NRC NEWS

 U.S. NUCLEAR REGULATORY COMMISSION 

 Office of Public Affairs Telephone: 301/415-8200

 Washington, D.C. 20555-0001 E-mail: opa@nrc.gov 

Web Site: http://www.nrc.gov

 

No. 07-110 August 31, 2007

NRC ISSUES FINAL SUPPLEMENTAL ENVIRONMENTAL ASSESSMENT FOR DIABLO

CANYON SPENT FUEL STORAGE FACILITY

The Nuclear Regulatory Commission has issued its final supplemental environmental

assessment for a spent fuel storage facility under construction at the Diablo Canyon nuclear power

plant in San Luis Obispo County, Calif., concluding that construction, operation and decommissioning

of the facility will not result in a significant effect on the human environment, even when potential

terrorist attacks are considered.

The NRC staff conducted the supplemental assessment by order of the Commission, in

response to last year’s ruling by the U.S. Court of Appeals for the Ninth Circuit in San Luis Obispo

Mothers for Peace v. NRC. A draft of the supplement was published May 31 for public comment.

The supplemental assessment considers the potential radiological impacts of terrorist acts on

the Diablo Canyon spent fuel storage facility. It concludes that the probability of a successful terrorist

attack resulting in a significant radiation release is very low. This conclusion is based on the NRC’s

continual evaluation of the threat environment and coordination with other federal, state and local

agencies; protective measures currently in place that reduce the chances of any terrorist attack being

successful; the robust design of dry cask storage systems, which provide substantial resistance to

penetration; and NRC’s security assessments of potential consequences of terrorist attacks at these

facilities.

Although the agency concludes the likelihood of a terrorist attack on the facility resulting in a

substantial radiological release is very low, the supplement also describes the potential impacts of such

an event at Diablo Canyon. It concludes that any radiation dose to members of the public near the plant

from a successful terrorist attack on the facility would likely be well below 5 rem, even in the most

severe plausible threat scenarios. In many scenarios, the hypothetical dose could be substantially less

than 5 rem, or none at all. (Five rem is the maximum annual occupational dose limit for workers in the

nuclear industry and the regulatory dose limit for persons outside the boundary of a spent fuel storage

facility to receive from accidents.)

The NRC received 32 comment documents regarding the draft supplement, of which 12 were

nearly identical. The staff grouped the comments into 17 general topics, and included its responses as

an appendix to the final supplement.
The supplemental environmental assessment will be available on the NRC’s Web site at

http://www.nrc.gov/waste.html, by selecting “Diablo Canyon” in the “Quick Links” box. The

supplement and related documents can also be viewed in the NRC’s ADAMS online documents system

at http://www.nrc.gov/reading-rm/adams/web-based.html by entering accession number

“ML072400303" in the search window.

###

News releases are available through a free list serve subscription at the following Web address: 

http://www.nrc.gov/public-involve/listserver.html . The NRC homepage at www.nrc.gov also offers a SUBSCRIBE link. 

E-mail notifications are sent to subscribers when news releases are posted to NRC's Web site.