The US Nuclear Regulatory Commission and the Nuclear Energy Institute have addressed concerns arising from the World Trade Centre terrorist attack. While it is clear that US nuclear power plants were not designed to withstand that kind of impact and fire unscathed, they are well designed for lesser impacts, and as with most other aspects of their construction, there is a high degree of over-engineering. As calculations have been revisited to take account of a multiple impact from a heavy aircraft (ie with two or more engines set out from the energy-absorbing fuselage), it appears that most reactors are sufficiently robust to survive without any significant radiation relaease - see below re EPRI study. Other security arrangements at nuclear plants have been re-examined and improved.
However, no-one has ruled out the possibility of damage within the reactor containment from such a suicide attack, though any radiological effects from this are likely to be of less consequence than the aircraft impact and fire itself. In other words it would be futile for terrorists to target a US nuclear reactor because of the assumed likelihood of multiplied effects with major radiation release along the lines of some Chernobyl scenario. In fact the containment engineering and the internal design of the vast majority of the world's reactors would preclude that scenario, whatever the damage sustained.
"The tragic terrorist attacks on the United States were a wake up call to us all," said Mohamed ElBaradei, IAEA Director General, to the IAEA General Conference on 21 September 2001. "People with evil intent can do great harm to civilization and the targets reach across all areas of modern society. We can't build fortresses or become police States. Nuclear [power], like any other technology we benefit from, has its vulnerabilities and no absolute guarantees exist. But we should not lose sight that nuclear power plants are among the most secure and robust industrial facilities in the world."
Since the World Trade Centre attacks in September 2001 various studies have looked at similar possible attacks on nuclear power plants - which must be considered likely. A thorough study was undertaken by the Electric Power Research Institute using specialist consultants and paid for by the US Dept. of Energy. It concludes that US reactor structures "are robust and (would) protect the fuel from impacts of large commercial aircraft".
The analyses used a fully-fuelled Boeing 767-400 of over 200 tonnes as the basis, at 350 mph - the maximum speed for precision flying near the ground. The wingspan is greater than the diameter of reactor containment buildings and the 4.3 tonne engines are 15 metres apart. Hence analyses focused on single engine direct impact on the centreline and on the impact of the entire aircraft if the fuselage hit the centreline (in which case the engines would ricochet off the sides). In each case no part of the aircraft or its fuel would penetrate the containment. Looking at spent fuel storage pools, similar analyses showed no breach. Dry storage and transport casks retained their integrity. "There would be no release of radionuclides to the environment".
EPRI Dec 2002 report on NEI web site - safety & security section, Resources.
see also: Briefing paper on Safety, especially Appendix 3.
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