San Onofre nuclear plant can withstand up to 7.0 quake, is protected by a 25-foot tsunami wall, Edison says

Operators of the concrete-domed San Onofre nuclear plant Monday were trying to reassure jittery Southern California residents that the nuclear disaster unfolding in Japan won't happen here.

The 84-acre generating station in the northern corner of San Diego County is built to withstand a magnitude 7.0 earthquake, said Gil Alexander, a spokesman for the generation station's operator, Southern California Edison. That is greater than the 6.5 shaker that scientists predicted could strike the plant before it was built 42 years ago, he said. But it's less than the 8.9 quake that hit Japan last week.

A 25-foot-high "tsunami wall" of reinforced concete was also erected between the plant and the adjacent ocean, a height based on scientists' best estimates of the potential threat, he said. The geological fault most likely to directly threaten San Onofre lies about 5 miles offshore, Alexander said.

The Nuclear Regulatory Commission also sought to allay fears that small releases of radiation from Japan's crippled Fukishima reactors were a threat to the U.S.

Available information indicates that weather conditions have carried any radioactive vapors out to sea and away from the Japanese population. Given the thousands of miles between the two countries, Hawaii, Alaska, the U.S. territories and the U.S. West Coast are not expected to experience any harmful levels of radioactivity, the commission said Monday.

San Onofre's three domed units were built in layered shells, like Russian nesting dolls. The outer shell is made of reinforced concrete that is four-feet thick, and is designed to capture any unexpected release of radiation. The inner steel casing housing the reactor is 8 inches thick.

Inside the reactor, fuel rods and control rods that make up the nuclear core are surrounded by pressurized water. In Japan, units of at least two nuclear plants were damaged and lost electrial power after the massive earthquake and tsunami, making it difficult to continue cooling the cores.

Two explosions have occurred in separate units but authorities so far have been able to contain radiation within the steel containment vessels surrounding the fuel rods. Alexander said San Onofre has multiple safety systems should the Southern California plant find itself in a similar situation.

In addition to diesel generators, the plant has a battery system and a gravity-driven emergency cooling system, Alexander said. The utility's operators were watching the Japan situation closely and will take any lessons learned from it to heart, he said.

"We will comb through the details of their emergency very carefully and whatever lessons can and should be applied here will be noted,'' he said. "That process will unfold very vigorously."

The Union of Concerned Scientists, a group that has been critical of nuclear energy, said it was also watching the Japanese crisis unfolding. It was planning a news conference Monday to release its findings.

San Onofre had three operating domes when built but Unit 1 was retired in 1992. Spent fuel road are stored there.

Annual energy output at the plant is the equivalent of that produced by 20 million to 25 million barrels of oil, Southern California Edison officials say. The plant generates 2,200 megawatts of electricity, about 20% of Southern California's usage, or enough to power 1.4 million homes.

 
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Photo: San Onofre nuclear power plant. Credit: Los Angeles Times file. Illustration: How the plant works. Source: Southern California Edison

Comments

[Jenifer Massey]

The tsunami that hit Japan reached the height of 4 story buildings. I think that is higher than the 25' high wall at San Onofre. SanO is designed to withstand a 7.0 earthquake. Japan's was more than anyone expected and has now been raised to a 9.0 from 8.9. I don't believe San Onofre is a safe plant. Time to take it down.

[JD]

Close San Onofre Now!

[Blueeyedgal]

The Japanese nuclear plants now undergoing meltdown were similarly protected with tsunami walls that the best Japanese engineers were convinced was high enough to protect them from even larger tsunamis, but in the actual event, power went out, and all backup generators were flooded.

And I respect their skill in building. I don't believe our building standards are better than theirs.

[Colin]

How will the 25 foot wall help against a 35 foot wave?

[Atom Kraftistschlecht]

7.0 is nothing. Let's replace San Onofre with wind turbines & solar energy, because if those break down when we get a big earthquake, at least there's no risk of being nuked and have our environment irradiated for thousands and thousands years to come.

[Brad]

All Western designed and built nuclear power plants including San Onofre, Fukashima and Three Mile Island are built within the self-contained bubble as described in the article. As typical of the Soviet Union, Chernobyl was designed and built without a self-contained bubble, hence, the disastrous results.

[Robert]

It's insane to have this plant keep running after witnessing the disaster in Japan. If a 8.0 earthquake rattles Southern California, the so-called BIG ONE, we'll have a nuclear catastrophe the likes of which we have never seen.

[Brad]

As evident of the recent videos and photographs, Fukashima was the safest place to be during the quake and resulting tsunami. Fukahima is still standing while every car, train, boat, ship, plane and building are appear destroyed. I did not see a nuclear power plant floating in that wreckage.

[uncle_sax]

How about the Diablo Canyon Nuke Plant?

[Towers One]

A 7.0 quake is not what Japan planned for and the US Agency self serving industry lobby controlled nuclear agency cannot police itself. A quake major then 7 and similar to Japan would cause Orange County to be vacated, poison the air for north San Diego County and the closure of the main north south arterial freeway the 5. Do not expect the truth to be told. Prepare your exit, relocation, water/food supplies if you survive it. A 25 foot wall is a joke! We have serious faults. The earth was shifted 4 degrees and Japan moved 8 inches.

[Marcia Twane]

"The 84-acre generating station in the northern corner of San Diego County is built to withstand a magnitude 7.0 earthquake, said Gil Alexander, a spokesman for the generation station's operator, Southern California Edison."

We are due for a larger earthquake than a 7.0...

"The geological fault most likely to directly threaten San Onofre lies about 5 miles offshore, Alexander said."

New faults are still being discovered...

Typical human hubris - thinking humankind can control Mother Nature...

[BrianM]

It will withstand a 7.0 quake, and 25 foot waves? Great! So basically the 8.9 that hit Japan would have completely leveled the San Onofre plant.

We are so going to be so screwed.

[anon328]

Whenever I drive by that facility, I get a chuckle looking at those two mounds with tips.

[Annie Oakley]

Oh Yes, nothing can go wrong, we've anticipated every potential threat, just go on watching Dancing with the Stars and American idol, nothing to be concerned about here...

:(

[Bob W.]

The picture from the beach in front of the San Onofre nuclear plant shows no obvious seawall. Perhaps it only protects the domes. If so, is there a tsunami risk to backup systems? What about all the nuclear waste stored at the site?

[J. Priest]

How well does 8-inch steel and 4 feet of concrete stand up to the 4000-5000 degree temperatures of a meltdown?

Like a knife through butter.

[wisey]

The potential risks with nuclear power are far too great. I notice nuke supporters suddenly become quiet when a huge disaster happens.

The fact that the best option for the waste is to "store" it in a retired dome should tell you something. We have no idea what to do with this waste at all.

[Collin]

"Sure, it happened over there...BUT it will never happen here."

Reassuring.

[Brendan]

As the videos from Japan show, no "wall", 25 foot high, 50 foot, or more, will hold back miles of ocean rushing to shore. Nothing can hold it back. This plant is right in its path. It has ALWAYS been a sore point because of its vulnerability. Edison, your justifications are laughable.

[KenF]

What about an 8.0 shaker and/or a 40 foot tsunami ? I guess we're doomed if this happens, because they didn't plan for a disaster that large...

[Zenzoë]

The tsunami in Japan reached nearly forty feet, way above that which the San Onofre power plant could withstand. The Japan quake was also of a 9.0 magnitude, way above that which the San Onofre plant could withstand. There is also the Cascadia fault up north under the ocean that could produce a tsunami all the way down to Southern California.

C'mon guys, it's time to get out of denial about nuclear power. It is pure folly to think we can control Mother Nature. Think of the new science—chaos theory, how the more complex a system is, the less predictable it is. Shut down all the nuclear plants and do as Germany is doing now, where the solar power industry is flourishing.

[h2o dude]

How will a 25-foot wall protect the San Onofre nuclear plant from a Tsunami with waves up to 33-METERs high ?

======== . . . from the article . . . ========

"A 25-foot-high "tsunami wall" of reinforced concete was also erected between the plant and the adjacent ocean, a height based on scientists' best estimates of the potential threat, he said. The geological fault most likely to directly threaten San Onofre lies about 5 miles offshore, Alexander said."

........ . . . end of article excerpt . . . ........

Duh ! Just who are these "scientists" ?

Can we string-'em-up after their "best estimates" are proven to have been way TOO low?

I'm no scientist, but I would base my Wall-size estimate *NOT* on the height of the waves that might be triggered by

the "geological fault most likely to directly threaten San Onofre lies about 5 miles offshore,"

BUT on the size of the waves that could hit Southern California from a Great Quake anywhere in the world -- especially in the "Ring of Fire."

[David H.]

It may or may not be a good idea to have nuclear power in earthquake zone, but it's certainly not a good idea to store spent fuel in an earthquake zone. It's an unnecessary risk.

[Lazy Jane]

This is no where near safe enough!!! A 7.o earthquake is nothing compared to what we can expect. A 25 foot wall? WE ARE IN TROUBLE.

[Citizen 1000]

To quote Frank Zappa:

It can't happen here,
It can't happen here,
It can happen over there,
but it can't happen here....

(Keep chanting that over and over and it will help you actually start believing it!)