Dungeness B Maintenance Update
Dungeness B has been undergoing one of its busiest periods of maintenance for many years, with staff and specialist contractors carrying-out a huge amount of technical tasks as part of the ongoing double-reactor outage.
The current workload has included a programme of enhanced inspection and remediation of back-up systems susceptible to the effects of environmental corrosion.
This programme of work had been accelerated following formal challenge from the Office for Nuclear Regulation (ONR). Hence utilising a dedicated and experienced Event Recovery Team numerous systems have been thoroughly inspected and repairs enacted accordingly.
During this accelerated inspection and remediation programme, corrosion was discovered on pipework and/or supports to systems important to safety. It is judged that a number of these systems may have been challenged under significant external hazard such as seismic or severe flooding. However, our repairs and remediation programme, agreed with the regulators, has now given us confidence that our systems will perform as designed.
In response to this programme of work EDF Energy has informed the regulator of new expectations on return to service, and we intend to have both reactors back online in the coming weeks.
EDF Energy has rated the corrosion issue as Level 2 on the International Nuclear and Radiological Event Scale (INES).
An INES Level 2 rating can describe a radiological issue – but in this case it relates solely to an incident of deficiency in back-up safety provision – namely systems needed in case of seismic and other external hazards occurring (there was no direct impact or harm from this shortfall to the environment of the public).
The current wide-ranging maintenance programme is an investment aiming to build on positive performance and output indicators, as Dungeness B continues its trend towards improving reliability, and achieving world-class performance.