Dry used fuel storage facility now planned for HPC

NNB GenCo (HPC) Ltd was originally issued a radioactive substances environmental permit for the receipt and disposal of radioactive waste at Hinkley Point C in March 2013. In the original design, used nuclear fuel was to be stored on-site in wet storage - a method of submerging and storing in water. The fuel will be stored on-site before being sent to a Geological Disposal Facility (GDF).

However, the company has now decided that dry storage technology would be used at HPC, which will see used nuclear fuel stored in sealed containers within a facility before it is sent to the GDF.

Last month, NNB GenCo (HPC) Ltd applied to the Environment Agency to change its existing radioactive substances environmental permit for HPC, calling for specific conditions related to the previous wet storage technology that are no longer relevant to be removed or amended.

"An initial concept design was developed for a wet Interim Spent Fuel Storage (ISFS) facility by the HPC Project and this was used as the basis for the original Radioactive Substances Regulation (RSR) and Development Consent Order (DCO)," NNB GenCo (HPC) Ltd said in a 31 May letter to the Environment Agency. "Further design studies identified a number of technical challenges including the complexity of building an aircraft protection shell over such a large pool which meant that the original concept of a modular build was not considered technically feasible.

"Additionally, Sizewell B has since successfully licensed and begun to operate a dry ISFS meaning HPC obtained valuable experience in dry ISFS technology."

NNB GenCo (HPC) Ltd noted the dry ISFS building will "have a very simple structure" and that all cooling for the casks holding the used fuel is passive and independent of the building. It added the necessary shielding and protection from external hazards is afforded by the design of the cask system.

Separately, the company is applying to the Secretary of State for the necessary changes to its Development Consent Order for HPC, which was granted based on a wet ISFS.

Changing the storage method will not alter the expected radiation dose to the general public from discharges or the wider environment, which remains incredibly small, NNB GenCo (HPC) Ltd said.

The Environment Agency has now launched a public consultation on the change of used fuel storage technology at HPC. The consultation will finish on 14 August.

"We will take consultation responses into consideration as part of our determination of the application," it said. "If we decide to grant the application, we will explain how we made our decision and how we have addressed the comments that were raised.

"We will only vary the permit if we believe that it is appropriate to do so. If the applicant can demonstrate that the varied permit will meet all the legal requirements, including those for the use of best available techniques, public radiation dose and wildlife radiation dose, then we are legally obliged to grant the application."

Construction of Hinkley Point C - composed of two EPR reactors of 1630 MWe each - began in December 2018. The start of electricity generation from unit 1 is expected in June 2026, with unit 2 following in 2027.

NNB GenCo (HPC) Ltd estimates that some 7346 used fuel assemblies will be generated from HPC during its projected 60-year lifespan.