For the want of a nail

For want of a nail the shoe was lost.
For want of a shoe the horse was lost.
For want of a horse the rider was lost.
For want of a rider the message was lost.
For want of a message the battle was lost.
For want of a battle the kingdom was lost.
And all for the want of a horseshoe nail.

Proverb, Author Unknown

I’d like to direct your attention to the most important place on earth. It’s not Washington, DC, or Moscow, or Beijing. It’s not Tehran or Damascus or Bagdhad. It’s not even an entire city, but our fates hang on it.

The most important place in the world is a large concrete box about 100 feet above ground level located next to the #4 reactor in Fukushima, Japan. It contains, for the moment, water and hundreds of zirconium clad nuclear fuel rods. The #4 spent fuel pool was damaged by the earthquake and aftershocks of March 11^th last year, and by a hydrogen gas explosion. It is in rough shape. Workers have temporarily reinforced it with steel beams, but all of the observers I have read doubt that the structure would survive another moderate earthquake.

Unfortunately, the earthquake that precipitated this situation has weakened the fault line along the east coast of Japan in the Fukushima area. European seismologists have concluded that the major after shock known as the Iwaki event (magnitude 7) was caused by this weakening. It is virtually certain that another earthquake of this magnitude will occur in the next two or three years.

 What then? The #4 pool will crack open and lose its cooling water, perhaps even spilling fuel rods to the ground. The rods will overheat almost immediately and the zirconium cladding will start them burning like radioactive road flares. That in itself will be a major release, spreading radioactive iodine, cesium, strontium, and uranium in the resulting aerosol. The secondary effect will be the evacuation of the Fukushima site, rendering all work on the other five reactors impossible. Even robots can’t survive such high levels of radiation. These already compromised units will lose their jury rigged cooling schemes, resulting in cascading exposures and fires across the entire site. After 30 days or so the common spent fuel pool next to reactor #4 will lose enough water to expose its rods to the air, with the attendant road flare effect.

From an article in Japan Forum:

“Based on U.S. Energy Department data, I assume a total of 11,138 spent fuel assemblies are being stored at the Daiichi site, nearly all of which is in pools. They contain roughly 336 million curies (~1.2 E+19 Bq) of long-lived radioactivity. About 134 million curies is Cesium-137 - roughly 85 times the amount of Cs-137 released at the Chernobyl accident as estimated by the U.S. National Council on Radiation Protection (NCRP). The total spent reactor fuel inventory at the Fukushima-Daiichi site contains nearly half of the total amount of Cs-137 estimated by the NCRP to have been released by all atmospheric nuclear weapons testing, Chernobyl, and world-wide reprocessing plants (~270 million curies or ~9.9 E+18 Becquerel).”

Consider that for a minute. Eighty-five Chernobyls. Half the world’s cumulative exposure to Cesium-137 over the past 65 years, except that it is released in a month.

What happens to Japan depends upon the wind at the time of the release. Japan was lucky in its misfortune last year as the wind was from the west, blowing most of the radioactivity out over the Pacific. Winter winds from the northwest would drive the plume right into Tokyo. Southern summer winds would drive the plume up the island and over Hokkaido. In any event it would cut off the northern half of Japan from the south with a radioactive no-go zone. Where the cloud goes in the world depends on the nature of the release (steam vs. fire vs. explosion) and the vagaries of seasonal winds.

The problem for the Japanese authorities is that the crane for removing the fuel rods from the #4 pool was destroyed. In fact, the hardware is mostly in the pool, lying on top of the fuel rods. Removal of the rods isn’t scheduled to start until the end of 2013, and it is predicted to take a decade. In the meantime we are relying on the magnanimity of the Pacific tectonic plate. In other words, pure luck.

A few grim questions occur to me.

Evacuate Tokyo? How? To where?

How could Japan function as a nation and an economy after being irradiated and cut in half?

What would the world economy look like if Japan becomes a failed state?

When the ultra-hot radioactive gases from the fire plume up into the jet stream, what happens to Hawaii and the west coast of the U.S.? Or, depending on the wind and altitude, what happens to eastern China and the Korean peninsula? It would all have to fall out somewhere.

There are a number of voices around the world calling for an international effort to stabilize Fukushima. The Japanese government is downplaying the risks and resisting outside interference. Apparently even the Yakuza (Japanese mafia) is making money providing people (with Yakuza debts) to work in the high radiation zones. The emphasis seems to be more on cost control and political damage control than physical damage control. This can’t continue. An earthquake could hit Fukushima tomorrow, next week, six months from now, or two years from now. As the situation now stands the consequences would be world altering.

We need to pressure our government to put pressure on Japan on the following fronts:

• To push aside Tokyo Electric Power Co. and their efforts at cost containment
• To accept foreign assistance and expertise
• To design and deploy emergency containment measures now, in advance of any seismic event

This would be in parallel with:

• A first priority effort to seismically stabilize the Fukushima site
• Acceleration the transfer of radioactive material to dry cask storage

Write or call your senators and representatives:

https://writerep.house.gov/writerep/welcome.shtml

http://www.senate.gov/general/contact_information/senators_cfm.cfm

Prompt Criticality

(With a hat tip to Green Mountain Daily)

Arnie Gunderson of Fairewinds Associates, Vermont’s own nuclear watchdog, has been making a series of video commentaries about events in Fukushima. One of his latest covers the explosion at reactor #3. It addresses the question of when an explosion is not an explosion and when it is more than your usual explosion.

Gundersen Postulates Unit 3 Explosion May Have Been Prompt Criticality in Fuel Pool from Fairewinds Associates on Vimeo.

Long story short, the spent fuel pool at reactor #3 actually detonated. Hydrogen was the initial culprit, but Gunderson presents evidence that the initial hydrogen explosion compressed the spent fuel rods of mixed uranium and plutonium enough that they achieved critical mass. That is, enough neutrons shot around in a tight enough space to create an uncontrolled and fast chain reaction. Gunderson called it a “prompt criticality.” The fuel pool walls and open top acted like the barrel of an upturned cannon and shot pieces of fuel rods as much as two miles away.

“Prompt criticality.” Hmmm.

As I recall from studying physics and technological history, compressing uranium and plutonium in order to create a critical mass that detonates is the job description of an atomic bomb. That flash and column of smoke we saw on the news at reactor #3 was probably a small, but quite real nuclear blast.

This is a new idea for me, and probably for a lot of people. There are spent fuel pools all over the world, including one in the southeast corner of Vermont. The concept of one boiling off and spraying radiation is bad enough, but “micro-nuke” is a new level of risk. They are not just water filled boxes of radioactive materials. They are all potential atomic bombs. It’s not that we should anticipate Hiroshima-like devastation. The engineering that goes into an efficient nuclear weapon is not trivial, and compressed spent fuel rods are not going to get anywhere near that.

The risks of a prompt criticality are catastrophic loss of containment and a wide and high spread of heavier radioactive materials. I doubt that the spent fuel pool at Fukushima #3 has any real structural integrity left, and getting near enough to it to either remove the materials or repair the containment is problematic (understatement alert). The fact that solid bits of the spent rods traveled two miles is an indication of how far dust and volatile gases must have traveled. We’ll have to wait and see how much of the nuclear material is still left in the pool, but a significant amount of uranium and plutonium must have shot up into the air. The next question is, having shot into the air, where did it, or will it, all come down?

The question after that is, how much more of this stuff do we want to make and have sitting around?

Japanese Nuclear Problems

Here’s an overview of the nuclear power crisis in Japan. History will probably overtake this post within a day, but I thought people might like a general picture of the problems.

The worst hit plant is Fukushima Dai-ichi, located about 180 miles north of Tokyo on the east coast of Japan’s main island of Honshu. It is a set of six boiling water reactors, meaning that the water heated by the nuclear reaction is not pressurized, so it boils. This is an important point, which I will get to later.

Three of the six reactors were operating at the time the earthquake hit. They all immediately shut down. That means that a number of rods were dropped into each reactor core, these rods absorbing radiation and stopping the reaction. The problem is that the cores of these reactors don’t immediately cool down, so the cooling water needs to circulate through them for another week. During a normal shutdown the cooling water pumps run on electricity from the utility grid. This being absent, the pumps are powered by diesel generators on site. In this case, the generators were swamped by the tsunami, so the pumps fell back on batteries, the problem being that the batteries can only power the pumps for 8 hours.

Adding to the problem, each reactor has a pool of water holding used fuel rods. These pools need to have water circulated through them to keep the spent rods cool, although to a lesser extent than the reactor cores. Some of these pools lack circulating water due to the multiple failures and are starting to boil off their water. The danger is that if the spent rods are exposed they could catch fire and spew radioactive particles into the air.

Already there have been releases of radiation. Units 1, 2, and 3 are all at risk, with the cores of all three having been exposed several times and partially melted. The pool on Unit #4 is at risk of exposure. Local residents have been evacuated, and even outside the evacuation zone people have been ordered to stay indoors.

Those explosions you may have seen on television were from hydrogen produced when steam reacted with the superheated casings of the nuclear fuel rods. The hydrogen vented out of the steel and concrete containment vessel and into the building around it. Usually any gas that gets vented into this building gets run through filters to remove radioactive particles and is then blown off, but the venting system was overwhelmed and the hydrogen built up and detonated. Now any radioactive gas that gets vented from those primary containment vessels goes directly into the atmosphere.

Japanese utility workers have been flooding the cores of reactors 1-3 with seawater in an attempt to keep the cores cool. Apparently they have also been mixing some boron containing compound into the water as well. Boron absorbs the neutrons that maintain a nuclear reaction, so this gives double duty, cooling and slowing the reaction at the same time.

There is presently a problem in the #2 reactor, in that the operators can't open the pressure relief valves. The pressure has built up to the point where they are unable to pump water into the core. Unless the valves open on their own, this can't end well.

Key concept: Flooding a boiling water reactor with seawater and boron is a permanent shut down. The Japanese authorities decided that the situation was bad enough to write off these reactors forever.

Second key concept: A small percentage of the fuel rods in reactor #3 are mixed oxide, or MOX, meaning that they contain plutonium as well as the usual uranium. This raises the probability of containment failure, because the plutonium helps to keep the reaction going and because it tends to create more gas when the core gets uncovered. It also poses a higher cancer risk than pure uranium.

Third key concept: These reactors are 40 years old, of a type called the General Electric Mark 1. There have always been questions about the probability of catastrophic failure with this design. This is, by the way, the same age and design as our own Entergy/Vermont Yankee plant in Vernon, as well as 22 other plants in the U.S.

A good site for ongoing information about the Fukushima plant, with excellent explanations of the technology, is at the Union of Concerned Scientists website.