Nuclear reactor design has safety flaw
Federal regulators say a nuclear reactor design chosen by FPL and another Florida utility has structural flaws that might not stand up to natural disasters such as hurricanes.
BY CURTIS MORGAN
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The nuclear reactor design that Florida Power & Light has chosen for its expansion at Turkey Point has safety flaws, federal regulators said Thursday.
The problem, according to the Nuclear Regulatory Commission, is weakness in a structure called the shield building. It is erected around an internal nuclear containment building primarily to protect it from natural disasters such as tornadoes and hurricanes.
In a letter to the Westinghouse Electrical Co., manufacturer of the reactor, the NRC said that part of its AP1000 reactor design did not withstand design loads. The agency said it would require additional analysis, testing and possibly redesign.
FPL is one of several utilities that have chosen the Westinghouse design as part of a resurgent effort to build nuclear plants. Progress Energy, which is planning a nuclear plant in Levy County, is also using the design. Overall, 14 AP1000 units are under review in the country, and Westinghouse is building several overseas, with one in China farthest along.
Roger Hannah, a spokesman for the NRC in Atlanta, said the agency did not yet know whether fixing the flaw would de lay permitting or construction of any of the plants. FPL did not return calls and e-mails seeking comment Thursday.
On its website, Westinghouse posted a statement that it had expected the NRC action and is already working to address the issue. The company said it hoped to have the design certified by 2011 and the first reactors online by 2016. ``We have fully committed the resources necessary to both quickly and definitively address the NRC's concerns, and we are confident that we will meet all applicable requirements,'' the statement said.
In a release, Michael Johnson, director of the NRC's office of reactors, said the agency had been discussing the flaws with the company since October 2008.
``This is a situation where fundamental engineering standards will have to be met before we can begin determining whether the shield building meets the agency's requirements,'' he said.
Hannah said one concern was about potential building failure, regarding a large water tank mounted at the top of the structure that contains an estimated six to eight million pounds of water.
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--Addendum--
NRC Decision Tests Nuclear Plant Plans
By REBECCA SMITH
The Nuclear Regulatory Commission rejected the modified design of a next-generation nuclear power station from Toshiba Corp.'s Westinghouse Electric Co. because of concerns about structural strength, a decision which could pose a setback for the utility industry's plans to roll out a new fleet of nuclear reactors in the next several years.
The Westinghouse reactor, the AP1000, has garnered more interest among U.S. utilities than any competing design. Seven U.S. utilities are seeking licenses to build 14 of the reactors in five states, about half the number of new reactors now contemplated, and there are plans to build multiple units in China, as well. As a result of the NRC action Thursday, the U.S. projects face possible delays although it's too early to say of what duration.
The NRC noted that it was concerned about whether the outermost structure, called the "shield building," could withstand the destructive force of earthquakes or tornados.
"Westinghouse is going to have to make design modifications, if they want to move forward," said David Matthews, director of the new reactor licensing division at the NRC.
The NRC decision is also a blow to new modular construction techniques that reactor vendors have proposed to control costs and speed construction. Some utilities have been garnering permission to being charging consumers for reactor development costs based on assurances the process would go smoother this time than a generation ago.
In a release, Westinghouse said it has "already begun to address certain portions of the design" and would "quickly and definitively address the NRC's concerns." It said it is committed to getting its plant design cleared for U.S. construction by 2011 so that there could be completed units around 2016.
Southern Co. is regarded as the utility most likely to first start construction at its site in Georgia. The utility already is preparing the ground for a foundation. The plant was expected to enter service around 2016. A spokesman said the Atlanta-based company expects to stick to its original development schedule.
The NRC's finding casts a shadow over plant construction because it found inadequacies in the design of the shield building, which houses the nuclear reactor and its primary containment structure. Under NRC rules, power-plant designs must withstand tornado-force winds and flying debris.
The shield building is one of the most important parts of a modern-day nuclear plant. Westinghouse's design for the building incorporates a "passive" cooling system in which six million to eight million pounds of water are held in a tank above the reactor where it would be released in an emergency for cooling purposes. The water is kept at a level higher than the reactor so that gravity flow would be used to flood the vessel.
In its original design, which was certified by the NRC in 2006, steel walls would have been erected and filled with concrete that would have been poured at the site. Under Westinghouse's modified design, which the NRC rejected, the shield building would have been assembled from steel-and-concrete sections fabricated elsewhere. The building would be built in building-block fashion.
But the NRC staff said the construction method has not been used before and there was inadequate testing to prove it is hardy enough to satisfy strength and loading requirements.
Although the AP1000 was certified by the NRC in 2006, additional requirements have been imposed more recently.
A new rule, issued this spring, requires reactor vendors to analyze what would happen to each plant if it were hit by a large commercial aircraft. The NRC said it was rejecting the design on the basis of the threat of a natural disaster and not an aircraft strike.
Write to Rebecca Smith at [email protected]