Is Fukushima Worse Than Chernobyl   1 comment

In a word, yes!  The Fukushima nuclear accident is way outside of the design based disasters that nuclear engineering plans for.  Their worst case scenarios have been exceeded and the problem is getting worse, not better, more unstable not less.  As bad as it was Chernobyl took place in a relatively isolated area and the Soviets were able to establish a ‘dead zone’ around the accident fairly rapidly.  Fukushima is within a densely populated area on a densely populated island.  There are between 3 and 7 million people who are within conceivable ‘dead zones’ which may be established around the plant. In addition if the situation deteriorates, and there is still a possibility of that happening, Tokyo may be directly effected by nuclear contamination.

Design Disasters and Nuclear Engineering

Let’s deal with some basic nuclear power plant information.  Nuclear plants are designed to be closed systems.  Nuclear reactors generate tremendous amounts of heat and radiation.  To prevent melt down (and to generate electricity) Boiling Water Reactors (BWR) are designed to be cooled by water in a closed loop.  The water circulates past the nuclear fuel, is heated and then passes to a passive system which exchanges the heat in the water into another isolated water system (the details of which are not important to the present discussion).  What is important is the design of the system to prevent the nuclear fuel from having direct contact with the environment and that the water in the closed system (which itself can become radioactive in a disaster) must also be isolated from the environment.

As a nuclear power plant operates the fuel becomes increasingly radioactive.  To help isolate the fuel from the environment the fuel is enclosed in a thick steel walled container (the primary reactor pressure vessel – RPV).  The RPV is also known as the primary containment for obvious reasons.   In order to allow fuel, water  and control rods into the RPV there are holes in the top of the RPV.  To allow water to escape from the system there are holes in the bottom of the vessel. The whole system is enclosed in a secondary containment vessel.  Three of the secondary containment building at Fukushima have exploded.  Three of the reactors have undergone partial or total meltdowns.  The RPV are damaged or cracked in at least two and probably three of the reactors.

Because nuclear fuel grows increasingly radioactive and the efficiency of the reactions decreases through time, the reactors are brought to a cold shutdown and the fuel is removed.  In most of the world, Japan and the United States the fuel removed from the reactors are stored in spent fuel pools.  The fuel in these pools is highly radioactive and the fuel gives of substantial amounts of heat.  The term ‘spent fuel’  refers to the ability of the fuel rods to be used to produce electricity.  When it is removed from the reactor the ‘spent fuel’ is more radioactive than when it was first inserted.  To control the radiation and control the heat (to prevent the fuel from melting) the pool are filled with water which is circulated around the fuel rods.  Note carefully that the radioactive fuel in the pools is not contained within a RPV.  There is no steel tank surrounding the fuel (think of a swimming pool filled with radioactive material).  In general for any given reactor which has been operating for a substantial amount of time there is more fuel and more total radioactivity in the pools than in the reactors.

If water fails to circulate in the pools the fuel may melt.  When fuel rods melt, either in the reactor (as a melt down) or in a spent fuel pool the melting gives off hydrogen gas which may explode.  The explosions at Fukushima occurred within the RPV due to melting and hydrogen release and the explosions may have split the vessels, corrupting the isolation of the fuel from the environment.  There is strong evidence that the nuclear pool are likewise compromised with the danger of further contamination being released into the environment.

Recovery from nuclear accidents are premised upon: a steady flow of water around nuclear fuel rods which are not themselves damaged and that the primary containment vessel is structurally intact (a closed system is maintained).  None of these conditions hold for Fukushima.  In addition the pool containing the spent nuclear fuel in each of four reactors have cracks (do not have structural integrity), the fuel rods in one or more pools is damaged and the pool themselves are not isolated from the environment by a primary contain vessel (the system is not closed).

Due to the explosions and melting and cracks in the containment vessels and the spent fuel rod pool the work environment is highly contaminated.  The explosions released actual nuclear products at great speed out of the reactors and into the surrounding towns.  The design basis for recovery from nuclear accidents do not allow for these high levels of radiations.   In essence, Fukushima is the accident t that they told us could not happen and the recovery from which there are no reasonable technical plans.  At Three Mile Island, about 1/3 of the nuclear fuel melted and the RPV was not breached.  It took four years to remove the fuel from the RPV and a full  11 years and 11 Billion dollars to finish the clean up that disaster.

How do things stand today at Fukushima?

It’s the water.

According to Bloomsbergs:

Radioactive water accumulating in Japan’s crippled Fukushima plant may start overflowing from service trenches in five days, potentially increasing the contamination from the worst nuclear crisis since Chernobyl. Tokyo Electric Power Co. has been manually pumping water into overheating reactors after cooling systems broke down and much of that has overflowed into basements and trenches. The water is rising at a rate that means it will overflow as early as June 6, Bloomberg calculations from the company’s data show.  There is still a risk of radioactive water leaking into the sea,” Hikaru Kuroda, an official at the utility known as Tepco, said in Tokyo today. “We may have between five and seven days before the water levels reach the top of the trenches.”

From Greenpeace:

Tepco on April 5 said it had dumped almost 10 million liters (2.6 million gallons) of radioactive water into the sea from the Fukushima plant, which led to radioactive cesium being found in fish at levels exceeding health guidelines.  The company said at the time the decision was the lesser of two evils as it needed to find space for storing water that was highly radioactive and more toxic that what was released into the sea.

According to the Pro-Nuclear Industry: Idaho Samizdat:

The utility has 15 million gallons of radioactive liquid created by efforts to cool its crippled nuclear reactors.  TEPCO is a bearer of a water problem that sets daunting challenges ahead of its ambitious plan to decommission the Fukushima reactor site. In many ways, getting the millions of gallons of radioactive water out of buildings at the site is a path to getting the decommissioning program in place and working against a predictable schedule.

The basic rule in responding to emergencies involving environmental cleanup is that you can never do just one thing without something else coming up. In the case of TEPCO’s three crippled reactors at Fukushima, pouring hundreds of tons a day of water on the leaking units to cool the hot nuclear fuel inside them has resulted in creating a huge volume of radioactive water.

Left uncontrolled the water is seeping into the ground and running off into the sea. Evaporation leaves a residual trail of radioactive debris which will be hard to clean up. The Bloomberg wire service reported June 2 that TEPCO may see radioactive water overflowing the storage it has on-site by early this week resulting in flows of the contamination into the sea. TEPCO has to get control of the water before it makes the situation at Fukushima even worse.

Estimates of the amount of radioactive water that has accumulated since March 11 range from 15-to-28 million gallons. The rate of accumulation of new radioactive water is estimated to be 300-to-500 tons per day or 72,000-to-120,000 gallons per day. In a month the amount of new radioactive water would be to 2.1 million to 3.6 million gallons.  It turns out TEPCO will be able to put about half of the 15 million gallons of uncontrolled radioactive water in the tanks.

The water treatment plant is a stop gap action. For real progress to be made, TEPCO must find a way to achieve recirculation of cooling water inside the reactors and contain the leaks.  Removing as much of the initial volume through storage and treatment is a good first step because it will allow plant workers to enter areas that are closed to them now due to the high levels of radioactivity in the water.  Areva will have some steep technical challenges to meet to achieve these results.

TEPCO and the Japanese government are betting the ranch that the French nuclear giant can do it.  The other choice is almost unfathomable, and that is to run a pipe from the Fukushima shoreline to the continental shelf and pump the radioactive water into the abyss of the Pacific trench.

It’s The Radiation.

According to the New York Times:

The agency also said it now estimated that the radioactive release from the plant totaled 770,000 terabecquerels in the first week after March 11. The agency had previously estimated 370,000 terabecquerels released in the first month.  The agency suggested that the higher emissions estimate was equivalent to only about 10 percent of the radioactive materials released in 1986 by the explosion and fire at Chernobyl, still widely considered the world’s worst nuclear plant disaster, in the former Soviet Union. But the 770,000 terabecquerels figure in fact comes to about 40 percent of the official Soviet estimate of emissions from Chernobyl.

According to the New York Times:

Responding to fury among parents in Fukushima, Japan’s education minister said Friday that the country would set a lower radiation exposure limit for schoolchildren in areas around a stricken nuclear plant and pay for schools to remove contaminated topsoil from fields and playgrounds.  In recent days, worried parents have spoken out over what they say is a blatant government failure to protect their children from dangerous levels of radiation at local schools. The issue has quickly become a focal point for anger over Japan’s handling of the accident at Tokyo Electric Power’s Fukushima Daiichi nuclear power plant, which was ravaged by the March 11 earthquake and tsunami. There had been particular anger over new government guidelines that allowed schoolchildren to be exposed to radiation doses that were more than 20 times the previously permissible levels. That dose is equal to the international standard for adult nuclear power plant workers.  There had been particular anger over new government guidelines that allowed schoolchildren to be exposed to radiation doses that were more than 20 times the previously permissible levels. That dose is equal to the international standard for adult nuclear power plant workers.

According to MSN:

Japanese children can now be exposed to 20 times the radiation that was permissible before the March 11 tsunami caused a meltdown at the Fukushima nuclear plant, sparking the world’s worst nuclear crisis since Chernobyl.  Around 400 protesters, many from areas around the stricken plant, flocked to the education and science ministry to demand a rethink on the new limit, which allows exposure of up to 20 millisieverts a year.  A group of Fukushima residents submitted a letter for the education minister demanding the ministry do all it can to lower radiation levels at schools and offer financial support.

More than 20 elementary and junior high schools within 30 kilometres have been forced to close since the accident, affecting some 5,000 pupils, the Yomiuri daily newspaper reported on Monday.  Earlier this month, the company released an updated plan to bring all reactors at the plant to a stable state known as a “cold shutdown” in six to nine months. But that goal was based on an understanding that workers could efficiently cool the fuel in the three reactors, a harder task if their inner pressure vessels are breached.

It’s The Melt Down!

Arnie Gundersen at Chris Martenson’s Excellent Site

The Overall Situations.

It was pretty clear to a lot of people, including apparently to the NRC, but they weren’t telling people back in March, that that had occurred in reactor one. There was essentially a blob of lava on the bottom of the nuclear reactor. So I have to separate this – a nuclear reactor – and that is inside of a containment. So there is still one more barrier here. But the problem is that the reactor had boiled dry and they were using fire pumps connected to the ocean to pump saltwater into the reactor. Now, if this thing were individual tubes, the water could get around the uranium and completely cool it. But when it’s a blob at the bottom of the reactor, it can only get to the top surface and that would cause it to begin to meltdown. Now, on these boiling water reactors, there are about seventy holes in the bottom of the reactor where the control rods come in and I suspect that those holes were essentially the weak link that caused this molten mass. Now it’s 5,000 degrees at the center, even though the outside may be touching water, the inside of this molten mass is 5,000 degrees. It melts through and lies on the bottom of the containment.

That’s where we are today. We have no reactor essentially, just a big pressure cooker. The molten uranium is on the bottom of the containment. It spreads out at that point, because the floor is flat. And I don’t think it’s going to melt its way through the concrete floor. It may gradually over time; but the damage is already done because the containment has cracks in it and it’s pretty clear that it is leaking. So you put water in the top. And the plan had never been to put water in the top and let it run out the bottom. That is not the preferred way of cooling a nuclear reactor in an accident. But you are putting water in the top and it’s running out the bottom and it’s going out through cracks in the containment, after touching directly uranium and plutonium and cesium and strontium and is carrying all those radioactive isotopes out as liquids and gases into the environment.

Unit 3.

Unit 3 may not have melted through and that means that some of the fuel certainly is lying on the bottom, but it may not have melted through and some of the fuel may still look like fuel, although it is certainly brittle. And it’s possible that when the fuel is in that configuration that you can get a re-criticality. It’s also possible in any of the fuel pools, one, two, three, and four pools, that you could get a criticality, as well. So there’s been frequent enough high iodine indications to lead me to believe that either one of the four fuel pools or the Unit 3 reactor is in fact, every once in a while starting itself up and then it gets to a point where it gets so hot that it shuts itself down and it kind of cycles. It kind of breathes, if you will.

Now, Unit 3 has another problem and the NRC mentioned it yesterday for the first time and it gets back to that saltwater and the effect on iron. They are afraid that the reactor bottom will break, literally just break right out and dump everything. Because it’s now hot and it’s got salt on it and it’s got the ideal conditions for corrosion. So the big fear on Unit 3 is that it will break at the bottom and whatever else remains in it, which could be the entire core, could fall out suddenly. And if that happens, you can get something called a “steam explosion,” and this may be a one in a hundred chance. I don’t want your listeners to think it’s going to happen tomorrow, but if the core breaks you will get a steam explosion, but we’re not sure the core is going to break. And that is a violent hydrogen explosion like the one we’ve already witnessed.

Interviewer Chris Martenson: Reactor 3 caught me when it blew, because what I saw there with my eyes was a fairly focused upwards very high-energy event, which completely looked different from what I saw when Unit 1 blew. Are you talking about – is that or I know you have postulated in the past that you think that might have been — what’s the name for it a “prompt” criticality?

Arnie Gundersen: I called it a “prompt criticality,” that created a detonation and engineers differentiate – either way it’s going to be a big explosion. But the violence of Unit 3’s explosion and I did some calculations to show that the speed at which the flame traveled in order to through particles as far as this one threw particles – the speed of that shockwave had to be in excess of a thousand miles per hour. That’s a detonation, where the shockwave itself can cause incredible damage and that can happen if we were to have one of these steam explosions at the bottom of the reactor in Unit 3 falls out – you could have another one of those all over again

Unit 4.

Arnie Gundersen: You are absolutely right and there is no reactor running there. Everything has been taken out and it was put in the spent fuel pool. But that means there is no containment either, so the entire spent fuel pool is visible literally. When they have those helicopter fly-overs, you can look down into this blown out shell of a building and see the fuel in the spent fuel pool. It’s still relatively hot, because it only shut down in November. So there is still a lot of decay hear in that pool. Brookhaven National Labs did a study in 1997 and it said that if a fuel pool went dry and caught on fire, it could cause a hundred and eighty-seven thousand fatalities. So it’s a big concern and probably the biggest concern.  I note  the Chairman of the NRC said that the reason he told Americans to get out from fifty miles out was that he was afraid that Unit 4 would catch fire, that exposed fuel pool would volatilize plutonium, uranium, cesium, and strontium. And if the Brookhaven Study is to be believed could kill more than a hundred thousand people, as a result.

What is to be done:

Arnie Gundersen: Hopefully, they are no longer allowed to receive any more radiation – period. Not just for a year or for a month, but they really shouldn’t receive any more than that. Here’s a general rule of thumb: 250 rem will kill you. So that means that if ten people get twenty-five rem, one of them will develop a cancer. And if a hundred people get 2.5 rem, one of them will get a cancer. So it doesn’t mean lesser doses assure you of not getting a cancer. So what these people are doing is they are increasing the likelihood the they will get a cancer – 250 millisievert is 25 rem by the way – but they are increasing the likelihood that they will get a cancer by 10 percent.

The Russians needed thousands of people because large fragments of the fuel had fallen on the surrounding farmland, so literally people would pick up a fragment in a wheelbarrow and run toward where the reactor was – throw that fragment into the reactor pit and they were done. They had received their lifetime exposure. In this case, while the radiation is not contained, it’s not coming out of solid particles that can get picked up, it’s coming out of this liquid. Woods Hole has already said that the ocean has ten times more radiation from Fukushima than the Black Sea did from Chernobyl. So the Chernobyl reaction was a large staff of people and because it sort of blew up and the Fukushima reaction, while it did blow up, a lot of it is going down and we’re just beginning to deal with it.

Interviewer Chris Martenson: … is there some way that they can maybe just throw up their hands and just pour a bunch of concrete on it and call it a day?

Arnie Gundersen: I think eventually they may get to the point of throwing up their hands and pouring the concrete on. They can’t do that yet, because the cores are still too hot. So we are going to see the dance we’re in for another year or so, until the cores cool down. At that point, there’s not anywhere near as much decay heat and you probably could consider filling them with concrete and just letting sit there, like we have it at Chernobyl, as a giant mausoleum. That would work for units 1, 2, and 3. Unit 4 is still a problem, because again all the fuel is at the top and you can’t put the concrete at the top because you will collapse the building and it’s so radioactive, you can’t lift the nuclear fuel out. I used to do this as a living and Unit 4 has me stumped.

I think they will be forced to build a building around the building and then, because you need heavy lifting cranes – cranes that lift a hundred and fifty tons, which are massive cranes, to put the put the nuclear fuel into canisters, which then can get removed. That is sort of what happened at TMI, but all of the fuel at TMI was still at the bottom of the vessel. But it was a three-year process to get the molten fuel out of Three Mile Island – four years actually. So the problem here is that all of the cranes that do that have been destroyed, at least on units 1, 3, and 4. And you can’t do it in the air. It has to be done under water. So my guess is that they will have to build a building around the building to provide enough shielding and water, so that they can then go in and put this fuel into a heavy lift canister.

Where Can I Get Further Up To Date Information on the Continuing Disaster?

(and the sources for this blog post)

New York Times

General Nuclear Coverage

 Reports by HIROKO TABUCHI

This Blog Here Here Here And Here

Fukhihama Update

Beyond Nuclear

Nuclear Industry Site:  Idaho Samizdat

Arnie Gundersen Interview Of Chis Martenson

 CHRIS MARTENSON.COM

Bloomberg.com

MSN

One response to “Is Fukushima Worse Than Chernobyl

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  1. Pingback: Chernobyl and Fukushima Disasters: Two New Reports Released « Cloud2013 Or Bust

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