The threat is from air attacks, say critics of government security efforts. They push for more safety measures.
Since Sept. 11, critics of the nuclear power industry have warned repeatedly that the nation's 103 atomic generating stations are vulnerable to terrorist attacks using hijacked airliners or smaller planes packed with high explosives.
Now, activists and watchdog organizations are pushing for countermeasures they say will improve safety and deter terrorist assaults from the air.
The U.S. government already has increased precautions against ground attacks on nuclear power plants, including California's two: San Onofre in northern San Diego County and Diablo Canyon on the Central Coast.
But environmentalists and nuclear-safety activists say the government has been far too slow in confronting the possibility of an air attack. At the same time, the Department of Justice and the Department of Homeland Security have continued to warn that Al Qaeda remains interested in targeting nuclear plants.
Critics of the industry point to a secret German government study leaked to the European media late last year. It suggests that nuclear plants may be more vulnerable than the U.S. Nuclear Regulatory Commission and power companies have maintained.
The critics have two concerns: A crashing jetliner might trigger the meltdown of a reactor core, or it could ignite fires in storage ponds for spent nuclear fuel at power plants. The concrete-and-steel pools contain some of the largest concentrations of radioactive material on Earth.
In late July, the Committee to Bridge the Gap, a California-based organization that has been a persistent critic of the nuclear power industry, formally petitioned the Nuclear Regulatory Commission, asking that it require the construction of barriers made from steel I-beams and cables that could deflect or stop an airliner from hitting a nuclear power plant. NRC officials say consideration of the committee's petition is pending.
Though he does not have firm estimates, the committee's founder, Dan Hirsch, said the beams, which would be spaced at intervals, could be put in place for about 1% of the $1-billion to $2-billion cost of building a power plant.
"Today, there is nothing to prevent an air attack," Hirsch said, "nothing except hope."
Steve Lloyd, vice president of regulatory affairs for the Nuclear Energy Institute, a trade organization and lobbying arm for the industry, countered that cages could cost far more — $300 million to $500 million per power plant — far too expensive for utility companies to build. The industry estimates are based on constructing geodesic domes to protect reactors, he said.
"Our basic position is that the plants are strong. They have redundant safety systems, and there is plenty of time to prevent the release of radiation," Lloyd said. "We don't see the need for very expensive actions."
The industry contends that environmental groups and critics of atomic power are using the threat of terrorism to further an anti-nuclear agenda.
"They are not doing this kind of thing for chemical plants," Lloyd said. "They want to make nuclear power so expensive there is no incentive to do it anymore."
If an airplane were to hit a nuclear power plant and emergency systems and evacuation plans proved inadequate, worst-case scenarios indicate that a reactor core meltdown or spent-fuel fire could result in hundreds of thousands of people killed or stricken with cancer or genetic damage. An area the size of Pennsylvania could be transformed into a no-man's land for centuries.
Such a disaster at the San Onofre Nuclear Generating Station, just south of San Clemente, could have devastating health and economic effects on many millions in the Southland. The Nuclear Regulatory Commission and the nuclear power industry have undertaken separate studies indicating a disaster of that sort is unlikely.
In interviews, regulators and industry officials said their faith in existing security measures is based partly on the fact that nuclear power plants are much smaller targets for a pilot to hit than the sprawling Pentagon and towering World Trade Center.
John Mazor, a spokesman for the Air Line Pilots Assn., agrees. Jetliners, he said, are difficult to maneuver with pinpoint accuracy and tricky to handle at very low altitude, as with the Pentagon attack. He said the Pentagon crash probably had more to do with luck than skill.
Even if an airplane smashed into a facility, NRC officials and plant operators said, a reactor core meltdown or catastrophic fire involving spent fuel in storage ponds is highly unlikely. Plants are built robustly and have emergency backup systems that can be activated quickly, they said.
Rather than spend time and money fortifying plants, NRC and industry officials say, the most cost-effective strategy to prevent air attacks on reactors remains continued improvements in airport and aircraft security.
The government has beefed up security for commercial airlines, improving passenger screening and armoring and locking cockpit doors.
Critics of the industry dispute the NRC and industry studies, and point to the research undertaken in 2002 for a German government ministry that regulates nuclear power. That research indicates that a variety of jetliners, if crashed into Germany's atomic power stations, could trigger the release of radiation into the atmosphere.
Much of the debate over the risk posed by possible air attacks on nuclear plants involves the vulnerability of containment domes — structures that in the United States are built of steel-reinforced concrete, ranging in thickness from 3 1/2 to 6 feet.
Nuclear power plants are not designed to withstand a direct hit by a commercial jetliner. Nevertheless, some research suggests that they could.
The debate goes back at least to 1981, when the Argonne National Laboratory in Chicago conducted a study for the NRC indicating that an airliner crashing into a nuclear plant could cause fires and explosions that would pose serious threats. The NRC now considers that study obsolete, said Eliot Brenner, an NRC spokesman.
More recent studies by the NRC and the Nuclear Energy Institute indicate that containment domes of the nation's nuclear generating stations can withstand a direct hit from a large jetliner without a significant release of radiation.
Except for that main conclusion, the NRC study is classified and unavailable to the public. Commission officials, however, have told the federal General Accounting Office that certain types of aircraft hitting certain locations at power plants pose a risk, but safety features and emergency preparedness plans should lessen that risk.
Brenner said the government spent $15 million on the research and relied on computer analyses at national laboratories to look at all-important reactor facilities.
Nuclear Energy Institute officials said they spent about $1.5 million on their own study, which showed that a low-flying Boeing 767-400, traveling about 350 mph, would not penetrate containment structures.
"A nuclear power plant can withstand an airliner crash, either deliberate or otherwise," said Ray Golden, a spokesman for Southern California Edison, which conducted its own analysis of the San Onofre plant. "They are a hard and hardened target."
The German researchers, by contrast, concluded that crashes of large jetliners, under a wide range of circumstances, could result in uncontrollable situations and the release of radiation from reactor buildings and storage ponds for spent nuclear fuel.
Spent-fuel ponds, though often housed in lightly constructed buildings, also have thick concrete walls and steel liners, where the waste is stored under 20 feet of water.
Industry critics in the United States say the German study is more realistic than the NRC and Nuclear Energy Institute studies because it considered crashes at a speed higher than 350 mph.
The German study used computer simulations to analyze the impact of jetliners, including large Boeing 747s and smaller Airbus 320s, on five types of plant designs in Germany's inventory of 18 reactors. The simulated crashes were at speeds of 224 mph and 390 mph.
Using flight simulators, six pilots were able to hit a facility similar in size to a nuclear power plant about half of the time. A glancing blow was considered a hit. In the computer models, the most modern and robust plants fared well, with a few exceptions involving the largest jetliners. Older and more lightly constructed stations were the most vulnerable.
German containment buildings range in thickness from 2 feet to more than 6 feet of reinforced concrete, compared with 3 1/2 feet to 6 feet for U.S. plants. But many of that country's nuclear power stations — built against the backdrop of domestic terrorism and the Soviet military threat during the Cold War — are in some ways more protected than U.S. commercial reactors.
NRC and NEI officials said they had not seen the latest German research.
Industry critics in the U.S. point particularly to the part of the German study saying radiation can be released from fires in spent-fuel storage areas.
Because no permanent waste storage facility has been opened in the United States, radioactive material — about 45,000 tons of it — has accumulated in spent-fuel ponds. If a pond were heavily damaged and the cooling water drained away, industry critics say, the result could be an uncontrollable inferno and the release of radiation.
A 1997 report by the Brookhaven National Laboratory in New York concluded that a fire in a pool of spent nuclear waste could render 188 square miles uninhabitable and cause as many as 28,000 cancer deaths.
"These spent-fuel pools present the most severe consequences and vulnerability at nuclear power stations. They are the ultimate dirty bomb," said Robert Alvarez, a nuclear policy expert who served throughout the 1990s as an advisor and investigator for the U.S. Senate and Department of Energy.
Congress Asks Academy
At the request of Congress, the National Academy of Sciences, a nonprofit organization that advises the federal government, has prepared a classified report and proposals for the nuclear power industry related to the storage of spent fuel.
Academy sources say the report recommends that the NRC and nuclear industry take steps to strengthen fuel ponds and the waste containers inside them.
Lloyd, of the Nuclear Energy Institute, said his group does not believe that fuel ponds are particularly vulnerable, based on the institute's computer study that simulated two 767 crashes into two types of fuel ponds used at power plants.
The NRC's most recent study, said agency spokesman Brenner, "took in all aspects of plant operations [including fuel ponds] and found that significant releases of radioactivity are very unlikely."
But professor Frank N. von Hippel, who took part in the National Academy of Sciences study, said the NRC and the industry have not taken the spent-fuel problem seriously enough.
"The current situation is unsatisfactory," said Von Hippel, co-director of the science and global security program at Princeton University's Woodrow Wilson School of Public and International Affairs.
"The NRC has been in a state of denial," Von Hippel said. "The process at the academy and the subcommittees has been enough for them to do something, but it is a reluctant something."
Dan Weikel, Times Staff Writer