Two of the high priorities for UFDC disposal R&D are design concept development and disposal system modeling; these are directly addressed in the Generic Disposal Systems Analysis (GDSA) work. This report describes specific GDSA activities during fiscal year 2015 toward the development of the enhanced disposal system modeling and analysis capability for geologic disposal of nuclear waste. The GDSA framework employs the PFLOTRAN thermal-hydrologic-chemical multi-physics code and the Dakota uncertainty sampling and propagation code.
High-burnup spent nuclear fuel cladding has a significant amount of microcracks and hydrides which will reduce the stress intensity required for crack growth. Characteristics of cladding, fuel pellets, and interface between cladding and fuel pellets are likely to change after high burnup; these material modifications may impact the structural integrity and vibration response of SNF rods in transport. The research object is to develop a system for testing the response of high-burnup fuel rods under simulated loading conditions. The report provides recent test results derived from the Cyc
The purpose of the research effort is to determine the effects of canister and/or cask drying and storage on radial hydride precipitation in, and potential embrittlement of, high-burnup (HBU) pressurized water reactor cladding alloys during cooling for a range of storage temperatures and hoop stresses.
The objective of the Crystalline Disposal R&D Work Package is to advance our understanding of long-term disposal of used fuel in crystalline rocks and to develop necessary experimental and computational capabilities to evaluate various disposal concepts in such media. The major accomplishments are summarized in the report: 1) Development of Fuel Matrix Degradation Model (FMDM), 2) Thermal limit study of clay materials, 3) Short-term (< 35 days) study of uranium sorption and diffusion in bentonite, 4) Long-term (6 years) study of uranium diffusion in bentonite, 5) Colloid stability
The goal of work described in this document is to assess the effects of the manufacturing process on canister performance by evaluating the properties of a full-diameter cylindrical mockup of an interim storage canister. The mockup has been produced using the same manufacturing procedures as fielded spent nuclear fuel interim storage canisters. The document describes the design and procurement of the mockup and the planned characterization work; it provides status of the project and sample preparation for different analysis, and results of initial stress (and stress corrosion cracking, S
The report provides a technically based gas sampling frequency strategy for the High-Burnup (HBU) Confirmatory Data Project. The evaluation of 1) the types and magnitudes of gases that could be present in the project cask, and 2) the degradation mechanisms that could change gas composition culminates in an adaptive gas sampling frequency strategy. The adaptive strategy is compared against the sampling frequency that has been developed based on operational considerations. Comparison evaluation of the Technically based and Operationally based sampling frequency strategies indicates there
This study has evaluated the technical feasibility of direct disposal in a geologic repository, of commercial spent nuclear fuel (SNF) in dual-purpose canisters (DPCs) of existing designs. The investigation considered waste isolation safety, engineering feasibility, thermal management, and postclosure criticality control. The 3-year study concludes that direct disposal is technically feasible for most DPCs, depending on the repository host geology. Thermal management and postclosure criticality control are two important aspects of disposability, and both of these could be relatively sim
The document summarizes how a new round of staged thermal field testing will help to augment the safety case for disposal of heat generating nuclear waste in salt. The objectives of the proposed test plan are to: (1) address features, events, and processes (FEPs), (2) build scientific and public confidence, (3) foster international collaboration, (4) evaluate disposal concepts, and (5) validate coupled process models. The test proposal is designed to address long term performance assessment (PA) and shorter term operational uncertainties.
This report documents experimental work evaluating localized corrosion of container and canister materials performed at Sandia National Laboratories. The report also documents the results of analyses of the dust samples collected by the EPRI-led in-service inspections of dry storage canisters at existing ISFSIs (Hope Creek NJ, and Diablo Canyon CA).
The objective of the Crystalline Disposal R&D work is to advance our understanding of long-term disposal of used fuel in crystalline rocks and to develop necessary experimental and computational capabilities to evaluate various disposal concepts in such media. The major accomplishments during the year include: 1) R&D plan was developed for used fuel disposal in crystalline rocks; 2) established a generic reference case for crystalline disposal media; 3) developed and applied THMC models to the analysis of coupled EBS processes in bentonite-backfilled repositories; 4) examined t
This report provides a status of the performance of a systematic study of used nuclear fuel (UNF, also known as “spent nuclear fuel” [SNF]) integrity under simulated transportation environments using the Cyclic Integrated Reversible-Bending Fatigue Tester (CIRFT) hot-cell testing technology developed at Oak Ridge National Laboratory (ORNL) in August 2013. Under Nuclear Regulatory Commission (NRC) sponsorship, ORNL completed four benchmark tests, four static tests, and twelve dynamic or cycle tests on H. B. Robinson (HBR) high burn-up (HBU) fuel.
The purpose of this research effort is to determine the effects of canister/cask vacuum drying and storage on radial hydride precipitation in high‐burnup (HBU) pressurized water reactor (PWR) cladding alloys during cooling for a range of peak drying‐storage temperatures, internal gas pressures, and hoop stresses. The HBU PWR cladding alloys have a wide range of hydrogen contents and varying hydride morphology after in‐reactor service.
This report describes the current status of international collaboration regarding geologic disposal research in the Used Fuel Disposition (UFD) Campaign. To date, UFD’s International Disposal R&D Program has established formal collaboration agreements with five international initiatives and several international partners, and has started several specific collaborative R&D activities. These international activities include testing and modeling studies and address the following key research areas: Near-Field Perturbation, Engineered Barrier Integrity, Radionuclide Transport, and
The report describes implementation and planning of websites that allow visualization or manipulation of data in the UFD GIS Database; e.g., the distribution of crystalline rock, basement depth, and salt and shale formations within the contiguous United States, and visualizations of the relationships between geologic media and selected natural and cultural features pertaining to potential siting guidelines for repository siting.
This report documents the development, demonstration and validation of a mesoscale, microstructural evolution model for simulation of zirconium hydride d-ZrH1.5 precipitation in the cladding of used nuclear fuels that may occur during long-term dry storage. The precipitation and growth of zirconium hydrides during dry storage is one of the most likely fuel rod integrity failure mechanisms either by embrittlement or delayed hydride cracking of the cladding. The model being documented in this work is a computational capability for the prediction of hydride formation in different claddings
This report describes a test of an instrumented surrogate PWR fuel assembly on a truck trailer conducted to simulate normal conditions of truck transport. The purpose of the test was to measure strains and accelerations on a Zircaloy-4 fuel rod during the transport of the assembly on the truck. This test complements tests conducted in FY13 in which the same assembly was placed on a shaker and subjected to vertical vibrations and shocks simulating truck transport. The strains measured on the instrumented Zircaloy-4 rod over a 40.2 mile route never exceeded 150 μin./in.
Radioactive waste disposal in shale/argillite rock formations has been widely considered given its desirable isolation properties, e.g., low permeability, potential geochemically reduced conditions, anomalous groundwater pressures, and widespread geologic occurrence.
The collaborative approach to the glass and metallic waste form degradation modeling activities includes process model development (including first-principles approaches) and model integration—both internally among developed process models and between developed process models and PA models, and cross campaign integration between activities in the Used Fuel Disposition (UFD) Campaign and the Separations (to be Materials Recovery) and Waste Forms (SWF=>MRWF) Campaign. Experimental work is conducted within the UNFD area and results are utilized in development efforts. The primary outputs
[In Support of a Comprehensive National Nuclear Fuel Cycle Strategy, Volumes I and II (Appendices)]
This study provides a technical basis for informing policy decisions regarding strategies for the management and permanent disposal of spent nuclear fuel (SNF) and high-level radioactive waste (HLW) in the United States requiring geologic isolation.
This Test Plan for the High Burnup Dry Storage Research Project (HDRP) outlines the data to be collected, the high burnup fuel to be included, and the storage system design, procedures, and licensing necessary for implementation.
Clay and granitic units are potential host media for future repositories for used nuclear fuel. The report addresses the representation and characterization of flow in these two media within numerical process models. In low permeability crystalline rock, flow is primarily in relatively sparse networks of fractures.
The objective of this work is to develop a spatial database that integrates both geologic data for alternative host-rock formations and information that has been historically used for siting guidelines, both in the US and other countries. The Used Fuel Disposition Campaign (UFDC) is considering three alternative geologic host rocks for mined repositories (granitic / crystalline, salt, and clay / shale) and crystalline basement rock for deep borehole disposal. This report documents progress in populating a GIS Database with information concerning the distribution of alternative host rock
International research collaborations on deep geological disposition of nuclear waste are a key aspect of the nation’s strategy to investigate disposal design concepts in geologic settings considered by other countries. This report centers on results obtained on THM simulations, reactive transport model development, and engineered barrier system (EBS) material characterization studies.