More Lessons From the Fukushima Daiichi Accident: Containment Failures and the Loss of the Ultimate Heat Sink

In this Monday's video, Fairewinds investigates a recently released report from Tokyo Electric. Arnie Gundersen discusses TEPCO's latest analysis that, almost two years after the accident, fully substantiates Fairewinds long held position that the explosion at Fukushima Daiichi Unit 3 was the result of a detonation shock wave. Arnie also discusses troubling reports that the Nuclear Regulatory Commission has been avoiding the analysis of damage to many nuclear plants' emergency cooling systems (Ultimate Heat Sink) from storm surges, tsunamis or dam failures. The ramifications of both of these issues on old designs and also the AP1000 are also analyzed in depth.


Associated Material

TEPCO Containment Leak Slideshow



Hi, I am Arnie Gundersen from Fairewinds.

This is the second December since the Fukushima Daiichi accident. I thought I would use this video to talk about things that were painfully obvious to Fairewinds viewers back in 2011, that really have not been internalized by the Nuclear Regulatory Commission even since then. So we are going to use this video as a training video for the Nuclear Regulatory Commission, so that they can better understand what Fairewinds viewers have known for the last 2 years.

The problems that I want to talk about today are twofold. One is the containment integrity and the other is what happens when you do not cool a nuclear power plant, something that we call the loss of the ultimate heat sink. Well let's get right to it. The first topic is the containment integrity. Tokyo Electric released a report in September of this year, and they gave it to the IAEA, the International Atomic Energy Agency. The report is a more thorough analysis of the explosions at Fukushima Daiichi. And it discusses things that they have learned in 2012 that they did not incorporate in their analysis back in 2011. Well, if you have been watching the Fairewinds site, we knew exactly the problems that Tokyo Electric is now identifying in 2012.

The report is posted on the site. I want to go to Slide 7. Slide 7 on the TEPCO presentation is an examination of where a Mark I containment can leak. Now, you have seen our famous video where the top of the containment lifts and gasses are sliding out. Union of Concerned Scientists also identified it in 2011. And here, now finally in 2012, Tokyo Electric announces as an improvement to it's analysis that, oh by the way, containments can leak. Well, viewers of the Fairewinds site have known that all along. But more importantly, the Nuclear Regulatory Commission has known it since 1976.

We brought to your attention that the top of the containment lifting was known to the Nuclear Regulatory Commission since about 1976 when it happened at the Brunswick plant. But now, in Slide #7 on the TEPCO slides, they say, oh my God, a Mark I containment can leak if the top begins to lift. They also show that the bottom of the containment can leak in an area where it is called the equipment hatch, almost an identical design as the top of the containment. And they also show that containment penetrations can leak. Well, this Slide 7 absolutely refutes something that the Nuclear Regulatory Commission said in a meeting that I was at just 6 months before the accident and it was an Advisory Committee on Reactor Safeguards meeting about containment integrity.

The Nuclear Regulatory Commission staff told the Advisory Committee on Reactor Safeguards that when they are analyzing a nuclear accident, they do not assume any leakage from the nuclear containment. Well, Fukushima Daiichi proved not once, not twice, but three times that nuclear containments can and do leak. But yet in all of the NRC's analyses, they continue even to this day, to assume that a nuclear reactor containment is essentially leakproof.

Moving on to Slide 19, is Tokyo Electric's assumptions about what happened to the Unit III containment. You will recall that is the one that blew straight up about a mile high. Well, they assume that about 1,000 kg of hydrogen was somehow leaked out of the nuclear containment. And they blame that 1,000 kg on the explosion at Unit III. Now, if you look at the bottom of that slide, somehow they assume that 1,000 kg of hydrogen got stuck in the basement. And from the basement it blew upward through the building. Now I think hydrogen is lighter than air and one would expect that that hydrogen would have moved up through the building and Tokyo Electric is not telling us how they can assume that something that is lighter than air can wind up in the basement.

The other part of the problem though, is they have not explained how the hydrogen got out. Did it leak through a side containment like the containment hatch? Did it leak out through penetrations? They do not know.

Now, I have stated that the explosion was due to a prompt criticality, moderated, but prompt criticality in the fuel pool that created the upward force. They state that it was caused by hydrogen in the basement. I submit to you that that is a secondary problem. What is really important is the word at the bottom of slide #19 by Tokyo Electric. Tokyo Electric acknowledges that this was a detonation. Now if you recall, a detonation is a shock wave that travels faster than the speed of sound. And no one is designing containments to withstand a detonation shock wave. So I am pleased actually that Tokyo Electric has finally agreed with me that this was a detonation shock wave and not a deflagration, like in Unit I. So I think the first important thing for the Nuclear Regulatory Commission to admit, is that containments leak. But the second thing is that they can explode with a detonation shock wave.

Now since Fukushima Daiichi, I have been following the Nuclear Regulatory Commission's analysis pretty closely and no one is talking about the effects of a detonation shock wave on a nuclear reactor containment. This has major ramifications for all containment designs and, like an ostrich in the sand, the Nuclear Regulatory Commission is simply ignoring the fact that Fukushima Daiichi Unit III had a detonation shock wave hit it. This Tokyo Electric slide show shows a couple of things about containment integrity. First, it is clear evidence that containments leak. It would be nice if the Nuclear Regulatory Commission acknowledged that containments can leak when they factor in their exclusion distances and evacuation of populations. But the second thing is the fact that a nuclear containment can be destroyed by detonation shock wave.

We talked about in a previous podcast, that Unit III is so damaged now as a result of the explosion, that it can no longer handle the crane used to lift the nuclear fuel out of the fuel pool. That damage was caused not by a deflagration, but by a detonation. And yet, the Nuclear Regulatory Commission pretends that that cannot happen here. Well, it did happen. And if it did happen, that means it can happen again. So our containment analysis needs to reflect the fact that a shock wave traveling faster than the speed of sound can occur as the result of a hydrogen explosion.

Now. this is not just a problem with the old Mark I designs. The AP 1000's brand new design being built in Georgia are a tenth of a pound from the design limit of the containment and they do not assume a detonation shock wave. When a containment is so close to the design limit, if it did have a detonation shock wave like we know can occur, it would shatter the containment. This is a lesson the nuclear industry needs to learn and needs to analyze for and strengthen it's operating containments moving forward.

Moving away from the Tokyo Electric report, and onto a new topic is the issue of what happens if the cooling water for a nuclear plant is unavailable. We call that the loss of the ultimate heat sink. Now, I was on CNN the second week after the accident and I explained that not only were the diesels flooded, but even if they were not flooded, the plant would have had a meltdown anyway because the pumps along the ocean had been destroyed by the tsunami.

I was also on another show; it was called Five O'Clock Shadow, and we were talking about the issue of the Fort Calhoun plant that had been flooded. And I talked about the fact that an upstream dam failing at Fort Calhoun would have caused the same accident as Fukushima Daiichi. It would have flooded the pumps that are used to cool the plant. That same radio show, I talked about the fact that the Okonee Plant down in the South, was also subject to that because upstream from it is a huge dam.

Well, guess what. Here we are in 2012 and two whistleblowers at the Nuclear Regulatory Commission have come out and said the NRC has known all along what we knew back in 2011. Not only did the whistleblowers tell us that the NRC has a report about the problem, but the whistleblowers are telling us that the NRC is not doing anything about the problem, even though they know about the problem. Well, they wrote a report to the Inspector General and they asked for the Inspector General to investigate the Nuclear Regulatory Commission to see why they have been covering up a vital safety issue, loss of the ultimate heat sink at 23 different nuclear plants around the country. Here is the first sentence from their report to the Inspector General. They allege, "that the Nuclear Regulatory Commission has intentionally mischaracterized relevant and noteworthy safety information." What they did was they called it security related. And because it was security related, that meant that you and I were not privy to that information. In fact, it had nothing to do with security. It had to do with protecting the nuclear industry from the expense of having to protect their plants against an upstream dam failure. It does not matter where the excess water comes from that floods the cooling pumps. It does not have to be a tsunami. It can be the failure of an upstream dam, like at Okonee or like at Fort Calhoun. Or, it can due to the tidal surge that happened after Hurricane Sandy at the Oyster Creek plant.

In any event, dozens of nuclear plants in the United States are subject to loss of the ultimate heat sink because their intake structures can become flooded. Now this is a problem that can be fixed. There are things called submersible pumps, pumps that work under water. The intake structure pumps could be made submersible so that no matter what Mother Nature throws at them, they can withstand it and continue to cool the nuclear reactor. I think that that is an important modification that should be made across the board. I hope that in 2013, the Nuclear Regulatory Commission takes a real serious look at this loss of the ultimate heat sink and suggests that we modify those cooling pumps to make them submersible so that a Fukushima Daiichi accident will not happen here.

I think the reason you watch Fairewinds videos is because we provide accurate information and timely information about nuclear problems in the United States, as well as at Fukushima Daiichi and around the world. That kind of analysis costs money. Now, I work for free; I volunteer my time for these videos. Maggie does too. But that does not mean we do not have production costs that need to be covered. So it is the end of the year and I hope that you will consider giving to Fairewinds as a 501 c 3. That means we are tax deductible and you can do a good deed for Fairewinds and at the same time reduce your tax bill if you will give to Fairewinds before the end of the year. Thank you very much. I'm Arnie Gundersen.