The Miami Herald
Posted on Sat, Mar. 19, 2011
Despite approval, critics question new Turkey Point reactor design
By Curtis Morgan
Turkey Point nuclear plant
Lynne Sladky / AP
Turkey Point nuclear plant
The next-generation reactors Florida Power & Light hopes to install at Turkey Point have been touted as simpler and safer, boasting an emergency cooling system that automatically kicks on during a power loss like the one that sparked the crisis at a Japanese plant.
A tank high atop the Westinghouse AP 1000 holds 780,000 gallons of water. That’s enough, Westinghouse calculates, to control reactor heat for 72 hours — without electricity or anyone even pushing a button. Instead, the system relies on gravity to deliver water and on evaporation and condensation to re-circulate it until generators or outside power can be brought on line.
The “passive” cooling design was a key reason FPL selected the unit for its proposal to add two reactors to Turkey Point, said spokesman Michael Waldron. “Every decision made by this company from the line worker to the CEO is done with, first and foremost, safety in mind.’’
But critics contend the AP 1000 — also picked by Progress Energy for a new plant in Levy County and the leading model in the nuclear power industry’s expansion plans — may have flaws that could make it less safe under assault from an earthquake, tornado or hurricane and leave it more exposed to damaging corrosion along the salty coastline of South Biscayne Bay.
In a March 7 letter, sent before Japan’s 9.0 earthquake and tsunami, U.S. Rep. Ed Markey, D-Mass., urged the Nuclear Regulatory Commission to revaluate its all-but-final approval of the AP 1000, citing concerns raised by John Ma, the agency’s own lead structural reviewer for the design.
An outer shield building that serves as first line of defense was too brittle, Markey wrote, and could fail during a quake or “if struck by an airplane or an automobile or other missile carried by a storm. In fact, Dr. Ma warned that if the AP 1000 shield was struck it could shatter like a glass cup.”
Failure of the building, Markey’s letter said, could expose the steel reactor containment vessel inside to damage. It also could potentially compromise the massive tank holding more than 3,000 tons of water atop the 130-foot structure.
Another analysis commissioned by environmental groups last year questioned whether the steel containment vessel — a critical barrier against accidental radiation release — was too vulnerable to rust that could cause dangerous holes and cracks, which have been discovered in a half-dozen older reactors nationwide.
Arnie Gundersen, a Vermont-based nuclear engineer and consultant who authored that study, said the flaws potentially could undermine the AP 1000’s safety features.
“There is a concept in the nuclear industry called a single point of vulnerability,’’ Gundersen said. “Remember, Goliath was a pretty tough guy but there was a hole in his armor.’’
After more than five years of review, and numerous design changes, the NRC announced last month that it had approved the AP 1000, pending a public comment period ending May 10.
The NRC has not yet responded to the letter from Markey, a longtime critic of the industry and agency. But spokesman Roger Hannah said, “We don’t see any reason to believe at this point that the overall AP 1000 design doesn’t meet all safety requirements.’’
The AP 1000 and other new designs, he said, are all intended to provide a “greater margin of safety” than existing facilities. But Hannah stressed regulators also intend to scrutinize the disaster in Japan and apply any lessons learned to domestic reactors.
If nuclear power maintains its public and political support, the AP 1000 stands to be in wide use over the next decade. Half of the NRC’s 28 pending reactor applications are AP 1000s — with projects proposed for Florida, Alabama, North Carolina, South Carolina and Georgia. China also has purchased four and is scheduled to flick the switch on the first new-generation nuclear reactor in 2013.
Older designs, such as the ones at FPL’s Turkey Point and St. Lucie County plants, encased reactors in steel containment vessels surrounded by several feet of concrete that acts as a secondary barrier to accidental radiation release.
The AP 1000 design is, as Gundersen puts it, “entirely different.” It employs a single steel vessel around the reactor — but with a wall more than four times thicker, at 1.75 inches, than older steel linings. Another change is a reactor shield building, constructed of a concrete-steel composite, which works as protection from the elements and terrorist attacks and as a thermal vent. The design allows air from outside to flow around the vessel, shunting heat out a rooftop hole, much like a chimney.
While the thicker steel vessel is good, Gundersen believes the design removes the concrete radiation barrier while inviting rust in places difficult to inspect and could worsen accidents by spewing out radioactive isotopes through its chimney.
For the nuclear industry, securing NRC certification for the AP 1000 represents a milestone in a nuclear revival now threatened by the disaster in Japan. It’s the furthest along in a new generation of reactors designed to improve safety and the operator’s bottom line. Westinghouse claims it will cost less to build and operate and last longer, up to 60 years.
The design dramatically reduces potential trouble spots by reducing components — valves by 50 percent and piping by 80 percent. The reduction in components also means a reduction in the size of the earthquake-proof structures operators must build — a huge savings for many operators. At the same time, the company says, NRC’s risk models suggest it will be 100 times less likely to suffer core damage than current reactors.
Westinghouse, FPL and the Nuclear Energy Institute, the industry’s policy organization in Washington, D.C., all defend the design, saying it meets or exceeds all regulatory requirements that it withstand the worst quakes and other natural forces — as well as airplane strikes.
Turkey Point, FPL’s Waldron points out, has already weathered Category 5 Hurricane Andrew in 1992. The plant, with its reactors shut down as a standard precaution, lost a fuel tank and some backup generators but never lost cooling capacity. Waldron said the federal review process should ensure that the AP 1000 is equally robust. And South Florida is not considered at any serious seismic risk.
“In the nuclear industry, we’re not going to compromise when it comes to safety,’’ he said.
The NRC and its independent panel, the Advisory Committee on Reactor Safeguards, had examined issues raised by Ma, Gundersen and others, said NEI spokesman Mitch Singer. He dismissed the concerns, saying they were pushed by groups with anti-nuclear agendas.
“They would like to see no nuclear and of course they would be critical of any reactor design,’’ he said.
Westinghouse spokesman Vaughn Gilbert said the shield building has been exhaustively reviewed and thoroughly tested in the lab and with computer modeling that replicates earthquake and aircraft strikes.
“A broad spectrum of industry experts have revived the design and concurred with the NRC’s conclusion that it is a safe design,’’ Gilbert said in an e-mail.
But NRC approval, announced in February, came with an internal dissent from Ma, who filed a “non-concurrence’’ statement last November. Even after Westinghouse redesigned the shield building walls after an initial NRC rejection, Markey’s letter said Ma still found points of concern.
Among those detailed in Markey’s letter: Sections of a first-of-its-kind steel-concrete module to be used in much of the building “failed miserably” in a direct physical test of its toughness. Ma also questioned whether Westinghouse’s computer models overstated the ability of the structure to withstand violent seismic shaking. The design, Ma wrote, also did not meet codes set by the American Concrete Institute requiring the structure to be flexible enough to absorb quake shocks.
The NRC noted it would “advantageous’’ to develop such a ductility standard for the new design but approved the design anyway.
Hannah, from the NRC , said Ma’s letter was “an expected part of the process’’ intended to ensure issues were throughly vetted. The NRC found that while Ma’s changes might be an improvement, the design still meets safety standards and, Hannah said, changes could still be ordered to address site-specific issues, such as hurricanes.
There have long been concerns about the nation’s aging nuclear plants. Almost all of the 104 operating reactors are at least 20 years old and half are 30 years old or older. Turkey Point, the oldest plant in Florida, will mark its 40th year of operation next year, but FPL’s Waldron said all “critical components’’ undergo a constant cycle of upgrades and replacement.
But industry critics remain skeptical.
Mark Oncavage, conservation chair for the Sierra Club in South Florida who has long monitored Turkey Point, said newer designs continue — among other issues — to treat potentially volatile spent fuel, stored in large volumes in pools, in buildings that aren’t as strong or secure as reactors.
But the overriding concern about the AP 1000, he said, is that “none of them have been built and proven yet. It’s an experimental design.’’
Gundersen believes the last reactors built in the 1980s had ironed out most problems and should be what the industry builds in the future. Newer designs, he said, stress economic savings along with safety.
He and David Lochbaum, director of nuclear safety for the Union of Concerned Scientists, also question the glowing safety numbers produced by the NRC’s risk models. With fewer components, routine operating risks might be lowered, Lochbaum said, but he doubts they’ll endure natural disaster any better.
“We don’t think new plant designs are significantly safer than the current ones,’’ he said.
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