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
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.
The Department of Energy’s Office of Nuclear Energy, Used Nuclear Fuel Disposition Research and Development Office (UFD), performs the critical mission of addressing the need for an integrated strategy that combines safe storage of spent nuclear fuel with expeditious progress toward siting and licensing a disposal facility or facilities. The UFD International Program plays a key role in this effort.
Irradiation is known to have a significant impact on the properties and performance of Zircaloy cladding and structural materials (material degradation processes, e.g., effects of hydriding). This UFD study examines the behavior and performance of unirradiated cladding and actual irradiated cladding through testing and simulation. Three capsules containing hydrogen-charged Zircaloy-4 cladding material have been placed in the High Flux Isotope Reactor (HFIR). Irradiation of the capsules was conducted for post-irradiation examination (PIE) metallography.
Regulations which govern the operation of commercial nuclear power plants require conservative margins of fracture toughness, both during normal operation and under accident scenarios. In the irradiated condition, the fracture toughness of the RPV may be severely degraded, with the degree of toughness loss dependent on the radiation sensitivity of the materials. As stated in previous progress reports, the available embrittlement predictive models, e.g.
The U.S. Department of Energy Office of Nuclear Energy (DOE-NE), Office of Fuel Cycle Technology, has established the Used Fuel Disposition Campaign (UFDC) to conduct the research and development activities related to storage, transportation, and disposal of used nuclear fuel and high-level radioactive waste. The mission of the UFDC is to identify alternatives and conduct scientific research and technology development to enable storage, transportation and disposal of used nuclear fuel (UNF) and wastes generated by existing and future nuclear fuel cycles.
Fiscal year (FY) 2011 marks the ten-year anniversary of the founding of the International Nuclear Energy Research Initiative, or I-NERI. Designed to foster international partnerships that address key issues affecting the future global use of nuclear energy, I-NERI is perhaps even more relevant today than at its establishment. In the face of increasing energy demands coupled with clean energy imperatives, we must clear the hurdles to expanding the role of nuclear power in our energy portfolio.