Risks to Spent Fuel Pools

A “spent” fuel pool is a 45-feet deep concrete pit that stores highly radioactive fuel assemblies after they have become “used up” and removed from the reactor core. Water storage is required because “spent” fuel assemblies continue to emit considerable amounts of heat and radiation for many years.

Indian Point nuclear power station has three spent fuel pools, one for each reactor unit. (The reactor at unit 1 was shut down in 1974, but its “spent” fuel pool still contains irradiated fuel assemblies, approximately 100 tons.) The pools for the operating units, 2 and 3, each contain approximately 600 tons of irradiated fuel. Each of the spent fuel pools is housed in buildings that contain less than 18 inches of concrete in the walls and approximately 6 inches of concrete in the roof.

Even Entergy admits that the spent fuel pool building’s roof is “penetrable.”

A February 2001 Nuclear Regulatory Commission (NRC) report, Technical Study of Spent Fuel Pool Accident Risk at Decommissioning Nuclear Power Plants (NUREG-1738), estimated that “1 of 2 aircrafts is large enough to penetrate a 5-foot-thick reinforced concrete wall.” Furthermore, “the conditional probability that a large aircraft crash will penetrate a 5-foot-thick reinforced concrete wall is taken as 0.45 (interpolated from NUREG/CR-5042).” The report “further estimated that 1 of 2 crashes damages the spent fuel pool enough to uncover the stored fuel.”

The above-mentioned report has significance not only for the spent fuel pools at Indian Point, but for the concrete containment domes at units 2 and 3, which are 6 to 7 feet thick at the base and 3 1/2 feet thick at the top of the dome.

NRC has not properly evaluated the consequences of terrorist attack on the spent fuel storage area. In a study conducted by the NRC in February 2001 (NUREG-1738), it stated that: “the risk analysis in this study did not evaluate the potential consequences of a sabotage event that could directly cause off-site fission product dispersion, for example, a vehicle bomb driven into or otherwise significantly damaging the SFP [Spent Fuel Pool], even after a zirconium fire was no longer possible.”

On average, spent fuel ponds hold five to 10 times more long-lived radioactivity than a reactor core. Particularly worrisome is the large amount of cesium 137 in fuel ponds, which contain anywhere from 20 to 50 million curies of this dangerous isotope. With a half-life of 30 years, cesium 137 gives off highly penetrating radiation and is absorbed in the food chain as if it were potassium. According to the NRC, as much as 100 percent of a pool’s cesium 137 would be released into the environment in a fire.

In comparison, the 1986 Chernobyl accident released about 40 percent of the reactor core’s 6 million curies of cesium 137 into the atmosphere, resulting in massive off-site radiation exposures. A single spent fuel pond holds more cesium 137 than was deposited by all atmospheric nuclear weapons tests in the Northern Hemisphere combined.

In June 2001, the NRC staff reported that terrorist threats against spent fuel ponds are credible and cannot be ruled out. “Until recently, the staff believed that the [design basis threat] of radiological sabotage could not cause a zirconium fire. However, [NRC’s safety policy for spent fuel storage] does not support the assertion of a lesser hazard to the public health and safety, given the possible consequences of sabotage.”

A reduction of cooling water in the spent fuel pools could lead to a catastrophic release of radiation. As the water in the fuel pool is reduced the remaining water will heat up and evaporate. This could expose the zirconium cladding, which surround the spent fuel rods to oxygen and steam, resulting in an exothermic reaction that will lead to a spent fuel rod assembly fire. This event would release deadly amounts of radiological material and toxic fumes.

In the event of loss of cooling water from irradiated spent fuel pools, some contingency plans for maintaining water level in pools may not be logical or realistic, i.e. firefighters and plant employees are expected to maintain water level.

A 1997 Brookhaven National Lab Study claims that a disaster from a spent fuel pool could cause anywhere from 1,500 to 143,000 cancer deaths and $800 million to $566 billion in damage, and could make an area of 1 to 2,790 square miles around the plant uninhabitable. The dramatic range is due to several factors, such as weather conditions, differences in population and the age of the spent fuel.

According to the Institute for Resource and Security Studies, the offsite consequences of a pool fire at Indian Point Unit 2 could include the rendering uninhabitable of a land area of about 95,000 square kilometers, and a pool fire at Unit 3 could render uninhabitable a land area of about 75,000 square kilometers. For comparison, the area of New York State is 127,000 square kilometers