In the committee’s opinion, there are several relatively simple steps that could be taken to reduce the likelihood of releases of radioactive material from dry casks in the event of a terrorist attack:
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Additional surveillance could be added to dry cask storage facilities to detect and thwart ground attacks.15
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Certain types of cask systems could be protected against aircraft strikes by partial earthen berms. Such berms also would deflect the blasts from vehicle bombs.
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Visual barriers could be placed around storage pads to prevent targeting of individual casks by aircraft or standoff weapons,16 These would have to be designed so that they would not trap jet fuel in the event of an aircraft attack.
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The spacing of vertical casks on the storage pads can be changed, or spacers (shims) can be placed between the casks, to reduce the likelihood of cask-to-cask interactions in the event of an aircraft attack.
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Relatively minor changes in the design of newly manufactured casks could be made to improve their resistance to certain types of attack scenarios.
4.3 POTENTIAL ADVANTAGES OF DRY STORAGE OVER WET STORAGE
Based on the analyses presented in Chapter 3 and previously in this chapter, the committee judges that dry cask storage has several potential safety and security advantages over pool storage. These differences can best be illustrated using scenarios for both storage systems based on the Sandia analyses reviewed by the committee. The use of such scenarios should not be taken to imply that the committee believes that these scenarios are likely or even possible at all storage facilities. They are used only for illustrative purposes.
The following statements can be made about the comparative advantages of dry-cask storage and pool storage based on the Sandia analyses:
Less spent fuel is at risk in an accident or attack on a dry storage cask than on a spent fuel pool. An accident or attack on a dry cask storage facility would likely affect at most a few casks and put a few tens of metric tons of spent fuel at risk. An accident or attack on a spent fuel pool puts the entire inventory of the pool, potentially hundreds of metric tons of spent fuel, at risk.
The potential consequences of an accident or terrorist attack on a dry cask storage facility are lower than those for a spent fuel pool. There are several reasons for this difference:
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There is less fuel in a dry cask than in a spent fuel pool and therefore less radioactive material available for release.
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Measured on a per-fuel-assembly basis, the inventories of radionuclides available
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15 |
As noted in Chapter 1, the committee did not examine surveillance activities at nuclear power plants and has no basis to judge whether current activities at dry cask storage facilities are adequate. |
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16 |
The ISFSI at the Palo Verde Nuclear Power Plant in Arizona, which was visited by a subgroup of committee members, incorporates a berm into its design to provide a visual barrier. |
