Fukushima “cold shutdown” announcement up to 25 years too soon

The Japanese government has announced that the wrecked Fukushima Daiichi power station has reached a “cold shutdown”. The BBC quotes Prime Minister Noda:

“The nuclear reactors have reached a state of cold shutdown and therefore we can now confirm that we have come to the end of the accident phase of the actual reactors.”

It is meaningless to still use the term “cold shutdown” for a reactor in which the fuel rods and containment vessel have lost their integrity. It’s like saying the bleeding has been stopped in an injured patient who had actually bled to death.

The normal definition of “cold shutdown” is when, after the chain reaction has been stopped, decay heat inside the fuel rods has been reduced enough that the cooling water temperature finally drops below 100 C. This means the cooling water no longer boils at atmospheric pressure, making it possible to open the pressure vessel cap and remove the fuel rods from the reactor core into the spent fuel pool. After that the reactor core no longer needs to be cooled.

Only units 4, 5 and 6 have reached a genuine cold shutdown. Unit 4 had been shut down for repairs in 2010 and did not contain any fuel at the time of the accident. In units 5 and 6 a single emergency diesel survived the tsunami and prevented a meltdown there.

In units 1, 2 and 3 of Fukushima Daiichi the fuel melted, dropped to the bottom of the reactor pressure vessel and penetrated it. The melted rods then dripped down onto the concrete floor of the containment vessel and are assumed to have partly melted into the concrete up to an unknown depth.

While in a regular cold shutdown fuel can be unloaded within weeks, the Japanese government estimates it may take as much as 25 years before all fuel will have been removed. The technology to remove fuel in the state it’s in now does not even exist yet and will have to be developed from scratch. Even the most optimistic schedule puts it at 5 years, during which time the reactors will have to be cooled 24 hours a day, with no new earthquakes damaging them or knocking out cooling again, no major corrosion problems, no clogged water pipes, etc.

In my opinion, the announcement of a “cold shutdown” at Fukushima Daiichi is greatly exaggerated and was made mainly for political purposes. More than anything, it is meant to provide political cover for restarting other idled nuclear power stations during the coming year.

Radiation maps for Eastern Japan

The Japanese government has released updated radiation maps for Eastern Japan from its helicopter survey. The maps now cover prefectures as far west as Gifu and as far north as Iwate and Akita. Previously there was map data only for Tokohoku (excluding Aomori) and the Kanto area. The PDF can be downloaded here.

The previous set of maps documented caesium contamination and background radiation levels in Fukushima, Tochigi, Miyagi, Ibaraki, Chiba, Saitama, Tokyo and Kanagawa. The latest set adds maps for Iwate, Shizuoka, Nagano, Yamanashi, Gifu and Toyama. Akita, Yamagata and Niigata have also been surveyed and are shown on the overview map.

The most heavily contaminated areas are in the eastern half of Fukushima prefecture, within about 80 km of the wrecked nuclear power stations. The southern part of Miyagi to the north and the northern part of Ibaraki to the south also took a hit.

A major radioactive plume moved south-west from Fukushima, polluting the northern half of Tochigi and the northern and western part of Gunma. A separate plume reached the southern part of Ibaraki, the north-west of Chiba and the eastern part of Tokyo.

There is also some caesium in the mountainous far west of Tokyo and Saitama that extended from Tochigi, but most of Saitama, Tokyo and Kanagawa seem relatively OK, as are Shizuoka, Yamanashi, Nagano, Gifu, Tokyama, Niigata, Yamagata and Akita. There is some fallout in a strip from southern Iwate to northern Miyagi, while central Miyagi and the rest of Iwate look clean. There is no published data for Aomori and Hokkaido yet, but based on the distance and the absence of significant pollution in Akita and adjacent parts of Iwate they will probably be fine.

The maps only give the overall picture, as there may be local hotspots in areas that are relatively clean overall, based on rainfall and wind patterns as well as soil and vegetation that can retain more or less fallout.

Update 2011-12-06:
The ministry has also published radiation maps for Aichi, Aomori, Ishikawa and Fukui prefecture.

How (not) to decontaminate Japan

An article in Japan Times (2011-11-09, “Scrub homes, denude trees to wash cesium fears away”) provided advice on how to decontaminate areas affected by nuclear fallout, such as in Fukushima, Tochigi and northern Chiba prefecture. Most of the advice is sound, but some is downright alarming:

As for trees, it’s best to remove all their leaves because of the likelyhood they contain large amounts of cesium, Higaki [of University of Tokyo] said.
(…)
What should you do with the soil and leaves?
(…)
Leaves and weeds can be disposed of as burnable garbage, a Fukushima official said.

So let me get this right: you should collect all those leaves because they contain so much radioactive cesium (cesium 134 has a half life of 2 years and cesium 137 of 29 years). And then, when you have all that cesium in plastic garbage bags, you have it sent to the local garbage incinerator, so the carefully collected cesium gets spread over the whole neighbourhood again via the incinerator smokestack. That makes no sense at all.

My Terra-P dosimeter (MKS-05) by Ecotest

Yesterday my geiger counter arrived here in Japan. It is a Terra-P dosimeter made by Ecotest, a company based in L’viv/Ukraine, about 300 km west of Chernobyl.

I bought the device on eBay from a supplier in Australia for US$399 including shipping. It arrived within 9 days and seems to work well. Although the buttons on my Terra-P are labelled in Cyrillic (either Russian or Ukrainian) and so is the manual, English manuals for it are easy to find online, so that’s not really a problem.

The Terra-P is a consumer grade dosimeter, so it’s not quite as versatile or as precise as professional devices costing $1000 or more, but it covers the basics very well. Its power source are two AAA-batteries, accessible via a lid at the back of the unit, which are easy to replace. It measures gamma rays and is suitable for checking for caesium contamination.

The user interface consists of an LCD, two buttons and speaker. One push of the right hand button (“режим” = mode) switches the dosimeter on and puts it into the measuring mode. The display switches to a microsievert per hour (µSv/h) readout. For the first 70 seconds the resulting number blinks, as it averages the dose over that period and the number gradually becomes more meaningful. After the initial sampling period, the number displayed will always be the average of the last 70 seconds, so you can move it from location to location and will get a decent result provided you wait for about a minute.

After several minutes the device enters power save mode, in which it continues counting radioactive decays, but the LCD is off and less power is used. To turn it off completely when it’s active, push the mode button once more and then push and hold it for four seconds, until the LCD blanks.

The Terra-P also has a user-settable alarm threshold (default: 0.30 µSv/h) and a clock mode. The built-in speaker usually makes one click for every gamma photon detected and sounds an alarm if the radiation exceeds the alarm threshold.

Checking my home after unpacking the device, I found the radiation level was a little higher than the 0.055 µSv/h reported for Tokyo by the local government, but still somewhat lower than the 0.10 µSv/h in my home town in Germany. On the other hand, I was relieved to see the wooden deck outside our living room was no more radioactive than inside the house. As expected, the gutters at the edge of the road, where rain water drains into the sewers, was more radioactive, with about 0.20 µSv/h, which is still far from alarming.

See also:

Radiation map of Japan

The Japanese government has published online map data about radiation levels in Eastern Japan. You can zoom in and out, scroll around and select data from:

  • Background radiation in microsievert per hour
  • Contamination by caesium 134 and 137 combined (Cs-134+Cs-137) in becquerel per square metre
  • Contamination by caesium 134 (Cs-134) in becquerel per square metre
  • Contamination by caesium 137 (Cs-137) in becquerel per square metre

The data was collected via helicopter flights carrying instruments that detect gamma radiation of different energy spectrums, allowing a breakdown by isotopes causing it.

There are the following data sets:

  • April 29
  • May 26
  • July 2
  • Miyagi prefecture, July 2
  • Tochigi prefecture, July 16
  • Ibaraki prefecture, August 2
  • Chiba and Saitama prefecture, September 12
  • Tokyo and Kanagawa prefecture, September 18

Click on this link:

either the online maps or download PDF files of the maps and click on “同意する” (“I do agree”, the left button) to get access.

The government is planning to extend the radiation survey to the whole of Japan, not just within about 250 km of the wrecked reactors as is currently the case.

See also:

Tepco’s unfiltered vent path

On August 13, 2011 I wrote about TEPCO not adding filters to their reactors even decades after Sweden did. Since the, on August 16, 2011, Tepco defended not having any kind of filters in the so-called “hardended vent” path between the containment and the exhaust stack:

Corrections and Clarification of a news report program, “ETV Special” by NHK, broadcasted on August 14

August 16, 2011
Tokyo Electric Power Company
NHK TV program regarding Fukushima Daiichi Nuclear Power Station reported contents that are incorrect and could cause misunderstandings. We hereby provide facts below.
(…)
3. Claim on the PCV ventilation has no filtration
In the program, it was mentioned several times that there were no filters in the primary containment vessel ventilation line. However, boiling water reactors that we operate use “wetwell vent”, which has scrubbing effect to mitigate emission of radioactive materials at the comparative level to the filters. That is to say, in principle, our venting procedure uses the water in the suppression chamber as filteration and we have prepared and added the necessary equipment and procedures for accident management measures.

Tepco’s reactors have a “Standby Gas Treatment System” for filtering gases released into the atmosphere. This system is claimed to be at least 97% effective in unit 1 and at lest 99.9% effective in units 2 and 3. However, it can’t be used for venting high pressure gas from the drywell or wetwell (the containment) in emergencies. In the above press release Tepco defends its decision by claiming that the water pool in the suppression chamber (wetwell) is as effective as some other kind of filter system that it could have had installed when adding the hardended vent path in 1999-2001.

This claim is disingenuous. The FILTRA system installed at the Swedish Barsebäck nuclear power station was in addition to any filtration provided by the wetwell pool, not in place of it. Barsebäck had boiling water reactors like in Fukushima (the plant has since been decommissioned).

Furthermore, it’s not clear how effective the filter effect of the wetwell on its own really is. A US report from 1988 entitled “Filtered venting considerations in the United States” writes:

Within the United States, the only commercial reactors approved to vent during severe accidents are boiling water reactors having water suppression pools. The pool serves to scrub and retain radionuclides. The degree of effectiveness has generated some debate within the technical comnunity. The decontaminatlon factor (DF) associated with suppression pool scrubbing can range anywhere from one (no scrubbing) to well over 1000 (99.9 % effective). This wide band is a function of the accident scenario and composition of the fission products, the pathway to the pool (through spargers, downcomers, etc.), and the conditions in the pool itself. Conservative DF values of five for scrubbing in MARK I suppression pools, and 10 for MARK II and MARK III suppression pools have recently been proposed for licensing review purposes. These factors, of course, exclude considerations of noble gases, which would not be retained in the pool.

The decontamination factor of 5 for the Mark I containment (as used in units 1 through 5 of Fukushima Daiichi) means that 80% of the radioactive substances (excluding noble gases) is retained, while 20% is released. The FILTRA system installed at 10 Swedish nuclear power plants and one in Switzerland is designed to ensure that in a severe accident 99.9% of core inventory is retained in the containment or the filters. The difference between releasing up to 20% versus 0.1% is huge, it means up to 200 times more radioactivity is released in the system defended by Tepco versus the enhanced system used in Europe and commercially available worldwide.

Fukushima: Keep out indefinitely

The government of Japanese prime minister Kan is finally telling evacuees from within the 20 km exclusion zone around the wrecked Fukushima-I nuclear power plant that they won’t be able to return any time soon.

For months the official line had been that residents could not return until the reactors had achieved “cold shutdown”, which normally means that the chain reaction had stopped and the decay heat in the core had subsided enough for the coolant to be below 100 degrees C (below boiling point). This line ignores the fact that three of the reactors no longer have a cooling system in the usual sense and more importantly, that the area around the power station was severely contaminated by radioactive fallout from the broken reactors.

That reality has finally been accepted, explains the New York Times:

The government was apparently forced to alter its plans after the survey by the Ministry of Science and Education, released over the weekend, which showed even higher than expected radiation levels within the 12-mile evacuation zone around the plant. The most heavily contaminated spot was in the town of Okuma about two miles southwest of the plant, where someone living for a year would be exposed to 508.1 millisieverts of radiation — far above the level of 20 millisieverts per year that the government considers safe.

The survey found radiation above the safe level at three dozen spots up to 12 miles from the plant. That has called into question how many residents will actually be able to return to their homes even after the plant is stabilized.

Many of the evacuees had been led to believe that most of them might be able to return to their homes some time after the turn of the year, based on Tepco’s promises of establishing some sort of a cooling system and generally stabilizing the situation at the plant. Probably over 100,000 people will have to rebuild their lives from scratch elsewhere now, with no prospect of returning for decades, just like in the exclusion zone in Ukraine and Belarus near the Chernobyl plant, that has been off-limits for over a quarter of a century already. Besides a semicircle of 20 km radius around Fukushima-I there is also a strip of land to the North West, towards Fukushima City, that includes the village of Iitate mura, which is just as badly contaminated as the vicinity of the reactor itself.

People from the area should have been told much sooner, but presumably the prospect of having to pay compensation played a part in holding off giving people the facts. If somebody other than Kan was prime minister, they may well have waited for another 6 months. Kan will probably step down shortly and frankly I don’t hold much hope for how his successor, whoever he may be, will deal with the situation.

Kan famously took on ministerial bureaucracies and vested interests as health minister before and he tried his best in this situation. Many others would try to avoid confrontation with the nuclear industry, following the path of least resistance instead. Kan’s support ratings are extremely low now, but perhaps his efforts, however imperfect they were, may not be fully appreciated until we have his successors to compare with…

Tepco and the dirty secret of the radioactive stack

On July 31, 2011 Tepco detected a radioactive hotspot at the base of an exhaust stack serving units 1 and 2 of Fukushima Daiichi. The following day, a measurement showed the activity to be more than 10 Sv/h (10,000 mSv/h), the highest measured in any accessible part of the wrecked nuclear power station so far (see “The worst hot spot in Fukushima“).

The high activity is assumed to date from attempts at venting the containment of unit 1 on March 12, after it had suffered core damage the previous evening. The venting, necessary to prevent the containment from bursting from excessive pressure, used a so called “hardened vent path” installed by Tepco between 1999 and 2001, following similar upgrades in the US after the Three Mile Island accident.

The reactors have filter system known as the “Standby Gas Treatment System” (SGTS), located on the second floor of the reactor building right next to the turbine hall, but the SGTS doesn’t work without electricity, i.e. the condition that triggered core damage in Fukushima Daiichi. Also, gas from the containment is released at high pressure, which would overwhelm the SGTS.

Therefore the gas is released untreated. Via a strong steel pipe it flows directly into the base of an over 100 m tall exhaust stack. High altitude winds carry it away from the plant. The only filtering that has taken place before than is by water in the pressure suppression pool at the bottom of the containment, through which any gas releases from the reactor pressure vessel are forced to bubble. As the high radioactivity level around the stack demonstrates some 5 months later, there is still plenty of activity left in the gas after that “wet scrubbing”.

It didn’t have to be that way. First of all, if Tepco had built the reactors at a higher location or surrounded them with a sea wall to protect them from a 14 meter high tsunami, there probably would not have been a total station blackout and hence a failure of the residual heat removal system (RHR). The cores wouldn’t have melted. It has long been known that the relatively small Mark 1 containment of these Boiler Water Reactors (BWRs) have problems dealing with vast volumes of hydrogen gas produced when core damage occurs. There was no way to make the containment bigger, short of decommissioning the old reactors and building new ones, which would have cost a lot of money. But that wasn’t the only option.

In 1981, Sweden came up with the FILTRA system for their Barsebäck nuclear power station, which consisted of two BWRs similar in size and functionality to the units in Fukushima. Construction of Barsebäck had started in 1969, only two years after the first unit in Fukushima. It was located about 500 km south of the Swedish capital of Stockholm, but only 20 km from the Danish capital of Copenhagen. The Copenhagen metropolitan region is home to about 1.9 million people in Denmark and South Sweden is also one of the most densely populated parts of the country.

The FILTRA system consists of concrete pipes or rock tunnels filled with gravel, through which the released gas must flow. It gives off heat to some 10,000 m3 of rock, which condenses steam and radioactive fission products, which collect at the bottom of the gravel chambers. After the gas has cooled it is sent through sand or water for further filtration. Only then is it released in the stack. The system is simple and robust enough to cope with high pressure and temperatures. Since it doesn’t use any high technology it was relatively cheap to build.

There was plenty of space available at Fukushima. The Swedish system was no secret. Here is the 30 year old report that discussed its details. Why did Tepco not build a filter system like that, to be shared among its 6 units at Fukushima Daichi? By building the hardened vent path, it already admitted to the possibility of a core meltdown, so why not make sure the venting could be cleaned up? Perhaps Tepco didn’t want to spend more money on safety than it absolutely had to. Perhaps it was also because the Swedish reactors were designed by Asea-Atom AB, whereas the Fukushima design was by GE. Whatever the reason, the technology to protect the people of Japan in a nuclear accident has been available for three decades and Tepco chose not to use it.

The worst hot spot in Fukushima

A week ago, Tepco detected radiation exceeding 10,000 mSv/h (i.e. 10 Sv/h) at an outdoor location near unit 1. This is the highest dose so far recorded outside a reactor core at the site. The previous record was 4,000 mSv/h in unit 2. To put this in perspective, about 7 Sv is already a fatal dose. Therefore 40 minutes at that location would mean certain death from radiation sickness. The local hourly dose of 10 Sv is 100 times as much as the 100 mSv a nuclear worker may normally be exposed to over a total of five years. It is 40 as much as the 250 mSv the government has permitted workers to be exposed to during the Fukushima disaster efforts.

While it’s alarming to hear about record radiation levels being found months after three of the reactor buildings exploded, most likely this radiation is not something new but has been there since the early days of the disaster. It was detected at two locations, an outdoor stack serving units 1 and 2 for venting purposes, and an indoor filter room on the second floor of the turbine hall of unit 1. Both locations are connected using a high pressure steel pipe used for emergency venting. Tepco recently started some construction work near the stack, erecting a steel and plastic cover around unit 1 and perhaps that increased human activity around there led to the discovery.

When Fukushima-I was hit by a station blackout (total electric power failure) after being flooded by a 14 meter high tsunami on March 11, 4 of its reactors and their spent fuel pools were left without cooling. As a result, the cores of units 1, 2 and 3 overheated and their fuel rods melted. During the overheating, steam was vented from the reactor pressure vessel into the suppression chamber of the containment vessel, until the relatively low design limit of the containment was exceeded. In order to not risk an explosion, the operators at that point decided to release radioactive gasses from the containment through the emergency venting system, which is connected to the exhaust stacks.

If during normal operation of the power plant any gases have to be released, they are treated via the Standby Gas Treatment System (SGTS), which comprises HEPA filters followed by active charcoal filters. The unit 1 SGTS is claimed to capture better than 97% of iodine, while units 2 and 3 have a claimed retention rate of better than 99.9%. Treated gas is sent by electrically operated blowers to the exhaust stack, where winds would usually disperse it over the sea. If you look at aerial pictures of the station (see last picture), you see large pipes running from the units to the stacks. Unit 1 and 2 share one stack, units 3 and 4 another (unit 4 was shut down for repairs at the time). These are low pressure pipes, designed for relatively slow releases. Each unit has two systems capable of handling 0.5 m3/s (unit 1) or 0.75 m3/s (units 2/3) each. Because the SGTS relies on electric blowers it is not usable during a total station blackout.

Next to the fat pipes are much thinner high pressure pipes, which are part of the “hardened venting system” installed by Tepco between 1999 and 2001. They were added specifically for major disasters, when the pressure inside the containment reaches dangerous levels, requiring an urgent release of pressure. The hardened venting system skips the charcoal filters. Its only filtering mechanism is the water pool in the suppression chamber, through which steam vented from the reactor core first bubbles. Its scrubbing effect is much more crude than the normal gas filters. The efficient filtering system can not be used during high pressure containment venting because it would offer too much resistance and could not stand the heat or pressure of an emergency release. Yet I still remember when a government spokesman announced that Tepco was going to vent the unit 1 containment into the atmosphere on March 12, we were told that the venting would be filtered, which wasn’t really true.

radiation measurement at bottom of unit 1/2 vent stack

A June 2011 report by the Japanese government to the IAEA explains on page IV-13:

TEPCO built new vent pipes extending from the S/C and D/W [suppression chamber and dry well, the two parts of the containment vessel, JW] to the stacks from 1999 to 2001 as PCV [primary containment vessel, JW] vent facilities during severe accidents as shown in Figs. IV-2-13 and IV-2-14. These facilities were installed to bypass the standby gas treatment system (hereinafter referred to as SGTS) so that they can vent the PCV when the pressure is high.
The facilities are also provided with a rupture disk in order to prevent malfunction.

As the pressure dropped in the hot, compressed gases from the containment and they came into contact with the cooler pipes leading to the stack, the gas cooled off and there was condensation inside the pipes. Some radioactive fission products from the melted fuel rods must have been deposited on the pipe walls. Radiation from these deposits is penetrating the pipe walls, causing high levels at the base of the exhaust stack and inside the filter room through which the venting pipe runs.

What we eat after Fukushima

When people ask me how things are here in Japan after the Fukushima nuclear disaster, I tell them life is mostly normal for my family down here in Tokyo, except that we are very careful what we eat. Given the relatively high food prices in Japan I used to pay more attention to how much things cost, but now I watch more where everything is from. I do it not just for me and my wife but also for our kids (two teenagers).

I really do feel sorry for the farmers in areas affected by the radioactive plumes released after the cores of units 1, 2 and 3 melted down and the buildings of units 1, 3 and 4 blew up in hydrogen explosions, but I largely avoid several prefectures as places of origin. I do not have faith in the government or the food distributors to protect us. The sad fact is, there is very limited capacity for inspections and the surprises just keep on coming. Consumer level geiger counters are not suitable for food safety inspections. That takes high end hardware that costs more than US$100,000 apiece and it’s very time consuming. There are not many of these machines around.

Much of the early radioactive scares were about iodine 131, which decays with a half life of only 8 days. It showed up in Tokyo drinking water and in leafy vegetables as far south as Chiba, in Tokyo’s commuter belt. Within 2 months more than 99% of that I-131 had decayed. By now it’s no longer an issue.

Then attention turned to cesium, which is a more long term problem. It will be with us for much longer, for the rest of our lives in the case of Cs-137 (half life: 30 years). If ingested, about half of radioactive cesium is removed again from the body every 3 months, so it’s not as severe as strontium, which stays in the bones forever, but any internal contamination must be taken seriously. There are parts of my native Bavaria, 1200 km from Chernobyl, where 25 years later most wild pigs shot by hunters still have to be disposed of because they exceed government limits for radioactive cesium. They tell us the radioactive release from Fukushima was much smaller than from Chernobyl, but we’re also much closer to it than Germany was to Ukraine and much of our food is grown even closer to it.

Japanese tea as far away as Shizuoka, some 300 km from Fukushima-I, has exceeded government limits for cesium. Rice straw from northern Miyagi prefecture, some 150 km north of Fukushima-I was too contaminated to be fed to cattle.

Rice prices in shops have increased 20-30% recently, from under 1500 yen per 5 kg bag to 1800-2000 yen per bag. This is the result of consumers stocking up on 2010 rice ahead of the next harvest, which is less than 2 months away. People appear to be concerned about what levels of cesium will be measured in 2011 rice. Beef exceeding government limits had already made it to supermarket shelves and dinner tables before the problem was detected, so people are naturally concerned if this won’t also happen with rice. It’s not an easy problem. By mixing rice from different areas, perhaps no single bag of blended rice exceeds government limits, but that is not the answer. According to current scientific theory, a given amount of radioactivity does not cause fewer cases of cancer by spreading it over more people. The proper answer would be to test rice from every field that is potentially affected and exclude rice from contaminated production areas. Naturally farmers will want compensation for food that can’t be sold, which ultimately will be paid by the government. This sets up a direct conflict of interest: The more testing the government does and the more it does to not dilute contaminated rice among uncontaminated rice, the more money it will have to pay to farmers. It is hard to have confidence that consumer safety will take priority under these circumstances.

A lot of the vegetables for stores in Tokyo are grown in Ibaraki, Fukushima prefecture’s southern neighbour, but whenever I can, I buy produce grown either further north (Hokkaido, Aomori) or further west or south (Gunma, Nagano, Shikoku, Kyushu) or imported (e.g. South Korea). Hokkaido in the far north is about as far from Fukushima-I as Kansai (Osaka, Kyoto) is to the west. Most of the dairy products on my shopping list are now from Hokkaido. Our sea food consumption has gone way down compared to pre-3/11 levels.

Domestically produced (koku-san) foods have been near-religiously venerated in Japan for many years. Consumers have been paying huge markups to eat domestically grown food instead of imports and expected the price to reflect higher quality. For example, I could buy twice was much Chinese eel or three times as much Chinese garlic as their Japanese equivalents for the same money. The Japanese government has maintained domestic rices prices above world market levels. People here always had some suspicion about pesticides or other contaminants in imported food, especially from China, but also from the US. With the nuclear disaster, the tables have turned. Gone is the assumption of safety of “koku-san” food, which will make it hard to maintain the price premium that came with it. The radioactive contamination problem is not just a health worry for millions of Japanese, it is also a devastating blow for the future of farmers and fishermen across much of Japan.