If you’ve felt jumpy since Fukushima, you’re not alone. Even the tiniest burp from a nuclear power plant gets people fearing the worst, so it was scary news indeed when the San Onofre plant in San Diego County announced at 6:30 PM (PST) on Tuesday night that one of it’s reactors might have begun leaking radioactive steam. The alarm was sounded at the plant at 3:30 PM, engineers began an emergency power down at 4:30, and the reactor was completely shut down and offline by 5:30.
The three-hour time lag between possible leak and public announcement did not inspire a whole lot of confidence, nor did the fact that the plant is located right next to heavily populated San Clemente as well as Camp Pendleton Marine Corps Base (indeed, it leases its land from the Marines). But Scott Andresen, spokesman for Southern California Edison, which owns and operates the plant, insists all is under control — even if it’s still too early to say all is well.
“We started shutting down the plant out of an abundance of caution,” he told TIME. “We’re investigating, doing the whole root cause analysis, and trying to determine how much steam was released — if any — and how much radiation it could have contained.” Encouragingly, whatever steam did escape remained within the containment dome. Not so encouragingly, the plant is well beyond middle age as nuclear reactors go, and it does not have a spotless safety record.
The San Onofre generating station consists of three reactors, one of which was built in the 1960s and was decommissioned in the 1980s, after its 20-yr. operating license expired. The other two came online in the early 1980s and have a 40-yr. license, putting them on schedule to close on 2021. One of those units, Unit 2, was shut down for a planned upgrade in January. It was in Unit 3 that the maybe-leak occurred on Tuesday.
As recently as November, San Onofre had another sketchy moment when an ammonia leak in the coolant portion of the plant led to a Level 2 (out of 4 levels) alert. The plant was shut down, the ammonia was cleaned up and operations resumed, but not before 25 gal. of the caustic chemical escaped.
The current incident is not the kind of thing that should cause too much public worry — but it is precisely the kind that usually does. It surely didn’t help matters that on the same day, the Nuclear Regulatory Commission, the Department of Energy and a nonprofit research group issued an updated map of all earthquake zones in the U.S. east of Denver. The purpose of the study was to help nuclear plant operators better assess their vulnerability to quakes. While it’s nice to know the government is on the case, it was one more reminder of the potential perils of nuclear power — and of the need, once and for all, for clean, safe renewable power sources to replace the dirty and dangerous ones of the past.