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. Even when major refurbishments are performed to extend operating life, these plants continue to represent cost-effective, low-carbon assets to the nation’s electrical generation capability.
Nine commercial NPPs in the Unites States have passed their 40th anniversary of power operations, and about one-half of the existing fleet will reach the same 40-year mark within the next decade. While recent performance has been excellent (capacity factors approaching or exceeding 90%), the fleet is facing a number of technical challenges related to long-term operation. Those challenges include uncertainties in material safety margins and degradation rates under extended operating conditions, obsolescence of instrumentation and control systems, safety analysis methods that would benefit from updating, and others. A regulatory process exists (10 CFR Part 54) for obtaining approval from the U.S. Nuclear Regulatory Commission on extended NPP operations beyond 60 years. However, the U.S. Nuclear Regulatory Commission will require plants applying for license renewals to extend NPP service life to demonstrate that adequate design and operational safety margins will be maintained over the duration of the extended operations period.
If current NPPs do not operate beyond 60 years (due to owner decisions or regulatory restrictions), the total fraction of domestic electrical energy generated from nuclear power will begin to decline—even with the expected addition of new nuclear generating capacity. Replacing these units will require long-lead planning periods (10 to 15 years prior to unit retirement). In addition, significant capital investments (hundreds of billions of dollars) will be needed to design, construct, and commission the replacement generation capacity. Further, if the new capacity has to meet any carbon-neutral criteria (i.e., the replacement units must not produce more greenhouse gas emissions than the units being retired), the costs for replacement generation capacity will be even higher.
Recognizing the challenges associated with pursuing commercial NPP operations beyond 60 years, the U.S. Department of Energy’s (DOE) Office of Nuclear Energy (NE) and the Electric Power Research Institute (EPRI) have established separate but complementary research and development programs (DOE-NE’s Light Water Reactor Sustainability [LWRS] Program and EPRI’s Long-Term Operations [LTO]Program) to address these challenges. To ensure that a proper linkage is maintained between the programs, DOE-NE and EPRI executed a Memorandum of Understanding in late 2010 to “establish guiding principles under which research activities (between LWRS and LTO) could be coordinated to the benefit of both parties.” The Memorandum of Understanding calls for DOE-NE and EPRI to “provide and annually update a coordinated plan for the LWRS and LTO programs. The plan should provide for the integration of the separate LWRS and LTO Program Plans at the project level, showing projectscope, schedule, budgets, and key interrelationships between the LWRS and LTO programs, including possible cost sharing.” This document represents the first annual revision to the initial version (March 2011) of the plan as called for in the Memorandum of Understanding.