Allowing nuclear generators to operate some of the existing 100 U.S. nuclear reactors longer than their 60-year licensed limit could help offset a potentially massive power supply gap that could ensue as those nuclear plants begin shutting down by the year 2030, the American Physical Society (APS) suggests in a report released last December.

The report notes that there are no statutory prohibitions against renewing nuclear plant licenses beyond 60 years (the Nuclear Regulatory Commission is considering if new rules may be required for license renewal beyond that term) and that 20-year renewal periods are currently authorized under existing regulations. But if no licenses are renewed beyond 60 years and no new reactors are built to compensate, about 100 GW—20% of the nation’s power supply—could begin shutting down by the year 2030 and would need to be replaced by other generating sources.

As of June 2013, 73 of 100 operating units had been granted renewal to 60 years, though one was subsequently closed. At least 15 units are under review, nine units are intending to renew, and seven will shut down, not intending to renew (Figure 5).

5. An atomic age. By the end of 2013, at least 42 of the nation’s 100 commercial operating reactors were between 30 and 39 years of age, 37 were between 20 and 29 years of age, and 20 reactors were more than 40 years old. This figure shows the timeframe in which current reactor licenses are set to expire. Courtesy: NRC

“The decision to extend nuclear plant life is both complex and urgent,” says the nation’s leading physicist organization, whose 50,000 members hail from academia, national laboratories, and industry. According to the study’s committee, which included members from the Electric Power Research Institute (EPRI) and two federal laboratories, long-term license extensions will involve interrelated technical, economic, regulatory, and policy issues. “Further, replacing these units will require long-lead planning, estimated at 10 to 15 years prior to scheduled retirement of the plant. Hence, the window of opportunity is short—utilities will begin facing a decision of whether to renew licenses starting in five years,” they say.

Several efforts are under way to examine the potential for long-term operation of the nation’s existing reactors. The Department of Energy (DOE) oversees, with cost sharing from industry, the federal Light Water Reactor Sustainability Program, and EPRI, backed by industry, runs the Long-Term Operation Program. Current results from both programs do not “indicate any technical show-stoppers that would prevent the renewal of licenses from 60 to 80 years, assuming rigorous application of maintenance, inspection, and aging management programs,” the report says.

One focus that will require particular attention, however, is component and materials aging, but both programs are “establishing a pathway of research, surveillance, and response that can manage these challenges,” the APS contends. “There are uncertainties involved in any engineering assessment, especially over long periods of time. For example, no mathematical model can identify what bolt will corrode on which day; instead, the models predict the likelihood, with a range of uncertainty, that a portion of the bolts are likely to need replacement within an estimated period of time. The more substantial the research program is, the better the overall activity will be: uncertainty will be reduced, lead time for preventive action will be increased, predictions will be more accurate, surveillance will be better informed, and the response will be more targeted.”

Yet, the organization warns that with a mere five years left before plants should begin facing renewal decisions, U.S. energy strategies must make renewal a feasible choice. This could come from policies to boost energy security and climate change mitigation—and on the basis that nuclear reactors today account for more than 60% of the nation’s near-zero-carbon energy production. Because a utility’s decision to renew a license hinges on an assessment of the costs of long-term operation of the plant against costs of constructing a new coal, natural gas, or nuclear plant, the APS recommends a “more substantial fundamental research effort” by the DOE that would “buy down risk” and reduce uncertainties.

The renewal of licenses is “not an end in itself,” the APS says, admitting it is not a long-term solution. However, “it does provide valuable time to establish a balanced and durable energy future for the nation,” which can be used to “develop a clean energy future.”

Sonal Patel, associate editor (@POWERmagazine, @sonalcpatel)