NRC mulls new dry cask security measures

By BOB AUDETTE

BRATTLEBORO -- If a rule that is under consideration is accepted by the commissioners of the Nuclear Regulatory Commission, nuclear power plant operators around the country will be required to evaluate the effects of a land-based or waterborne vehicle bomb attack against their dry cask storage facilities.
Operators could also be required to calculate whether the potential dose that could be received by an individual on or beyond the storage site's controlled area boundary would not exceed 5 rems.
If in the evaluations it is determined an operator can't limit the 5 rem dose at the boundary, it would have to expand it. Those that can't expand the boundary would have to consider the use of security barriers and armed security personnel to prevent an attack on the dry casks, which is called a "denial" protective strategy.
When asked how the dry casks are protected at Vermont Yankee nuclear power plant in Vernon, a spokesman said that most of its security measures are not public information.
"However, Vermont Yankee, and the rest of the nuclear industry, are committed to a strong response capability and remain confident that appropriate safeguards are in place that meet federal regulations," said Rob Williams.
In addition, he said, Yankee will continue to work with federal regulators to improve its security programs.
Most commercial nuclear power plants have on-site dry storage.
Some are located the plant's protected
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area, a fenced in security zone. For others, the storage is located in its own separate fenced security zone.
At Yankee, the dry storage is located within the main protected area around the plant.
The staff's "draft technical basis" for the proposed changes was published in the Dec. 16, 2009, Federal Register.
Since 1973, the NRC has required plant operators to protect spent fuel in dry casks stored on site at facilities such as Yankee, where five dry casks containing 340 fuel assemblies stand just outside of the plant's reactor building.
Following the terrorist attacks of Sept. 11, 2001, the NRC added to existing security regulations with the issuance of security orders. From 2003 to 2005, the NRC evaluated dry storage cask designs to determine how they would withstand attacks using large aircraft and ground assaults.
"The results of assessments indicated that no significant vulnerabilities were indicated and thus no immediate changes in the security requirements for (dry cask facilities) were necessary," stated the notice in the Federal Register.
However, stated the notice, the assessments "did challenge previous NRC conclusions on the ability of a malevolent act to breach shielding and/or confinement barriers and thus release radiation or radioactive materials."
Those assessments indicated that more in-depth security measures should be implemented.
While assessments included security inspections and force-on-force exercises, because the possibility that the results of the assessments could be used as "potential targeting tools," the results weren't released.
In response to the assessments and the hodge-podge of regulations regarding the security of dry cask storage, the NRC staff drafted the new regulation.
"Now that these requirements have been in place for quite some time, the NRC is moving toward formalizing, or making permanent, the interim requirements," said Neil Sheehan, spokesman for the NRC. "Among other things, the proposed changes would seek to make the assorted and at times difficult-to-understand security requirements currently in effect more consistent and coherent."
How any changes might affect Yankee, he said, depends on the final shape of the security requirements and whether they are approved by the Commission.
"The Commission could accept the proposed requirements in their entirety, ask the staff to modify them, reject some or reject all," said Sheehan. "Therefore, it would be speculative at this point to discuss the likely impact on Vermont Yankee or any other nuclear power plant."
The draft does not apply to spent fuel pools located inside reactor buildings, which are already subject to vehicle bomb blast analysis requirements, said Sheehan.
"Power plants are among the most hardened commercial structures in the country and are designed to withstand extreme events, such as hurricanes, tornadoes, and earthquakes and significant releases due to a terrorist attack on a spent fuel pool are very unlikely," he said.
Bob Audette can be reached at [email protected], or at 802-254-2311, ext. 273.