Friday, July 13, 2012

San Onofre's steam generators are not SanO's biggest problem... spent fuel is.


Dear Readers,

If you look at the inspection results of nearly 10,000 U-shaped tubes inside one of San Onofre's four steam generators (two steam generators per reactor) you can clearly see where their current problem is.

There's a large circle representing a cutaway slice of the steam generator, and within that large circle is a smaller circle, about a quarter the diameter of the larger circle and offset to one side. Within the smaller circle is a dot.

That's the area where there was a rupture of one of the tubes last January (2012). The innermost dot represents where a single tube failed while the reactor was running, and where seven more tubes failed subsequent pressure testing.

The inner circle that surrounds the dot shows that the wear is less and less severe as you get further and further away from where the tube ruptured.

Off to one side is a smaller area of concentrated wear, and a few other locations also show some isolated damage.

This is very bad for San Onofre. But perhaps very good for humanity.

Prior to failure, the tubes evidently vibrated for some time (minutes? hours? months?): Since the plant was shut down in January, hundreds of tubes in that one steam generator have been plugged due to damage. Within those tubes there were thousands of locations with damage, such as where the tubes pass through restraining plates that were supposed to limit their vibration to tolerable amounts.

Southern California Edison has determined that the "root cause" of the steam generator failure in January was probably "fluid elastic instability", a synchronized, uncontrolled vibration that sometimes occurs when a fluid rapidly traverses large bunches of parallel tubes. The tubes wore down until one ruptured, radiation was released, and the reactor was shut down.

Hundreds of tubes in the other three (virtually identical) steam generators also have significant wear, indicating the problem is not unique to that one steam generator.

A report by Fairewinds Associates, commissioned by Friends of the Earth (and linked to below) shows that the amount of wear is unprecedented in the nuclear power industry.  Here is a relevant quote from the Fairewinds' report, quoting Edison's own Condition Report:

"'The location of the tube-to-tube wear in the Unit 2 SG was in the same region of the tube bundle as in the Unit 3 SGs. This indicates the existence of causal factors similar to those resulting in tube-to-tube wear in the Unit 3 SGs.' This quote from Edison's Condition Report is just one example indicating that the failure modes between Unit 2 and Unit 3 are identical."

But here's the thing: Southern California Edison wants to claim they can operate reactor Unit 2 at reduced power and thus avoid the problem entirely. But even if they run at 50% power, there's always the possibility they will end up pushing a steam generator beyond its capacity: For example, if one steam generator fails, they would have to immediately start removing 100% of the heat from the reactor with the only remaining steam generator (this is a "fatal flaw" of having only two steam generators, where most pressurized water reactors have three or four). Because there are only two steam generators to remove the heat, 50% power (the minimum power output SCE said they would try) seems to this author to be well above whatever maximum would ensure adequate heat removal with the other steam generator in the event of the total loss of one steam generator.

But far more frightening even than having to rely on one faulty steam generator is the possibility of a nuclear reactor runaway power surge. Such an event could cause the reactor operators to have little choice but to try to run the steam generators at full capacity (and even that might not be adequate). Such power surges were described in detail (and carefully modeled on a computer) by the late Dr. A. Stanley Thompson a decade ago.

But even that isn't San Onofre's biggest problem. In a letter to this and other activists (shown below), Dr. Thompson explained what San Onofre's biggest problem really is: The spent fuel.

If they restart the reactors, they'll begin again to produce 500 pounds per day (250 pounds per reactor) of the deadliest, most difficult-to-contain hazardous waste on the planet: Spent fuel. Spent fuel is approximately 10,000,000 times more lethal than "fresh" unused nuclear reactor fuel and contains plutonium, cesium, strontium and other radioactive poisons. Mere millionths of a gram are lethal, and they'll be making 250 pounds per day per reactor.

The taxpayers, ratepayers, local citizens, and future generations will all have to shoulder this burden forever.

So there's no reason to restart San Onofre. Don't do it.


Ace Hoffman
Carlsbad, CA

(1) Letter from Friends of the Earth (2012)
(2) Letter from A. Stanley Thompson, (2003)
(3) Southern California Edison press release (added just after this newsletter was first circulated and posted)
(4) Contact information for the author of this newsletter

(1) Letter from Friends of the Earth (June 12th, 2012)

Dear All,

Friends of the Earth was leaked an internal Edison document regarding the tube wear in the San Onofre steam generators. It revealed that the steam generators are by far the worst in the nation. Attached you'll find our press release, the Edison document, and the recent Fairewinds report. We also just received word that the NRC just released the most comprehensive data yet on the San Onofre steam generators.

Friends of the Earth
Washington, DC

FOE press release:

Fairewinds report:

Edison document:

(2) 2003 letter from the late Dr. A Stanley Thompson (with some of his cv):

Dear [Ace] Hoffman and others:

I've been wondering about our future as anti-nuclear activists.
I want to thank you, my anti-nuclear friends, and wish us every success.

After the bombs were dropped on Japan in 1945 I accepted an invitation
into what I thought was to be my lifetime engineering occupation: to help
develop for peacetime use this limitless and safe source of energy "too
cheap to meter." I studied reactors and how to design the best possible
nuclear power plant. Based on a design course I taught to engineers at Oak
Ridge National Laboratory, I wrote the book, "Thermal Power from Nuclear
Reactors" (John Wiley, 1956).

In my study I discovered many reasons why no one should build nuclear
devices of any kind. I became unpopular with Congressional committees.
Professors in nuclear departments would not let me talk with their
students. No one would publish what I wrote. Members of the public
questioned why I was trying to spoil the gift of nuclear energy to human
society? I felt alone in my effort.

As many of you have stated, nuclear reactors have demonstrated that they
are neither cheap nor safe. They are of necessity designed, built and
operated by fallible human beings, some of whom may be vindictive. The
failure of Chernobyl demonstrated failure and some of its results,
including the death of thousands of Ukrainians, of birds in the Pt. Reyes
sanctuary in California, and the discard of polluted milk in Italy and of
reindeer meat in Lapland. The most intolerable reactor of all may be one
which comes successfully to the end of its planned life having produced
mountains of radioactive waste for which there is no disposal safe from
earthquake damage or sabotage.

Who still wants to build nuclear reactors? The military establishment in
any country can use a nuclear reactor to produce Pu-239 for nuclear bombs,
a symbol of status. With a nuclear reactor NASA can produce even more
dangerously radioactive Pu-238 for super batteries in its space projects.
With a nuclear reactor available, a university professor can head a
prestigious Department of Nuclear Engineering. With the promised
construction of nuclear reactors, his students can look forward to
prestigious employment. There is now an immense effort by vested military
and civilian groups to continue various expensive and expansive nuclear

I have self-published a pamphlet, "Comments on Nuclear Power" (100 pages).
I no longer feel alone in the fight against nuclear proliferation, thanks
to all of you. Each of us approaches the battle against military and
civilian nuclear reactors from a different life experience. Let us not be
torn asunder by our differences in viewpoint. Let us not weaken each
other's credibility with bickering and slander. Our differences of
viewpoint should be a source of strength. I hope we can use that strength
to advantage against our entrenched "paid" opposition.

A, Stanley Thompson, Eugene, Oregon, USA 13 May, 2003


The author of this newsletter (see below) has a copy of Dr. Thompson's pamphlet, which discusses runaway nuclear reactor power surges, and hopes the Nuclear Regulatory Commission considers Dr. Thompson's remarks carefully before relicensing San Onofre or any other reactor, anywhere. They are all deathtraps.

Southern California Edison press release (seen just after this newsletter was first posted and circulated):


July 13, 2012

Media contact:
Media Relations, (626) 302-2255
Investor relations contact: Scott Cunningham, (626) 302-2540

ROSEMEAD, Calif., July 13, 2012  Southern California Edison (SCE) has released steam generator tube wear data associated with the San Onofre Nuclear Generating Station (SONGS) to the Nuclear Regulatory Commission. The data show that most of the wear, or tube wall thinning, was less than 20 percent. This is far below the 35 percent wall-thinning limit, which would require that the tube be plugged. The majority of this wear is related to support structures. The nature of the support structure wear is not unusual in new steam generators and is part of the equipment settling in.

"We're using this information and additional detailed data collected through testing to develop our repair plans according to best practices and industry standards, particularly the data on the unexpected tube-to-tube wear," said Senior Vice President and Chief Nuclear Officer Pete Dietrich. "Safety continues to be the guiding principle behind all the work we are doing."

The data include the various types of wear on the tubes and the number of tubes affected.

There were three major categories of wear: anti-vibration bar wear, tube support plate wear and tube-to-tube wear. Two minor categories of wear were also included: retainer bar wear and wear due to a foreign object. The foreign object wear, also not unusual in new steam generators, was only found in Unit 2 and was caused by a piece of welding material about the size of a quarter rubbing against two tubes.

  • In Unit 2, 1,595 tubes showed wear of some type and 510 tubes were ultimately plugged; six tubes for showing wear of more than 35 percent and the rest for preventative measures.
  • In Unit 3, 1,806 tubes showed wear of some type and 807 tubes were ultimately plugged; 381 tubes for wear of more than 35 percent and the rest for preventative measures.

The complete data for both units is available on the commission website for SONGS information:

Both units of the plant are currently safely shut down for inspections, analysis and tests. Unit 2 was taken out of service Jan. 9 for a planned outage. Unit 3 was safely taken offline Jan. 31 after station operators detected a leak in a steam generator tube. The units will remain shut down until SCE and the commission are satisfied that the units are safe to operate.

About Southern California Edison
An Edison International (NYSE:EIX) company, Southern California Edison is one of the nation's largest electric utilities, serving a population of nearly 14 million via 4.9 million customer accounts in a 50,000-square-mile service area within Central, Coastal and Southern California.

(4) Contact information for the author of this newsletter:


Ace Hoffman
Author, The Code Killers:
An Expose of the Nuclear Industry
Free download:
Carlsbad, CA
Email: ace [at]


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