The U.S. Nuclear Regulatory Commission denied a petition by the Nuclear Energy Institute to extend by nine months a deadline for new security requirements.
Owners of nuclear reactors must meet the tighter security rules by March 31 as planned, or seek a waiver, the commission said in a statement. The Nuclear Energy Institute is an industry lobbying group in Washington that represents about 350 members.
 
The new rules include installing physical barriers and detection systems, as well as requirements for testing and training, the statement said.