April 16, 2005
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US panel: Fuel pool attack could trigger zirconium fire
Thecla Fabian, Nuclear Engineering
A terrorist attack on the spent fuel pools at some US nuclear plants could trigger a high-temperature zirconium fire that would lead to a significant release of radioactivity, though not on the scale of the 1986 Chernobyl explosion, concluded a blue-ribbon panel of scientists assembled by the National Research Council of the US National Academies. The unclassified academies' report, Safety and Security of Commercial Spent Nuclear Fuel: Public Report, contains all the findings and recommendations of the classified report, but with all national security and safeguards information removed, said Louis Lanzerotti, who chaired the 15-member expert panel pulled together by the academies' Board on Radioactive Waste Management in response to a mandate from congress. The panel spent six months gathering and analyzing data, and meeting with regulators, nuclear industry experts, and independent scientists. Lanzerotti is a geophysics expert consulting for Bell Laboratories and Lucent Technologies and a distinguished professor for solar-terrestrial research at the New Jersey Institute of Technology. Other panel members included a former NRC division director in nuclear materials management, and experts in the behaviour of nuclear materials at high temperatures, penetration mechanics, ballistics and weapons technology, health physics, actinide chemistry, heat transfer, thermal hydraulics, structural engineering and terrorism. The panel unanimously concluded that an attack that caused either partial or complete draining of a plant's spent fuel pool might be capable of starting a high-temperature fuel cladding fire that could lead to the Òrelease of large quantities of radioactive material into the environment.Ó The risk depends on a number of factors, including the type of attack, the design of the fuel pool, and the configuration of the fuel in the pool. The panel recommended two immediate measures that could reduce the potential for fuel cladding fires: (1) The reconfiguration of the position of fuel assemblies in the pools to more evenly distribute decay heat loads; and (2) Making provisions to cool the fuel with water spray systems that could continue to operate even after a pool or the building housing it is damaged. The panel noted that water spray systems might not be needed at plants where the fuel pools are located below ground or otherwise protected.
... Pools are and will continue to be needed at all nuclear plants for the foreseeable future, the panel stressed, noting that fuel newly removed from the reactor needs about five years cooling time in a water pool before it can be loaded into casks. For older fuel, however, dry storage has two advantages. It is a passive system that relies on air circulation for cooling, and it divides the spent fuel inventory into a number of individual, robust containers that contain only a small amount of the total inventory. Different dry cask systems available on the US market differed only slightly in robustness under different terrorist attack scenarios, the panel found.
March 13, 2004
March 3, 2004
* Grand Gulf - hi rad levels found on incoming fuel sip support stand, from hot particle
December 31, 2003
* Defense-in-depth as it applies to spent fuel pools
November 29, 2003
* N-plants use inconsistent load drop calculation methods
July 21, 2003
June 21, 2003
* Spent fuel pool fire could far exceed release at Chernobyl
* Spent fuel pools - biggest security threat is probably small plane
* Spent fuel pools make poor targets for terrorist planes, missiles
* Spent fuel - dry cask storage much better, risk management-wise, than pools
April 24, 2003
Bubble from pool and iodine alarm prompt Alert at Perry - see Event report.
April 15, 2003
* McGuire-2 has an old bent fuel rod, NRC OKs plan to degas and store it