to failure.  I judged that this did not meet the requirements of Licence Conditions 23, 27 and 28, and have therefore raised a number of Regulatory Issues, and have rated Licence Conditions 23, 27 and 28 Amber.  Consequently based on my sampled inspection my overall judgement was that the system did not adequately fulfil the requirements of the safety case.

However, in light of the above findings I judge that there is sufficient redundancy and diversity within the system in order to safely shut the reactor down in the event of a fault occurring.  Therefore, I do not consider that the shortfalls identified prevent continued safe operations.

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

I performed a sample focused inspection of the Licensee’s arrangements and associated documentation for the six License Conditions.  I also performed a plant walkdown and had discussions with various System Engineers, Training Group Heads and Nuclear Safety Group personnel.

I identified four shortfalls, three of which are significant I have therefore raised regulatory to track the progress of the station’s resolution of them.

Site Licence Condition 10 – Training – Inspection Rating Green (No Formal Action)

I examined the training arrangements for individuals to become suitably qualified and experienced for the tasks they undertake a part of maintenance and inspection activities being undertaken.  I judged that the personnel undertaking and supervising these activities were suitably qualified and experienced.  I therefore assigned an inspection rating of Green (No Formal Action) for LC10.

Site Licence Condition 23 – Operating Rules– Inspection Rating Amber (Seek Improvement)

The technical specifications, surveillance and commentaries specified the limits and conditions of operation, reflecting those specified in the living safety cases.  It was noted that the living safety cases also contained a record of modifications identifying the current safety case update documentation (SCUD).  My sample identified a valve that required a shiftly surveillance to confirm the valve was closed as part of the Operating Rules. The Licensee was unable to adequately demonstrate that this shiftly surveillance was performed and therefore that configuration control was adequately managed. In addition, the Licensee had no arrangements in place for the regular review of Operating Rules other than when modifications were performed.

Site Licence Condition 24 – Operating instructions – Inspection Rating Green (No Formal Action)

I judge that the Licensee has an adequate process in place for the production and implementation of Maintenance and Operating Instructions.  I therefore consider a rating of Green (No Formal Action) to be appropriate for License Condition 24.

Site Licence Condition 27 – Safety Mechanisms, Devices and Circuits – Inspection Rating Amber (Seek Improvement)

I consider that the Licensee has shortfalls in the implementation of their arrangements to ensure that plant is not operated, inspected, maintained or tested unless suitable and sufficient safety mechanisms, devices and circuits are properly connected and in good working order. The valve sampled could not be confirmed as correctly connected and in good working order due to no shiftly surveillance, and its status as run to failure (see License Condition 28).  I therefore consider that the implementation of the Licensee’s arrangements for LC27 do not meet regulatory expectations, so have assigned a rating of Amber (Seek Improvement).

Site Licence Condition 28 – Examination, Inspection, Maintenance and Testing – Inspection Rating Amber (Seek Improvement)

I judge that the Licensee has an adequate process in place for the production and implementation of Maintenance Instructions.  However, I consider that the Licensee has shortfalls in the implementation of their arrangements for the regular and systematic examination, inspection, maintenance and testing of all plant which may affect safety.  There was also a large backlog of Work Order Cards on the system which could prevent learning from previous Work Order Cards being promulgated to inform subsequent activities.  Due to these shortfalls, and the fact that the valve sampled was part of an operating rule, I consider a rating of Amber (Seek Improvement) to be appropriate for LC28.

Site Licence Condition 34 – Leakage and Escape of Radioactive Material and Radioactive Waste – Inspection Rating Green (No Formal Action)

The licensee demonstrated that systems were in place to detect the presence of CO2 in auxiliary cooling water.  I judged that the Licensee had an adequate process in place for identifying a loss of reactor gas through the auxiliary cooling system so considered an inspection rating of Green (No Formal Action) to be appropriate.

Conclusion of Intervention

After examining the evidence sampled against LCs 10, 23, 24, 27, 28 and 34 during my inspection, performing a walkdown, and having discussions with various System Engineers for the areas sampled, Training Group Heads and Nuclear Safety Group personnel, I judge that the Auxiliary Cooling System (System 4) does not adequately fulfil the requirements of the safety case. However, in light of my findings,  I judge that there is sufficient redundancy and diversity within the system in order to safely shut the reactor down in the event of a fault occurring.  Therefore, I do not consider that the shortfalls identified prevent continued safe operations.

In view of the findings of this inspection the Enforcement Management Model will be consulted to determine whether further Regulatory action is required.