The two companies bidding to build new nuclear reactors in the UK may have to make modifications to their designs to satisfy regulators that they are safe.
A report published today by the Health and Safety Executive as part of the generic design assessment (GDA) identified “a significant number of issues” with the safety features of both Areva’s EPR reactor and Westinghouse’s AP1000 design.
The HSE said design changes to both reactors could not be ruled out in the next phase of the GDA, which will establish whether they can be built in Britain. It has already asked Areva to improve the arrangements for segregating four protection “trains” within the EPR design, each of which is independently meant to be capable of providing the full means to safely shut down the reactor.
“We have requested that EDF and Areva improve the arrangements for ensuring the integrity of the hazard barriers through implementation of door control measures. EDF and Areva have agreed to achieve this through a design modification,” the HSE report said.
It also questioned the use of bonded pre-stressing tendons in the EPR containment dome design, which have not been used before in nuclear applications in the UK. “We have been unable as yet to gain sufficient confidence in the likely quality of the construction,” the regulator said. The HSE also raised “significant concerns” about the lack of independence of control and protection systems in the Areva design. “There is significant additional work to be done by EDF and Areva to satisfy our questions and to make and present an adequate safety case.”
For Westinghouse’s AP1000 design, the regulator said the next phase of the GDA could result in “design modifications”. It said Westinghouse had yet to present an adequate safety case for external hazards to the reactor, such as earthquake or the impact of an aircraft. The HSE also expressed dissatisfaction with the safety case for mechanical aspects of the AP1000. The HSE said that the design of a special “squib valve” – a fast acting valve operated by propellant charges and used as part of the core cooling system – was questionable because it was at an “incomplete” phase of development.
Areva is already constructing its new EPR design at sites in Finland and Normandy, France, but the Finnish project has been beset by delays and wrangling over costs. Westinghouse is currently building the first AP1000s in China and has signed deals to build more reactors in the United States – the country’s first for decades. Mike Tynan, Westinghouse UK chief executive, acknowledged that there were “many areas” in the report which identify work that still needs to be done to give regulators confidence in the AP1000 design.
He added: “These reports demonstrate unequivocally that the UK regulatory process for potential new reactor designs is working as intended. The regulators are clearly – and quite rightly – subjecting both designs to very rigorous, comprehensive and detailed scrutiny. That should provide great confidence to the UK public and investors that the highest levels of safety, security and environmental protection can be expected from any new nuclear build in the UK.”
