U.S. NRC Blog

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Two years after Fukushima: Enhancements to U.S. Nuclear Plants Continue

David Skeen
Director, Japan Lessons-Learned Directorate
 

JLD vertical CToday is the second anniversary of the terrible earthquake, related tsunami and the resulting nuclear accident in Japan. Two years ago, the world watched in horror as the tragedy unfolded. Almost from those very first days, the NRC began to focus on learning from the incident to enhance our reactor safety – and to make sure such an incident would never happen here at home.

For example, U.S. nuclear power plants are using existing programs to address issues identified during last year’s walkdowns, which examined each plant’s earthquake and flooding protection features. Our resident inspectors are watching over that work using our Reactor Oversight Process, and we expect to audit approximately 20 plants (10 for earthquake walkdowns and 10 for flooding) in the spring and early summer to ensure the plants remain protected from such hazards.

We also continue to work with the plants on their re-analysis of flooding and earthquake hazards. We prioritized the flooding re-evaluations last year, examining several factors to give plants one, two or three years to submit their work. The first set of plants should have their responses in by tomorrow, and we’ll review the re-evaluated hazards before issuing a safety assessment for each site. The first set of earthquake hazard re-evaluations, for plants in the central and eastern United States, will be due in September. We’ll give those documents a similar review and resulting safety assessment for each plant.

The plants have also obtained additional equipment that can help keep the reactor and spent fuel pools cool if normal power sources are lost for extended periods of time, as was the case at Fukushima. This work responds to one of three Orders we issued to U.S. nuclear power plants in March 2012. Every plant provided a status report on complying with those Orders in October 2012, and we’ve found that all plants appear to be on track to meet the Orders’ requirements by the required deadlines.

The plants have also recently submitted their integrated approaches to comply with the Orders, and we’re reviewing those plans. By the end of April we’re also expecting the plants to provide the their assessments of how many staff a plant needs to have on hand to respond to a loss of power involving every reactor at a given site

The staff’s latest update to the Commissioners on Fukushima-related activities provides a more detailed look at how each of the NRC Near-Term Task Force’s recommendations is being implemented. While all of the Fukushima-related items are important, we’ve made sure U.S. reactors are paying proper attention to maintaining plant safety, any ongoing work of greater safety benefit or other existing high-priority actions protective of safety.

11 responses to “Two years after Fukushima: Enhancements to U.S. Nuclear Plants Continue

  1. Aladar Stolmar March 12, 2013 at 2:07 am

    A typical whitewashing by NRC, circumventing the real key process of stagnant steam bubble extending down to the core and igniting a firestorm of zirc-water reaction.
    Zircaloy Mass in Fuel Cladding [kg / lb] 16,465/ 36,300 in the PWR and 40,580 /89,500 in BWR from NRC-2012-0022-0002 and NRC-2012-0022-0003.

    Zr (91) + 2 H2O (36) = ZrO2 (123) + 2 H2 (4) + 5 MJ/kgZr
    Water required for complete reaction for the PWR 16,465 * 36/91 = 6513,6 kg or about 6.5 m3 (available), it produces 16,465 * 123/91 ZrO2 = 22,255 kg zirconium dioxide and 16,465 * 4/91 = 723.7 kg Hydrogen and 82,325 MJ heat. For a 10 second firestorm duration it gives 8GW power… or twice the full power of the reactor…
    Water required for complete reaction for the BWR 40,580 * 36/91 = 16053,6 kg or about 16 m3 (available), it produces 40,580 * 123/91 ZrO2 = 54,850 kg zirconium dioxide and 40,580 * 4/91 = 1784 kg Hydrogen and 204,250 MJ heat. For a 10 second firestorm duration it gives 20GW power… or five-six times the full power of the reactor…
    Considering that NRC does not require a top of the reactor depressurization vent to prevent the zirconium firestorm in the reactor, the above back of the envelope calculated worst case scenario should be considered.

    What I am proposing is a direct rapid depressurization vent allowing the operators to vent the steam directly out of the upper part of the reactor before a stagnant steam bubble would extend down into the core.

    In the PWR the accumulator injection (ECCS) ports connected to the hot leg side could be utilized for such vent, in the BWR the existing safety relief lines could be rerouted to the vent stack.

    The use of this rapid depressurization vent is proposed in three cases:(1) the state of the reactor is unknown, (2) the forced circulation through the core is lost or (3) the heat transfer to the ultimate heat sink is severed

    And please, add these to the existing plants too with sufficient gravity water reserves.

    And here is my December 15, 2011 letter, a serious answer I’m still waiting for…
    Dear Director Skeen,

    Considering the TMI-2, Fukushima Daiichi 1, 2 and 3 reactor severe accidents and the Paks-2 fuel washing vessel incident, also the SFD and other related nuclear reactor fuel severe damage experiments it is evident that the ignition and firestorm of the Zirconium-steam reaction occurs several hours after the severe reduction in cooling capability arises. The attached solution utilizes this time gap and proposes the equipment and response modifications aiming the elimination of ignition of Zirconium-steam reaction in PWR and BWR reactors. Also the same solution deals with the results of such ignition and Zirconium-steam reaction in the maximum extent, in case the ignition despite the efforts occurs.
    Aiming the public safety in presence of nuclear power plant two questions have to be answered: Do You prevent the ignition of Zirconium in the steam? And Do You protect the surrounding of the plant from radioactive releases in case the entire Zirconium inventory burned in a firestorm? The presented here solution gives positive answers to both questions.
    The key element of this solution is the rapid reactor depressurization using a top vent from the reactor head. The same will provide a controlled routing for the Hydrogen generated in case the ignition of Zirconium-steam reaction still occurs.

    Regards,
    Aladar Stolmar
    astolmar@gmail.com

  2. joy cash March 11, 2013 at 11:43 pm

    When we see NRC decommissioning & removing nuclear waste from densely populated areas, we will believe we have learned the lessons Fukushima taught us. Simple enough.

  3. James Greenidge March 11, 2013 at 5:59 pm

    Re: “This is all really not acceptable.”

    Nothing nuclear will EVER be “acceptable” to implacable idealistic greens with pitchforks and torches out for nuclear plants, so why come here if one doesn’t intend on constructive criticism but really to slur and dump on the efforts and projects of hard working administrators and engineers with families they care about to hone proven clean and reliable and safe a power source that has — even in its worst accidents worldwide over sixty years — a mortality and damage score light-years from any other industry? You all act as though no one else sees the “Doomsday” kinks and flaws you do and are happily glossing over them solely for old man profit, which is pretty disingenuous toward the talents and intelligence and humanity of nuclear workers and engineers. I tire of carping critics with philosophical anti-nuclear beefs and who don’t have a wilt of responsibility for keeping the lights on and factories running and homes warm. The NRC and nuclear “industry” have their moments, but my hat’s off toward their professionalism and record of accomplishment and vigil on cleanly delivering real-life vital goods despite adversaries of fear, ignorance and prejudice.

    James Greenidge
    Queens NY
    Thanks atomicinsights.com!

    And no, I don’t get a penny from anyone or anything nuclear. Wish I did!

    • Anonymous March 12, 2013 at 9:44 am

      The NRC is a public agency who is accountable to the public that funds them. Asking for detailed progress reports on tangible changes is a reasonable request. This is an issue between the public and the regulator.

      BTW, if one google’s James Greenidge it shows this screen personna is used solely to spam the internet on news stories and the like with nuclear industry propaganda. It would be more useful if people stuck to the actual regulatory issues rather than harping on whatever philosophical bias they have or calling people names. But this is a tried and true tactic of many industries to try to troll or derail online comments and discussions. If you devolve something into name calling and banal nonsense then the actual issue at hand is no longer being discussed and they hope people will be turned off and not participate in the conversation. The oil industry is well known for employing this tactic.

      • James Greenidge March 12, 2013 at 6:08 pm

        Gee, my name’s no phoney “personna”, it’s ME! And Google must be funking on the data-mining front because I’ve lots more interests online than just spamming nuclear! The anti-nuke hysteria and prejudice here is something to behold. But let’s get down to brass tacks about biases vs facts, okay? At the very least ask yourselves that were the anti-nuclear rants of Greenpeace or Arnie and Helen were so factual and true, how come they NEVER come to debate on highly regarded pro-nuclear sites the likes of atomicinsights.com or atomicpowerreview.com or HiroshimaSyndrome.com? Better — ASK your anti-nuclear champions why not. You’ll get crickets. The door’s been long open to them to trip pro-nuclears in a lie or untruths. No takers. Their and your move.

        James Greenidge
        Queens NY

    • joy cash March 12, 2013 at 12:25 pm

      More is being revealed about the cozy relationship between NRC & nuclear energy industry. The public’s well founded concerns are viewed as bothering nuisances. The abject arrogance in our tax-funded regulatory agency & energy industry is duly noted.
      The public will not back down from guarding our children’s future.
      This is a new era that has just begun to rock long hidden safety issues.

      • Aladar Stolmar March 13, 2013 at 8:26 am

        I filed my Safety Concern against the installation of useless Hydrogen re-combiners, based on the erratic computer model of the zirc-water reaction in Westinghouse, with NRC knowledge (and objection) about 25 years ago.

        Yes. It is a long suppressed (hidden?) safety issue…

        And the stress tests were conducted after Fukushima concluded that the installed re-combiners can handle the calculated by the same erratic codes Hydrogen releases…

        How many more severe accidents NRC wants, before allows the consideration of the real process?!

    • CaptD March 16, 2013 at 1:21 pm

      James, I guess that Germany does not qualify, since they are keeping their lights on, while also phasing out their Nuclear ASAP! Why, because they don’t want the RISK of a Trillion Dollar Eco-Disaster like Fukushima and/or the nuclear waste & Health implications nuclear poses…

      Even the NRC is concerned about San Onofre, since it’s almost new replacement steam generators have failed due to their poor in-house design…

      More here:
      I think you missed the point that San Onofre’s replacement steam generators have major design flaws, they now have more damage than the rest of the US “fleet” combined and one is less than a year old and the other is less than two years old!

      Edison told ratepayers they would last 18+ years and save them over a Billion Dollars and now about two years later we have PAID 1.3 BILLION DOLLARS (and are still paying 54 million dollars a month) while Edison tries to figure out how to not get stuck with the bill!

      Edison has sold US a phony bridge, A Bridge To N☢ Energy!

      So save your rants and name calling for another topic, since there has been a huge amount of Expert comments on this subject, which you seem to ignore.

  4. CaptD March 11, 2013 at 1:00 pm

    Since the NRC is in Nuclear Denial and shrugs off the realization that all land based reactors are at risk, the American people are left holding their breath, hoping they will continue to be “LUCKY” that nothing bad happens, just so the nuclear Industry can profit! The USA should be “racing” Germany toward a non nuclear future and decommissioning our oldest reactors instead of giving them 20 year life extensions!

    * http://is.gd/XPjMd0

    The illogical belief that Nature cannot destroy any land based nuclear reactor, any place anytime 24/7/365!

  5. Lilly March 11, 2013 at 12:33 pm

    This is all really not acceptable. The detailed report shows no actual physical changes have been done anywhere. Has any equipment been retrofitted yet? Additional equipment brought on site at a plant? What and where? A specific list of physical safety implementations for each plant as a progress report would be much more useful than updates about meetings and throwing things into long term consideration rather than actually doing something.

    • Fred Stender March 11, 2013 at 6:22 pm

      I agree, I request a detailed and specific report on what has actually been completed, and timelines for the rest of the requirements.

      I am feeling like a long tailed cat in room full of Carrington events.

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