This report, part of a series of publications on nuclear licensing reform at the Center on Global Energy Policy at Columbia University SIPA, focuses on how the NRC can fulfill the new legal mandates on time and page limits for environmental reviews and in general improve the efficiency of these reviews. The report demonstrates that earlier (1970s–80s) environmental reviews for nuclear power reactors licensed under the 10 CFR 50 licensing pathway took less time and generated shorter review documents than those conducted under 10 CFR 52 during the 2000s and 2010s. The latter reviews—all of which were for large light water reactor projects—also utilized substantial NRC resources, thereby incurring significant costs to the applicants. None of these reviews found that the reactor projects were expected to create what the NRC calls “large adverse” environmental impacts, which could destabilize environmental resources. Although some “moderate adverse” impacts were identified, they typically came from unavoidable elements such as new transmission lines and traffic that would result from any large construction project. And beneficial impacts always came in the form of jobs and taxes. At the very least, these findings raise questions about the allocation of time and resources to various aspects of the NRC’s environmental review.