Feds say design flaw led to US nuke plant woes

Jun 19, 2012 by MICHAEL R. BLOOD
A March 1, 2010 file photo, shows the San Onofre nuclear power plant in north San Diego County, Calif. Federal regulators say design flaws appear to be the cause of excessive wear in tubing that carries radioactive water through the San Onofre nuclear power plant. (AP Photo/Lenny Ignelzi, File)

(AP) — Federal regulators said Monday that a botched computer analysis resulted in design flaws that are largely to blame for unprecedented wear in steam tubes at the San Onofre nuclear power plant, but it isn't clear how the problems can be fixed.

The preliminary findings by a team of Nuclear Regulatory Commission investigators were disclosed nearly five months after the seaside plant was shut down following a break in a tube that carries radioactive water. There is no date to restart either of its two reactors.

The problems center on excessive tube wear in steam generators that were installed at San Onofre during a $670 million overhaul in 2009 and 2010. Tests found some tubes were so badly corroded that they could fail and possibly release radiation, a stunning finding inside the virtually new equipment.

Long unknown was what was causing tubes to vibrate and rub against each other inside the massive machines, manufactured by Mitsubishi Heavy Industries.

Greg Werner, who headed the federal team, said a Mitsubishi computer analysis vastly misjudged how water and steam would flow in the reactors. Also, changes intended to improve manufacturing were never thoroughly reviewed in the context of the generator design, resulting in weaker support around bundles of tubes that contributed to vibration, he said.

The plant's operator, Southern California Edison, could face penalties, while problems at the plant have raised fears of a nuclear accident in Southern California and cut off one of the region's important sources of power.

"The ultimate responsibly resides with them ... because they are responsible for safety," said Regional Administrator Elmo Collins, the agency's top official in the western U.S.

When the generators were designed, the crucial tool Mitsubishi used, a computer model, failed to predict conditions inside the machines and resulted in the tube shaking, Collins said.

Edison agreed with the findings.

In an interview with The Associated Press on Sunday, Collins said missteps in fabrication or installation were considered as possible sources of the rapid tube decay but "it looks primarily we are pointed toward the design" of the generators.

In this Sunday, June 17, 2012 photo, Elmo Collins, regional administrator of the Nuclear Regulatory Commission, speaks during an interview in San Juan Capistrano, Calif. The NRC is holding a public meeting to discuss the state of the San Onofre nuclear power plant on Monday in San Juan Capistrano. After months of investigation, federal regulators have determined that design flaws appear to be the cause of excessive wear in tubing that carries radioactive water through the power plant. (AP Photo/Grant Hindsley)

Collins didn't rule out that one or more of the generators might have to be replaced. "We think it's too early to tell," he told reporters.

The findings were released during a three-hour meeting Monday in which officials also faced sometimes-testy questions from local citizens concerned about safety.

Outside the hearing, protesters from Friends of the Earth and other groups critical of the nuclear industry displayed signs that said "Not another Fukushima" and "Shut unsafe San Onofre."

The group on Monday filed a petition asking the NRC to keep the plant offline until the company amends its license to reflect design changes in the generators.

"This is a safety problem," said Friends of the Earth consultant Arnie Gundersen, a former nuclear industry executive and licensed reactor operator who has written several reports on the San Onofre generators. "These changes put the public at risk."

So far, a fix has remained elusive.

"It's not too hard to frame up the problem," Collins told AP. "The answers are very difficult, or they already would have emerged."

The disclosure will rivet new attention on a series of alterations to the equipment design, including the decision to add 400 tubes to each generator and installing V-shaped supports that were intended to minimize tube wear and vibration. According to company documents, each of the replacement generators weighed nearly 24 tons more than the original generators.

The generators were designed to meet a federal test to qualify as "in-kind," or essentially identical, replacements for the original generators, which would allow them to be installed without prior approval from federal regulators.

The agency is reviewing how that was handled.

Inside the guts of the machinery, the original steam generators and the replacements "look substantially different," Collins said.

Company officials and Collins said safety would remain the first consideration at San Onofre. About 7.4 million Californians live within 50 miles of San Onofre, which can power 1.4 million homes.

"These are significant technical issues. They are not resolved yet," Collins said.

The company said in a statement that the Unit 2 reactor likely would remain offline at least through August, pending NRC approval for a restart. It did not project a restart date for Unit 3, where tube damage has been more severe. The company is expected to submit a plan to the NRC later this summer to restart one, or both, reactors, which would have to outline how the company can control the tube damage.

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antialias_physorg
1.8 / 5 (5) Jun 19, 2012
This should give a heads-up to all those who naively bandy about the "we have newer/better technology and can build 100 percent safe reactors"-argument.

I'm as technophile as anyone, but no technical system is perfect. There is always something you didn't think of when designing it. Usually this isn't a problem, because these things happen so infrequently. But slap a million such systems together (as in the case of nuclear reactors) and your MTBF drops drastically. And that is not even counting these 'unexpected' failures.

And with nuclear reactors it isn't like with cars. One breakdown here is one too many.
ab3a
3.4 / 5 (5) Jun 19, 2012
antialias, allow me to point out that they DID catch this problem before it got serious.

You're right, these things do happen. Nuclear Reactors will never be 100% safe. Neither will coal fired power plants, gas Fracking, Solar energy (what does rain water wash off the cells?), wind energy or anything else.

Weigh the costs of a nuclear breakdown against the costs of what a coal fired power plant will put in to the air. Weigh these costs against the cost of doing NOTHING. The problem I have with any "Ban this" or "Ban that" stance is that none have viable alternatives. They always seem to point to something else that isn't workable.

Before saying "No Nukes," consider the alternatives.
ryggesogn2
2.5 / 5 (8) Jun 19, 2012
US Navy has been building and living with nuclear reactors for decades.
TkClick
1.6 / 5 (7) Jun 19, 2012
The Soviet Navy did it as well. They burrowed whole nuclear reactors in Barents sea. Did you know about it? You see: no info, no problem..
Before saying "No Nukes," consider the alternatives.
Why not to consider safe and more effective alternative first? When A.Rossi will release his E-Cat device, it will be a sensation for media. But who will realize, the very same technology was published before twenty years with Piantelli and Focardi? A.Rossi was just first who was brave enough to invest into it.
antialias_physorg
2.3 / 5 (3) Jun 19, 2012
antialias, allow me to point out that they DID catch this problem before it got serious.

It was a design flaw, nonetheless. A design flaw that made it into production. Sometimes you catch those and some times you don't - and there is no way to make 100 percent sure that you do.
With nuclear reactors we cannot afford the "sometimes you don't".

Neither will coal fired power plants, gas Fracking, Solar energy

The difference is that with all these the worst case desaster is local. Mostly even confined to the site of the plant (fracking being an obvious exception. That's why it shouldn't be allowed.
ShotmanMaslo
2 / 5 (4) Jun 19, 2012

And with nuclear reactors it isn't like with cars. One breakdown here is one too many.


Nope, even nuclear does not need to be perfect, just good enough. It is all about deaths per produced energy. Nuclear is the best by this metric, even above renewables.
antialias_physorg
3.4 / 5 (5) Jun 19, 2012
Weigh the costs of a nuclear breakdown against the costs of what a coal fired power plant will put in to the air.

This is just a totaly wrong way of going about it. You're just multiplying chance of failure by cost of failure. That works as long as failure does not mean 'game over'.

It's like saying: "I will invest in the stockmarket. There will be some ups and downs but I will make, on average 1 percent return on investment so it's all good" (or the naive "I will double my wager on 'red' every time I lose at roulette").

The flaw in this kind of thinking is: if you ever lose all your money at one point then no amount of future gains will even that out. A thousand percent future winnings on zero dollars is still zero dollars.

Coal, solar (and even fracking) mishaps can be cleaned up. Nuclear ones can't.
"Weighing the cost" is not a sensible approach here.
bhiestand
5 / 5 (1) Jun 20, 2012
I don't know why antialias's statement is controversial here. Draw a 50-mile radius around San Onofre. Calculate the economic impact of a major event.

There's a reason these plants have to be shielded from liability. No insurer would touch these risks, even at extremely low probabilities. Definitely not for a price that allows nuclear to remain "affordable".

I imagine they'll have even more rolling blackouts than normal this summer. Fun times.
The Lords Little Helper
2 / 5 (4) Jul 07, 2012
Did not the investigating commission that was appointed by the Japanese Parliament just concluded, That It was very sadly a Profoundly Man-made Disaster that Could and Should have Been Foreseen and at all cost been Prevented. This commission dose hold the Japan Government, Regulators and its Nuclear Owners and Operators Responsible for the Meltdown that occurred at Fukushima, after a Powerful Earthquake that generated a Large Tsunami that struck the countrys northeast coast in March of the year 2011.

This Plant was built by "GE" or know as "General Electric" A American Company and there are 23 of them in America just like the one they built at Fukushim Japan. At least one in the state of Illinois. Thank GOD Illinois dose not have a lot of Earthquakes. Yet ? and are the 23 power plants that are built just like the Fukushima one Safe of the 100+ Nuclear Power Plants in the United States of America??? Or are they a Disaster looking to come?

There is enough Energy coming from our S
Vendicar_Decarian
1.8 / 5 (5) Jul 07, 2012
The fact that there is any design work at all, 50 years after nuclear power was initiated, is an indictment of the failed free market system.

These plants should be built at first by design, but then by experience.

A free market in which there are dozens of competing designs isn't conducive to mass production and reliability that comes from experience rather than esoteric designs.

America = Fail.
Vendicar_Dickarian
2 / 5 (4) Jul 08, 2012
The fact that there is any design work at all, 50 years after nuclear power was initiated, is an indictment of the failed free market system.

These plants should be built at first by design, but then by experience.

A free market in which there are dozens of competing designs isn't conducive to mass production and reliability that comes from experience rather than esoteric designs.

America = Fail.