nuclear-news

Design flaws cause safety problems in San Onofre nuclear reactors

An environmental group, Friends of the Earth, has claimed Edison misled the NRC about the changes that it has identified as the likely culprit in excessive tube wear. The federal agency previously disputed that charge, but Collins said that’s under review as part of the
investigation. The group on Monday filed a petition asking the NRC to keep the plant offline until the company amends its license to reflect the design changes……
The NRC has said there is no timetable to restart the reactors.

Feds: Design led to nuke plant woes, Fuel Fix June 18, 2012  by Associated Press  CAPISTRANO BEACH, Calif. — 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 California’s troubled San Onofre nuclear power plant, a top federal regulator said.

The twin-reactor plant between Los Angeles and San Diego has been idle
since January, after a tube break in one of four, massive steam
generators released traces of radiation. A team of federal
investigators was dispatched to the plant in March after the discovery
that some tubes were so badly corroded that they could fail and
possibly release radiation, a stunning finding inside the virtually
new equipment.

Flaws 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 heavily modified generators, Nuclear
Regulatory Commission Regional Administrator Elmo Collins told The
Associated Press in an interview Sunday.

Collins couldn’t rule out that one or more of the generators, installed in a $670 million overhaul in 2009 and 2010, might have to be replaced.

Eight tubes failed during earlier pressure tests in the Unit 3 reactor
and “we have not seen that in the industry before,” Collins said.

“It’s these four steam generators that either have, or are susceptible
to, this type of problem,” Collins said, referring to the unusual
damage caused when alloy tubes vibrate and rattle against each other
or brackets that hold them in place.

So far, a fix has remained elusive.
“It’s not too hard to frame up the problem,” he added. “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.

It’s possible operator Southern California Edison could face penalties
stemming from the federal investigation, Collins said.

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.

An environmental group, Friends of the Earth, has claimed Edison misled the NRC about the changes that it has identified as the likely culprit in excessive tube wear. The federal agency previously disputed that charge, but Collins said that’s under review as part of the
investigation. The group on Monday filed a petition asking the NRC to keep the plant offline until the company amends its license to reflect the design changes……
The NRC has said there is no timetable to restart the reactors.

Edison has been facing pressure from some nearby communities and
anti-nuclear activists that have raised safety concerns, while the
company looks for a solution to the tube problem and a path to
restarting the plant, an important source of power in Southern
California. The design of the generators is also under congressional
scrutiny….. http://fuelfix.com/blog/2012/06/18/feds-design-led-to-nuke-plant-woes/

June 20, 2012 - Posted by Christina Macpherson | safety, USA