Nuclear meltdowns at the Fukushima Daiichi facility in Japan are leading U.S. regulators to consider changing reactor requirements--but any alteration in design and safety measures for the nation\u2019s nuclear reactors is not going to happen soon, according to Nuclear Regulatory Commission members. They testified on lessons being learned from the Japanese meltdowns to the Senate Environment & Public Works Committee June 16. The panel of NRC commissioners noted the agency may reconsider basic design theory, blackouts, emergency cooling, and multiple units affected at a single site. We could \u201cgo back and look at \u2018design basis\u2019 events and \u2018beyond design basis\u2019 events,\u201d said commissioner George Apostolakis. \u201cOf course, Mother Nature doesn\u2019t distinguish between the two.\u201d That is, the commission only requires nuclear plants to be hardened to potential emergencies to a certain extent (design basis). More severe theories of what may go awry could require the plants to be further hardened, or require more safety measures. Blackouts and emergency cooling are twin problems for nuclear reactors. They need outside power in order to create power because they cannot operate on their internally generated energy. If the transmission lines fail and the back-up diesel generators fail, as they did in Fukushima Daiichi, there is no way to pump water to the reactor for cooling fuel. Without cooling the fuel, meltdowns and explosions can occur. \u201cI expect we\u2019ll have to make some changes\u201d to current loss-of-power rules, said NRC chair Greg Jaczko. Currently, the NRC only considers a catastrophe at a single unit. In California, for instance, there were three units at San Onofre Nuclear Generating Station (with two remaining in operation). At Diablo Canyon, there are two units. Both California reactors are rated in the highest zone nationwide for potential seismic damage by federal regulators. Committee chair Senator Barbara Boxer (D-CA) questioned the NRC process for relicensing Diablo Canyon. Jazcko noted Diablo\u2019s owner, Pacific Gas & Electric, \u201cdid not ask us to delay review\u201d of the utility\u2019s plan to keep the plant operating an extra 20 years. Instead, the commission \u201cis waiting\u201d for seismic studies to come in before completing the process. Boxer urged the commission chair not to \u201crush\u201d relicensing--especially on the earthquake-prone and populated California coast. \u201cIn our state, we gotta a lot of sun, a lotta wind, a lotta geothermal [to replace nuclear power]. Please put on your safety hats.\u201d Some people in California don\u2019t understand \u201ctheir well-being depends on your [commission] being vigorous in assuring safety,\u201d said Boxer.