As the largest domestic source of low-carbon energy, nuclear power is making major contributions toward meeting our nation’s current and future energy demands. The United States must continue to ensure improvements and access to this technology so we can meet our economic, environmental and energy security goals. We rely on nuclear energy because it provides a consistent, reliable and stable source of base load electricity with an excellent safety record in the United States.
A significant effort is being placed on silicon carbide ceramic matrix composite (SiC CMC) nuclear fuel cladding by Light Water Reactor Sustainability (LWRS) Advanced Light Water Reactor Nuclear Fuels Pathway. The intent of this work is to invest in a high-risk, high-reward technology that can be introduced in a relatively short time. The LWRS goal is to demonstrate successful advanced fuels technology that suitable for commercial development to support nuclear relicensing.
The most life-limiting structural component in light-water reactors (LWR) is the reactor pressure vessel (RPV) because replacement of the RPV is not considered a viable option at this time. LWR licenses are now being extended from 40y to 60y by the U.S. Nuclear Regulatory Commission (NRC) with intentions to extend licenses to 80y and beyond. The RPV materials exhibit varying degrees of sensitivity to irradiation-induced embrittlement (decreased toughness) , as shown in Fig. 1.1, and extending operation from 40y to 80y implies a doubling of the neutron exposure for the RPV.
There are over 100 nuclear power plants operating in the U.S., which generate approximately 20% of the nation’s electricity. These plants range from 15 to 40 years old. Extending the service lives of the current fleet of nuclear power plants beyond 60 years is imperative to allow for the environmentally-sustainable energy infrastructure being developed and matured.
This report provides an update on the assessment of environmentally-assisted fatigue for light water reactor (LWR) extended service conditions. The report is a deliverable in FY11 under the work package for LWRS under the Advanced Reactor Concepts.
The FY10 activities for development of a nuclear concrete materials database to support the Light Water Reactor Sustainability Program are summarized. The database will be designed and constructed using the ORNL materials database infrastructure established for the Gen IV Materials Handbook to achieve cost reduction and development efficiency.
The UFD Campaign is developing generic disposal system models (GDSM) of different disposal
environments and waste form options. Currently, the GDSM team is investigating four main disposal environment options: mined repositories in three geologic media (salt, clay, and granite) and the deep borehole concept in crystalline rock (DOE 2010d). Further developed the individual generic disposal system (GDS) models for salt, granite, clay, and deep borehole disposal environments.
Licensees of commercial nuclear power plants in the United States are expected to submit license renewal applications for the period of operation of 60 to 80 years which has also been referred to as long term operation (LTO). The greatest challenges to LTO are associated with degradation of passive components as active components are routinely maintained and repaired or placed through maintenance programs.
The Department of Energy’s Office of Nuclear Energy (DOE-NE) invests in research and development (R&D) to ensure that the United States will maintain its domestic nuclear energy capability and scientific and technical leadership in the international community of nuclear power nations in the years ahead. The 2010 Nuclear Energy Research and Development Roadmap presents a high-level vision and framework for R&D activities that are needed to keep the nuclear energy option viable in the near term and to expand its use in the decades ahead.
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.
The Risk-Informed Safety Margin Characterization (RISMC) pathway is a set of activities defined under the U.S. Department of Energy Light Water Reactor Sustainability Program. The overarching objective of RISMC is to support plant life-extension decision-making by providing a state-of-knowledge characterization of safety margins in key systems, structures, and components (SSCs).
The report describes selected aspects of progress for four major tasks: (1) development of a detailed R&D plan for natural system evaluation and tool development; (2) in-depth analsis of key attributes and new concepts identified in the R&D plan; (3) preliminary demonstration of new modeling and experimental tools; and (4) conceptual design of a databse for natural system evaluation.
The Department of Energy (DOE) sponsored a workshop on nuclear separations technologies in Bethesda, Maryland, on July 27 and 28, 2011, to (1) identify common needs and potential requirements in separations technologies and opportunities for program partnerships, and (2) evaluate the need for a DOE nuclear separations center of knowledge to improve cross- program collaboration in separations technology. The workshop supported Goal 3 of the DOE Strategic Plan1 to enhance nuclear security through defense, nonproliferation, and environmental management.
The reactor pressure vessel (RPV) in a light-water reactor (LWR) represents the first line of defense against a release of radiation in case of an accident. Thus, regulations that govern the operation of commercial nuclear power plants require conservative margins of fracture toughness, both during normal operation and under accident scenarios. In the unirradiated condition, the RPV has sufficient fracture toughness such that failure is implausible under any postulated condition, including pressurized thermal shock (PTS) in pressurized water reactors (PWR).
The Next Generation Nuclear Plant (NGNP) project was established under the Energy Policy Act in August 2005 (EPACT-2005). EPACT-2005 defined an overall plan and timetable for NGNP research, design, licensing, construction and operation by the end of FY 2021. At the time that EPACT-2005 was passed, it was envisioned that key aspects of the project included:
This study has been prepared by the Used Fuel Disposition (UFD) campaign of the Fuel Cycle Research and Development (FCR&D) program. The purpose of this study is to provide an estimate of the volume of low level waste resulting from a variety of commercial fuel cycle alternatives in order to support subsequent system-level evaluations of disposal system performance.
The engineered barrier system (EBS) plays a key role in the long-term isolation of nuclear waste in geological repository environments. This report focuses on the progress made in the evaluation of EBS design concepts, assessment of clay phase stability at repository-relevant conditions, thermodynamic database development for cement and clay phases, and THMC coupled phenomena along with the development of tools and methods to examine these processes; it also documents the advancements of the Disposal System Evaluation Framework (DSEF) for the development of repository design concepts and potential variants according to waste form and disposal environment characteristics.
The U.S. Department of Energy Office of Nuclear Energy (DOE-NE), Office of Fuel Cycle Technology (OFCT) has established the Used Fuel Disposition Campaign (UFDC) to conduct the research and development (R&D) activities related to storage, transportation and disposal of used nuclear fuel (UNF) and high level nuclear waste (HLW). The Mission of the UFDC is
The Used Fuel Disposition campaign (UFD) is selecting a set of geologic media for further study including variations on the design of the repository, the engineered barrier, and the waste. Salt, clay/shale, and granitic rocks are examined; granitic rocks are also the primary basement rock to consider for deep borehole disposal. UFD is developing generic system analysis capability and general experimental data related to mined geologic disposal in the three media (salt, clay/shale, and granitic rocks), and the use of deep boreholes in granitic rocks.