• 2010: Site preparation began for two new reactors - Units 3 and 4 - at Plant Vogtle near Waynesboro, Ga.

• Late 2011: The Nuclear Regulatory Commission is expected to certify the design of the Westinghouse AP1000 and grant a combined operating license for the new reactors to be built.

• 2016: Unit 3 reactor at Plant Vogtle to be completed.

• 2017: Unit 4 reactor at Plant Vogtle to be completed

Source: Southern Nuclear Operating Co.

By the end of the year, Georgia Power, Dalton Utilities and the other owners of the Plant Vogtle nuclear plant hope to secure the first combined operating license to build and operate two new reactors near Waynesboro, Ga.

But in a news conference Monday, anti-nuclear groups charged that the containment building in the new reactor design is still not secure enough to avoid the risk of a deadly radioactive leak. And they said the Nuclear Regulatory Commission, which has recommended approval of the design, is ignoring those issues.

Arnold Gundersen, a former nuclear industry executive hired by a dozen anti-nuclear groups, said the proposed Westinghouse reactor design -- known as the AP1000 -- is more susceptible than today's reactors to cracks and holes which have shown up in at least 40 currently operating plants.

"A large body of work indicates that radiation releases from containment failures in the AP1000 could exceed federal safety limits by up to 1,000-fold," Gundersen, the chief engineer at Fairewinds Associates, an engineering consultant, told reporters during the media briefing.

John Runkle, an attorney for the Waste Awareness & Reduction Network, said the AP1000 containment structure lacks the structural strength of existing reactors and would release far more radiation if a leak develops.

"We think it is unreasonable, if not unlawful, for the NRC to ignore these problems," Runkle said.

But NRC officials dismissed such criticisms, noting that an independent group of nuclear scientists known as the Advisory Committee on Reactor Safeguards reviewed Gundersen's complaints last year and found them lacking.

NRC spokesman Scott Burnell said the commission's technical staff has recommended that regulators certify the Westinghouse reactor design, which is intended to be simpler and safer than existing reactors.

If regulators certify the design as expected this fall, that could clear the way for Plant Vogtle to get a combined operating license by the end of 2011, making it the first new nuclear reactor built in the United States in two decades, with the completion of Unit 3 in 2016 and Unit 4 a year later. Combined, the new Vogtle plants are projected to cost $13.5 billion.

"We don't anticipate anything that is going on now with the NRC review will affect that schedule," said Beth Thomas, a spokeswoman for Southern Nuclear Operating Co., the company that owns and operates the Vogtle reactors.

The Tennessee Valley Authority also is considering building the Westinghouse AP1000 reactors at the Bellefonte site in North Alabama sometime after 2020.

Westinghouse spokesman Vaughn Gilbert said Gundersen's claims about frequent corrosion in existing reactor buildings fails to account for design differences in the new AP1000 reactor.

The containment vessel for the AP1000 "is a standalone steel containment and both the inside and outside surfaces are accessible for visual inspection" for early detection of any problems, Gilbert said.