Decon or Con? How is remediation being managed, and how effective is it?

In ニュース, 主要記事, 放射線, 測定, 論説 by azby


Does the Japanese government have a clear plan for decontaminating Fukushima Prefecture? Are the aims they’ve stated really feasible? Is anyone really able to keep track of the changing standards and guidelines? Lately the ministries tasked with managing this work, as well as spokespersons from various corners, seem to be falling all over themselves acknowledging on the one hand that the work is falling short but insisting on the other that it’s been successful. How reliable is government information about decontamination, and is it possible to weed through the contradictions to find some real data on which to base decisions?

We’d like to argue that yes, it’s possible to find informative data. But as has been the case with so many aspects of the post-Fukushima infosphere, it’s necessary to know exactly where to look, and it helps to have your own data handy for comparison.

Safecast wanted to survey a few sites that had been decontaminated and compare our readings with official before-and-after readings taken by the government. It ended up being extremely time-consuming to locate appropriate sites and get our hands on detailed government data. In this long blog post, we cover as much ground as possible, literally and figuratively. We describe what we found out, and what we had to do to find it out, and come up with a few conclusions. We provide plenty of maps and links to original sources of information. Since it’s long (did we mention that already?) here’s a brief synopsis and jump links:

Part 1: GOALS and POLICIES: Many places in several prefectures fall under decontamination guidelines of some sort, many more in fact than most people realize. We explain how the government has divided land into different categories for decontamination, how it’s intended to work and what it’s intended to accomplish, and who has responsibility for various areas.

Part 2: FINDING INFORMATION: One of the biggest problems with the decontamination process so far has been communication. Technically speaking, the government provides information to the public openly about decontamination policies, practices, and progress, but as has often been the case, it takes a bit of sleuthing to find it. No wonder people get upset and feel uninformed and misled. We discuss these and other criticisms, look at some official publications, and make some recommendations for improvement.

Part 3: OUR COMPARISONS: Depending on the particular conditions of any site, it may or may not be worthwhile to spend a lot of time and money decontaminating it, since natural decay and weathering achieve the same ends very effectively in some cases. We surveyed two sites in Fukushima that had been decontaminated in late 2011- early 2012, and estimate what the levels would have been if they had not been decontaminated.

SOME CONCLUSIONS:Was all the decontamination worth it? The answer is, “In some cases at least.” We explain why, and what we might expect to see in the future.

Iitate schoolyard

This schoolyard in Iitate was decontaminated in January, 2012. Will it ever be deemed fit to use again?


Recently the Asahi Shimbun published a news item about changes in government decontamination plans titled Government secretly backtracks on Fukushima decontamination goal.

To summarize the situation as described in the article:

  • The govt initially considered it feasible to decontaminate residential areas of 11 municipalities in Fukushima Prefecture to a exposure level of 1 millisievert annually (1mSv/y) of additional radiation (above natural background), by March 2014.
  • The work is behind schedule in five of the municipalities, and will need to be continued through fiscal 2014.
  • 25 municipalities have said that radiation levels have yet to decline to 1mSv/y in some of their areas even after decontamination work was completed.
  • The government will not pay for additional decontamination work in areas where work has already been done, i.e., if they tried and couldn’t get levels down to 1mSv/y, they will not allow a second round of work.

Most of the areas in question are places where residents were required to evacuate, and adequate decontamination is a prerequisite for their return. The article also notes that, “Citizens are also having growing doubts on the cost-benefit performance of the decontamination work.”

Evacuation zones as of August, 2011.

Official map of evacuation zones, as of May 7, 2013.

Link to map pictured above

English-language government document from March 30, 2012, giving basic definitions of the 3 types of evacuation zones, in terms of dose rates, etc..

It’s important to understand that the policies and practices in place in areas which were evacuated by government decree are different from how unevacuated areas are being handled. The problems surrounding how the evacuation zones themselves were initially determined, the political decisionmaking, the failure to utilize all the available information about which areas were at risk (particularly SPEEDI), the lateness with which the decision to evacuate areas to the northwest was made, including Iitate and parts of Namie, Minamisoma, Katsurao, and Kawamata: all of these contentious issues are too involved to be discussed in detail here. But it can’t be emphasized enough that every aspect of the management and implementation of the movement of populations, of the remediation process, of health monitoring, of food monitoring, of just about everything that has happened in Fukushima since March, 2011, is rooted in these hastily-made, flawed decisions about where to draw the lines dividing those who were allowed to stay from those who weren’t.

Decontamination, or remediation, of evacuated areas is being directly managed by the national government (chokkatsu josen), and almost all the news we hear, including the above, relates to these efforts. The attention paid to this is understandable, because the return of evacuees and their health and livelihoods are at stake. Also, the areas with the highest ground contamination, and therefore the most difficult to decontaminate, lie within this zone. Other areas, such as the cities of Fukushima and Koriyama, manage their own decontamination. In most cases subsidies help support it, but it is essentially a local effort. In fact, parts of these cites are more contaminated than some of the evacuated zones, and although the government has tried to reshape the boundaries step by step based on actual contamination levels, overriding the original 20km circular arc, centralized oversight of decontamination is not based on the dose rates as much as it is a legacy based on where the government told people they had to leave.

In fact, when the “Act on Special Measures Concerning the Handling of Radioactive Pollution” came into force in January, 2012, areas that were deemed necessary to receive decontamination assistance were divided into two areas overall, the “Special Decontamination Area”, where decontamination is implemented by the national government, and the “Intensive Contamination Survey Area”, where decontamination is implemented by each municipality with financial and technical supports by the national government. Another way to describe these are “evacuated areas” and “unevacuated areas”. The “Special Decontamination Area” was initially further divided into two categories, the “Restricted Area” (located within 20km radius from the Power Station) and the “Deliberate Evacuation Area” (areas where the annual cumulative dose could exceed 20mSv); together these included 11 municipalities in Fukushima prefecture. These areas were reconfigured later into the three zones described above.

The “Intensive Contamination Survey Area”, where decontamination is implemented by each municipality with financial and technical supports by the national government, includes not only unevacuated towns in Fukushima, but over 100 municipalities in 8 prefectures where additional doses over 1mSv/y were determined to be likely. Because of this, not only is Fukushima receiving decontamination assistance, but also much of Tohoku and Kanto. In order to manage this large project, the Ministry of the Environment has 500 staff, at its headquarters in Tokyo and in two regional offices; the Fukushima Office for Environmental Restoration (in Fukushima City) covers 53 municipalities in Fukushima, Iwate, and Miyagi, and has five branch offices, while the Kanto Regional Environment Office in Saitama covers 51 municipalities in Tochigi, Ibaraki, Gunma, Chiba, and Saitama.

Maps of “Intensive Contamination Survey Area” and “Special Decontamination Area”

Description and maps of “Special Decontamination Area” and “Intensive Contamination Survey Area”

Organizational Chart for MOE Decontamination Management

In terms of dose reduction targets decided upon in early 2012, the following charts from the MOE’s “Off-site Decontamination Measures” homepage describe the basic goals.

Government Exposure Reduction Targets

Decontamination Policy for Special Decontamination Area

Finally, these documents describe policies and procedures in place at the end of 2012, and report progress towards the goals the government had set:

Decontamination Policies and Procedures in Japan

Progress on Offsite Cleanup Efforts in Japan


The underlying purpose of evacuation and decontamination, of course, is to minimize harm to people from the radiation the accident released into the environment. This is not the same as keeping people “safe,” however, because absolute safety is known to be unattainable. Rather, the pragmatic goal is to keep people “safe enough.” A lot is known about the hazards of radiation, but not really enough to allow specialists to assess the health risks in most parts of Fukushima with absolute confidence.

The Japanese government relied on the IAEA for guidance about how much radioactive contamination was too much, which is what most governments would do when faced with a similar disaster, and the 1mSv/yr and 20mSv/yr standards for evacuation and decontamination emerged mainly from the government’s consultations with the IAEA. 20mSv/yr can be called the “don’t let people live with this much radiation, at least not for a long time” level. So in areas with this level of contamination, residents were required to be evacuated, and can be allowed to return if decontamination is effective in reducing their potential doses significantly, and if the level of contamination can realistically be reduced to 1mSv/yr or less in the span of several years.

In this sense, from the standpoint of the government and the IAEA, the 1mSv/yr level can be called the “clean for all practical purposes” level. Radiation health specialists continue to debate the risks these dose levels present, but it seems even the most outspoken anti-nuclear activists and concerned residents in Japan have been willing to accept an extra 1mSv/yr; and while the point is often made by people with questionable motives, the fact is that adding even more than 1mSv/yr to background radiation levels in Japan would still keep it well within the typical range of normal background radiation worldwide, which is about 1 to 3 mSv/yr (not including so-called “high natural background radiation” areas like Ramsar, Iran, and Kerala, India, which are many times higher). Finally, it’s important to point out that these calculations and estimates deal with people’s risk from external contamination exclusively, and not with internal contamination, particularly from food, which warrants its own separate guidelines and monitoring, and which needs to be carefully accounted for when evaluating people’s overall exposure risks.

Both the “1mSv/yr” and “20mSv/yr” target levels are for additional doses beyond the pre-disaster background. The government’s dose rate calculations are not based on simple arithmetic, but assume dose reduction benefits from the shielding provided by buildings, and reflect an attempt to account for time spent indoors. To determine the amount of radiation coming from contamination, the pre-existing background radiation needs to be subtracted from whatever reading is obtained in any one spot. Terrestrial background gamma radiation (from the ground) in Fukushima ranges from about 0.03-0.06μSv/hr, higher towards the coast in the east and the mountains in the west, and lower in the center of the prefecture. In its allowable dose calculations, however, the government uses a figure of 0.04μSv/hr for terrestrial gamma radiation. To calculate the allowable level of additional radiation beyond that, instead of simply multiplying air dose rates by 24 hours and 365 days, the government assumes that people would spend 16 hours a day indoors, during which they would only be exposed to 40% of the dose. They arrive at a total figure of 0.23 μSv/h allowed in order to stay under 1mSv/yr from the “additional” radiation. That is: 0.04μSv/h [from background] plus 0.19μSv/h [from accident] = 0.23 μSv/hr total.

Japanese-language MOE page describing 1mSv/yr dose rate calculations, April 2011

Similarly, the 20 mSv/year limit becomes an hourly dose of 3.8 μSv/h, instead of the 2.28 μSv/h that simply multiplying 24 hours x 365 days would lead to. The government reports linked below state that schoolchildren whose school yard gives a 3.8μSv/h dose would actually receive only 10mSv/yr once actual school days and hours spent indoors were taken into account.

Japanese-language MEXT page describing schoolyard dose rate calculations, April 2011

English-language explanation of schoolyard dose rate calculations

On the one hand, this seems like the government is fudging the calculations in order to find a way to allow people to get higher doses, but subsequent personal dosimeter (“glass badge”) surveys of residents in most parts of Fukushima Prefecture have indicated that for most residents actual received doses are significantly lower than the estimated environmental dose rates based on these calculations would suggest. Others say that the government should subtract more from current readings to more accurately reflect the pre-existing background in the most affected areas closer to the coast, and should try to find a way to accurately subtract the contribution from cosmic radiation as well; the government simply ignores the 0.03μSv/hr Japan gets from cosmic radiation as too difficult to measure accurately with standard Nal scintillators under field conditions (a questionable assumption for several reasons).

Adjusting the terrestrial background estimates to be more accurate, and including the contribution from cosmic radiation as well, would mean a higher natural dose would be subtracted from current measurements, and generally result in lower contamination readings. But the 40%,16-hours-a-day shielding coefficient is probably not accurate for most residents; quite a few probably spend less time indoors, while some spend more, and the shielding afforded by buildings varies widely with their size, placement, and type of construction (indeed, recent surveys have shown that some Fukushima residents, albeit very few, actually receive a higher dose indoors at home than outdoors).

Some observers point out that the 0.23μSv/h allowable dose rate is arbitrary in so many respects that it should be replaced with evacuation guidelines based on continually-gathered, individual data reflecting the actual doses being received, replacing hazy estimates of what people might get with accurate measurements of what they actually are getting. Still, we can understand the concern and suspicion that met these calculation decisions. Residents deserve a significant margin of safety, and decisions based on “best case” scenarios are questionable. Nevertheless some fairly arbitrary assumptions like these underlie the entire decontamination project.


As the IAEA pointed out in late 2011:

“In the Japanese administrative system, municipalities and prefectures have strong autonomy and play significant roles in disaster management and environmental protection, including the remediation process. The national government provides the legal framework, policies, standards, and financial and technical support, and conducts remediation for areas which are in “emergency exposure situations”

In this case, “emergency exposure situations” specifically refers to areas where citizens could be exposed to an annual dose above 20 mSv. Local governments implement remediation plans for areas which are in “existing exposure situations”, i.e. areas below 20 mSv/y, and the IAEA reported that in Japan, “In these areas the ultimate decision whether to remediate or not rests with the landowner.”

It was never so simple. This combination of local autonomy and the necessity of adhering to centrally-determined guidelines has had many real-world consequences in Fukushima, for better and for worse. The dominance of the central government overall cannot be underestimated; it sets the legal conditions and consequences, and can choose to provide or withhold funds. In so many aspects of post-3.11 recovery, the central government makes decisions, the prefectures try to stay on the good side of the central gov’t, and the local governments try to stay on the good side of the prefectures. Because there are many unevacuated towns, and each can make its own decisions about what, where, and when to decontaminate, and because policies and practices have been evolving over time, it’s very difficult to collect enough information to gain a good overview. But things often work better when the local governments are handling the details. To give one example, a contact in who lives in Koriyama pointed us to the relevant parts of the city’s website.

The front page of Koriyama City’s site has a link to decontamination info, which leads to maps, schedules, tenders, and results. Work commissioned in November 2012 was being completed in late June 2013, while work commissioned in December 2012 had not started yet.

A typical map available on the Koriyama City web site, showing areas of the city for which decontamination work bids are being sought. This one is from Oct., 2012.

Koriyama City decontamination info page

Official Koriyama City list of areas going out to bid for decontamination work (with maps)

Koriyama City decontamination general plan, last revised in January 2013

The general plan file linked to above includes a detailed map of radiation levels in Koriyama and surrounding towns, an explanation of how decisions are being reached, and timelines with achievement goals. They clearly point out how they are adhering the central government’s targets, prioritizing areas where children live and go to school, and aiming for a 50% dose rate reduction overall by August of this year (60% in areas with children), and to get the levels below 1 mSv/y (in addition to natural background) by 2015. Based on the quantity of detailed information available, and the clear efforts it has taken to inform citizens through PTAs, neighborhood associations, volunteer groups, and companies, and to pay attention to the feedback they have gotten, Koriyama seems to be managing its decontamination very transparently. Our contact described having received clear announcements of many setsumei-kai (“explanatory meetings,” i.e. Q&A sessions) with local officials, and attending several, and feels that the local government has been very responsive. Not all the residents feel that way, however, and a group of citizens filed a lawsuit last year demanding financial compensation for the voluntary evacuation of their children from the city. The plaintiffs lost.

Asahi newspaper, April 15, 2013: “Lawsuit seeks evacuation of Fukushima children”

Yahoo news, April 25, 2013: “Japan court rejects demand to evacuate children”

Koriyama City leaders seem to have realized that transparency and seeking the involvement of citizens is the best course of action. They don’t seem downplay or underestimate the challenges the city faces, either. Some people will continue to insist that parts of the city will always be too radioactive to live in safely, while the local government is making the case that it will only really be safe, and people will only really feel safe, if their decontamination goals are met within a reasonable time. We can’t say if this is the case or not in other Fukushima municipalities which are managing their own decontamination. We’d welcome comments from anyone with first-hand observations to offer.


The decontamination of forcibly evacuated areas is a different kettle of fish entirely. It’s hard to say that the process has been transparent, responsive, cooperative, or efficient by any standards. The background to the recent backtracking on decontamination goals in evacuated areas is that the Japanese government initially intended to just decontaminate down to a 20mSv/yr level, and only accepted demands from the public to set a 1mSv/yr level after much outcry and protest. In fact, the government had sought the guidance of the IAEA when setting these levels, and in October 2011, the IAEA recommended setting initial decontamination targets “in the range of 1-20 mSv/y,” with a “long term target of keeping the estimated annual exposure dose below 1 mSv.” According to graphs in the documentation at the time, the long-term that was being considered was about 20 years. In other words, 20 mSv/y was considered a realistic goal in all but the most hard-hit places, while 1 mSv/y was accepted from the beginning as an end goal, but only in some unspecified but distant future.

IAEA Final Report of the International Mission on Remediation of Large Contaminated Areas Off-site the Fukushima Dai-ichi NPP, Oct 2011

The initial optimism and promises were probably predicated on assurances from contractors that they had the manpower and techniques necessary to get living zones down to 20mSv/yr at first, and when asked to get it down to 1mSv, they promised to try. There has been some information as well that 5mSv/yr was suggested as a realistic alternative, but was considered politically unacceptable and was rejected. Quite a few of the early documents discuss results only in terms of a 20mSv/yr target, such as this comment on the JAEA (Japan Atomic Energy Agency) “Cleanup Navi” site:

Cleanup Navi: Fukushima Remediation Knowledge Base

Wide area decontamination:

“In terms of estimated annual dose reduction to less than the initial evacuation level of 20 mSv, this has been demonstrated for areas with annual doses of 20 – 30 mSv before decontamination. However, this goal could not be assured for areas exceeding 40 mSv before decontamination. In the case of highly contaminated agricultural and residential areas, the annual dose was decreased by 70%, but could not be reduced to below 50 mSv. In general, the fractional reduction was smaller in areas of relatively initial low contamination, compared with more highly contaminated areas.”

In other words, by early 2012, when pilot decontamination projects had been completed and the results examined, the government knew they could get areas with dose rates less than 30mSv/yr down to below 20 mSv/y, but not if they were originally 40mSv or above. In addition, they could reduce very highly contaminated areas (100-200mSv/yr or more) by as much as 70%, but still couldn’t get them below 50mSv/yr. At the same time, some of the techniques were shown to be extremely effective in certain situations, and judged to warrant optimism concerning many areas. The realignment of the evacuation zones last year and again in March, 2013 was intended to reflect this experience and the further progress that had been promised.

At this point, evacuation zones included the original 20km semicircle, as well as an additional “planned evacuation zone” to the northwest, encompassing Iitate and parts of other towns.

Evacuation zones were reorganized in March 2012, incorporating experience gained through decontamination trials, and areas were more specifically demarcated based on how effective decontamination was ultimately expected to be and how soon residents would be able to return.

Current boundaries follow environmental dose rates fairly closely, but divide many communities in the process. The reduction of radiation doses through natural decay and weathering over time, as well as optimistic projections of future gains through decontamination, have provided a rationale for progressively relaxing restrictions in many towns.

The line demarcating areas which were over 50mSv/yr in 2012 and not expected to be reduced below 20 mSv/y by any combination of technique and natural decay for the next 5 years (Area 3: the “Residence Prohibited Zone,” –indicated in Pink — which most of us refer to as the “Exclusion Zone”) is probably a very firm one. The over 25,000 people who used to live within the boundaries of this area have been told they will not be allowed to return for years, if ever, and various compensation settlements are being discussed. Nevertheless, at this point most are allowed to visit their property in the daytime with special permits, and local governments continue to hold out hope that most of their townships will eventually be repopulated. We occasionally hear of suggestions to turn this zone into a closed nature preserve, like that in Chernobyl, which strikes many of us as the safest and most beneficial course of action, but these plans do not seem to be taken seriously at high levels.

The other two evacuation areas, Area 2: “Residence Restricted Zone” (orange) and Area 1: “Preparing for returning Zone” (green) seem to have a much more conditional and ambiguous status. In the “Preparing” zone, on the one hand, quite a lot of progress seems to have been made in lowering additional doses in residential areas, at schools, etc., below 1mSv/yr, but not everywhere. And while roadside decontamination can be very effective, it usually extends only 10 meters away from the road, beyond which, in the woods and underbrush, we should not be surprised to find much higher levels, up to 20mSv/yr perhaps. And of course, a town can show fairly low readings overall and still have hotspots many times higher. Efforts are usually made to locate and decontaminate small hotspots, but usually only after request by residents, and often not very effectively.

In the “Residence Restricted Zone,” decontamination work is being carried out intensively, and travel within the zone is unrestricted. Like the “Preparing” zone, people are legally not allowed to live there, but authorities look the other way — there is no desire to forcibly remove people from their property. The dose rates in these areas were over 20mSv/yr before decontamination, but under 50, and where decontamination has been effective it can be much lower than 20mSv/yr. Governments and residents are holding out hope that enough decontamination can be done to allow people to return, but there is no guarantee this can be accomplished, and as we’ve learned, probably not enough money. Most of Iiiate-mura is in this zone, and the mayor of the town has continued to insist that the residents will be able to return soon, polarizing the town into those who wish to return as soon as it is allowed, regardless of the actual contamination levels, and those who demand greater assurance regarding the health consequences. This kind of polarization, which some have likened to a “war,” exists to some degree in every town that was subject to evacuation orders, and in many that were not.



It took a lot of hunting to find clear data on the effectiveness of decontamination in Fukushima.

If it’s hard for SAFECAST to find good information about the results of decontamination, it must be even harder for everyone else. Lack of transparency, changing goals and arbitrary guidelines, different sets of policies depending upon whether a town is in the evacuated zone or not; it’s hard to make sense of, and hard to figure out exactly where to place blame when things go wrong. But in the process of gathering data about decontamination sites we planned to visit, eventually were able to locate extremely detailed official information about how things were done and how much success the government was claiming for its efforts in specific locations.


For all the reasons described above and more, decontamination has been a contentious issue, criticized from the start on many sides for questionable effectiveness, poor oversight, and unclear goals. We generally side with the critics, while pointing out that sometimes problems may be found by journalists which on closer examination are not necessarily representative of general practice. It was hard to find clear information on what the goals are, what the plans are, what has been done, and what the results have been. This lack of clarity should probably be expected when so many players are involved: the JAEA (Japan Atomic Energy Agency) was tasked with organizing and implementing a pilot decontamination program in late 2011; three joint ventures were established at the time, centered on large construction companies: Obayashi, Taisei, and Kajima. The Environment Ministry seems to have taken a dominant role since early 2012, and the most detailed information comes from them now. Fukushima Prefecture and local governments are involved in selecting sites to be decontaminated and in monitoring and reporting progress. Lastly, there are dozens of smaller companies actually carrying out the work, with hundreds if not thousands of employees.

Report on the development of remediation pilot projects

This situation is ripe for abuse, and back in January, 2013, the Asahi Shimbun published a scathing series of exposes detailing sloppy work practices and fraud, titled “Crooked Cleanup:

“Crooked Cleanup” (possible paywall)

People were outraged, of course, and based on the reporting were justified in assuming that these kinds of abuses are commonplace. The only way to know for sure, however, if work was being carried out effectively, would be to allow independent monitors to check the levels at each site before work begins and again once it is completed, and to report their findings. While this kind of third-part verification is not expressly forbidden, and the decon workers we encounter usually are willing to talk with us (at least a bit), there is no official recognition process for “verifiers.” Safecasters usually end up feeling unnecessarily inhibited from taking readings. We can empathize with the decon workers as well, because even the conscientious teams are viewed with suspicion.

Recently, in Tamura, for instance, we stopped to chat with a couple of workers, including one who appeared to be a foreman, about their work. We introduced ourselves, of course, and described what Safecast does, and while they were friendly in return, the foreman felt obliged to tell us, unprompted, “We’ve got nothing to hide!” They politely declined our request for a photo, and when saying goodbye told us that they would have to report speaking with us. It was definitely a “Please go away!” vibe.

None of the citizens’ groups we know of, Safecast included, has the manpower that would be necessary to check every remediation site. And in the absence of trusted verification, residents will find ample cause for suspicion and will either stop caring, learn to live with uncertainty, or move away. Ideally local communities would find volunteers to do the verification themselves, but the fact is nearly every able-bodied male in the smaller towns is already doing decon work. There’s already a lot of social tension between those who vocally oppose the government’s policies and those who just want to get on with life; for neighbor to follow neighbor with a geiger counter is a sure recipe for long-lasting animosity.

Nevertheless, the government recognized the seriousness of the Asahi’s accusations, and quickly established the “Taskforce for Securing Appropriate Decontamination Works” in response. They found many of the criticisms to be justified, and announced the “Appropriate Decontamination Promotion Program” on January 18, 2013.

MOE Securing Appropriate Decontamination Works document, Jan, 2013

Interestingly, the ministry presents “Lack of viewpoints of locals and third-parties” as one cause of problems, and suggests “Effective monitoring by a third-party etc.” as part of the solution, along with “Collaboration w/ municipalities on check and info exchange” and “Information provision to the local residents about decontamination implementation (time and place).” But we have not been able to find out what is involved in becoming an accepted third-party monitoring group.

WHAT’S WRONG WITH HOW THEY COMMUNICATE? (And what are they doing right?)
As mentioned above, it’s been hard to find good information about what areas in the evacuation zones are scheduled to be decontaminated, what has been done already, and what the results have been. But lately, more than two years after the disaster, probably due to the “Appropriate Decontamination” initiative, the Environment Ministry seems to have gotten better about anticipating what people will want to know, and making it available online. The timing certainly suggests that this is the case.

For instance, maps like these showing decontamination progress in Naraha and Kawauchi can now be found online (the maps linked to are for the week of May 27, 2013, but more recent ones are also available). Only a few are available at this point, and they seem to have magically appeared a few months ago, but they are welcome:

Naraha decontamination progress May 25, 2013

Kawauchi decontamination progress May 27, 2013

Other decontamination schedules can be found here:

Decontamination schedule 5-31-2013

This map available online shows the areas of Katsurao scheduled to have decontamination work done the week of June 25, 2013. Maps like this were once nearly impossible to find but now are more easily available.

A fairly detailed English-language site called “Cleanup Navi” was launched at the end of May, 2013.

And pamphlets like this one, released in Feb. 2013, which details the effectiveness of 14 remediation pilot projects undertaken in the evacuated areas, have been produced and made available:

Things that were verified before starting decontamination

Cover of an Environment Ministry information pamphlet about decontamination issued in Feb., 2013.

This pamphlet is titled “Josen suru mae ni, kenshō shita koto,” or “Things that were verified before starting decontamination,” with the subtitle, “Decontamination is proceeding based on these findings.” It’s about fifty pages long, and contains more specifics about what was measured, how work was done, and what the results were than we have seen before in one easily accessible place. What particularly caught our eye was the series of maps of 14 remediation sites with detailed “before” and “after” radiation measurements. The sites are grouped according to general type and use — “farmland valley,” “residential,” “level ground,” etc. — and each site is further subdivided based on ground cover, trees, streets, buildings, etc.. They are also grouped by initial contamination level, starting with “less than 5mSv/yr,” and proceeding through “5-10,” “10-20,” “20-50,” “50-100,” and “over 100 mSv/yr.” The treatment of the debris is also described, where it was put, and what the doses received by the workers were. In a design sense, as infographics, it’s very well done and informative, but it left several important questions unanswered.

Each of the 14 sites described in the pamphlet includes “before” and “after” maps of radiation levels, plus details about reductions achieved in parts of the site with different conditions.

For one, the sites were identified generally on a map, but not with enough information to locate them easily. Two, the dates that the “before” and “after” measurements were taken were not given; this is important to know because if enough time had passed in the interim, natural decay and weathering might in fact be responsible for some if not most of the decrease. Third, we quickly noticed that the color scales used to indicate radiation levels were not consistent. All range from blue for “low” to red for “high,” but in some cases the scale is from 0 – 1μSv/h , in others 1.2 – 4.4, or 0.8 – 7.2 μSv/h, and in one case from 0-100 μSv/h. We understand that the starting contamination levels varied widely, so finding one scale to use for all of them would be a challenge, but the way it was done is confusing at best, and some might justifiably argue that it seems intentionally deceptive. We think the color scales should at least be consistent within in the same set of maps.

gov map scales

Map scales for radiation levels

We called the Environment Ministry, using the Tokyo number given on the pamphlet cover (03-6741-4535) to ask if they could answer our questions about when the sites had been measured. The representative on the phone was very friendly and well-trained, and tried to be helpful. She immediately knew which pamphlet we were talking about, and asked us the pages of the particular maps we were interested in. After a few minutes on hold, she came back to say that they could find out for us, but that it would take several days, and asked us to call back the following week. Though we were surprised they asked for so much time, we agreed, and in the meantime we went to Fukushima and measured two sites, one in Iitate and one in Kawamata; another site we were interested in in Namie was inaccessible without a pass, which we had not applied for. We discuss our findings in detail further in Part 3 below.

When we called the Environment Ministry again after our return we got a different representative on the phone, who had the info ready. She directed us to another document online, a very detailed set of JAEA reports from March 2012, on which the pamphlet we had was based:

JAEA decontamination trial reports, March, 2012

It was accessed from this page:

JAEA “Major Initiaves” page

It was the mother lode. It was also a head-scratcher. The “Things that were verified ” pamphlet we talked about was released in Febury 2013, even though according to this larger report the data had been available somewhere since March 2012. Why did it take nearly a year to make it publicly available? We suspect that the change in jurisdiction from JAEA to the Environment Ministry is partly to blame, as is the time involved in rolling out a carefully-designed PR push, of which the pamphlet is only one small part. But while we may not have been on the trail of this information single-mindedly, we have been keeping an eye out for it, have asked many colleagues and volunteers who live in Fukushima, have searched the web fairly frequently, and had never seen any of this. We can only conclude that it’s another case of making it As Difficult As Possible for people to find information, as we described in our post about the monitoring droids:

Information, Misinformation, Disinformation (or, “These aren’t the droids you’re looking for.”)

To their credit, it’s now easier to find this kind of information about decontamination, a lot of which is accessible from this “friendly” page:

Environment Ministry’s “Josen (“decontamination”)Plaza” page

The Environment Ministry’s friendly-looking online access page for decontamination information, called “Decontamination Plaza.”

And once you’re there, a bit more hunting will turn up useful English-language reports like these:

Overview of Decontamination Projects

Report of the Results of the Decontamination Model Project

But here’s the thing: Not only does the whole “friendly” facade and design language of this PR blitz smack of doublethink — we’re talking about health risks here, not vacation travel spots, so this feels like a bizarre attempt to “normalize” radioactive contamination — they’re still not really getting it right. So much information that residents need to know is not yet easily available. We told the Environment Ministry phone representative that we had been looking for detailed before-after information for months, and that even with their help we still can’t find everything we’re looking for, and asked what they tell citizens who call asking for details about specific areas. She said,”Yes, I understand how frustrating it is. We try to help everyone who calls, but sometimes all we can do is suggest they consult the web pages of particular towns.” That is, “We know we have the information somewhere, but we’re so disorganized and dysfunctional that a lot of people will get better results by calling their town office instead.” I could tell it pained her to admit it though.

EIGHT THINGS PEOPLE NEED TO KNOW: Safecast’s suggestions for improvement

It’s worth laying out some suggestions, even at this late date, about the kind of information regarding decontamination that should be made easily available in a consistent fashion for each site being decontaminated. As described earlier, some towns outside the evacuation zone, like Koriyama, already provide most of this:

  • Precise location, ideally with Google map coordinates
  • Who signed off on it, i.e what government jurisdiction and the responsible individuals
  • Who is contracted to do the work, including the chain of contracts leading upward to large corporations
  • What the initial radiation level monitoring showed (with independent verification)
  • When work was scheduled to start and end, and when it actually did
  • What the final radiation level monitoring showed (with independent verification)
  • Where the debris went
  • What the total cost was

We suspect that all of this information in fact exists, and it should simply be a matter of making it public and accessible. We’d go even further and ask that it be made machine-readable.




At the difficult site we checked in Kawamata, the ultimate gains from decontamination were very modest. It might make more sense in cases like these to wait for nature to do more of the work. In Iitate, on the other hand, the gains appear to have been significant.(CLICK TO ENLARGE)

Was it worthwhile for the government to spend so much time and money decontaminating difficult sites inside the evacuation zone in Fukushima? The only way to find out was to measure a few of them ourselves and try to calculate what their dose rates would have been if they had not been decontaminated. We were only able to check a couple of sites this time, but the results provide a lot of food for thought.

Decontamination sites we checked, showing main road access; the Namie site was inaccessible.


We initially planned our route to allow us to check three sites, one in Kusano, Iitate, one in Sakashita, Kawamata, and another in Matsukiyama, Namie, which we intended to hit first. All were detailed in the “Things that were verified” pamphlet published by the government earlier this year. About three kilometers short of our goal, however, at the Namie border, we found the road blocked. It has often been a bit unpredictable where exactly roadblocks will be placed, but in this case it was right where the official demarcation line is for Area 3: Difficult to Return (pink on the map). These roads were accessible several months earlier, and as successive evacuation zone maps reveal, this northwest portion of Namie is an example of access being made more highly restricted. We continued to Kawamata and Iitate, and as we measured the sites in those towns we immediately noticed that our readings were lower than the “after” readings given in the pamphlet. At the time we didn’t know when those measurements were taken, but at least we could confirm that the gov’t had not grossly understated the levels. Based on the appearance of the sites, their overgrowth, etc., we suspected that several months at least had passed. In fact, as we eventually learned, it had been about a year and a half.

With the information we received later, we understood that the sites featured in the pamphlet were the original pilot test remediation sites, chosen for their range of topography, land uses, and radiation levels. They had been selected by the fall of 2011, measured in Nov., 2011, decontaminated in most cases beginning in Dec., 2011, completed generally in Jan., 2012, and measured again in Feb., 2012. The tables and maps below give details.

(The fine print in the detailed government documents says that in both the Kawamata and the Iitate sites, snow covered the ground when post-decontamination measurements were taken in Feb., 2012. In one document, for every site except Kawamata it clearly states that this was taken into consideration when stating the final levels, specifically, that they adjusted for the shielding effect of the snow. In the case of Iitate, this was 30% from the maximum 25cm of snow that was present there. Fairly full explanations are given about how adjustments were made for snow on other sites, but we had to search through three detailed documents before we could confirm that this had also been done for the Kawamata site as well.)

Kawamata site

The site in Kawamata is a steeply sloped hillside covered with terraced fields; it has extremely uneven topography and may places for water, and hence contamination, to collect.

Kawamata gov before

Kawamata gov after

Sakashita , KAWAMATA

Gov’t measurements:

  • Before decontamination: (Nov 2011) 1.2-4.4 μSv/h
  • After decontamination: (Feb 2012) 1.2-3.2 μSv/h. This is an up to 27% reduction
  • Gov’t average: overall 3.0 μSv/h reduced to 1.7μSv/h; on asphalt and other areas, half of this.

SAFECAST measurements:

  • (Jun 2013) 0.72-1.75 μSv/h

This is 37-60% reduction from gov’t “before” levels; 37-45% from “after” levels

The pamphlet indicates that at the Kawamata site, gov’t decontamination produced the following reductions:

  • fields:    54%
  • houses: 43%
  • roads:    35%
  • forests:  27%

We know what the actual decay and weathering rates were between Feb. 2012 and when SAFECAST measured in June 2013. If we apply those same reduction rates to the levels the gov’t measred before decontaminating, while it would not be absolutely precise for a variety of reasons, it would nevertheless give us a close enough approximation to estimate how much the decontamination contributed to the overall reduction in dose rates, and how much the levels might have decreased if no decontamination had been done. We estimate that without decontamination, the levels at the Kawamata site would have been:

  • 0.71 – 2.3 μSv/h instead of 0.72-1.75 μSv/h

Iitate site

The site in Iitate is mainly school grounds, including large buildings, parking lots, and sandy fields.

Iitate Gov after Iitate Safecast

Kusano, IITATE:

Gov’t measurements:

  • Before decontamination: (Dec 2011) 3.2-6.4 μSv/h
  • After decontamination: (Feb 2012) 0.8-3.2 μSv/h. This is a 75-50% reduction.
  • Gov’t average: schoolgrounds: 4.6μSv/h reduced to 1.7μSv/h
  • Woods and houses: 3.6μSv/h reduced to1.6μSv/h

SAFECAST measurements:

  • (Jun 2013) 0.25-2.45 μSv/h overall

This is about a 93-62% reduction from gov’t “before” levels; 25-70% from “after” levels.

  • 0.25-0.94 μSv/h  playgrounds only

So natural decay and weathering reduced the dose rate 25-70% from Feb 2012 to June 2013.

(The highest reduction, 70%, was at the school playground, much of which nevertheless remains above 0.23μSv/h, and is above the acceptable level.)

At the Iitate site, the gov’t claimed reductions of:

  • large buildings: 63%
  • houses: 57%
  • fields: 40%
  • roads: 37%
  • forests: 32%

We estimate that without decontamination, the levels at the Iitate site would have been:

  • 0.95 – 4.7 μSv/h instead of 0.23 – 2.3 μSv/h

The Kawamata site seems to have a fairly even reduction of 40% or so since the grounds were decontaminated in early 2012. The Iitate site has decreased about 25% at the highest range, but over 50% at the lowest. The highest levels there are at the edges of the site, on a slope covered with trees. The lowest spot is an area in the center of the large playground, which is still slightly over 1 mSv/y “additional” radiation.


There are several reasons why this estimate is not precise, some of which have been alluded to already. One is that we were able to measure the actual rate of decay and weathering from Feb. 2012 to June 2013 at each site, and applied those same rates to the period from Dec. 2011 to June 2013 for our “if not decontaminated” estimates. As we can see, the earlier months experienced some of the steepest natural declines due to radioactive decay, and we aren’t really able to factor that into our estimates closely. Secondly, the decontamination process at each site involved a large disruption to the ground surface and other parts of the environment which are likely to have affected the subsequent rate of weathering afterward, possibly accelerating it. We can’t really gauge this enough to account for it, either. Thirdly, although both of these sites have been evacuated since 2011, there has been a bit of activity at each, some of which may have affected the actual dose rates we were able to measure. And finally, while we concentrated on measuring the areas which were highest and lowest on the government maps, and taking a broad sample in-between, we would prefer to have more sample points, which time did not allow. So take these as fairly close ballpark estimates, and no more.



As we expected, the results really are case-by-case. Every large site like these encompasses a range of dose rates, and focussing on averages can be deceptive. Experience and prior information told us to expect different rates of reduction in high dose rate areas as opposed to low dose rate ones, and this proved to be the case. A look at the graphs above will show the overall relative gains, and how the various levels compare to the government’s 1mSv/yr and 20mSv/yr guidelines. Notably, decontaminating the Iitate site allowed the lowest dose areas (points at the center of the flat, sandy school grounds) to fall to 0.25 μSv/h in mid-2013 instead of the 0.95 μSv/h it likely would have been if it hadn’t been decontaminated and had only experienced natural decay and weathering. This is a very large reduction percentage wise, but still above the government’s 1mSv/yr limit. The high dose rate parts of the site, on the other hand, would probably have been about 4.7 μSv/h by now without decontamination, but are about half that because of it. This is a sizable gain, and one way to look at it is that while it is insufficiently effective in itself, it has accelerated the process of decline through decay by quite a few years.

For the Kawamata site, there was almost no change on the low dose rate end, because the decontamination was not very effective there; the dose rate would probably be the same as it is now, about 0.72 μSv/h, with or without the decontamination. This is several times the government’s 1mSv/yr limit. At the high end, the gains were greater, and decontamination allowed the dose rate to fall to 1.75 μSv/h, instead of around 2.3 μSv/h. This is about a 25% reduction, which is meaningful, but it may well be more efficient, not to mention cost-effective, to allow time and natural weathering to take its course in similar situations. The rate of natural weathering should already be tapering off, because most of the loose and easily washed away contaminants have probably already found their way to the watershed (becoming a different kind of problem). Because of the 2-year half-life of Cs-134, which represented about half the overall initial Caesium contamination (by activity) a lot of it decayed over the first two years (half of the initial Cs-134, or 25% by activity of the total). Nevertheless, the next several years should see another large reduction due to the continued natural decay of Cs-134, while Cs-137 has a half-life of 30.7 years, so it will take until 2044 for half of it to be gone.

This graph released by the IAEA in late 2011 showed its estimate that radioactive contamination from the Fukushima Daiichi NPP would have naturally decayed by 35-40% by mid-2013 (in reality it has been more than 50% in some areas, thanks to weathering). Natural decay should lead to a 50% or more reduction overall by mid-2014, and a 70% reduction by 2018. After that the decline will be much slower. The graph also illustrates that although Cs134 and Cs137 were initially present in almost equal amounts when measured by activity (Bq), due to it’s emission characteristics Cs134 has so far contributed a much higher proportion of the risk to humans in terms of exposure. It decays much more quickly (having a half-life of 2 years, compared to Cs137’s 30.7 years), and its relatively rapid disappearance means a rapid overall decline in dose rates over the first several years.

The IAEA seems to have anticipated these kinds of mixed results, and in October, 2011, observed:

“The Team notes that the main strategy adopted by the Japanese authorities relates to the concept of decontamination. At this stage, it is important to stress that decontamination is only one of the many available options to be used to achieve the reduction of doses in the case of radioactivity concentrations in the environment caused by an accidental release.”

They went on to describe the problems that might result from the huge amount of contaminated soil and debris that blanket decontamination would produce. And in fact, we’ve barely touched on the issues surrounding the disposal of debris here, but they are equally serious and contentious.

Similar discussions have certainly been occurring in the halls of power as bureaucrats and pursestring-holders evaluate the decontamination results. And indeed, these kinds of calculations have probably played a major role in the decisions, described in the Asahi newspaper article at the start of this series, not to attempt further decontamination in places where it has proven ineffective. In situations where intensive decontamination has not produced a large enough decrease in dose rate, specifically where the decrease has not been much larger than what would have been produced by natural decay and weathering, it probably makes more sense to hunker down for a long wait instead. And for residents of much of the exclusion zone, the wait will probably be very long indeed.



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Azby Brownは、Safecastのリードリサーチアであり、Safecast Reportの主要著者です。デザイン、建築、環境の分野で広く出版された権威である彼は、30年以上日本に住んでおり、2003年にKIT Future Design Instituteを設立しました。2011年夏からSafecastに参加し、国際専門家会議で頻繁にグループを代表しています。