House Oversight Chairman Darrell Issa (R-Calif.) is asking the top U.S. nuclear regulator to provide data supporting his recommended evacuation of Americans living within 50 miles of a severely damaged nuclear plant in Japan.

Issa asked Nuclear Regulatory Commission Chairman Gregory Jaczko last Thursday why he failed to provide data to support his March 16 recommendation to the U.S. ambassador to Japan.

Jaczko recommended that all Americans within 50 miles of the Fukushima Daiichi nuclear plant be evacuated after the complex was hit by a powerful earthquake and tsunami on March 11. His recommendation raised questions because the NRC only evacuates Americans within 10 miles of damaged U.S. nuclear plants, and Japanese officials were evacuating individuals within 12 miles of the Fukushima plant.

Following Jaczko's decision, the NRC released initial calculations for the 50-mile evacuation that were "incomplete and misleading," Issa said.

When NRC staff were pressed last month by members of the agency's Advisory Committee on Reactor Safeguards for more information, NRC workers acknowledged they were forced to rely on limited and uncertain data, and said they would provide the advisory committee with all of the information they had at the time (E&ENews PM, April 7).

The advisory committee -- which includes part-time government employees with expertise in nuclear engineering, risk assessment and engineering -- has not yet received that information, Issa said.

Issa also questioned Jaczko's use of emergency authority under a 1980s law that allowed him to make the recommendation without input from other commissioners. Jaczko also banned other commissioners from accessing the emergency operations center established at the NRC, where workers responded to the Japanese nuclear crisis, Issa said.

Issa sent a separate letter to Said Abdel-Khalik, chairman of the advisory panel, to learn why the committee hasn't received the requested information from the NRC. Issa has asked Jaczko and Abdel-Khalik to reply by June 9.