Southern California Edison (SCE) has made it official: the utility informed the Nuclear Regulatory Commission (NRC) that it has closed down the San Onofre Nuclear Generating Station -- forever.
In a notice sent to NRC on June 12, the Southern California utility told the NRC that it "certifies that it has permanently ceased power operation of the San Onofre Nuclear Generating Station, Units 2 and 3 effective June 7 2013." The notice, termed a Certification of Permanent Cessation of Power Operations, makes the closing official.
SCE owns 78.2 percent of San Onofre, and operated it for its partners San Diego Gas and Electric and the city of Riverside. The power plant has been shut down since January 2012, when a small leak in steam generator tubes in Unit 3 released radioactive steam. The leak was traced to tube wear in new steam generators built for San Onofre by Mitsubishi Heavy Industries and installed in 2009 and 2010.
"Safety will remain our top priority as we transition to the decommissioning process," said Pete Dietrich, SCE senior vice president and chief nuclear officer, in a release announcing the certification. "We take very seriously our obligation to protect the health and safety of the public and our employees as we take the regulatory and planning steps to decommission San Onofre."
Decommissioning the plant to the point where it can be torn down may well take decades, and some observers are speculating the containment domes could still be there 50 years from now. In the short term, simply mothballing the plant will allow some of the shorter-lived radioactive substances in the plant's two units to decay to the point where they pose less threat to decommissioning workers. Tritium, for instance, is known to exist inside the plant. A radioactive isotope of hydrogen, tritium has a half-life of 12.32 years: it takes that long for half a sample of tritium to decay into non-radioactive form. After 50 years, 94 percent of the tritium on the site will have decayed.
About 3 million pounds of spent fuel is currently on the site, according to the Los Angeles Times, and it will stay there for the foreseeable future as the United States doesn't have a high-level waste repository that can handle it.
In other words, despite being closed down, the San Onofre nuclear power plant will remain a fixture on the Southern California coast for many years to come.