This work plan proposes to build a systematic knowledge base for the thermal aging behavior of cast stainless steels (CASSs) within a limited time of five years. The final output of execution of the plan is expected to provide conclusive predictions for the integrity of the CASS components of LWR power plants during the extended service life up to and beyond 60 years.
The document describes the initial work on designing and developing requirements for a total system performance assessment (TSPA) model that can support preliminary safety assessments for a mined geologic repository for high-level waste (HLW) and spent nuclear fuel (SNF) in salt host rock at a generic site. A preliminary generic salt TSPA model for HLW/SNF disposal has been developed and tested for an isothermal repository in salt, for emplaced waste that is assumed to have no decay heat; for salt repositories containing heat-generating HLW/SNF, the present study develops model requirements based on features, events, and processes (FEPs) screening and proposed sensitivity analyses for heat-generating waste. These may better guide the construction of a more representative salt TSPA model.
The study summarizes the initial work on numerical modeling, simulations, and experimental results related to nuclear waste storage in a salt repository. The study reflects the project's preliminary effort at simulating the fluid flow and heat transport processes, before treating the fully coupled thermal-mechanical-hydrologic-chemical (TMHC) coupled processes in the future.
The natural barrier system (NBS) is an integral part of a geologic nuclear waste repository. The report describes progress in development of an integrated modeling framework that can be used for systematically analyzing the performance of a natural barrier system and identifying key factors that control the performance. This framework is designed as an integrated tool for prioritization and programmatic decisions.
This report summarizes research activities on engineered barrier system (EBS) model integration with the generic disposal system model (GDSM), and used fuel degradation and radionuclide mobilization (RM) in support of the EBS evaluation and tool development within the UFD campaign.
This roadmap is intended to advance deep borehole disposal (DBD) from its current conceptual status to potential future deployment as a disposal system for spent nuclear fuel (SNF) and high-level waste (HLW). The objectives of the DBD RD&D roadmap include providing the technical basis for fielding a DBD demonstration project, defining the scientific research activities associated with site characterization and postclosure safety, and defining the engineering demonstration activities associated with deep borehole drilling, completion, and surrogate waste canister emplacement.
Safety is central to the design, licensing, operation, and economics of Nuclear Power Plants (NPPs). Consequently, the ability to better characterize and quantify safety margin holds the key to improved decision making about light water reactor design, operation, and plant life extension. A systematic approach to characterization of safety margins and the subsequent margins management options represents a vital input to the licensee and regulatory analysis and decision making that will be involved.
The Nuclear Power 2010 (NP 2010) Construction and Operating License/Design Certification (COL/DC) Demonstration program together with the financial incentives provided by the Energy Policy Act of 2005 are the two primary reasons why a number of license applications for new nuclear construction are before the NRC today, and why the first new nuclear plants in over 30 years are under construction in the United States.
Clay/shale has been considered as potential host rock for geological disposal of high-level radioactive waste throughout the world. Coupled thermal, hydrological, mechanical, and chemical (THMC) processes have a significant impact on the long-term safety of a clay repository. This report documents results from three R&D activities: (1) implementation and validation of constitutive relationships, (2) development of a discrete fracture network (DFN) model for investigating coupled processes in the excavation damaged zone, and (3) development of a THM model for the Full-Scale Emplacement Experiment tests at Mont Terri, Switzerland, for the purpose of model validation. One major goal is to provide a better understanding of the evolution of the excavation damage zone in clay repositories.
While both wet and dry storage have been shown to be safe options for storing UNF, the focus of the program is on dry storage of commercial UNF at reactor or centralized locations. This report focuses on the knowledge gaps concerning extended storage identified in numerous domestic and international investigations and provides the UFDC’s gap description, any alternate gap descriptions, the rankings by the various organizations, evaluation of the priority assignment, and UFDC-recommended action based on the comparison.
Development and implementation of future advanced fuel cycles including those that recycle fuel materials, use advanced fuels different from current fuels, or partition and transmute actinide radionuclides, will impact the waste management system. The UFD Campaign can reasonably conclude that advanced fuel cycles, in combination with partitioning and transmutation, which remove actinides, will not materially alter the performance, the spread in dose results around the mean, the modeling effort to include significant features, events, and processes (FEPs) in the performance assessment, or the characterization of uncertainty associated with a geologic disposal system in the regulatory environment of the US.
The United States (U.S.) currently utilizes a once-through fuel cycle where used nuclear fuel is stored onsite in either wet pools or in dry storage systems with ultimate disposal envisioned in a deep mined geologic repository. This report provides an estimate of potential waste inventory and waste form characteristics for the DOE UNF and HLW and a variety of commercial fuel cycle alternatives in order to support subsequent system-level evaluations of disposal system performance.
This Nuclear Energy Advanced Modeling and Simulation (NEAMS) quarterly report includes highlights, a spotlight on personal achievements, accomplishments, milestones and a technical spotlight on multiscale material model development for fuel performance codes.
Today, welding is widely used for repair, maintenance and upgrade of nuclear reactor components. As a critical technology to extend the service life of nuclear power plants beyond 60 years, weld technology must be further developed to meet new challenges associated with the aging of the plants, such as control and mitigation of the detrimental effects of weld residual stresses and repair of highly irradiated materials. To meet this goal, fundamental understanding
of the “welding” effect is necessary for development of new and improved welding technologies.
The report is intended to help assess and establish the technical basis for extended long‐term storage and transportation of used nuclear fuel. It provides: 1) an overview of the ISFSI license renewal process based on 10 CFR 72 and the guidance provided in NUREG‐1927; 2) definitions and terms for structures and components in DCSSs, materials, environments, aging effects, and aging mechanisms; 3) TLAAs and AMPs, respectively, that have been developed for managing aging effects on the SSCs important to safety in the dry cask storage system designs; and 4) AMPs and TLAAs for the SSCs that ar
Nuclear power currently provides a significant fraction of the United States’ non- carbon emitting power generation. In future years, nuclear power must continue to generate a significant portion of the nation’s electricity to meet the growing electricity demand, clean energy goals, and ensure energy independence. New reactors will be an essential part of the expansion of nuclear power. However, given limits on new builds imposed by economics and industrial capacity, the extended service of the existing fleet will also be required.
In the United States currently there are approximately 104 operating light water reactors. Of these, 69 are pressurized water reactors (PWRs) and 35 are boiling water reactors (BWRs). In 2007, the 104 light-water reactors (LWRs) in the United States generated approximately 100 GWe, equivalent to 20% of total US electricity production. Most of the US reactors were built before 1970 and the initial design lives of most of the reactors are 40 years.
The report presents information related to the development of a fundamental understanding of disposal-system performance in a range of environments for potential wastes that could arise from future nuclear fuel cycle alternatives. It addresses selected aspects of the development of computational modeling capability for the performance of storage and disposal options. Topics include radionuclide interaction with geomedia, colloid-facilitated radionuclide transport (Pu colloids), interaction between iodide (accumulate in the interlayer regions of clay minerals) and a suite of clay minerals
The assessment of generic EBS concepts and design optimization to harbor various disposal configurations and waste types needs advanced approaches and methods to analyze barrier performance. The report addresses: 1) Overview of the importance of THMC processes to barrier performance, and international collaborations; 2) THMC processes in clay barriers; 3) experimental studies of clay stability and clay-metal interactions at high temperatures and pressures; 4) thermodynamic modeling and database development; 5) Molecular Dynamics (MD) study of clay hydration at ambient and elevated temperatures; and 6) coupled thermal-mechanical (TM) and thermo-hydrological (TH) modeling in salt.
The Fuel Cycle (FC) Subcommittee of NEAC met February 7-8, 2012 in Washington (Drs. Hoffmann and Juzaitis were unable to attend). While the meeting was originally scheduled to occur after the submission of the President’s FY 2013 budget, the submission was delayed a week; thus, we could have no discussion on balance in the NE program. The Agenda is attached as Appendix A.
Reference 1 discussed key elements of the process for developing a margins-based “safety case” to support safe and efficient operation for an extended period. The present report documents (in Appendix A) a case study, carrying out key steps of the Reference 1 process, using an actual plant Probabilistic Risk Assessment (PRA) model.
Nuclear power has contributed almost 20% of the total amount of electricity generated in the United States over the past two decades. High capacity factors and low operating costs make nuclear power plants (NPPs) some of the most economical power generators available. Further, nuclear power remains the single largest contributor (nearly 70%) of non-greenhouse gas-emitting electric power generation in the United States.