Nuclear reactor manufacturer Westinghouse’s efforts to deliver a new generation of nuclear power plants ran into trouble this week when United States nuclear regulators sought further clarification about its AP1000 design.
The country’s Nuclear Regulatory Commission (NRC) has uncovered “additional technical issues” during the licensing process which is required before these new reactors can be built.
The NRC’s concerns focus on the AP1000 containment building − which houses the nuclear reactor − and the peak pressures expected within it.
The NRC is seeking further clarification about the seismic and thermal load combinations used to calculate pressures within the containment building. Experts believe that Fukushima disaster in Japan prompted the extra scrutiny.
University of Warwick nuclear researcher Paul Dorfman believes that the US concern could be because the design does not have a core catcher.
“If the nuclear fuel does burn through, which has almost happened in Fukushima, then [the core] would be unprotected”
University of Warwick nuclear researcher Paul Dorfman
A core catcher is a structure built under the reactor to contain it in the event of a meltdown.
“If the nuclear fuel does burn through, which has almost happened in Fukushima, then [the core] would be unprotected,” said Dorfman.
“However, if the authorities want a core catcher, it would add significantly to the design costs.”
Dorfman added that Westinghouse competitor Areva’s European Pressurised Reactor (EPR) does have a core catcher, but this design has experienced major construction problems in Finland and France.
Independent nuclear expert Tony Roulstone added that the NRC’s request for clarification about the AP1000 should concern Westinghouse given the amount of analysis its reactors have undergone. Westinghouse has said its AP1000 is “one of the most studied, reviewed and analysed nuclear power plant designs in the history of the commercial nuclear power industry”.
“The AP1000 is a safe, robust design and is worthy of receiving design certification”
It has played down the NRC’s concerns. “We characterise these changes as minor,” said a Westinghouse spokesman. “The AP1000 is a safe, robust design and is worthy of receiving design certification.”
But independent nuclear engineer Arnie Gundersen working for Friends of the Earth believes that there is no “containment shield” but rather a shield building.
Calls for licensing process to be suspended
Friends of the Earth wants the NRC to suspend its licensing process due to its concerns over the shield building.
Westinghouse must satisfy the NRC before it can obtain a licence. This follows on from the Health & Safety Executive (HSE) raising similar concerns about the shield last year (NCE 6 May 2010).
The UK’s Office of Nuclear Regulation (ONR), which works closely with NRC, said “this is an issue that we are currently discussing with NRC.”
Westinghouse is currently competing against Areva to be selected by nuclear new-build consortium Horizon for its site in Wylfa on the Isle of Anglesey.