Testing and analyses of the TN-24P PWR spent-fuel dry storage cask loaded with consolidated fuel

Abstract

SUBJECTS Light water reactor fuel I High-level radioactive waste management TOPICS Spent-fuel storage Thermal hydraulics models AUDIENCE Fuels engineers I R&D scientists Heat transfer Shielding Testing and Analyses of the TN-24P PWR Spent-Fuel Dry Storage Cask Loaded With Consolidated Fuel Full-scale testing has confirmed that the TN-24P storage cask offers a technically sound and practical method for storing consolidated spent fuel. COBRA-SFS code predictions of cask performance at conditions near its design limits agreed very well with actual test data. BACKGROUND As at-reactor storage basins attain maximum capacity, many utilities are expected to implement dry spent-fuel storage systems. To demonstrate the storage of dry spent fuel in large metal casks, EPRI and DOE have sponsored tests of metal casks loaded with unconsolidated fuel at the Idaho National Engineering Laboratory (INEL). This most recent study was initiated to investigate a TN-24P cask containing consolidated fuel. OBJECTIVES To demonstrate the thermal, shielding, and operational performance of the TN-24P cask loaded with consolidated spent nuclear fuel; to assess the ability of the COBRA-SFS heat transfer code (developed by Pacific Northwest Laboratory) to model the cask system and predict thermal performance. APPROACH Prior to the testing, the TN-24P cask contained 24 unconsolidated PWR assemblies from Virginia Power's Surry nuclear power station. The project team replaced the assemblies with 24 canisters of spent fuel, consolidated at a ratio of two assemblies per canister. INEL's rod consolidation project provided the filled test canisters. Researchers used the COBRA-SFS computer code to predict cask thermal performance. The team then instrumented and tested the cask in horizontal and vertical positions with three internal storage environments (nitrogen, helium, and vacuum). They compared the COBRA-SFS predictions with actual test data, refined the code to reflect test results, and performed posttest predictions. Transnuclear, Inc., the cask manufacturer, sponsored an additional test to simulate the insulating influence of impact limiters. RESULTS The TN-24P cask is well suited to store consolidated spent fuel. Its heat transfer performance was exceptionally good, as peak cladding temperatures for a cask heat load of 23.3 kW were well under 300°C with helium, ORDERING INFORMATION Requests for copies of this report should be directed to Research Reports Center (ARC), Box 50490, Palo Alto, CA 94303, (415) 965-4081. There is no charge for reports requested by EPRI member utilities and affiliates, U.S. utility associations, U.S. government agencies (federal, state, and local), media, and foreign organizations with which EPRI has an information exchange agreement. On request, ARC will send a catalog of EPRI reports.

Spent nuclear fuel integrity during dry storage - performance tests and demonstrations

“…The TN-24P (McKinnon et al 1987a) cask has a forged steel body for structural integrity and gamma shielding, surrounded by a resin layer for neutron shielding, and is enclosed in a smooth steel outer shell. The TN-24P cask, shown in Figure 3.3, is 5.0 m (16 ft) long and measures 2.3 m (7.5 ft) in diameter; it weighs approximately 100 tons when loaded with unconsolidated PWR spent fuel.…”

Application of muon tomography to fuel cask monitoring

“…The resulting fuel compositions have been incorporated into a GEANT-4 [15] model of a TN-24P fuel cask [22] in order to study the signatures of fresh and spent fuel, the impact of β-decay on muon scattering of spent fuel, and the change in the signature from various materials that could be used to replace diverted fuel bundles.…”

Thermal performance sensitivity studies in support of material modeling for extended storage of used nuclear fuel

“…The zircaloy cladding of the fuel rods in the CE 14x14 assemblies was assumed to have an emissivity typical of fuel at end of life in the reactor. This has been determined to be in the range of 0.6 to 0.9, with 0.8 as a typical value (Creer et al, 1987;Davis 1980;McKinnon et al, 1987).…”