Radiation visualizations paint a different picture of Japan

Radiation data collected in Japan contradicts some media reports.

This piece was originally posted on The Daily ACK. Updated visualisations are now available with data spanning from 17:00 16th March – 17:00 20th March.

Over the weekend I came across some data on levels of radiation in Japan collected by the Japanese government, and helpfully translated into English by volunteers.

The data was somewhat stuck in PDF format. However, Gemma Hobson, Pete Warden, and I transcribed, mostly by hand, some of the more helpfully formatted files into CSV format (16KB) making it acceptable for Pete’s OpenHeatMap service. The map embedded below shows our first results.


Environmental Radioactivity Measurement, 17:00 16th March – 17:00 18th March — For data from the Fukushima site itself see the “Readings at Monitoring Post out of 20 Km Zone of Fukushima” data sets online. Data collection from Mlyagi (Sendai) ceases at 17:00 on the 17th of March and does not resume. Several other smaller duration data drop outs also occur during the monitored period.


As you can see from the visualisation, environmental radiational levels change fairly minimally over the time course of the day. Most measurements are steady, and within the historic ranges, except around the troubled Fukushima plant where readings are about double normal levels.

Things become more interesting however when we look at the historic baseline data. The two maps below show the typical range of background environmental radiation in Japan. The first shows typical minimum values, while the second shows typical maximum values. Put together they illustrate the observed range for environmental radiation across Japan.


Environmental Radioactivity Measurement, Typical Minimum



Environmental Radioactivity Measurement, Typical Maximum


Finally, the map embedded below shows the environmental radioactivity measurements with respect to the typical maximum values for that locale. From this visualisation it is evident that the measured values throughout Japan are normal except in the immediate area surrounding the Fukushima reactors, where levels are about double normal maximum levels.


Environmental Radioactivity Measurement, Ratio with respect to typical Maximum Values


When analysing this data you should bear in mind that the normal environmental range in that area is actually fairly low compared to other areas in Japan. Currently the levels of radiation at the plant boundary are actually still lower than the typical background levels in some other parts of the country. Levels also seem fairly static over time, and do not seem to be increasing as the situation progresses.

Unless the situation significantly worsens, which admittedly is always possible, human habitation in close proximity to the plant will not be affected in the medium term. From talking to people on the ground in Japan, and by looking at the actual measurements across the country, a very different picture seems to be emerging than that reported by the Western media. Some of those media reports seems highly skewed, and heavily politicised, by comparison.

I think everyone should take a deep breath and look at the evidence, which is suggesting this is not another Chernobyl in the making. It may not even be another Three Mile Island. If the remaining functioning reactor units are decommissioned following this incident it may well have more to do with politics than the science.

With thanks to Pete Warden and Gemma Hobson.

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  • Lynn Jaeger

    Thank you for this — am a visual processor and all the data presented in table form over the last few days has had my eyes crossing.
    Do think of these two things: the remaining reactors (#5 & 6) are old – this installation is the oldest in Japan – and were just given an extension on their work permits that went beyond original life-expectancy. They were due to be decommed last month.
    Now that everyone knows how lax PETCO has been with servicing these units, and what CAN happen, that may be justification enough for taking all 6 apart and burying them very deep somewhere where they won’t be exposed to both a 9.0 earthquake and a 45′ tsunami wave.

  • NOT HERE

    “If the remaining functioning reactor units are decommissioned following this incident it may well have more to do with politics than the science.”

    And you apparently are only interested in denial politics here, because there WAS and IS an ongoing uncontrolled release of highly radioactive particles coming from the reactors.

    THAT is the science, now tell me again where this is political?

    If the drinking water is so safe that one could drink it for a year, then why are the authorities telling people to stop drinking the tap water?

    Gee, it must be political, unfortunately, it’s the bad kind of political, the kind you seem to support.

  • John Szurek

    Thanks for the independent analysis and visualizations. The way in which comments have been slung around in the last 2 weeks by people who clearly did not have or understand the real underlying data has been disturbing. Japan does have an issue, but it is an operational issue, not a technological issue. Fact is that they have been sloppy in operating these facilities, particularly with storage of spent fuel, and they were way too slow in getting backup generators on site given that they knew or should have known that neither their reactors nor their fuel storage facilities were stable without cooling water circulation. The lessons here are less about the inherent safety of nuclear facilities and moore about the fact that incompetent and irresponsible operation can negate any number of safety factors.

  • http://www.oreillynet.com/pub/au/3904 Alasdair Allan

    “And you apparently are only interested in denial politics here…”

    Quite frankly I’m not interested in any sort of politics. Alarmism is not helpful, especially when dealing with emotive issues such as nuclear power. Looking at the evidence base and attempting to communicate that to the public so they can calculate and manage their own levels of risk is a much better strategy.

    “If the drinking water is so safe that one could drink it for a year, then why are the authorities telling people to stop drinking the tap water?”

    That seems like an eminently sensible risk management strategy. It doesn’t imply there is anything wrong with the drinking water, just that it would eliminate unnecessary risk for people not to drink it until actual risk can be quantified.

  • http://www.oreillynet.com/pub/au/3904 Alasdair Allan

    “Japan does have an issue, but it is an operational issue, not a technological issue…they were way too slow in getting backup generators on site given that they knew or should have known that neither their reactors nor their fuel storage facilities were stable without cooling water circulation.”

    It hasn’t been widely reported, at least in the Western press, however Japan is still suffering magnitude 4 and 5 earth quakes daily, in fact sometimes more than one per day,

    http://earthquake.usgs.gov/earthquakes/recenteqsww/Maps/region/Asia.php
    http://earthquake.usgs.gov/earthquakes/recenteqsww/Maps/region/Asia_eqs.php

    This is understandably somewhat slowing operations. I think we’re only really going to find out if something went wrong, or whether the staff did as well as humanly possible under extreme circumstances, with some degree of hindsight.

  • http://grandcanyonhiker.com Ken McNamara

    Thank you for this excellent work.

    The press chooses to treat the world in sound-bites – thankfully the Web is challenging them with facts.

    I’ve been looking for facts about this situation – this is the first place I’ve found them.

    Deming would approve – gather facts to base your decision on.

  • Andre

    “If the remaining functioning reactor units are decommissioned following this incident it may well have more to do with politics than the science.”

    This does not hold any water, between the accident and the age of the reactors, and the damage that would have been done due to the quake, cooling efforts, fire, etc., these reactors should be permanentely shuttered.

    Q: Given what we know and what has happened, would _you_ want your family to live and work nearby these reactors?

  • Tom Sepp

    See nytimes: Tokyo Says Radiation in Water Puts Infants at Risk

    http://www.nytimes.com/2011/03/24/world/asia/24japan.html?_r=1&hp

    also from same article:
    “The accident at Chernobyl caused an epidemic of thyroid cancer — 6,000 cases so far — in people who were exposed as children. The risk in that group has not decreased over time, and many more cases are expected.”

    Why would the contamination be broader than the published radiation levels would suggest?

    Also the evidence published by the NY Academy of Sciences:
    http://www.ens-newswire.com/ens/apr2010/2010-04-26-01.html

  • http://www.oreillynet.com/pub/au/3904 Alasdair Allan

    The Register has an excellent piece explaining why the restrictions placed on drinking water by the Japanese government are both reasonable, and yet also entirely precautionary,

    http://www.theregister.co.uk/2011/03/23/tokyo_tapwater_fukushima/

    Japan’s Ministry of Health, Labour and Welfare says that tests have revealed levels of the radioactive isotope iodine-131 in tapwater samples in Tokyo that range from 100 to 210 becquerels/litre. The radio-iodine health limit in force for iodine-131 is 300 Becquerels/litre, but there is a separate limit for baby milk fed to infants less than a year old of 100 Bq/l – hence the recommendation.

    They go on to say,

    However the health safety limits in question are based on a year’s consumption: in other words, a baby could drink milk containing 100 Bq/l of radio-iodine for a year without ill effects. The same dose could be sustained by drinking the Tokyo tapwater (assuming continuous iodine-131 levels at the maximum so far seen) for a bit under six months. However as iodine-131 has a half-life of just eight days. Most of what was in the plant when it shut down Friday before last has now turned into Xenon, and the heat which drove initial emissions to atmosphere is now a small fraction of what it was in the first days of the incident. Levels in the water can be expected to peak soon and then drop, fast at first and then slowly, to almost nothing over a six-month timespan.

    In other words as I initially guessed, this is an eminently sensible risk management strategy. However there is no real long term risk involved.

  • http://www.fairewinds.com/ FloBEE

    If you want the truth, then you must check out:

    http://www.fairewinds.com/

  • Colin Saultry

    Key factor in any monitoring results released is the accuracy of the released results and have they have been doctored. For example, monitoring devices that were registering levels far in excess of acceptable levels were systematical taken off line so the public could observe what the true readings were. Most likely your data obtained is a reflection of the numbers they want you to see and probably no where near the correct levels. This is based on 15yrs of dealing with the Japanese both govt and private industries.