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Nuclear Safeguards Education Portal
  

Spent Nuclear Fuel Storage

Figure 6. Horizontal spent fuel storage vault (Source: NNSA)
Figure 6. Horizontal spent fuel storage vault (Source: NNSA) 

Currently, there are two storage methods for spent fuel after it is removed from the reactor core: spent fuel pools and dry cask storage.  Both are interim (temporary) storage and are designed to be effective in the decade time scale.

Please review the Spent Fuel Storage section from the Nuclear Fuel Cycle Module.

Storage inventory, whether in spent fuel pools or dry cask storage, can either be at the at-reactor (AR) sites or away-from-reactor (AFR) storage facilities.  In the United States, for example, Interim storage facilities (AFR) have been employed at the Idaho National Environmental and Engineering Laboratory.  The bulk of the spent fuel inventory (74% of spent fuel in storage) is still in AR pools, but the AFR storage has begun to multiply in an increasing number of sites around the world.  Due to the large and increasing amount of spent fuel inventory at these facilities, as well as the significant amount of special nuclear material, safeguarding these facilities is a significant concern. Table 4 lists current storage options for spent nuclear fuel.

Table 4. Storage options for spent nuclear fuel 

TYPE OPTION HEAT TRANSFER CONTAINMENT
MEDIUM)
SHIELDING FEATURE EXAMPLES
Wet pool water water/building water classic option most ARs + many AFRs worldwide
Dry metal cask conduction through cask wall double lid metal gasket metallic wall dual purpose CASTOR, TN, NAC-ST/STC, BGN solutions
Dry concrete cask/silo air convection around canister cavity lining / seal welding (inert gas) concrete and steel overpack vertical CONSTOR, HI-STORM
Dry concrete module air convection around canister canister sealing (inert gas) concrete wall horizontal NUHOMS, NAC-MPC/UMS, MAGNASTO R
Dry vault air convection around thimble tube thimble tube (inert gas) concrete wall several cases MVDS, MACSTOR
Dry drywell/tunnel heat conduction through earth canister (inert gas) earth below ground Not commercial
(Source: Ref. 1)

Figure 7 contains a diagram of horizontal and vertical spent fuel dry storage casks. Figures 6 and 8 show real pictures of the loading of a horizontal spent fuel storage vault and vertical spent fuel dry storage/transfer casks, respectively.

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Figure 7. Diagrams of vertical and horizontal dry spent fuel storage casks. (Source: Ref. 7)

 

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Figure 8 Vertical spent fuel dry storage/transfer casks. (Source: Ref. 7)

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