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A special team of federal inspectors is investigating problems that led to the shutdown of Edison International's (EIX) California nuclear power plant, the Nuclear Regulatory Commission said Thursday.
One of two reactors at the San Onofre Nuclear Power plant in San Clemente, Calif., was unexpectly shut down Jan. 31 after critical equipment malfunctioned.
A type of pipe called a steam tube sprung a leak and released small amounts of radioactive steam. At the time, the NRC said the amount of radiation that was released posed no harm to workers or the public.
Nevertheless, reactor steam tubes must be strong enough to withstand high pressure without rupturing to ensure radiation doesn't escape the generators that use the steam to produce electricity, according to the NRC.
The plant's other nuclear reactor had been shut down for a scheduled procedure in which the fuel is replaced and equipment is inspected. Both units, which are owned by Edison's southern California utility and Sempra Energy's (SRE) San Diego utility, remained offline.
The NRC said it was compelled to send the special inspection team to the plant after the three tubes that leaked failed an important pressure test on Wednesday, which suggested the tubes would probably rupture again.
"We want to make sure we understand the cause of the degraded steam generator tubes and take appropriate actions based on our inspection results," Elmo Collins, the administrator of the NRC's Region 4 office, said in a statement.
During the test on Wednesday, water was pumped inside the tube while the pressure inside was increased.
The special team will include inspectors from Washington and from the NRC's Region 4 office in Arlington, Texas, which oversees nuclear power plants in western states.
-By Cassandra Sweet, Dow Jones Newswires; 415-439-6468; email@example.com