UK Raises ‘Regulatory Issue’ Over Westinghouse AP1000 Design
Written by NucNet
Tuesday, 16 February 2010
There is a lack of evidence to show that key structures within Westinghouse’s AP1000 reactor unit would be sufficiently robust to protect the unit’s safety systems under normal conditions, and also from severe weather and other external hazards, the UK’s nuclear safety and security regulator said today.
The Health and Safety Executive’s Nuclear Directorate said it had raised a “regulatory issue” (RI) against the AP1000 relating to the proposed new steel-concrete-steel construction design for key structures within the nuclear island.
The Nuclear Directorate said it is not yet satisfied that the proposed steel-concrete-steel modular construction method, which would be used for some key structures, could protect the reactor’s safety systems from severe weather and other external hazards such as physical impact. The directorate has asked Westinghouse for evidence to show that the strength and durability of the structures have been adequately justified.
The modular construction approach proposed by Westinghouse involves a sandwich of steel plates filled with concrete, rather than using more conventional reinforced concrete, which is strengthened with internal steel bars.
Westinghouse is considering a number of possible solutions, such as further analysis and testing and possible changes to the design. The company intends to provide detailed proposals and supporting evidence by the end of October 2010.
The US nuclear regulator, the Nuclear Regulatory Commission, has also raised an issue regarding the design. The UK’s Nuclear Directorate said it is working closely with the NRC to ensure “maximum leverage and harmonisation of outcomes”.
The Nuclear Directorate said raising RIs does not mean that the designs are unsafe. The directorate is still assessing designs on paper, so any safety detriment is still in the design stage.
Two nuclear reactor designs – the AP1000 and Areva/EDF’s UK European Pressurised Water Reactor (UK-EPR) – are going through a generic design assessment (GDA) process in the UK.
