Tuesday, March 22, 2011

Fukushima, Japan nuclear news update

Conditions appear to have stabilized on site. Grid power is now available in all the units. However, electrical equipment still must be checked before it can be switched on. Obviously, getting cooling systems back into operation is a priority. The lights are on in the control room for reactor three, and bringing this back into service will enable better monitoring of the situation. Operations to add water to the spent fuel pools of Reactor 3 and 4 continues. A concrete pumper with an extending boom has been brought in to provide water at unit 4. However, aerial surveillance suggests that water doesn't stay in the pools, and that they are leaking.

Some radiation has been detected leaking into the ocean.

The bottom line is that the situation is stable but still not safe.

When the Reactor buildings at unit 2 and unit 4 suffered explosions on March 15th, the blasts occurred within 6 minutes of each other. I think that this is odd. Perhaps it indicates that the explosions were somehow linked.

pdf status report from JAIF

Sunday, March 20, 2011

Why the Fukushima crisis has people worried

The images below have been adjusted to the same scale.  One is an image of  Northern Japan, and the other shows the size of the area affected by radiation from Chernobyl. The arrow indicates the location of the nuclear plant.

This only relates to long term health impacts. At Chernobyl, only workers at the site were affected by radiation sickness. The images show how bad a Chernobyl style release could be for the Japanese.

(Images from wikimaps and wikipedia)

The precise patterns of fallout would depend on wind directions and rain fall. Tokyo is the world's largest metropolitan area, with 35 million people.

Fortunately, the latest news from Japan is good. Major progress has been made in adding water to spent fuel ponds and restoring cooling. However, there is much still to be done.

Friday, March 18, 2011

More gadgets for Fukushima

Might disaster be avoided?


I can't find data on the height of the spent fuel pond, but it appears to be less than 50 meters above the ground.  Google Earth indicates that the original reactor buildings were 80 meters high. There are a few fire-fighting vehicles which can reach that high. Once positioned and aimed, the crew could abandon the vehicle, leaving it to deliver water to the spent fuel pond. If it could be connected to the  Hytrans water supply system which I mentioned in my last post, then a continuous stream of water could be delivered to the spent fuel pond indefinitely. Set up time for these systems is of the order of minutes rather than hours.

The HLA from Finnish firm Bronto Skylift can deliver 3800 litres per minute (228 tonnes per hour) of water to over 100 meters above ground level. It also has substantial horizontal reach, allowing it to poke into the reactor building to reach the fuel pond. The pictures show it in operation.

I think this might just work, but the setup time will expose the crew to a substantial radiation dose.


The M93 Fox is a vehicle used by the military to map areas affected by radioactive fallout and chemical contamination. If the worst happens in Japan, these vehicles and their crews will be in demand to map contaminated areas. The US military has a number of these vehicles.


This is normally used to carry soldiers on the battlefield. They are equipped with ventilation systems which can filter out radioactive particles and protect the troops inside. Thick steel armor also shields the occupants from radiation. Bradleys could be used to transport people through contaminated areas.


This large, high flying unmanned airplane can keep the reactors under surveillance and warn of any changes. It has infra-red cameras which would be ideal for detecting fires and hot spots.

UPDATE: Saturday:  The Japanese appear to be thinking along similar lines.  the Yomiuri Shimbun newspaper reports that they are sending some fire trucks and a hose laying system from Tokyo. Quote:
One large ladder truck is capable of spraying water from about 40 meters above the ground, while an elevating squirt truck can blast 3.8 tons of water per minute from a height of 22 meters by remote control, the fire department said. These high positions will allow water to be sprayed onto the storage pool, which is in the upper part of the reactor building. Other vehicles include a hose layer to extend hose lines. A hose layer carries 72 hoses, which can be connected to "Super Pumper" trucks to build a long-distance pumping system. The system is designed so water can be pumped from the sea or a river as much as two kilometers away to maintain a constant supply to the engines, according to the fire department.

The Fire Engine Photos website has a picture of one of the "Super Pumper" hose laying systems here. It belongs to the elite "Hyper Rescue" squad.

Thursday, March 17, 2011

Send in the robots!

I have noticed some people commenting elsewhere about sending in various types of robot to save the plant. So I looked around the web and found quite a few things that would be potentially useful.


This is capable of lifting about 2 tons, and it would be ideal for water drops onto the reactor. In fact it would have a lot of potential uses in this situation, and hopefully Japan is being made aware of its capability. This was developed for airborne resupply of isolated soldiers. It dropped 16 payloads in recent tests. It does have a cockpit so it can be flown manned if necessary.


There are a huge variety of small radio controlled helicopters which could be flown into the reactor buildings to get a closer look at the damage. A big limitation is that they have to be within line of sight of the radio controller, and maximum range is about 300 meters. Endurance is about 20 minutes before the battery runs out.

Tiny wireless cameras are available for these things, with a mass of only 9 grams.

Probably the coolest of all these is the Dragenflyer X6 flying camera. It looks like something out of James Bond. Be sure to check out the Youtube video below.



This is a really nice robotic flying camera. Endurance is 8 hours.



For clearing debris around the reactors, what about this 60 tonne robot bulldozer from Israel? The Israelis use it to clear roads of mines.



This system can deliver 3000 litres per minute of water over several kilometers, using flexible hoses like the one in the picture. The Berkeley,CA fire department recently bought one for fighting fires after an earthquake. It can be rapidly deployed from trucks. Something like this could potentially provide a way to get water to the reactors and spent fuel ponds.


The Japanese have developed a small robot fire engine called the Rainbow 5. If this could be lowered onto the roof of Reactor 3, maybe it could insert a hose into the spent fuel pond.


One potential snag is that most of these gadgets depend on silicon microchips. These microchips are somewhat vulnerable to strong radiation, which can cause computer errors.

Wednesday, March 16, 2011

Fukushima: Japanese for Chernobyl

What's the big picture here? Deep within the radioactive ruins of the Fukushima
Daiichi nuclear complex, there lie four swimming pool like structures. These are
the spent fuel ponds. These are full of used fuel rods from the nuclear reactors.
Spent fuel must be kept covered with water to absorb the radiation from it and
keep it cool.

Heat from the spent fuel is slowly evaporating the water in the ponds. Under
normal circumstances topping up the water level would not be a problem, but the
situation at Fukushima is not normal. Over the past few days, the reactor
buildings have been ripped apart by hydrogen explosions. The ponds are located on
the upper levels in the buildings, and normal access routes to them are probably
destroyed or blocked by debris. The blasts may have cracked the concrete
structure of the ponds themselves, causing water leaks. Piping and
instrumentation cables leading to the ponds have probably been destroyed.

What makes this much worse is that the hydrogen explosions have also punctured at
least two of the reactor containments. The whole Fukushima site is now covered in
dangerous radiation, and levels near the reactors are reported to be lethal.
The bottom line here us that there little chance that the plant workers will be
able to maintain the water levels in the fuel rods. That fuel is going to be
exposed to the air.

What happens then? The fuel will heat up, and the metal cladding will react with
the water to liberate hydrogen. This will lead to further hydrogen explosions. At
some point the water will all boil away. Fuel temperatures will then rise much

Expert opinion differs on what happens next. Some experts say that the fuel will
not catch fire. Others say that the fuel will burn, and I strongly agree with
that. Put a large pile of flammable stuff in a metal lined basin which tends to
retain heat, then raise the temperature, and something is going to ignite.
Experts I have read seem to agree that a spent fuel pond fire is one of the worst
things that can happen in a nuclear plant. It is as bad as a core meltdown, if
not worse. It will release huge amounts of radiation into the air, which will
then go where ever the winds take it.

Major spent fuel pond fires are now all but inevitable. This will be every bit as
bad as Chernobyl. That is why the French are telling their citizens to leave the
country, and why the US is advising Americans to stay 50 miles away.


Some US experts believe that the water in the spent fuel pond at Reactor 4 has
already gone. The reactor building has been blown apart by a hydrogen explosion,
and they think that the exposed fuel rods are the source of the hydrogen. There
have been signs of a fire inside the building.

I think the US experts are wrong. The spent fuel pond is at the top of the
structure. Hydrogen tends to rise, and it would not sink down into the lower
levels of the building. Hydrogen from the fuel ponds would blow the roof off, but
would not produce the kind of damage visible in building 4. The hydrogen that
blew up building 4 came from somewhere else. However it is possible that the
explosion damaged the pond and that all the water leaked out.

The Japanese say that the water is still there and that the temperature is 86
Celsius, far above normal. I suspect that the Japanese are correct, but it
doesn't really make much difference. There is no feasible way to top the water

Tuesday, March 15, 2011

Radioactive steam leaking at Fukushima

Various reports on the web indicate high radiation levels near Reactor 3. The media is reporting that radioactive steam is venting from that reactor and that containment has been lost.

This satellite picture shows Reactor 3 just after it exploded. There is steam venting clearly visible. This venting is almost certainly not a design feature. It is coming from an area which has been totally destroyed by the blast. I suspect it shows a breach in containment which was caused by the explosion. Various reports on the web indicate high radiation levels near Reactor 3.

There have been many reports of intentional venting of the containment. When the plant does that, the gas is passed through filters in order to remove as much radiation as possible. Then it is emitted from a tall smokestack.


Somewhere in the radioactive ruins of Reactor 3 there is a swimming pool like tank called a spent fuel pond. It has been reported that there is some fuel in the pond. Such ponds often contain many reactors worth of radiation.

Heat from the spent fuel evaporates the water, and under normal circumstances several percent a day of the volume would be lost. If the explosion has damaged the tank and it is leaking then levels could fall more quickly. If all the water were to be lost, then the fuel rods would overheat and probably catch fire. That would lead to a Chernobyl style release of radiation.

It is essential that the water in this pool is kept topped up, but how will this be done? The pool is high up in the reactor structure, in an area subject to intense radiation. Normal access routes to the pool may be impassable.  Pipes feeding the pool may have been destroyed in the explosion.
Here is the question. Do the Japanese know what the water level is, or were the instrument cables destroyed in the explosion? Do they have the ability to top up the water level?
If not, then Japan has a very big problem.


Latest reports are that the fire in Reactor 4 had nothing to do with spent fuel. It is now said that an oil leak was to blame.

UPDATE: There are conflicting reports on the fire.
UPDATE: Latest photographs make it clear that Reactor 4 has suffered a massive explosion. The damage is almost as bad as Reactor 3. I wonder if hydrogen from #3 somehow got into #4, perhaps via the ventilation system?

Monday, March 14, 2011

Nuclear disaster goes from bad to worse

The Fukushima disaster is now spinning out of control.


The explosion yesterday from Reactor 3 destroyed most of the pumps that were cooling Reactor 2. Reactor 2 started down the now familiar path of falling water levels, exposed fuel rods, fuel melting, and hydrogen generation.

However, this time the result has been a breach of the containment. At the base of the reactor there is a big circular steel tube called the "Wet well". This has the shape of a donut or torus, and it is normally partly filled with water. It is connected to the "Dry Well", which contains the reactor, by big steel tubes.

The Japanese now believe that this is leaking, maybe as a result of too much internal pressure, or maybe as the result of a hydrogen explosion.

The Wet well and the Dry Well together make up the containment. Both must stay intact to contain radiation if a meltdown occurs.


When I was annotating this diagram for the last post, I was wondering about something that looked like a spent fuel storage pond sitting at the top of the reactor. I was hoping that it was just temporary storage, which would be empty.

Today other people have started commenting on it, so I have marked it in tonight's post. It now seems as if there may be a lot of spent fuel stored in that pond.

It is in an extremely vulnerable position, right at the top of the reactor. Fortunately, the hydrogen explosions have so far blown away surrounding structure while leaving the spent fuel storage ponds intact. If the fuel was to be ejected from the pond it would subject the whole site to intense radiation which would be immediately detectable. If exposed to air, the fuel would probably also catch fire. This would release large amounts of radiation.

The fuel generates heat, and it will tend to boil water out of the pool. The pool needs to kept topped up.


When fuel is removed from a reactor it is extremely radioactive and still producing significant amounts of heat. A large crane lifts the fuel out of the reactor vessel and lowers it into a deep tank of water. This is the spent fuel pool. The water blocks the radiation, and keeps the fuel cool.
In time, the radiation and heat production drops. Eventually, the fuel is put into a large metal container, lifted out of the pool by a crane, and lowered onto a railway car for transport.


This is odd, because Reactor Four was supposed to be shut down for maintenance. It is possible that some supplies left behind by the maintenance workers caught fire. Things like electrical cables can burn, and there was a serious fire at Brown's Ferry many years ago which was started by a maintenance worker.

A far more disturbing possibility is that the spent fuel is burning. That might happen if all the water in the spent fuel pool boiled away. If fuel is burning, large amount of radiation will be detected.

Another Japanese reactor building explodes

This was rather more spectacular than the first. This building contained a larger reactor, which likely produced more hydrogen gas. Parts of the building were flung high into the sky. Fortunately, radiation levels remain stable.

Video from sky news

These reactor buildings are of the General Electric Mark 1 design. This dates from the late 1960s and it has faced a lot of criticism from anti-nuclear groups. It hasn't been legal for new construction since the 1970s.

A lot went wrong at Three Mile Island, but one of the success stories is that the containment building worked.  That building also faced a hydrogen explosion, but the explosion was contained within the structure and the building survived intact.

Here is a diagram of the Mark 1 containment, similar to the ones at Fukushima. You can recognize the square shape of the building. It can accommodate several different sizes of reactor. The containment vessel is within the building. It has the shape of an upside down light bulb. It seems that the containment vessel is still intact, although some of the concrete structures around it have been blown away by the hydrogen explosion.

One of the questions that needs to be asked is if a more modern design would have performed better. The latest containments, if I remember correctly, can survive about 200 atmospheres of pressure. The Japanese kept the pressure in this one under 8 atmospheres.

The image below is one of those pictures which really tells a story. On the left is a before picture of  the plant. Note all that equipment close to the ocean! On the right is a picture taken after the tsunami. Note that a lot of stuff isn't there anymore! This plant was massively damaged by the tsunami, and it is no surprise that it is in big trouble. There is a much better interactive version of this picture here. Scroll down their page to find it.

Obviously this was a very extreme event. One of the lessons that needs to be learned here is that the prediction of geological hazards is an imprecise business, and that a safety factor should be applied above and beyond the earth scientist's worse case projections.

Saturday, March 12, 2011

Bad News

Reports from Japan indicate an explosion and smoke coming out of their nuclear plant.

OK, smoke coming out of a troubled nuclear plant does not sound like good news. It might be steam, which isn't good news either. If hot molten metal drops into a pool of water, the result can be a steam explosion. A melted down core would be hot molten metal.

This may very well mean that the containment has been breached.

OK, I just found some video and it looks like a BIG explosion. NHK is reporting that the walls and roof of a building at the site have collapsed. This looks like a Chernobyl style release. The only good news here is that the cloud seems to be heading out to sea.

1.17am  Well at least California is 5000 miles east of Japan. I was in Europe in 1986 when Chernobyl blew, and it wasn't all that big a deal in Britain. Some milk and cheese had to be thrown out, but we didn't all get irradiated. Hopefully this cloud will disperse out over the Pacific without bothering anybody. I'm sure the Pentagon has a program to predict nuclear fallout, and they might want to get that fired up and try to predict where this cloud is headed.

1.50am  I remember seeing this a couple of hours ago: 'Japan's nuclear agency says radioactive cesium is detected in the air near one plant'

When Uranium reacts in a nuclear reactor Cesium is one of the products.


If this stuff is coming out it probably means severe heat damage to the fuel, which could mean that it has melted.

( Edit, Sunday, March 13 : Fortunately no major radiation release resulted from this event, but it looked really bad at the time. 'Explosion' and 'Nuclear Reactor' are words you don't want to see in the same sentence!)

Friday, March 11, 2011

Serious situation at Fukushima nuclear plant in Japan

Yesterday there was a massive earthquake off the coast of Japan, registering 8.9. This seems to have caused a serious problem at the nearby Fukusima 1 nuclear plant. This plant is right on the coast. Google Earth indicates it is maybe 20-60 ft above sea level. The tsunami from the earthquake is reported as being 25ft above sea level, so some parts of the plant might have been inundated.

When a nuclear reactor is shutdown the heat production does not immediately switch off. It is essential that cooling systems continue to run, or else the reactor core will rise in temperature until it melts. The nuclear industry has spent a great deal of time and money to ensure that core cooling  is never lost, under any circumstances. All reactors have multiple back-up systems to keep the core cool.

The news is now reporting that Unit 1 at Fukusima 1 has indeed lost core cooling. Unit 1 switched on in 1971, which makes it one of the oldest nuclear reactors currently operating. What is going on isn't clear, but I am reminded of what happened immediately after the Deepwater Horizon exploded and sank. Initial reports pointed to only a small oil leak, or maybe none at all. It took days for the full scale of the problem to become clear.

I going to speculate from here on. Loss of cooling in a nuclear plant implies multiple systems failures. This is not a case of a single generator failing. There are probably three separate systems, any one of which could keep the core cool. All must fail for cooling to be lost. That tends to imply severe damage to the plant. That could be consistent with inundation by a tsunami. Seawater isn't good for electrics, and tsunami waves could break piping and control cables. The plant would be trashed, with very many failed systems.

Pressure in the reactor is reported to be 50% above normal. That may be enough to open emergency pressure relief valves, which will vent moderately radioactive steam into the containment. This happens in order to keep pressure below the level which would burst the reactor pressure vessel. Radiation levels in the control room are reported to be far above normal, which could be due to steam venting plus failure of the ventilation systems. Steam venting means that the reactor is losing coolant, which raises the chance of a melt down.

In fact, a melt down might already be underway. If the damage includes failed instrumentation, and a control room which is becoming unusable, then plant operators might not have a clear picture of what is going on inside the reactor. That of course is speculation on my part, but the loss of cooling indicates that many, many things have gone wrong with this plant.

This kind of mess is why Japanese reactors, unlike Russian ones, are surrounded by containment buildings. At Three Mile Island, the containment building successfully contained the accident, and very little radiation was released. It seems quite likely that the containment building will be needed at Fukusima 1.

Latest reports indicate that four other reactors have also lost cooling. It looks like the situation is getting worse rather than better. If this follows the same course as Deepwater Horizon, then next few days are going to bring more bad news. There are at least 10 reactors along this stretch of coast, at least 3 of which were shut down for maintenance at the time of the quake. Out of the seven that were operating, at least five appear to be in trouble.

Wednesday, March 2, 2011

Part 9 - Conclusions

Since I started writing these posts, I have changed my mind about Professor Cowen's hypothesis. Looking at recent technologies, and comparing them with older ones, I struggle to find anything which had as much impact as farm mechanization or mass production. From a productivity point of view, those two innovations were huge.

If they drove the economy forward, then economic growth should have picked up after they were introduced. This is exactly what is observed. From 1880 to 1920, per capita GDP growth ran at about 1.3% per year. From 1920 to 1970 it grew at 2.4% per year. In 1914, mass production was perfected with the introduction of the assembly line, and by 1917 mass produced farm tractors were leaving the factory.

By about 1960 there were still a few million work animals left on American farms. After that date the Agriculture Department stopped tracking their numbers. By 1970 the fruits of farm mechanization and mass production had been fully harvested. Perhaps that is why per capita GDP growth slowed down after 1970. From 1970 to 2010 it grew at 1.8% per year.

However, if median incomes had grown along with GDP then they would have doubled over the period. A great deal of the reason for the stagnation in family incomes is the shift in income distribution towards the wealthy. After 1965 large numbers of entry level workers entered the workforce due to immigration, the baby boom, and the trend towards working women. However, entry level workers are not able to compete for the best paid jobs, which require years of experience. Given the expansion in the labor force, it is not really surprising that median wages stagnated, while a few continued to do very well.

There's another factor which is important for the slowdown in economic growth and  stagnation in the median wage.


As I showed in Part 6, the composition of the US economy has shifted greatly since 1970. Agriculture and manufacturing are industries which historically had excellent productivity growth. As their contribution shrinks, it is not surprising that growth in the overall economy slows down. Health care in particular does not have a good track record of productivity growth.
It is also possible that health care and finance require a different mix of skills from agriculture and manufacturing. That could explain the stagnation of median wages, combined with strong wage growth for those with the right skills.

Why has this shift happened? Foreign trade obviously plays an important role in manufacturing. A saturation of the market for manufactured goods and agricultural products is a more important factor. Government wealth transfers in the form of Medicare payments are a hugely important factor in the growth of health care.

The shift in economic activity towards health care and finance poses problems for the US economy. Agriculture and manufacturing are both industries with well functioning, highly competitive markets. In health care, markets do not function well because bills are paid by intermediaries. Consumers are weak and poorly informed. Medicare spending is mandated by the government.

In finance, many consumers are not really aware of the cost of financing a purchase rather than paying cash. People have to pay bank fees and charges, even if they feel they are unreasonable. Many end up paying far more to their bank or credit card company than they ever intended.

As health care and financial industries take a greater bite out of stagnant median incomes, it is not surprising that many people feel squeezed. A new car or  a steak dinner can be delayed when finances are tight. Mortgages, insurance, credit cards and medical bills are a must-pay. New products and services, like cable television, compete for a stagnant or shrinking number of discretionary dollars. It is not surprising that many Americans feel the squeeze.

Part 8 - Other suspects


The Hart-Cellar Act of 1965 lead to a drastic increase in immigration into the US . This expanded the labor force, which will tend to decrease the price of labor.  Immigrants can't compete for jobs which require years of experience, or the right social connections, so not all parts of the labor force are equally affected.

The 1970s also saw a surge of women into the work force. The late 70s saw the peak of the baby boom entering the job market. Given all these pressures on the labor force, it is perhaps not surprising that median wages stagnated.


After 1977 America's trade deficit exploded. In 2010 it accounted for about 3.5% of GDP. However, the real impact on the economy is greater than that figure suggests. Every factory job lost overseas means one less customer for service industries. This leads to additional economic shrinkage. Also, the industries that go overseas tend to be the labor intensive ones, which increases the impact on the labor force. Trade is definitely part of the reason for the stagnation in median wages. However it seems to be too small in relation to GDP to account for the whole problem.