I undertook a system inspection of Hinkley Point A's (HPA) cell containing Settling Tanks (STs) 1, 2 and 3 and the associated "Penthouse" ventilation systems which ventilate the tanks and ensure containment in the event of a leak. The information gained will be of value for future work to retrieve the intermediate level waste (ILW) stored on the site and place it in a passively safe form into self-shielding containers.
I was updated on progress with ILW decommissioning programmes on the site.
HPA provided me with a series of documents that together were the safety case for the ventilation systems in the "Penthouse" and cell. I inspected the "Penthouse" and its ventilation ducts and the equipment used to ventilate the cell including filter housings and trunking. HPA explained to me why and how the safety case was modified to incorporate ventilation into the cell. I sampled the training requirements, operating instructions, safety mechanisms, leakage and escape instrumentation and maintenance requirements relevant to the cell ventilation system.
I judged the ventilation systems to be adequate.
I believe HPA was working in a way that will minimise the risks to health and safety and nuclear safety from a failure to a settling tank containing ILW. I noted that once the potential for a tank failure had become apparent, the site implemented improvements to the ventilation of the cell in which the tank was located.
HPA staff was able to demonstrate how the safety case had been made and implemented. I also saw how the staff involved in the emptying of the tanks, were trained in how to respond if the cell ventilation system or "Penthouse" ventilation system failed. There was also a process for recovering the system. The health of the filters in the ventilation systems was checked periodically and I was satisfied that the site was able to show that the staff responsible for this work were qualified. Through my discussions and evidence provide by the site I gained confidence that HPA staff understood the safety issues arising from their work in the "Penthouse" and the cell associated with STs 1, 2 and 3. The work to improve the ventilation within the cell met ONR's Safety Assessment Principles on containment and ventilation adequately.
Hinkley Point A demonstrated to me that they were minimising the risks to the public, workers and the environment for the operation of emptying the ILW waste stored in STs 1, 2 and 3.