Westinghouse Electric Co. attempted to assure federal nuclear regulators today that its redesigned Advanced Passive 1000 reactor poses no safety threat.

Westinghouse, a subsidiary of Toshiba Corp., revised its design certification application for the reactor after the Nuclear Regulatory Commission expressed concerns last month that its shield building might not withstand pressure from both seismic events and extreme temperature changes. NRC was also concerned about the strength of tanks that hold water for cooling reactors during emergencies (E&ENews PM, May 25).

Westinghouse officials said today that revisions attempt to address NRC concerns and pave the way for a final rulemaking on the design of the 1,100-megawatt electric pressurized-water reactor. The changes, they said, are minor corrections and clarifications and the actual design -- certified by NRC in 2005 -- was not modified.

The design's critics, including Rep. Ed Markey (D-Mass.), have warned the AP1000 shield building could shatter during an earthquake or if struck by an airplane or missile (E&ENews PM, March 10). But Thomas Bergman, the director of NRC Office of New Reactor's engineering division, said today strengthening the shield building would not make it safer.

NRC will now decide whether the design should be changed or whether more public comment is needed before the agency's five commissioners vote on the design. NRC Chairman Gregory Jaczko said in February that a decision could be made this fall (Greenwire, Feb. 2).

The approved design could provide the technical basis for up to 14 reactors in the United States.

The first utilities to use the design could be Southern Co., which is moving ahead with two new reactors at its Plant Vogtle in Georgia, followed by South Carolina Electric & Gas Co.'s two proposed reactors at its V.C. Summer plant northwest of Columbia, S.C.

Applications are also before NRC to use AP1000 technology at Duke Energy Corp.'s proposed Lee reactors 1 and 2 near Charlotte, S.C.; Progress Energy Inc.'s Shearon Harris units 2 and 3 in Wake County, N.C. and its two reactors in Levy County, Fla.; Florida Power and Light Co.'s two new nuclear units at its Turkey Point plant in southern Florida; and Tennessee Valley Authority's two reactors at its Bellefonte site in north Alabama.