Why this issue is important: Spent fuel is stored in high-density pools at every reactor in the U.S. No spent fuel pool is protected by a containment or is required to have independent redundant cooling. They were meant for short-term cooling (~5 years) and weren’t intended to for multi-decade storage of 4-5 times more spent fuel than their original designs. Pools are not only vulnerable to accidents – as witnessed by the Fukushima accident – but they are prime terrorist targets. In the Draft Consequence Study, the NRC admits that a pool fire could displace more than 4 million people from their homes. After both 9/11 and the Fukushima accident, the NRC recognized the potential for a catastrophic pool fire. Furthermore the NRC’s Office of Nuclear Security and Incidence Response uses a predictive tool to aid emergency responders during nuclear accidents which indicates that the radiological release from a pool fire following an earthquake would dwarf that of a reactor meltdown. It also indicates that the consequence of the breach of a dry cask is thousands of times less severe. (U.S. Nuclear Regulatory Commission, Office of Nuclear Security and Incidence Response, RASCAL 3.0.05 Workbook, NUREG-1889, September 2007).
What decision is at stake: NRC is about to decide whether to require licensees to return to the pools to their original purpose of open-frame pool storage combined with dry storage, which would greatly decrease the risk of a pool fire. This is a crucial post-Fukushima decision that the NRC probably will never re-visit.
Overall criticism of the Draft Consequence Study: The Staff is proposing to rely on the Draft Consequence Study to recommend against expediting the transfer of spent fuel out of high-density storage pools into low-density open racks and dry storage. But the Draft Consequence Study is totally inadequate for that purpose, because it is too narrow in scope and because it lacks scientific rigor or integrity. The Draft Consequence Study should be scrapped and the NRC should start again with an actual scientific study of pool fire risks, as recommended in Dr. Thompson’s comments.
Key problems with the study:
1. The Draft Consequence Study lacks scientific integrity because it examines only complete drainage of a pool and ignores the more severe case of partial drainage. Based on the canard that complete drainage is the worst case, the NRC ignored spent fuel pool accident risks for decades. Then in 2001, in NUREG-1738, the NRC admitted that the most severe accident risk is posed by prolonged disruption of air or water circulation over the spent fuel assemblies. The point was confirmed by a panel of the National Academy of Science in 2004. (National Research Council, Board on Radioactive Waste Management, Committee on the Safety and Security of Commercial Spent Nuclear Fuel Storage, National Academies Press (2006), p. 38-39). By reverting to the discredited assumption that complete pool drainage is the worst case, the NRC fatally undermines the integrity and credibility of the Study.
2. The Study is too narrow because it significantly underestimates risk by considering only one type of initiating event – an earthquake – and ignoring other credible initiating events that are at least as probable. For instance, the Study ignores the impacts of aging and the potential for an attack on a pool and/or adjacent reactor to initiate a pool fire. Vulnerability of spent fuel storage pools to terrorist attack is perhaps the greatest risk of all. Furthermore, the Study does not analyze the potential for a core melt accident to cause or contribute to a pool fire. For instance, radiation released during a core melt accident could preclude access to the pool to supply emergency cooling.
3. The Study is misleading and biased because it only pretends to consider the relative merits of low-density storage. The Study purports to evaluate whether low-density pool storage of spent fuel would be cost-effective and safer than high-density storage. But NRC misleadingly uses the phrase “low-density” to refer to closed high-density racks that contain fewer fuel assemblies, not true low-density fuel storage in open-frame racks. The NRC decided not to consider true open-rack low-density storage because it was assumed to be too expensive. See page 23. The Draft Consequence Study shows an appalling lack of scientific integrity by including the result of the study as an assumption: the question of whether a return to open-frame low-density storage is justified is the very question the NRC set out to answer in the Study.
4. The NRC has nothing else to rely on. The NRC has never conducted a valid scientific study of pool fire risks, although it has had the capability since prior to 1990. Instead, over a period exceeding three decades, NRC published one bad analysis after another that ignored the characteristics and behavior of high-density fuel storage pools and falsely concluded they were safe. Only since 2001 has the NRC admitted the potential for a catastrophic pool fire; but after the 9/11 attacks, the NRC systematically hid its analyses behind a veil of secrecy. The Draft Consequence Study is the first public study the NRC has released since before September 11 – but it simply perpetuates the same bad science of the period before 9/11.
· NRC’s Draft Consequence Study should be scrapped.
· In addressing the pool-fire issue, NRC should focus its initial attention exclusively on establishing a solid technical understanding of phenomena directly related to a potential pool fire. To do this, NRC would start with a clean slate and use the best available modeling capability backed up by experiment. This modeling and experimental work must be done according to scientific principles.