2003-03-17 San Francisco Chronicle

San Francisco Chronicle on potential for terrorism at Diablo

San Francisco Chronicle

March 17, 2003 - Avila Beach, San Luis Obispo County -- For an installation that generates about 10 percent of California's electricity, the Diablo Canyon nuclear power plant near here seems remarkably unobtrusive.

Tucked between the wide Pacific and hills burgeoning with vernal greenery and grazing livestock, it's smaller than one might expect.

But some scientists and nuclear power critics claim this tranquil tableau is deceptive. Because of the threat of terrorist attack, they say, Diablo Canyon, which is owned by Pacific Gas and Electric Co., is capable of generating a truly diabolical scenario: A huge release of radiation that could dwarf Chernobyl and render thousands of square miles of the state uninhabitable for years -- perhaps decades or centuries.

Two nationally known scientists say the plant's spent nuclear fuel storage is vulnerable to terrorist attack. At that facility are two pools of water that collectively contain about 2,200 old "fuel assemblies" -- packs of refined uranium that are no longer useful for power generation but are still highly radioactive.

"The consequences of a spent fuel assembly fire would be huge," said Frank N. Von Hippel, a physicist and professor of public and international affairs at Princeton University.

An article describing the possible consequences of terrorist attacks on spent nuclear fuel pools is scheduled to appear later this spring in Science and Global Security, a Princeton journal.

A draft of the paper was released earlier this year.

The article, which has been reviewed by other eminent scientists, was written by several nuclear facilities experts, including Von Hippel and Gordon Thompson, the director of the Institute for Resource and Security Studies, a nonprofit group based in Cambridge, Mass., that analyzes threats to national and international security.

Both Von Hippel and Thompson said the high density fuel pools at Diablo Canyon made the plant vulnerable to a terrorist attack that could release clouds of deadly material.

"Basically," Von Hippel said, "you're talking about an event that would force the long-term abandonment of an area roughly the size of New Jersey."


The possible nightmarish scenario ensuing from a terrorist attack on a nuclear power plant is also something that terrorists have apparently already thought of.

Recently, on the CBS News program "Sixty Minutes II," Yosri Fouda, a reporter for the Arabic news network Al Jazeera, said that when he interviewed last spring the recently captured Khalid Shaikh Mohammed, architect of the Sept. 11 attacks, Mohammed said that al Qaeda's first choice of a target was nuclear "facilities" in the U.S. But it was soon "taken off the list for fear it might get out (of) hand," Fouda told the CBS News program.

Diablo Canyon's critics point out that the pools are not protected by a containment structure, as are the two reactors where power is generated -- even though the pools contain far more hard radiation than the two reactor cores, each of which houses only 193 assemblies. The pools are below ground, under a building that is less fortified than the structures that protect the reactors.

If the pools are breached by a terrorist attack, they say, water would drain away, exposing the fuel assemblies. These would then self-ignite and send up huge plumes of radioactive isotopes.

In preparing the report, Von Hippel said they had analyzed the pool containment protocols of plants around the nation. They also said they were aware of Diablo Canyon and its fuel pools and the possibility of terrorist attack.

Diablo Canyon is "most certainly" on a list of possible terrorist targets compiled by the California attorney general's office, a state official said on condition of anonymity.

"The list doesn't rank the targets like a top 100 or anything," the official said. "It just groups them -- bridges, law enforcement agency buildings, railroads and so forth. But let's face it: We're talking about a large nuclear power plant here."


Most nuclear engineers think it would be difficult, if not impossible, for a large airliner to score a hit on Diablo Canyon's pools.

Last year, the Nuclear Regulatory Commission concluded that fuel storage pools could sustain impacts from a Boeing 767 flying at 500 mph without coolant loss.

PG&E engineers point out that the pools are situated between the reactor containment domes -- which are 3 1/2 feet thick, and fabricated of concrete and steel -- and steep hillsides, making them an extremely difficult target. Multiple rings of concrete barriers on access roadways and numerous guards armed with assault rifles further make the possibility of a successful terrorist attack remote, they say.

In addition, the 40-foot-deep pools are protected along the sides and bottom by thick layers of concrete and stainless steel. Coolant leakage would therefore be most unlikely, they say, even in the event of an attack or large earthquake.

But dissenting analysts think terrorists wielding explosive missiles or flying small, maneuverable planes packed with high explosives could get through where a big commercial aircraft couldn't.

"Certainly, with enough explosives, a spent fuel pool could be penetrated," said NRC spokesman Victor Dricks. "Damage would be dependent on the scenario. But even with penetration, measures are in place to ensure public health and safety."

The critics say the threat to the plant is real -- and is compounded by the Nuclear Regulatory Commission's decision to allow PG&E to store more fuel assemblies in the pools than allowed by the original license. "The pools were originally designed to hold just a few years of fuel discharge, until a permanent federal repository could be built," said Gordon Thompson, one of the authors of the Princeton paper.


Because no repository has been constructed, said Thompson, nuclear plant operators went with the cheapest option, which has become the industry norm: high-density rackings of fuel assemblies in the pools.

But if there is a loss of coolant, Thompson said, recently stored "ultra hot" assemblies would catch fire in a few hours, which would then ignite cooler -- although still extremely radioactive -- assemblies.

"The fire could not be extinguished at that point, simply because it could not be approached due to the extreme radioactivity," said Thompson, a co-author of the Science and Global Security article who has studied nuclear fuel storage systems since 1978.

In such a scenario, Thompson calculates, between 10 and 100 percent of the fuel's cesium 137 -- an extremely volatile isotope -- would be released. Cesium 137 accounted for most of the contamination when one of the four reactors at Chernobyl, northwest of Kiev, melted down in April 1986.

At Diablo Canyon, winds typically blow from the west and north. If a fuel fire occurred during usual wind conditions, said Thompson, thousands of square miles of the south coast would be intensely contaminated for decades.

"The only solution would be permanent evacuation," he said.


In a recent report commissioned by the Citizens Awareness Network, a Massachusetts organization that studies nuclear contamination, among other things, Thompson analyzed likely modes of terrorist attack on civilian nuclear facilities, including commando assaults, truck bombs, antitank missiles, commercial aircraft and explosive-laden small aircraft.

In that report, he concludes that the defenses typical for nuclear plants -- guards armed with light weapons, alarms, fences and vehicle barriers -- are sufficient only to stop commando assaults and truck bombs.

But PG&E officials say generic statements about nuclear facilities don't necessarily apply to Diablo Canyon.

At a viewing pavilion above the plant, L. Jearl Strickland, Diablo Canyon's program manager for used-fuels storage, pointed to the spent fuel storage pool building below.

"It would be virtually impossible to hit that with an aircraft," he said. "The reactor containment structures protect it from the west. To the east, the topography of the land and transmission lines prevent a practical approach. Concrete buildings shield it from the south and north."

Strickland said the forthcoming Science and Global Security paper by Thompson, Von Hippel and several other analysts was too broad in scope to be applicable. "You have to be site specific, or your conclusions will simply be erroneous," he said. "The basic topography of the terrain here provides tremendous protection."

In the event of a land attack, Diablo Canyon officials said it would be extremely difficult for terrorists to get close enough to do any damage. Such an attack would be handled by PG&E's security staff, who company representatives say are highly trained and armed with AR-15 semiautomatic rifles and 9mm pistols. According to PG&E company spokesman Jeff Lewis, Diablo Canyon has been required to implement about 30 security upgrades since Sept. 11, 2001.


"We can't talk about specifics such as new weapons, but security has definitely been tightened since the World Trade Center attacks," said Lewis. "We own 13,000 acres around the plant, and I've heard talk that people could penetrate our outside perimeter. That may be. But as you get closer to the plant, the security tightens concentrically."

Local law enforcement agencies could offer only limited assistance in the event of an attack.

"We've been guarding (Diablo Canyon's) gates since 9/11," said California Highway Patrol Officer Mike Poelking. "We've had three additional officers assigned to us to provide 24-hour staffing. It's a commitment the governor made, and I don't see it ending anytime soon."

Poelking said his agency also flew air patrols regularly over Diablo Canyon.
In any case, PG&E needs an alternative method for storing its spent fuel because the pools will fill within a few years.

The company is seeking permission to transfer some assemblies to special stainless steel and concrete casks. Although the assemblies will still be extremely radioactive after five years in the pools, said Strickland, they would no longer be capable of self-igniting, and hence would be safe to store in the casks.

Each cask would hold 32 assemblies and would weigh about 175 tons. They would be stored on an open air pad about the size of a football field above the plant, where they would stay until a permanent federal repository for high level nuclear waste is built -- such as the one proposed for Yucca Mountain in Nevada. At that point, they would be transferred to the permanent dump.

Strickland said Diablo Canyon eventually would require 138 casks to handle all the high-level nuclear waste the plant would generate under its current licensing plans.

But such "dry casks" also may be vulnerable to attack.


"Basically, they're creating a high-level nuclear waste dump in a densely populated coastal area," said Klaus Schumann, a member of the Green Party and San Luis Obispo County's Nuclear Waste Management Committee. "They're calling it a temporary site, but it could easily become permanent. It isn't at all clear if Yucca Mountain or any other permanent federal repository will be built."

Experts have studied the vulnerability of dry casks to attack, and their conclusions vary.

Marvin Resnikoff, an engineer with Radioactive Waste Management Associates, a New York consulting group, analyzed the impact of a Boeing 757 on one variety of cask that is employed by some utilities to store used-fuel assemblies.

He concluded that planes traveling at 500 mph -- roughly the speed of the airliners that crashed into the World Trade Center towers -- would penetrate the casks.

But Strickland said Resnikoff's analysis represented a simplified approach and didn't use the type of cask that would be employed at Diablo Canyon.

The maker of that cask has concluded its product could withstand a direct impact from a large-body aircraft without rupturing, Strickland said.

Von Hippel advocates implementing a cask program and reducing the densities of spent fuel in pools. "That would definitely reduce the risk," he said.

There is also controversy over whether the casks are safer collected on one large pad, as planned -- which PG&E says makes them easier to guard -- or whether it is better to distribute them among several smaller pads, which PG&E's critics say lessens the likelihood of a catastrophic release of radiation.

In the final analysis, security at nuclear plants can be improved, but not made foolproof.

"We're constantly looking at ways to improve security," said Dricks, of the Nuclear Regulatory Commission. "Each of the national alert stages (employed since Sept. 11) requires nuclear facility security upgrades commensurate with the threat. And we verify that the plants do that. We have inspectors on site."

But Von Hippel said safeguards were still inadequate at most plants -- including Diablo Canyon. "Given the horrific consequences of a (pool) fire," he said, "we have to do everything we can to protect against one."