The Department of Energy’s (DOE) Office of Nuclear Energy (NE) is responsible for ongoing research and development (R&D) related to long-term disposition of spent nuclear fuel1 (SNF) and high-level radioactive waste (HLW). The mission of the Office of Spent Fuel and Waste Disposition (SFWD), which manages this work, is to protect people and the environment, now and in the future, by establishing an integrated system for storage, transportation, and disposal of the nation’s spent nuclear fuel and high-level radioactive waste.
Within SFWD are two offices that cover different aspects of this oversight. The Office of Spent Fuel & Waste Science and Technology’s (SFWST) mission is to provide confidence in the safe long-term management of the nation’s spent nuclear fuel and high-level radioactive waste by reducing uncertainty and advancing technology for extended storage, transportation, and geologic disposal. And the Office Integrated of Waste Management’s (IWM) mission is to construct one or more federal interim storage facilities, using a consent-based siting process, ready to receive commercial spent nuclear fuel as soon as practicable.
Activities include conducting system analyses to evaluate the integrated approach for transport, storage and disposal; identifying potential functional and operational requirements; examining interim storage design configurations; planning for transportation of radioactive materials with appropriate stakeholder interactions (including states and tribes); prototype railcar development and testing; and routing analysis tool development.
SFWD sponsors work with national laboratories, industry, and academia to examine alternatives and conduct scientific research and technology development to enable long-term storage, transportation, and geologic disposal of spent nuclear fuel and radioactive wastes. SFWD research has included investigation of SNF and wastes generated by existing and future nuclear fuel cycle options and technologies that minimize waste generation, improve safety, and complement institutional measures in limiting proliferation risk. The main objective in this R&D is to develop a suite of options that will enable decision-makers to make informed choices about how best to manage spent nuclear fuel and high-level radioactive waste. This R&D will be performed on functions in storage, transportation, and disposal in a variety of geologic environments including salt, clay/shale, and granite/crystalline rock media, as well as work to better understand the potential degradation mechanisms involved in long-term dry cask storage.
Current priorities of SFWD include the following:
- Evaluating the feasibility of the direct disposal of dual-purpose (storage and transportation) casks
- Continuing with implementation of a high burn-up, large scale, long-term, dry storage cask research and development project for spent nuclear fuel
- R&D related to other aspects of storage including thermal performance, cladding and other material response, and corrosion
The SFWD office also partners in international and bilateral activities, in order to provide the U.S. with an understanding of the spent fuel and waste disposition activities of other countries, allowing DOE to leverage the expertise and technical assessments for different geologic media and waste forms. SFWD will explore other international opportunities when they support SFWD R&D plan objectives.
Spent Nuclear Fuel Disposition R&D
SFWD conducts R&D to support the development of disposition-path-neutral waste management systems and options in the context of the current inventory of spent nuclear fuel and high-level waste including the following R&D efforts:
High Burnup Spent Fuel Data project
SFWST has a project involving inspection and preparation of the High Burnup Spent Fuel Data project cask for storage, as well as extraction of the 25 sibling rods, their shipment to Oak Ridge National Laboratory and commencement of the nondestructive analysis.
SFWD is involved in international collaboration with Spain and Korea on a transportation cask. This project is managed by SFWST, is the development of the detailed multimodel transportation test plan between DOE and Equipos Nucleares S.A. (ENSA), the Spanish cask designer and manufacturer. This involves obtaining the transportation cask system, determining the placement of accelerometers and strain gages on the surrogate assemblies through modeling at PNNL, and testing the sampling equipment and batteries. Learn more.
Full-Scale Storage Cask Demonstration
Although the nuclear power industry has used dry storage for many years, this storage option has been for low-burnup fuel; therefore, there is limited data available on the degradation of more contemporary high-burnup fuels. To address this data gap, DOE, the Nuclear Regulatory Commission (NRC), and nuclear industry have a collaborative agreement to investigate extended storage of high-burnup fuels, in cooperation with the NRC and industry.
This consortium is initiating a full-scale demonstration of storage for high-burnup fuel that will be beneficial by: 1) benchmarking the predictive models and empirical conclusions developed from short-term laboratory testing, and 2) building confidence in the ability to predict the performance of these systems over extended time periods.
Storage and Transportation R&D
In addition to the Full-Scale Storage Cask project, DOE will continue to support other lab testing, field studies, and modeling R&D related to the storage and transport of high-burnup fuel to include the following:
- Testing of cladding response with hydride reorientation and embrittlement
- The effects of atmospheric corrosion on storage welds
- Measuring the embrittlement of elastomer seals
- Determining thermomechanical degradation of bolts, welds, seals and poisons
- Analyzing thermal profiles of stored fuels
- Determining the stress profiles of fuels and casks
- Evaluating cask drying processes
- Laboratory post-irradiation examination of the fuel; and the development of sensors for internal and external cask monitoring
R&D will focus on contributing to the technical knowledge to support long-term storage and eventual transportation of high-burnup fuels.
Activities continue to further the understanding of long-term performance of disposal systems in three main geologic rock types: clay/shale, salt, and crystalline rock. These activities include collaborations with international partners to leverage and integrate applicable R&D being conducted by other countries into the U.S. disposal R&D portfolio. Evaluations will be completed to determine the feasibility of directly disposing existing single (storage only) and dual purpose (storage and transportation) spent fuel canisters in a mined repository.
Development of Cask, Buffer, and Escort Railcars
Activities continue to develop cask, buffer, and escort railcars for future spent nuclear fuel transportation (Atlas Railcar). Railcars are destination independent and will be approved by the Association of American Railroads in accordance with the safety standard for the transport of high-level radioactive materials (S-2043). The Atlas Railcar has 12 axles in order to carry the heaviest spent nuclear fuel transport casks. Railcar development is done in coordination with the U.S. Navy to leverage resources.
Commercial vendors develop and supply transportation casks certified by the U.S. Nuclear Regulatory Commission for use in transporting spent fuel. These cask vendors (or other transportation equipment vendors) also provide cradles to attach the casks to transportation vehicles. This Interface Control Document provides the information necessary to control the interfaces to the railcar to allow the cask and cradle vendors to ensure that their cradle designs along with the transport casks can be transported on the Atlas railcar.
Intergovernmental Outreach on Spent Nuclear Fuel Transportation Planning
Future large-scale transportation of commercial SNF will involve close coordination between DOE and state and tribal governments to ensure safe and uneventful transport of shipments through their jurisdictions. The Department will coordinate with other federal agencies responsible for regulating transportation and radioactive materials, e.g. NRC and the Department of Transportation.
To enable ongoing engagement with tribal and state governments that may be impacted by future DOE SNF shipments, IWM established cooperative agreements with four state regional groups and a committee of tribal representatives. The agreements contribute to the operations of the following tribal and state committees:
- Tribal Radioactive Materials Transportation Committee
- Northeast High-Level Radioactive Waste Transportation Task Force
- Midwestern Radioactive Materials Transportation Committee
- Southern States Energy Board’s Radioactive Materials Transportation Committee
- Western Interstate Energy Board’s High-Level Radioactive Waste Committee
Cooperative agreement funds support state and tribal participation in DOE’s National Transportation Stakeholders Forum and associated ad hoc working groups, travel to relevant meetings and trainings, production of communications materials and informational webinars, and involvement in DOE site visits to shutdown nuclear power plants.
IWM regularly communicates with federal agencies with missions relating to transportation of radioactive materials to keep them apprised of DOE analysis and planning activities, and maintain awareness of potential regulatory or policy changes that could impact future shipping operations. These agencies include the following:
- U.S. Nuclear Regulatory Commission -- responsible for certifying the Type B packages in which spent nuclear fuel is transported
- U.S. Department of Transportation -- regulates transportation on roadways and railways
- U.S. Coast Guard -- oversees inland and intercoastal waterway transport
Although DOE shipments of SNF are not expected to commence in the near term, continued interactions will contribute to close relationships with tribes, states, and other federal agencies that will form an important foundation for conducting successful transportation operations.
Stakeholder Tool for Assessing Radioactive Transport (START)
IWM has developed a geospatial data visualization and transportation routing analysis capability. The Stakeholder Tool for Assessing Radioactive Transport (START) is a web-based geographic information system (GIS) tool that enables users to visualize more than 50 data layers relevant to radioactive materials transportation planning including modal options, transportation infrastructure conditions, and emergency response assets. The tool also allows evaluation of possible transportation routes by highway, rail, waterway, or multiple modes, and incorporation of geo-tagged imagery from facility site visits. START is currently for official use only and therefore only available for government use.
There are several START one-pagers that explain aspects of this tool:
- START Overview
- START: Emergency Preparedness
- START: Transportation Infrastructure
Transportation Analysis: Removing Spent Nuclear Fuel from Nuclear Power Plant Sites
Site Infrastructure Reports
To prepare for future removal of spent nuclear fuel from nuclear power plant sites, DOE collects data on spent nuclear fuel inventories, on-site transportation and equipment infrastructure, near-site transportation infrastructure and facilities, and other operational considerations for removing packages of SNF from the nuclear power plant sites. This information is gathered from public information sources, data provided by the utilities, and through visits to the power plant sites. Information from 14 sites has been collected to date, and is available in DOE’s Preliminary Evaluation of Removing Used Nuclear Fuel from Shutdown Sites report.
Integrated Waste Management System Analysis Tools
The IWM office has been sponsoring the development of an analytical toolset for applying systems analysis, systems engineering, and decision analysis principles to the evaluation of various IWM system architectures. IWM system analysis considers various aspects of the back-end of the nuclear fuel cycle, i.e., transportation, storage, and disposal. A goal of the effort is to provide a solid basis for future decisions related to deploying spent fuel management strategies. Work on a suite of advanced analytical tools and models is being conducted to perform analyses associated with future deployment of a comprehensive system for managing nuclear waste. These tools include: a Next Generation System Analysis Model (NGSAM); an Execution Strategy Analysis (ESA) tool; a Multi-Objective Evaluation Framework (MOEF); the Used Nuclear Fuel – Storage, Transportation & Disposal Analysis and Resource Data System (UNF-ST&DARDS); and the Stakeholder Tool for Assessing Radioactive Transport (START) discussed previously. Use of these tools assist with understanding interdependencies between various system elements and can be used to inform overall system planning and guide future research. Although much of the work thus far has focused on U.S. commercial SNF, the tool set can be expanded and applied to include DOE SNF and HLW packages in the future. Research work is continuing to refine and enhance these system analysis tools and accompanying data. Additional information on NGSAM and UNF-ST&DARDS is provided below.
Next Generation System Analysis Model (NGSAM)
A NGSAM analytical tool has been developed to provide a capability to model and analyze various waste management system architectures with a focus on U.S. commercial SNF. The tool provides system analysts with an improved capability to quantify and better understand overall system behavior and SNF mass flows as a function of time. It also yields insights by allowing a more detailed assessment of interactions and dependencies between the different parts of the system based on a set of applied technical constraints and scenario assumptions. Such information is constructive when evaluating the merits of possible future approaches and new or improved technologies from a systems perspective, and can serve to help guide future R&D planning and program efforts.
Used Nuclear Fuel -- Storage, Transportation & Disposal Analysis Resource and Data System (UNF-ST&DARDS)
UNF-ST&DARDS is a comprehensive data and analysis system for the safe, secure and sustainable management of SNF. It has been developed in a manner to allow a unified domestic SNF system database to be readily used with integrated analysis capabilities. The unified database encompasses the technical data required to perform analyses, as well as data to support waste management system program planning, design, and operational requirements. Currently, UNF-ST&DARDS can perform SNF assembly depletion and decay analyses as well as SNF cask criticality, dose, containment, and thermal analyses. A feature of the analytical tool is that it can perform more realistic analyses for as-loaded SNF casks. Analytical results using UNF-ST&DARDS are currently being used to support focused research studies and broader system studies. The design and structure of the tool promotes its potential to support safe storage, transport, and disposal of SNF well into the future.
SNF and HLW Information
The IWM Office also supports development of information on SNF characteristics including periodic updates to the report on Spent Nuclear Fuel and Reprocessing Waste Inventory.
There is also an interactive map, publically accessible at https://curie.pnnl.gov/map, providing current and projected inventories of SNF at U.S. commercial nuclear power reactor sites.
1 The term used nuclear fuel is sometimes used in place of spent nuclear fuel; either terminology refers to irradiated fuel discharged from a nuclear reactor.