The purpose of this intervention was to gain confidence in the adequacy of NNB Generation Company (HPC) Limited’s (NNB GenCo) arrangements, and those of its supporting organisations, covering the development and implementation of design and safety case modifications, focussing on the modification to replace the reactor coolant pumps’ hydrostatic (HS) seals with hydrodynamic (HD) seals.
Office for Nuclear Regulation (ONR) fault studies specialist inspectors visited Framatome’s offices in Paris to form a judgement on the arrangements associated with implementation of HD seals design modification and supporting safety case for Hinkley Point C (HPC). This intervention was carried out in collaboration with NNB GenCo’s Independent Technical Assessment (ITA) function.
The relevant fault analysis ONR Safety Assessment Principles, principally FA.2, FA.3, FA.4 and FA.8, and expectations for compliance with Licence Condition (LC) 17 (Management systems) were used to inform ONR’s judgement during this intervention.
LC17 requires that “the licensee shall establish and implement management systems which give due priority to safety”.
The focus of this intervention was on development of the design of the HD seals, incorporation into existing systems, and development of the safety case for operation of HD seals in normal and accident conditions.
Not applicable as this was not a safety systems inspection.
Based on the evidence gathered, a number of good practices in the procedures for implementation of modifications were observed demonstrating that adequate arrangements are in place, and are undertaken by competent personnel:
However, a number of observations were noted for further consideration by NNB GenCo, which will be followed-up, as necessary, through the regular level 4 meetings with the licensee.
I judge that an intervention rating of GREEN (no formal action) is appropriate for LC17: Management systems. This is because I found the arrangements for the development and implementation of the HD seals modification to be adequate, with only minor areas for potential further improvement identified, which were raised as observations.