Statement on the Science
article Nuclear Power Plants
Dr. Edwin S. Lyman
Nuclear Control Institute
September 20, 2002
The authors of the article appearing in todays issue of Science (Douglas Chapin et al., Nuclear Power Plants and their Fuel as Terrorist Targets, Science 297, 20 September 2002) claim that it is virtually impossible for terrorists to cause a massive release of radioactivity by attacking nuclear power plants or spent fuel shipments, and that even if such a release of radioactivity were to occur, the public has nothing to fear because of a large body of scientific evidence showing that low levels of radiation are not harmful. To support their argument, the authors rely on misquotations, unsupported assertions, misinterpretations of data, and unpublished references that have not been peer-reviewed.
The authors are also firmly in the camp of the small group of dissidents who believe in a dose threshold for the carcinogenic effects of radiation. This controversial threshold theory has support among neither the established radiation protection authorities nor the scientific community at large. On the contrary, numerous recent studies have observed a so-called inverse dose-rate effect, in which the carcinogenic potential of ionizing radiation is actually greater at low doses and dose rates than at high doses. The Science article displays a lack of awareness of up-to-date technical literature that is especially surprising given the authors apparent belief that they are fully in command of all relevant simple scientific and engineering truths. In fact, the technical issues raised by the authors are not simple, and their complexities are trivialized by the oversimplified treatment in the article.
Contrary to the authors assertions, credible mechanisms do exist by which terrorists could cause large radiological releases by sabotaging nuclear power plants, nuclear research reactors or spent nuclear fuel shipments. In a series of force-on-force exercises on U.S. nuclear power plants, mock attackers were able to gain access to the plant and simulate the destruction of enough safety equipment to cause a meltdown nearly 50% of the time. In many of those exercises, the attackers also used explosives to breach the containment building. Terrorists with some basic knowledge of how nuclear power plants function could design their sabotage strategy to maximize the severity of the meltdown and guarantee the occurrence of a large radiological release into the environment.
The 1979 accident at Three Mile Island Unit 2 has little bearing on this scenario because core cooling was restored before the core became fully molten. With time, a molten core mass will indeed cause failure of the reactor vessel --- an event which was recently observed in tests at Sandia National Laboratories --- and the ensuing steam or hydrogen explosions could cause violent dispersal of the core materials into the containment. If the containment is breached either deliberately by the terrorists or is ruptured as a result of the accident, a large radiological release into the atmosphere would occur. In contrast to the sequence of events at TMI-2, if terrorists are able to seize the control room --- or if they have infiltrated it by posing as employees --- they could prevent anyone from taking corrective actions until it is too late.
With regard to the aircraft threat, the authors cite an unpublished industry-sponsored report and a videotape on the Internet of a plane crashing into a concrete block to support their claim that an aircraft attack cannot cause enough damage to a nuclear plant to cause a meltdown. In fact, straightforward engineering calculations, utilizing empirically derived formulas, demonstrate that such penetration is plausible. The videotape in question actually provides no information regarding the question of whether a fully fueled commercial jet plane can penetrate a concrete containment wall. The video documents a test at Sandia National Laboratories in which an F-4 fighter jet, with considerably lighter engines than a commercial jet like a 767, collided with a concrete block that was not fixed to the ground but was actually floating on an air cushion. The purpose of the test was to measure the impact force, not to measure the maximum penetration of the target. According to the test report, the major portion of the impact energy went into movement of the target and not in producing structural damage. Real-world nuclear power plant containments are anchored to the ground. Sandia National Laboratories, the sponsor of the video, has said that the nuclear industry is misrepresenting the results of the test.
Moreover, there are parts of a nuclear plant that are even more vulnerable than the containment. The control room, spent fuel pool and auxiliary building are not as well protected as the reactor core, yet causing severe damage to any of those locations could well result in a severe radiological release. The Electric Power Research Institute (EPRI) study referred to in the article concedes that a plane could penetrate the auxiliary building, according to a set of talking points on the report distributed to the press. (Note that the conclusions of the report have been provided to the press, but not the underlying report.)
Nuclear Control Institute (NCI) calculations utilizing the standard radiological consequence code MACCS2 indicate that a large radiological release from a nuclear power plant could lead to exposures to radioactive iodine exceeding FDA-recommended thresholds for potassium iodide prophylaxis at distances hundreds of miles downwind of the site. This is of particular concern for young children. Yet the authors of the Science article, instead of calling for greater protection for children, callously dismiss the more than 2000 childhood thyroid cancers --- a more than hundred-fold excess --- that are almost certainly attributable to radioactive iodine released from the Chernobyl accident.
This is a clear indication of their extremist views regarding radiation exposure --- views that put them well outside of a scientific mainstream that is built on a century of research on the health effects of radiation. Their chief reference on this subject is a database on the web site of an advocacy group (of which one of the authors is the vice-president) that claims there is a massive conspiracy to cover-up the health benefits of exposure to low-level radiation. The database contains links to bizarre papers such as those purporting to demonstrate the therapeutic effects of radon spa therapy.
On the issue of spent fuel transport, there are mechanisms by which a spent fuel cask could be attacked to release a significant fraction of its radioactive contents. For instance, if a heat source were introduced into a spent fuel cask breached by a shaped charge, a self-sustaining zirconium fire could result, releasing a large part of the cask inventory of radioactive cesium. If this event were to occur in a densely populated area --- which could be considered a severe version of a dirty bomb attack --- MACCS2 calculations indicate that more than ten thousand cancer deaths would eventually result. Concern about the potentially high consequences of this event was most likely behind the recent issuance of an order by the Nuclear Regulatory Commission (NRC) reportedly requiring that armed escorts accompany spent fuel transports at all times.
NCI has argued that the security around nuclear power plants and nuclear transports is not commensurate with the magnitude of the post September-11 terrorist threat and that the NRC must act to augment protection from armed commandos, truck bombs, aircraft and malevolent insiders. The costs of such measures are small in comparison to the benefits to the public. The authors of the Science article, many of whom bear responsibility for contributing to the creation of a widely distributed nuclear power infrastructure in this country that is vulnerable to terrorist attack, should take a realistic approach to these risks and help to mitigate the threat to the public posed by the situation that they have created, rather than continuing to deny its potential for grave harm.
Further information about the risks of nuclear terrorism and sabotage is available on Nuclear Control Institutes website, http://www.nci.org/