Officials of Westinghouse Electric Company say they are disappointed that recent U.S. NRC statements regarding the discovery of new issues relating to the approval of design amendments for the AP1000® nuclear power plant are being misinterpreted and sensationalized.
The company also said the NRC statements, including a news release issued May 20, do not reflect Westinghouse’s transparent and cooperative approach to the handling of the discovery and severity of the few remaining issues that need to be resolved before receiving approval from the NRC.
“The AP1000 nuclear energy plant is a highly robust and safe plant that has undergone an extremely intensive series of tests and reviews by the NRC, the independent Advisory Committee on Reactor Safeguards, university experts and numerous other independent third parties,” said Ric Perez, president of Operations for the company. “The AP1000 is very likely the most closely scrutinized nuclear energy plant in history, now having undergone several years of exhaustive system and component testing, public debates, design reviews and multi-national regulatory oversight. We are confident that it is extremely safe.”
The company is aware of only three issues remaining to be validated, none of which are safety significant. The issues involve the final submittal of confirmatory calculation in the areas described below. All three issues have undergone preliminary analyses which have been seen by the NRC for familiarity and clarity. All preliminary analyses results support the positions and bases taken by the staff in their advanced safety evaluation made in February 2011. None of the three issues is anticipated to lead to any design change in the plant as submitted by Westinghouse in December 2010 (DCD-18).
- In December 2010, the NRC and Westinghouse agreed that containment vessel internal pressure calculation would need to be revised. It was determined late in April that documentation of the calculation was required prior to the design certification amendment. The revised calculation will be reviewed with the NRC in a public forum on June 2.
- In April 2011, the NRC challenged the analytical guidelines used by Westinghouse in its comprehensive Shield Building Design Report submitted in May 2010. Specifically, the NRC challenged the position that climatic thermal loads (e.g. sunshine) need not be combined with seismic loads in structural design calculations due to their small impact and based on prior U.S. building code practice. Westinghouse disagreed with the NRC position that the load combination was a strict code compliance issue due to the shield building’s steel-composite structure and clear treatment in the design report. Nevertheless, Westinghouse agreed to perform the detailed load combination calculations to provide additional assurances to the NRC. To date, Westinghouse has completed preliminary calculations which, as expected, require no change to the shield building design. This information was presented to the NRC during a public meeting last week
- The third issue relates to what design model was used for the design of the passive containment cooling system (PCS) tank. There are two technically acceptable models but each treat differently the hydrodynamic forces from water in the tank. The May 2010 Shield Building Design Report references the specific model to be used for each structure contacting the PCS tank. However, during the confirmatory work on loads discussed above, Westinghouse self-identified that it did not use the specific model outputs for one corner structure of the tank. The specific model loads and structural analysis have now been used, and Westinghouse is working to verify preliminary conclusions that indicate that there is no reason to change the tank design.
While Westinghouse strongly believes that safety is the utmost priority and that a transparent review process involving the public is critical, it also believes that it has already proven to the NRC that the AP1000 pressurized water reactor is a highly robust design that will take nuclear safety to an even higher level. In any case, the company has pledged to work cooperatively and transparently with the NRC to address any outstanding technical issues.
“We have defended openly our claims of safety for the past six years, starting with the original design certification of the AP1000. We have always reiterated to the staff that getting things right is our first priority. Our behaviors towards these last few issues continue to reinforce that practice.” Mr. Perez said. “We are confident that we will resolve any legitimate and objective concerns and receive final approval of the design amendments as planned this fall.”
Westinghouse Electric Company, a group company of Toshiba Corporation (TKY:6502), is the world’s pioneering nuclear energy company and is a leading supplier of nuclear plant products and technologies to utilities throughout the world. Westinghouse supplied the world’s first pressurized water reactor in 1957 in Shippingport, Pa. Today, Westinghouse technology is the basis for approximately one-half of the world’s operating nuclear plants, including 60 percent of those in the United States.