Energy, Science and Natural Resources Program

Developing a Multipurpose Canister System for Spent Nuclear Fuel

State Legislative Report, Vol. 19, No. 4
By Sia Davis and Cheryl Runyon
March 1, 1994

Introduction
The Current System
Design of the MPC
Schedule (for implementation of canisters)
Cost Benefit Analysis
Feedback from Stakeholders
Legislative Role

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Introduction

The U.S. Department of Energy (DOE) was charged by Congress (through the Nuclear Waste Policy Act of 1982, as amended) to construct and operate a geologic repository for the disposal of spent fuel from commercial nuclear power plants and other forms of high-level waste. Because of the high levels of radiation emitted from the fuel, spent fuel currently is stored in large pools of water at the plants. Many plants have reached or are nearing the end of their available pool storage space and utilities are seeking alternative storage solutions such as dry cask storage. DOE is studying the development of a canister for spent fuel that can be loaded and permanently sealed at the power plant and used to store, ship and ultimately dispose of the waste in the repository. This multipurpose canister (MPC) system under consideration by DOE consists of the canister (a metal container holding spent fuel) and three separate, uniquely designed overpacks for transportation, temporary storage and permanent disposal.

U.S. Secretary of Energy Hazel O'Leary sees the development of the system as a near-term solution and requested that a portion of the FY 1994 budget for the Office of Civilian Radioactive Waste Management (OCRWM) be allocated for it. Congress approved $5.23 million in the FY 1994 appropriations for OCRWM for this project.

The Current System

Traditionally, spent fuel management and disposal required specialized containers for 1) storage at the utility site, 2) transporting to the central storage facility, 3) storing at the facility, and 4) disposing at the final repository. Current spent fuel management involves handling each spent fuel assembly up to 10 times. Most licensed dry storage casks cannot be used to both store and transport the spent fuel they contain. Without the multipurpose canister, each spent fuel assembly must be removed from the storage cask at the reactor site and placed into transport a cask. After arriving at the monitored retrievable storage facility (MRS, a centralized facility), the fuel would be transferred from the transport cask to another storage system; the process would be repeated for subsequent retrieval and transport to the repository, where the spent fuel would be loaded into a disposal container. Incorporation of the MPC into the waste management system could reduce significantly the routine handling of individual spent fuel assemblies. The canister would be loaded with approximately 20 to 40 spent fuel assemblies at the reactor, then stored on-site and later transported to the monitored retrievable storage facility or repository. It is projected that some 1,960 such canisters would be needed at a storage site and that 620 acres of land will be needed for the site.

Design of the MPC

A design envisioned by DOE for the multipurpose canister is a cylinder of steel or cast iron to provide radiation shielding. Once the fuel is loaded into the canister and sealed it is intended to remain there, thus eliminating the need to rehandle individual fuel assemblies. For storage, the canister would be enclosed in a concrete container. This overpack would provide weather protection, as well as shielding from neutron and gamma radiation (highly penetrating electromagnetic radiation emitted in the radioactive decay of certain nuclides). For shipping, the canister would be inserted into an overpack (transportation cask) made of high-strength stainless steel equipped with shielding and shock absorbers. Upon arrival at the repository, the canister would be placed in a metal overpack and sealed for disposal.

Conceptual Design Report

The management and operating contractor for OCRWM, TRW Environmental Safety Systems, completed a draft conceptual design report on September 30, 1993; it is under review by DOE and other interested parties. The report foresees using two kinds of multipurpose canisters (125 and 75 ton) and loading these in a transport cask for rail shipping. The larger one (125 tons fully loaded and shielded for transportation) would hold 21 spent fuel assemblies from a pressurized water reactor (PWR) or 40 assemblies from a boiling water reactor (BWR) while the smaller could hold 12 PWR or 24 BWR assemblies and weigh 75 tons when fully loaded and shielded. A preliminary survey of nuclear power plant facilities indicate that these canisters can be used at 102 out of 121 facilities. The remaining 19 facilities have equipment, structural or entry/exit limitations that will require shipment of uncanistered fuel in truck casks only. The spent fuel then could be encapsulated into canisters at the temporary storage facility (e.g. the MRS).

Testing, Licensing and Usage

The Nuclear Regulatory Commission (NRC), the agency responsible for licensing all aspects of the repository, the temporary storage facility and transportation casks, will examine the environmental assessment and safety analysis test results of the canisters to ensure they will perform safely and meet all applicable regulatory requirements. Analysis includes reaction to tornadoes and high wind, fire and explosion, earthquakes and mechanical stress. The transportation overpack also will undergo testing to demonstrate its ability to withstand a 30-foot drop onto an unyielding surface, intense fire, immersion in water and puncture. The canister will be designed to survive various transportation accidents, hypothetical fuel handling accidents, canister handling accidents and human loading errors. NRC officials believe that even though different requirements exist for storage and transportation, staff will be able to adequately integrate the licensing review process for each functional area.

Schedule

If DOE decides to deploy the canisters, a request for proposals could be issued by March 1994, making the first canister available for use at a power plant in January 1998. The first transportation cask for shipping the canisters to a temporary storage facility should be ready in January 2000.

Cost Benefits Analysis

Although the multipurpose canister will cost more than a canister designed for storage only, the costs are offset by the savings to the other components of the waste management system. Estimated costs per canister range from $276,000 to $432,000, depending upon materials and manufacturing techniques.

The canister system is designed to provide benefits for at-reactor and monitored retrievable storage, transportation and permanent disposal in a deep geologic repository. The MRS, which DOE is scheduled to open in 2000, will provide above-ground storage for spent nuclear fuel until a repository is licensed and operating. The monitored retrievable storage facility would employ a dual-capacity transfer room and one transfer cell for individual spent fuel handling for the 19 facilities not able to use the canister system. The repository will be the permanent disposal site for both commercial spent fuel and high-level radioactive waste from defense-related activities. DOE is conducting scientific investigations at Yucca Mountain, Nev., to determine whether it would be suitable for development as a repository. The multipurpose canister system would limit and speed up the waste-handling activities at the repository.

Feedback from Stakeholders

Stakeholders (the utilities, equipment manufacturers, potential MRS hosts, affected state and local governments, state legislators, public utilities commissions and public interest groups) have had an opportunity to comment on the conceptual design of the multipurpose canister. They generally believe the conceptual design is a good first step in developing a national strategy for spent fuel management. Perceived benefits include:

System integration
Reducing spent fuel handling
More efficient use of large rail casks

The stakeholders also have raised questions that will require further evaluation, including: .

Unknown disposal regulatory requirements at therepository could pose a risk to the use of the multipurposecanister;
Reopening the canisters may be necessary afterlong-term storage to inspect the spent fuel;
The cost of the multipurpose canister system should be analyzed in comparison to the current cask and storage technologies being developed by private industry;
The 1998 goal for providing canisters to utilities may be unrealistic if the Nuclear Regulatory Commission cannot license the canisters as quickly as DOE predicts; and
Health and safety concerns must be addressed to gain public acceptance, perhaps with a testing program.

Stakeholders believe DOE should continue to develop and complement the canister concept due to the diversity of interests and the need for direction, coordination and decision making. The utilities continue to remain concerned about the cost of the canister system and whether these costs will be covered by the special Nuclear Waste Fund account in the U.S. Treasury.

Legislative Role

Legislators in states operating nuclear power plants, along shipping corridors and in potential host states for a monitored retrievable storage facility and repository are interested in DOE's decision to develop the canister system. The proposed canisters will provide an extra layer of shielding between the bare fuel, the environment and workers at power plants.

Conclusion

Multipurpose canisters will be more expensive to develop but will have long term benefits. Among these are that the monitored retrievable storage facility and repository operations will be radiologically "cleaner" due to less fuel handling, reduced worker radiation exposure, uniformity in storage and handling operations, simplification of transportation operations, sooner and faster fuel acceptance at storage facilities and near-term progress in DOE's transportation program. The Nuclear Regulatory Commission will determine whether the canisters meet the safety, health and environmental requirements of licensing criteria contained in federal regulations.

References

"A Preliminary Evaluation of Using Multi-Purpose Canisters Within the Civilian Radioactive Waste Management System." Vienna, Va.: TRW Environmental Safety Systems Inc., March 1993.
Office of Civilian Radioactive Waste Management. "Multi-Purpose Canister (MPC) Implementation Program Conceptual Design Phase Report," MPC Conceptual Design Summary Report, Vol. 1, September 1993. Washington, D.C.: U.S. Department of Energy.
"Conceptual Design for a Waste Management System that Uses Multipurpose Canisters." Washington, D.C.: Roy F. Weston, Inc., December 1993.
"Multi-Purpose Canister Workshop Report to Participants." Vienna, Va.: Storage and Transportation Outreach/Institutional Civilian Radioactive Waste Management System, December 10, 1993.
Proposal to the DOE--Development and Demonstration of a Universal Container System, Richmond, Va.: Virginia Power, Westinghouse Electric Corporation and Newport News Shipbuilding, January 1993.
Trebules, Victor W. "MRS Update" presentation at NCSL Legislative Working Group on Monitored Retrievable Storage, Phoenix, Ariz., October 21, 1993.
U.S. Nuclear Regulatory Commission. "Issues in the Review of a Dual-Purpose Cask for Transportation and Dry Storage of Spent Fuel," Policy Issue Memorandum, (SECY-93-265), September 22, 1993.
"Universal Container Systems Concept Paper." Washington, D.C.: Edison Electric Institute, December 1992.

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