ML22107A007
| ML22107A007 | |
| Person / Time | |
|---|---|
| Site: | 07200009, Hermes |
| Issue date: | 06/30/2020 |
| From: | US Nuclear Waste Technical Review Board |
| To: | Office of Nuclear Material Safety and Safeguards |
| Dozier T | |
| References | |
| Download: ML22107A007 (5) | |
Text
U.S. NUCLEAR WASTE TECHNICAL REVIEW BOARD D E P A R T M E N T O F E N E R G Y -M A N A G E D S P E N T N U C L E A R F U E L A T F O RT S T . V R A I N OVERVIEW 1 The U.S. Department of Energy (DOE) manages approximately 2,500 metric tons of heavy metal (MTHM) 2 of spent nuclear fuel (SNF) that resulted mostly (85% by mass) from defense-related nuclear activities (primarily weapons plutonium production reactors and naval propulsion reactors). Nearly all the SNF is stored at four locations: the Hanford Site in Washington State, the Idaho National Laboratory (INL) in Idaho, the Savanah River Site (SRS) in South Carolina, and the Fort St. Vrain Independent Spent Fuel Storage Installation (ISFSI) in Colorado (see the Boards fact sheet on DOE-Managed Spent Nuclear Fuel). 3 The former commercial nuclear power plant at the Fort St. Vrain site in Colorado was a 330-megawatt (electric) high-temperature, helium-cooled, graphite-moderated reactor that operated between 1979 and 1989.
The Public Service Company of Colorado, which operated the reactor, built the ISFSI (Figure 1) adjacent to the Fort St. Vrain reactor site in 1989 and completed Nuclear Regulatory Commission (NRC) licensing for the facility in 1991. In 1996, DOE assumed responsibility for the SNF, and in 1999, the NRC license for the ISFSI was transferred to DOE (NRC 2011). Because the Fort St. Vrain SNF was fabricated with highly enriched uranium, 4 there is a relatively small amount of uranium in the Figure 1. Fort St. Vrain Independent Spent Fuel SNF compared to other types of SNF; the Storage Installation.
Fort St. Vrain SNF represents less than The building is 43.6-m (143-ft) long, 21.9-m (72-ft) one percent of the total mass (in MTHM) wide, and 24.4-m (80-ft) tall (CH2M-WG Idaho, LLC of DOE-managed SNF. 2012).
1 Unless explicitly stated, this fact sheet does not present Board findings, conclusions, or recommendations and none should be inferred from its content.
2 Metric ton of heavy metal is a commonly used measure of the mass of nuclear fuel. Heavy metal refers to elements with an atomic number greater than 89 (e.g., thorium, uranium, and plutonium) in the fuel. The masses of other constituents of the fuel, such as cladding, alloy materials, and structural materials (and fission products in spent nuclear fuel), are not included in this measure. A metric ton is 1,000 kilograms, which is equal to about 2,200 pounds.
3 Fact sheets providing summary information on DOE-managed SNF stored at the Hanford Site, SRS and INL can be found at the Board website: http://www.nwtrb.gov/our-work/fact-sheets. A more detailed description of DOE-managed SNF and SNF storage facilities is provided in the Board report, Management and Disposal of U.S.
Department of Energy Spent Nuclear Fuel (NWTRB 2017).
4 Highly enriched uranium is uranium that has been enriched through isotopic separation to 20 percent or greater uranium-235 by mass (naturally-occurring uranium contains uranium-235 at 0.72 percent by mass).
U.S. NUCLEAR WASTE TECHNICAL REVIEW BOARD 1 REVISION 1, JUNE 2020
SPENT NUCLEAR FUEL AND THE STORAGE FACILITY AT FORT ST. VRAIN Spent Nuclear Fuel. Fort St.
Vrain SNF consists of thorium-uranium carbide in a graphite matrix and is an uncommon type of SNF. The more common types of DOE-managed SNF are uranium metal SNF and uranium oxide SNF.
As shown in Figure 2, the Fort St.
Vrain fuel is made of micro-spherical particles comprising thorium-uranium carbide with three carbon-based protective coatings that seal the fuel material, prevent Figure 2. Details of a Fort St. Vrain Fuel Element (after Lotts water from contacting and reacting et al. 1992; Hunn 2010; and Martin et al. 2012).
with the fuel, and retain the fission products produced during reactor operation. The fuel particles are mixed with graphite and compressed into cylindrical rods called compacts that are about 5.08-cm (2-in) long with a diameter of just under 1.27 cm (0.5 in). The compacts are then loaded into hexagonal graphite fuel elements that are approximately 78.7-cm (31-in) tall and approximately 35.6 cm (14 in) across the flat faces of the hexagon. Each fuel element has 210 fuel holes running almost the full length of the element that each contains up to 15 fuel compacts. Each fuel element also has 108 axial coolant holes through which the helium reactor coolant flowed during reactor operation (Lotts et al. 1992).
Fort St. Vrain SNF contains highly-enriched uranium (originally enriched to 93.5 percent uranium-235) within the thorium-uranium carbide particles. The volume of Fort St. Vrain SNF is relatively large compared to many other types of SNF that produce the same amount of energy because of the graphite in the fuel element. Because of the chemically inert nature of the graphite and the outer protective coatings of the fuel particles, Fort St. Vrain SNF does not need to be stored in containers filled with inert gas (e.g., helium) as is common with other types of DOE-managed SNF.
Spent Nuclear Fuel Storage Facility. The Fort St. Vrain ISFSI holds the SNF inside a concrete structure (see Figures 3 and 4). The storage facility includes a foundation structure that supports six SNF storage areas called vaults. Each concrete vault contains vertical storage positions that can each store one fuel storage container. A fuel storage container holds as many as six graphite SNF elements, which are kept in an air environment. The outside of the storage container is cooled by natural air circulation. The facility has a design capacity of 1,482 SNF elements.
There are currently 244 positions with fuel containers loaded, giving a total inventory of 1,464 SNF elements (CH2M-WG Idaho, LLC 2012). The fuel storage containers are moved by a Container Handling Machine that can be positioned over each SNF storage location in each of the six vaults.
The Fort St. Vrain nuclear power plant generated approximately 23 MTHM of SNF. DOE transported 8 MTHM of the SNF to INL, where it remains in dry storage (see the Boards fact U.S. NUCLEAR WASTE TECHNICAL REVIEW BOARD 2 REVISION 1, JUNE 2020
Figure 3. Major Features of the Fort St. Vrain Figure 4. Inside the Fort St. Vrain Independent SNF Independent Spent Fuel Storage Installation Spent Fuel Storage Installation (CH2M-WG (Cross-section of One of Six Storage Vaults) Idaho, LLC 2012).
(Raddatz and Waters 1996).
sheet on DOE-Managed Spent Nuclear Fuel at the Idaho National Laboratory). As the result of an agreement with the State of Idaho (Idaho et al. 1995), DOE discontinued the SNF shipments and approximately 15 MTHM of SNF remain at the Fort St. Vrain ISFSI. Additional details about the Fort St. Vrain SNF and dry storage facility are provided in the Boards report Management and Disposal of U.S. Department of Energy Spent Nuclear Fuel (NWTRB 2017).
PATH FORWARD FOR MANAGING AND DISPOSING OF FORT ST. VRAIN SPENT NUCLEAR FUEL DOE has documented the following plans for managing and disposing of Fort St. Vrain SNF. First, DOE will continue to store SNF at the Fort St. Vrain ISFSI consistent with the requirements of the NRC storage license that will be due for renewal on November 30, 2031 (NRC 2011). Second, DOE plans to transport Fort St. Vrain SNF to INL for repackaging prior to transporting the SNF to an interim storage facility or deep geologic repository. If needed, SNF dry-storage facilities are available at INL. The timing of the shipments to INL remains to be determined; however, DOE must remove the SNF from Fort St. Vrain by January 1, 2035, pursuant to an agreement with the State of Colorado (Beller 2014).
The sealed Fort St. Vrain fuel storage containers are designed to prevent the release of radioactive materials.
The NRC approved the TN-FSV transportation cask Figure 5. TN-FSV Legal Weight Truck (Figure 5) for transporting these containers of Transport Cask (Greene et al. 2013).
U.S. NUCLEAR WASTE TECHNICAL REVIEW BOARD 3 REVISION 1, JUNE 2020
Fort St. Vrain SNF (NRC 2014). One fuel storage container fits in one TN-FSV transportation cask. DOE used this configuration to transport Fort St. Vrain SNF to INL. DOEs preliminary plans include repackaging at INL the Fort St. Vrain SNF into standardized canisters for future transportation, storage, and disposal. Based on the preliminary design of DOEs standardized canister, DOE estimates that all Fort St. Vrain SNF stored at INL and at the Fort St. Vrain ISFSI would require approximately 500 DOE canisters. Because of its design, the Fort St. Vrain SNF would require approximately 14 percent of all DOE canisters, even though it represents less than one percent of the total mass (in MTHM) of DOE-managed SNF (NWTRB 2017).
REFERENCES Beller, B. 2014. Management of Spent Nuclear Fuel at the Idaho National Laboratory - Office of Environmental Management. The U.S. Nuclear Waste Presentation at the 2014 NWTRB Summer Board Meeting, Technical Review Board August 6, 2014. is an independent federal agency established in the CH2M-WG Idaho, LLC. 2012. Fort St. Vrain Independent Spent 1987 Nuclear Waste Policy Fuel Storage Facility (ISFSI). Accessed May 13, 2020. Amendments Act.
https://www.yumpu.com/en/document/view/35163432/fort-st-vrain- The Board evaluates the independent-spent-fuel-storage-facility-idaho-cleanup- technical and scientific validity of U.S.
Greene, S.R., J. Medford, and S. Macy. 2013. Storage and Department of Energy Transport Cask Data for Used Commercial Nuclear Fuel - 2013 activities related to U.S. Edition. ATI-TR-13047. Oak Ridge, TN: EnergX LLC. implementing the Nuclear August. Waste Policy Act. The Board also provides Hunn, J.D. 2010. Module 7b. TRISO Fuel Manufacturing - objective expert advice on Fabrication and Quality Control. Presentation at HTGR nuclear waste Technology Course for the Nuclear Regulatory Commission. May management and disposal 24-27. Accessed May 13, 2020. https://art.inl.gov/NGNP/Training issues to Congress and the Secretary of Energy.
Modules HTGR Fundamentals/Module 7b - TRISO Fuel Manufacturing.pdf. The Boards eleven members are nominated Idaho, DOE, and Department of the Navy. 1995. 1995 Settlement by the National Academy Agreement. Accessed May 13, 2020. of Sciences and are https://www.deq.idaho.gov/media/550338- appointed by the President.
1995_Settlement_Agreement.pdf.
www.nwtrb.gov Lotts, A.L., W. Bond, C. Forsberg, R. Glass, F. Harrington, G.
Michaels, K. Notz, and R. Wymer. 1992. Options for Treating High-Temperature Gas-Cooled Reactor Fuel for Repository Disposal. ORNL/TM-12027. Oak Ridge, TN: Oak Ridge National Laboratory. February.
Martin, W.R., J. Lee, A. Baxter, and C. Wemple. 2012. Creation of a Full-core HTR Benchmark with the Fort St. Vrain Initial Core and Assessment of Uncertainties in the FSV Fuel Composition and Geometry. Final Report for Project 09-771. Ann Arbor, MI: University of Michigan. June.
U.S. NUCLEAR WASTE TECHNICAL REVIEW BOARD 4 REVISION 1, JUNE 2020
NRC (Nuclear Regulatory Commission). 2011. Final Environmental Assessment for the Amendment of U.S. Nuclear Regulatory Commission License No. SNM-2504 for Fort St. Vrain Independent Spent Fuel Storage Installation. Docket No. 72-0009. May.
NRC. 2014. Certificate of Compliance for Radioactive Material Packages, Certificate # 9253, Revision 13, Docket Number 71-9253, June 13.
NWTRB (Nuclear Waste Technical Review Board). 2017. Management and Disposal of U.S.
Department of Energy Spent Nuclear Fuel. Arlington, VA: U.S. Nuclear Waste Technical Review Board. December.
Raddatz, M.G. and M.D. Waters. 1996. Information Handbook on Independent Spent Fuel Storage Installations. NUREG-1571. Washington, DC: U.S. Nuclear Regulatory Commission.
December.
U.S. NUCLEAR WASTE TECHNICAL REVIEW BOARD 5 REVISION 1, JUNE 2020