AP1000 Oversight Group
Nuclear Design – “an Oil Tanker with a Single Hull”
Westinghouse is going backward with safety, and its new design increases the risk of nuclear disasters, industry veteran tells federal safety panel
Durham, NC – If ever built, a Westinghouse nuclear reactor would revert to a single containment shell subject to corrosion holes and increased risks of radiation releases. That’s what a veteran industry official told a federal safety panel on Friday, based on a flaw with the design of the AP1000 reactor, and corrosion problems documented at scores of existing U.S. nuclear plants.
Arnold Gundersen, a 38-year nuclear engineer and former industry senior vice-president, met Friday with a subcommittee of the U.S. Nuclear Regulatory Commission’s Advisory Committee on Reactor Safeguards. The ACRS had invited him to discuss his April report in which the engineer identified the design flaw he says could turn the AP1000’s “passive” emergency cooling system into a chimney that pulls radiation directly into the atmosphere during accidents.
“When the Exxon Valdez hit rock, the solution was to require double-hulled tankers, not make the single hull thicker,” Gundersen told the panel. “With most existing reactors, if one containment fails, we have backup. I am concerned about going back to the one liner.”
The containment is a key barrier intended to prevent radiation releases during meltdowns caused by pipe breaks and other accidents. Responding to Gundersen’s April report, Westinghouse claimed the AP1000 has a thicker containment than those at operating plants. But that refers only to the inner metal liner; most operating plants also contain a thick, outer concrete shell that is missing with the AP1000, which instead has an outer “shield building” that is open at the top.
As Gundersen explained, the gap between the AP1000’s inner liner and shield building contains numerous areas would be subject to rust and difficult – if not impossible – to inspect, and the outside of the liner will be routinely exposed to moisture. He also told the panel that operating reactor containments have suffered severe corrosion holes despite inspection programs and surface coatings intended to inhibit rust.
The ACRS, which is studying the Westinghouse reactor design, has expressed concerns about the corrosion holes, cracks and pits being found at U.S. reactors in recent years. Last year the science advisors noted that accident pressures would blow holes wider open, and that an enormous volume of radiation can pour through even a small hole in containment.
The NRC’s Inspector General found that ongoing coating failures and corrosion problems have persisted undetected for years even as the NRC touted those plants as having superior inspection and coating programs. “Experience shows that paint hides corrosion,” Gundersen said Friday.
The AP1000 design is the basis for new nuclear power plants proposed by electric utilities in North Carolina, South Carolina, Georgia, Alabama and Florida. Gundersen, Chief Engineer with Fairewinds Associates, Inc., is representing the AP1000 Oversight Group, a coalition of twelve environmental organizations that released the engineer’s technical analysis about the containment problem in April.
John Runkle, an attorney for the groups, also spoke Friday with the ACRS, repeating his request for a full investigation into Gundersen’s concerns about the potential for corrosion holes in the AP1000 containment. “This issue should be included in the list of unresolved issues, and resolved prior to certification of the AP1000 design. No licenses should be issued until all these problems are resolved,” he told the safety advisors.
“A coat of paint and inspections is no substitute for a double hull,” Gundersen added later. “The AP1000 takes a major step backward in technology with single-wall containment.”
Arnold Gundersen’s slide presentation to the ACRS are posted at www.fairewinds.com
An audio recording of the meeting will also be available.