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Survivability of nuclear plants to be re-examined

Keay Davidson, Chronicle Science Writer

Friday, October 5, 2001 2001 San Francisco Chronicle


After initially playing down the chance that a falling jetliner could disable or destroy a nuclear power plant, the Nuclear Regulatory Commission is now planning to study whether a plant could survive such a disaster.

The agency's shift comes amid heightened concern about the vulnerability of nuclear facilities to terrorist attacks. A Chronicle review of recent NRC inspections shows that although nuclear plants serving California are generally secure, they may not be 100 percent safe.

Immediately after the Sept. 11 attacks on the World Trade Center and the Pentagon, the NRC issued a reassuring statement: "Although nuclear power plants are not explicitly designed to withstand the crash of a large commercial airliner, plants have inherent capability to provide for the protection of public health and safety.

"Prestressed concrete containments -- typically 4 to 5 feet thick -- are so robust that it is unlikely that a jumbo jet could penetrate the containment structure. Furthermore, plant designs employ redundant safety equipment, along with highly trained operators, to limit potential consequences."

But three weeks later, NRC officials are sounding less confident. "Back when these plants were designed, we . . . did not assume that a heavy, wide- bodied airliner would be used as a guided missile to attack a plant," NRC representative Breck Henderson acknowledged this week.

Now, the agency is planning a study to determine whether a plant could survive an airliner crash. "I don't think it's going to be a real quick analysis -- it's going take some time," Henderson said. "We're being intentionally vague on this because we haven't decided how we're going to do it."

Asked whether the NRC can assure the public that a nuclear plant would withstand an airliner crash, Henderson replied: "I don't think we can be that strong and specific. . . . Would it be a big mess? Of course, it would be a big mess. Would it lead to multiple tens of thousands of deaths? That's much less certain."

The worst-case consequence of a reactor accident is a "meltdown," which could spew radioactive poisons into the environment. In 1979, the Three Mile Island nuclear reactor in Harrisburg, Pa., experienced a partial meltdown. The nuclear accident, the worst in American history, released what the plant owner characterized as a small amount of radioactivity into the atmosphere.

In Congress, heightened concern about the vulnerability of nuclear plants to a terrorist attack is prompting legislative action. The House Energy and Commerce Committee approved language this week that authorizes guards at NRC- licensed facilities to carry and use weapons to protect the facilities or prevent theft of special nuclear materials.

Meanwhile, a Chronicle review of NRC inspection records offers a generally - - but not totally -- reassuring picture of security at three nuclear plants serving California. Despite generally high scores, the Diablo Canyon, San Onofre and Palo Verde (which is near Phoenix) nuclear plants were cited by the NRC for a variety of security screwups this year and last.

The most dramatic inspections involve the NRC's simulated terrorist raids on the nuclear plants.

In a mock raid on the San Onofre nuclear plant north of San Diego in November 2000, guards' response made NRC inspectors suspect that had the raid been real, it might have left vulnerable facilities or equipment that help to prevent a reactor accident.

The raids are technically known as Operational Safeguards Response Evaluations. OSRE tests reportedly involve "terrorists" who "shoot" at guards, and vice versa, using laser "guns." If a laser beam hits a sensor on someone's body, he is recorded as disabled or killed.

On Nov. 28 and 29, the NRC's OSRE team made a simulated raid on the San Onofre plant. Monitoring the plant operators' response, NRC officials spotted a problem that in a real-life raid might have had "a credible impact on safety, " according to their official report.

Exactly what that "credible impact" was is classified. Both NRC and the plant's co-owner, Southern California Edison, refuse to give extensive details.

The NRC report does acknowledge that "a vulnerability in the (plant's) protective strategy was identified that could have resulted in the simulated loss of a target set."

In interviews, officials refused to specifically define "target set." However, they indicated it includes plant facilities and equipment that must be protected to prevent an accident up to and including the nightmare scenario:

a reactor meltdown.

"The issue was more than minor," the NRC report adds, "because the potential loss of a target set represents a credible impact on safety."

If a target set is lost, then conceivably "significant (nuclear) core damage would be the result, which is tantamount to a meltdown," says Cornell University-trained physicist Edwin Lyman of the Nuclear Control Institute of Washington, D.C. The private group has criticized security standards at nuclear plants.

In an interview, Southern California Edison spokesman Ray Golden stated that the simulated raid was terminated early for reasons he was unable to explain. Hence "we were never able to demonstrate our ability to stop the adversary, and they were never able to demonstrate their ability to penetrate our (plant). . . . We think we have a very good security program here."

At the three plants since mid-2000, NRC inspectors have generally praised their security. However, they cited slipups that include:

-- On Dec. 20, 2000, an NRC inspector managed to gain admittance to a Diablo Canyon power plant building when a plant employee opened the door to him without first checking a closed-circuit TV camera.

-- During dismantling of a decommissioned reactor at San Onofre in 2000, a "breach" or opening was formed in plant equipment that no one noticed for six days. The NRC report concluded that the breach posed a "very low" safety risk because it was probably too small for a human to pass through.

-- At the Palo Verde plant in July 2000, "significant safeguards information was stored in an unlocked safeguards container outside of the protected area. The safe contained numerous safeguards documents, including the (plant) protective strategy and the target set lists."

Jim McDonald, a spokesman for the Palo Verde plant, said the safe was unlocked for a mundane reason: After a routine change in the lock's combination, a staff member did not "spin the (safe) dial when he completed his work."

E-mail Keay Davidson at

-- Martin Thompson (, October 05, 2001


Survivabiity? It's about time.

-- Uncle Fred (, October 05, 2001.

It was the heat of a jet fuel fire that brought down the trade center. Perhaps the real threat to nuclear plants is not breaking through the containment vessel, but rather, generating such heat that the cooling system is overwhelmed. Any experts out there who can comment on this?

-- neil r (, October 05, 2001.

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