Newly disclosed documents show U.S. regulators privately doubt that some of the nation’s nuclear power plants can withstand a disaster akin to Japan’s following the earthquake and tsunami. In internal emails and memos, Nuclear Regulatory Commission members have questioned backup plans to maintain cooling systems in case main power sources fail. A July 2010 memo assessing Exelon Corporation’s Peach Bottom nuclear plant in Delta, Pennsylvania, concludes that contingency plans “have really not been reviewed to ensure that they will work to mitigate severe accidents.” The messages were released by the Union Concerned Scientists. In a statement, UCS nuclear expert Edwin Lyman said, “While [regulators] and the nuclear industry have been reassuring Americans that there is nothing to worry about … it turns out that privately NRC senior analysts are not so sure.”