Prepared By
Planning Information Corporation
Denver, Colorado
September, 1996

6.   Cask Options

Rail Transport Casks

Several casks are potentially available for rail shipment of SNF or HLW, some of which may also be used for above-ground storage of these materials:

• The NAC STC cask, designed by Nuclear Assurance Corporation, would have a capacity of 26 PWR assemblies at least 6˝ years old, or 57 BWR assemblies at least eight years old. The cask would weigh at least 125 tons loaded. The PWR version has been certified by NRC for storage and transport, while the BWR version was scheduled for license submission in the fall of 1995. No NAC STC casks have been fabricated and none are currently available for delivery to storage or shipment sites. It is estimated that fabrication and delivery would take about two years after the order for a certified cask is made.

• The IF-300 cask, designed by General Electric, has a capacity of 7 PWR or 18 BWR assemblies. The cask weighs about 70 tons loaded. Four such casks have been fabricated. Two have been used by Carolina Power and Light for transfer of PWR and BWR assemblies among their Robinson, Brunswick, and Harris facilities. Two are owned by Vectra Technologies, formerly Pacific Nuclear Corporation. The IF-300 is certified for transport only, and no new fabrication is permitted under its current NRC certificate of compliance, which expired in May 1995.

• The TN-8 and TN-9 casks, designed by Transnuclear Inc., have capacities for 3 PWR or 7 BWR assemblies. Assemblies transported in TN-8/9 casks are uncanistered—meaning that, on arrival at its destination, the transportation cask must be moved to a spent fuel pool, where bare fuel assemblies are removed for pool storage or canistering. Though four such casks are available, they are not currently certified for use in the U.S. The TN-8 and TN-9 casks weigh just under 40 tons loaded. They are designed for transport only, not for storage, and the current certificate of compliance expired in May 1996.

• The Hi-Star 100 cask, designed by Holtec International, has a capacity of 24 PWR and 68 BWR assemblies. It is designed for storage as well as transport. None are currently available, as its NRC license application is currently under review. The cask weight, empty or loaded, is currently considered proprietary.

• The Vectra MP-187 cask, designed by Vectra Technologies for storage as well as transport, would have a capacity of 24 PWR assemblies. Its NRC license application is currently under review. The cask is intended for storage and transport of spent fuel at the Rancho Seco plant (near Sacramento, California) which was shut down in 1989.

• The small MPC (multiple-purpose canister) cask, designed by Westinghouse Electric for transport, storage, and (possibly) permanent disposal, would have a capacity of 12 PWR or 24 BWR assemblies. The large MPC cask, also designed by Westinghouse Electric for transport, storage, and (possibly) permanent disposal, would have a capacity of 21 PWR or 40 BWR assemblies.

  Through FY 1995, MPC cask design and licensing was supported by DOE via the Nuclear Waste Fund, but this support was not continued in appropriations for FY 1995. While the U.S. Navy is considering an adaptation of the MPC design for the transport and storage of naval reactor fuel, the schedule for its design and licensing for use with SNF is uncertain. It appears unlikely that such casks could be delivered for a 1998 acceptance date.

• DOE has expressed its intention to adapt the MPC design for transport and storage of five canisters of vitrified HLW, each of which would be about 2 feet in diameter and 10 to 15 feet in length.¹⁴ (The 48" diameter cavity of the MPC-75 might accommodate four two-foot diameter canisters, while the 58" diameter cavity of the MPC-125 might accommodate six two-foot diameter canisters.)¹⁵ DOE has not begun detailed design or licensing of such a cask, however.

Dry Storage of Canistered Spent Fuel

Several designs for dry storage of canistered spent fuel have been approved by NRC. In these designs, spent fuel canisters are loaded and sealed in an operating spent fuel pool, then inserted into a nearby concrete or metal facility for onsite storage. The Electric Power Research Institute is currently developing a "dry transfer" facility, by which the sealed canisters could be transferred to a transport cask without return to a spent fuel pool. If successful, dry transfer could enable certain spent fuel pools to be shut down, even while spent fuel remains onsite in dry storage. Dry storage designs include:

• The NUHOMS concrete modules, designed by Vectra Technologies for storage of canistered PWR or BWR assemblies. The NUHOMS-7 design was licensed in 1986 and has a capacity of 7 PWR assemblies, while the NUHOMS-24P design was licensed in 1989 for storage of 24 PWR assemblies. A standardized version of the NUHOMS-24P and NUHOMS-52B (for 52 BWR assemblies) received an NRC certificate of compliance in January 1995. The NUHOMS-7 design is in use at Robinson 2, while the NUHOMS-24P design is in use at Oconee, Calvert Cliffs, and Rancho Seco.

• The VSC-24 ventilated cask, designed by Pacific Sierra Nuclear for storage of 24 PWR assemblies. The design received its NRC certificate of compliance in 1993 and is in use at the Palisades nuclear plant, about 40 miles west of Kalamazoo near the eastern shore of Lake Michigan.

Legal-Weight Truck Transport Casks

Several designs are potentially available for legal-weight truck shipment of SNF and HLW. In contrast to dry storage casks and recently-designed rail casks, legal-weight truck casks are designed to transport uncanistered assemblies—meaning that, on its arrival at its destination, the cask must be placed in a spent fuel pool or hot cell, where the assemblies are removed for pool storage or canistered for dry storage.

• The GA-4 and GA-9 casks, designed by General Atomics, would have capacity for four PWR or nine BWR assemblies. The design is currently in review by NRC. The cask would weigh 27 tons, loaded. Adding the truck and transportation tackle, shipments would barely meet legal highway weight (80,000 lbs.).

  There is some question whether General Atomics would find it advantageous to produce the GA- 4/9 casks for a shipment campaign which emphasizes rail transport and reduces the inventory shipped by truck. Ironically, the number of smaller capacity truck shipments in a shipment campaign emphasizing rail transport could be as large or larger than the number truck shipments in a campaign which uses the higher capacity GA-4/9 casks combined with less rail transport.

• The NLI-1/2 cask designed by National Lead Industries, but not currently certified for domestic use, and the NAC-LWT cask designed by Nuclear Assurance Corporation have capacity to transport a single 860 pound PWR assembly or two 360 pound BWR assemblies. Such casks have been used in most spent fuel transport to date. These casks weigh 24 to 26 tons loaded.

Transport Cask Options: This Assessment

This assessment limits the array of transport cask options to essentially four:

• A 75-ton rail transport and storage cask similar to the MPC-75 design.

• A 125-ton rail transport and storage cask similar to the MPC-125 design.

• A high-capacity legal-weight truck transport cask similar to the GA-4/9 designs.

• A standard legal-weight truck transport cask similar to the NLI-1/2 or NAC-LWT designs.

• In addition, we have included a 100+ ton rail transport and storage cask for canisters of vitrified HLW—an adaption of the MPC-75/125 designs.

Note that, with the exception of the standard legal-weight truck transport casks, none of the above cask options are licensed by NRC, in production, or currently-available for delivery and use. The GA-4/9 cask design is in review in NRC, but, even if it is licensed, its production is uncertain. Despite considerable DOE investment in the 1990's, the designs for the MPC-75 and 125 casks are conceptual, and have not yet been submitted to NRC for licensing.

This assessment considers the high-capacity and standard capacity truck casks as alternatives for legal-weight truck transport. We estimate truck shipments using either cask, but do not attempt to estimate the mix of high and standard capacity casks that could be used in legal-weight truck shipments.*