Opinion ID: 204775
Heading Depth: 3
Heading Rank: 2

Heading: Mothers for Peace Remand and NRC's Supplemental EA

Text: On remand, the Commission ordered its staff to prepare a revised EA addressing the likelihood and potential consequences of a terrorist attack at the Diablo Canyon ISFSI site. CLI-07-11, 65 NRC 148 (2007). NRC Staff issued a Draft SEA and Finding of No Significant Impact (FONSI) in May 2007 and a Final SEA/FONSI in August 2007. [1] The SEA concludes that the storage of spent nuclear fuel at the Diablo Canyon ISFSI will not have a significant effect on the quality of the human environment. Under 10 C.F.R. § 51.31, therefore, the NRC determined that an EIS was unnecessary. The SEA expands on the October 2003 EA/FONSI we found inadequate in Mothers for Peace. After reviewing the NRC's general post-9/11 security measures and requirements for ISFSIs, the SEA describes the NRC Staff's consideration of the potential radiological impacts of terrorist acts on spent fuel storage casks, despite the Commission's belief that the probability of such an act is very low. First, it explains that the spent fuel at Diablo Canyon is adequately protected, due to the resilient design of spent fuel storage cases, largely non-dispersible nature of the nuclear fuel, as well as Diablo Canyon's location and low profile, which make it a difficult target for a large commercial airliner. Second, the SEA reviews the NRC's generic analysis of plausible threat scenarios, such as a large aircraft impact and ground assaults, and it finds that current security measures at ISFSI's are adequate. The NRC's screening of threat scenarios was informed by information gathered through NRC's regular interactions with the law enforcement and intelligence communities. Next, the SEA describes its dose calculations, which began with a comparison between generic ISFSI assessments and the relevant features of the Diable Canyon ISFSI. NRC Staff determined that the assumptions in the generic assessments concerning storage cask design, source term (i.e. amount of radiological material released), and atmospheric dispersionwere representative, and in some cases, conservative, relative to Diablo Canyon's actual conditions. Using inputs from the generic assessments, Staff found a projected dose of less than 5 rem for the nearest resident; using Diablo Canyon's site-specific meteorology and source term would reduce this projected dose even further. Even under the most severe plausible threat scenarios (ground assault and aircraft impact), the NRC projected the dose to the nearest affected resident as likely . . . well below 5 rem; in many other scenarios, it would be substantially less than 5 rem, or none at all. Responding to public comments, the SEA also notes, inter alia, that: (1) the specific threat scenarios and source terms were sensitive information that cannot be disclosed publicly; (2) Staff selected plausible threat scenarios based on information gathered from federal agencies and the intelligence community; (3) a revised dose estimate, not an early fatalities indicator, was used to assess environmental impact; and (4) while the probability of an attack could not be readily quantified, it could be qualitatively assessed to be acceptable.