Spent Fuel Pool - Risks

Risks

If there is a prolonged interruption of cooling due to emergency situations, the water in the spent fuel pools may boil off, resulting in large amounts of radioactive elements being released into the atmosphere.

In the magnitude 9 earthquake which struck the Fukushima nuclear plants in March 2011, one of the spent fuel pools lost its roof and was reported to be emitting steam. According to The Nation, "Spent fuel pools at Fukushima are not equipped with backup water-circulation systems or backup generators for the water-circulation system they do have." Later, there was some disagreement among sources as to whether the pool had boiled dry.

TEPCO, the plant owner, announced that if the rods were exposed, there was a small chance they would reach criticality, setting off a nuclear chain reaction (not an explosion). According to nuclear plant safety specialists, the chances of criticality in a spent fuel pool are very small, usually avoided by the dispersal of the fuel assemblies, inclusion of a neutron absorber in the storage racks and overall by the fact that the spent fuel has a too low enrichment level to self-sustain a fission reaction. They also state that if the water covering the spent fuel evaporates, there is no element to moderate the chain reaction. On April 1, 2011, United States Energy Secretary Steven Chu said that after efforts by workers to pour water on the Fukushima pools, these were "now under control."

Spent fuel pools lack the "4-ft.-thick (1.2 m) concrete cocoons" of operating reactors but are "housed in more conventional buildings that are conceivably more susceptible to aircraft strikes or explosives".

According to Dr. Kevin Crowley of the Nuclear and Radiation Studies Board, "successful terrorist attacks on spent fuel pools, though difficult, are possible. If an attack leads to a propagating zirconium cladding fire, it could result in the release of large amounts of radioactive material." The Nuclear Regulatory Commission after the September 11, 2001 attacks required American nuclear plants "to protect with high assurance" against specific threats involving certain numbers and capabilities of assailants. Plants were also required to "enhance the number of security officers" and to improve "access controls to the facilities".

In 1997, the Brookhaven National Laboratory estimated that a "massive calamity at one spent-fuel pool could ultimately lead to 138,000 deaths and contaminate 2,000 sq. mi. (5,200 sq km) of land".