The Light Water Reactor Sustainability (LWRS) Program is developing the scientific basis to extend existing nuclear power plant operating life beyond the current 60-year licensing period and ensure long-term reliability, productivity, safety, and security. The program is conducted in collaboration with national laboratories, universities, industry, and international partners. Idaho National Laboratory serves as the Technical Integration Office and coordinates the Research and Development (R&D) projects in the following pathways: Materials Aging and Degradation Assessment, Advanced Light Water Reactor Fuel, Instrumentation and Controls, Safety Margin Characterization, and Efficiency Improvements. Because industry has a significant financial incentive to extend the life of existing plants, the Department will work to ensure that activities are cost-shared to the maximum extent possible.
Nuclear power has reliably and economically contributed approximately 20 percent of electrical generation in the United States over the past two decades. It remains the single largest contributor (more than 70 percent) of non-greenhouse-gas- emitting electric power generation in the United States. Domestic demand for electrical energy is expected to grow at an average rate of 1 percent per year.
As electricity demand increases, most currently operating nuclear power plants will begin reaching the end of their 60-year operating licenses (the 40-year initial license with one 20-year license renewal). If currently operating nuclear power plants do not operate beyond 60 years, the total fraction of generated electrical energy from nuclear power will begin to decline—even with the expected addition of new nuclear generating capacity. The oldest commercial plants in the United States reached their 40th anniversary and began operations under their first 20-year license renewal period in 2009.
Continued safe and economical operation of current reactors beyond the current license renewal lifetime of 60 years is a low-risk option to fill the gap and to add new power generation at a fraction of the cost of building new plants. The cost to replace the current fleet would require hundreds of billions of dollars. Replacement of this 100 GWe generating capacity with traditional fossil plants would lead to significant increases in greenhouse gas emissions. Extending operating licenses beyond 60 to perhaps 80 years would enable existing plants to continue providing safe, clean, and economic electricity.
To provide the technical basis for this life extension, the following five R&D pathways have been identified:
Materials Aging and Degradation Assessment R&D will enhance science-based fundamental understanding of materials and degradation to reduce the uncertainty in analytical predictions and provide insights for developing components with longer lifetimes. Enhanced understanding of key materials aging and degradation phenomena will support longer- term operation of existing reactors, licensing for extended operations, and component life predictions for critical structures and systems.
Advanced Light Water Reactor Fuel R&D will develop new long-life fuel designs using advanced materials for fuel and cladding. Long-life designs will achieve substantial increases in safety margins and performance, eliminate fuel failures, and achieve higher burn-ups. Goals include improving the fundamental understanding of nuclear fuel and cladding behavior under extended burn-up conditions and developing a predictive analysis tool for advanced nuclear fuel performance.
Instrumentation and Controls R&D will develop new systems and human/ machine interface capabilities, including advanced plant monitoring capacity, centralized monitoring of nuclear status and performance, and advanced condition monitoring and prognostics technologies to understand and measure the aging of systems, structures, and components of nuclear power plants.
Safety Margin Characterization R&D will improve modeling and analysis methods including uncertainty quantification to enhance industry’s ability to accurately predict safety margins; address aging effects to understand how safety margins change with aging plants; support power up-rates; and combine risk-informed, performance-based methodologies with fundamental scientific understanding of critical phenomenological conditions and deterministic predictions of nuclear plant performance.
With the 60-year licenses beginning to expire between the years 2029 and 2039, utilities are likely to initiate planning baseload replacement power by 2014 or earlier. The LWRS Program represents the timely collaborative research needed to retain the existing nuclear power plant infrastructure in the United States.