San Onofre Reactor 2 operated for several months with degraded nuclear fuel cladding

Three weeks after shutting down, problems continue to surface at San Onofre Unit 2.  Scott Burnell, a spokesman for the Nuclear Regulatory Commission in Washington, said the root cause of the faster-than-expected wear on tubes in replacement generators is yet to be determined.

One of the less-reported stories involves an accident the occurred during the outage, where a worker fell into the San Onofre Reactor 2 reactor pool on January 27th. David Lochbaum, who worked in nuclear plants for 17 years before joining the nonprofit Union of Concerned Scientists, said he believes small particles of uranium fuel —- sometimes called “fuel fleas” or “hot particles” —- could have been in the San Onofre Reactor 2 reactor pool when the worker fell in.

After looking at a set of reactor operation statistics published on the NRC’s website, Lochbaum said the radiation levels in the plant’s cooling system doubled from January to February 2011 and continued to climb through the end of the year.  He shared his findings that increasing levels of radiation in the water that cools the reactor probably indicates that the metal tubes — called cladding — that contain its fuel pellets are cracking.

Those cracks, he said, could have released particles into the reactor pool when uranium fuel was removed from the reactor core during refueling, well before the worker’s fall.

“The chart shows that San Onofre Unit 2 had operated for several months with degrading fuel cladding,” Lochbaum said. “The opening in the fuel cladding that allowed radioactivity to escape into the water at ever-increasing rates could have also been a pathway for fuel fleas —- small particles of fuel pellets —- to escape.”

When a nuclear reactor is in operation, the fuel expands on heating, the core of the pellet expands more than the rim.  In an water-cooled reactor the action of radiation on the water (radiolysis) forms hydrogen peroxide and oxygen. These can cause stress corrosion cracking of metal parts which include fuel cladding and other pipework.

The heating of pellets can result in some of the fission products being lost from the core of the pellet. If the xenon can rapidly leave the pellet then the amount of 134Cs and 137Cs which is present in the gap between the cladding and the fuel will increase.

 

Rochelle Becker, executive director of the Alliance for Nuclear Responsibility, said she was referred to Edison when she asked the NRC for more details about the radiation dose that the San Onofre worker received.

“When you’re telling the public to go back to the utility for any more questions, I think that’s an indication that there is too much trust,” Becker said.

 

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7 total comments on this postSubmit yours
  1. joybusey@gmail.com'

    WTF??? NRC claims they didn’t know about degradation of fuel rod cladding welds and crumbled fuel pellets? Really?

    Of course they know. They have always known. It’s how the reactor coolant systems gets “all crapped up” and manages to leak radioactive contaminates through leaks in steam generators and dump “hot particles” on humans unlucky enough to live nearby. Thus causing significant increases in things like leukemia to those unlucky people’s children. Good grief. When will people wake up to this ridiculous feigned ‘surprise’ every time their technology gets revealed to be garbage?

  2. dgilmore@cox.net'

    San Onofre refuses to share current radiation data with the public. The EPA refuses to install a radiation monitor near San Onofre. The California Department of Public Health has a radiation monitor in San Clemente (the city nearest San Onofre), but the data is months old and very limited. The City Council of San Clemente continues to ignore requests from their citizens to take the lead on getting the public the current radiation data they need. See details at http://sanonofresafety.org/radiation-monitoring/

    San Onofre has the worst safety record of of all U.S reactors and punishes employees for reporting safety issues. See NRC data and comments from whistleblowers at http://sanonofresafety.org/safety-allegations-8/

    California citizens, please download and sign the California Nuclear Initiative Petition to effectively shutdown San Onofre and Diablo Canyon. Do this before April, so we can get this on the November ballot. The government is not protecting us, so we have to protect ourselves. NO ONE IS GOING TO DO THIS FOR YOU. It’s up to YOU to protect your family and California. This is a grassroots effort, so we need your participation to make this a success.

    Go to http://californianuclearinitiative.com/

    You have a chance to be part of history. Will California be Fukushima USA or will California be the state that shows the world that the people are still in control of this country? Citizens from Japan have asked me to warn Californians to learn the lessons of Fukushima before it’s too late.

    Donna Gilmore
    San Clemente

  3. captddd@gmail.com'

    I believe that once California consumers and especially California property owners realize that they are NOT covered for any type of fallout, leakage or contamination caused by radioactivity, they will begin to reexamine their “trust” in nuclear because of their financial liability!

    Question: How many in Southern California (for example) could afford to just walk away from their homes if one of the reactors in California had a meltdown for any reason; without even considering the health implications later? The answer of course is NOT MANY! We have only to see what has happened in Japan to get a good idea; in short America cannot afford a Trillion Dollar Eco-Disaster any better than Japan.

    Remember most of the “rest” of America is downwind from the West Coast! Japan has been “lucky” in that regard ,since most of its radioactivity has move toward eastward North America and the rest of the planet; yet most of Northern Japan is now contaminated!

  4. captddd@gmail.com'

    +
    We are now are being ruled by those in Nuclear Denial*; instead of by Leaders that demand an end to the Trillion Dollar Eco-Disast­er RISK that Nuclear poses to mankind! The nuclear industry is fighting tooth and nail to maintain it’s market share; yet NOW Solar (of all flavors) is far less costly to construct, faster to construct and carries with it N☢ Nuclear radioactiv­e baggage that can kill a Countries economy and or those living nearby!
    Ask The Japanese!

    *Nuclear Denial
    http://is.­gd/XPjMd0
    The illogical belief that Nature cannot destroy any land based nuclear reactor, any place anytime 24/7/365! Remember Nature does not follow design basis calculations or even engineering RISK formulas…

  5. captddd@gmail.com'

    The NRC gave the Nuclear Industry a “PASS” on the tube wear issue before on San Onofre and other reactors around the Country http://wp.­me/p21p6a-­77L
    BUT NOW
    They are realizing that they have a much bigger problem than they first “imagined”­; metal erosion cannot be tolerated when the radioactiv­e leakage is not only high in temperatur­e but also high in amount of radiation!

    Would you use a dangerous leaking pressure pot day after day,
    … or would you be smart and replace it with something safer?
    +
    Why nuclear is on the way out:
    1. Radiation is dangerous to man
    2. Expensive to build compared to Competitive Power Sources.
    3. Creates long lasting radioactiv­e waste
    4. Risky because Nature can destroy any land based nuclear reactor,
    … Any place anytime 24/7/365!
    5. No meaningful insurance for MAJOR radioactive damages to property or people!

  6. david.bear42@yahoo.com'

    There are multiple stories going on at SONGS. 1) Failed reactor fuel cladding. 2) Failed steam generator tubing. 3) Levels of contamination in the spent fuel pool. 4) Increasing levels of radioactivity in the steam plant water during the past year. This would be directly related to #2, the failed steam generator tubing, because with failed steam generator tubing, the reactor water bleeds directly into the steam plant.
    Other nifty things about SONGS. 5) It has been around a long time (which in and of itself speaks well for it having not self-destructed) which puts it at increased risk for mechanical failure. 6) It sits on the Ring of Fire.
    Yes, SONGS is quite the place.
    - Bear

  7. joybusey@gmail.com'

    Fuel cladding failure is nothing new. Am working on an examination of these issues, but for some background check out this NRC Notice from August of 1998 entitled “PREDICTED INCREASE IN FUEL ROD CLADDING OXIDATION” -

    http://www.nrc.gov/reading-rm/doc-collections/gen-comm/info-notices/1998/in98029.html

    It began well before 1998, and got steadily worse from there. Cladding failures contribute MOST to releases of radioactivity through leaks in components like, say, equally crummy steam generator tubes…

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