Ibaraki & Tokyo Radioactivity

[last updated 06/19  22:20 ]

[Since 4/21 all Ibaraki MPs fit within regular radioactivity levels in Europe !]

Quick jumps to graphs

Intro

In this post I will be updating the graphical evolution of radioactivity in Ibaraki prefecture (region between Fukushima and Tokyo) since the Fukushima NPP accident. You can find graphs for other locations, earthquakes and water contamination @fleepcom ‘s invaluable website.

Original data and sources can be found in this online Excel workbook at any time. The workbook is being updated about every hour unless I’m sleeping or outdoors, whereas I won’t update the blog more than once a day.

Available data contains a total of 43 monitoring sites spread over the whole Ibaraki prefecture. Some of them are only available “live”, so I can’t retrieve them when I’m sleeping. To improve readability I’ve chosen to graph only:

  • The average and maximum radioactivity levels among the 43 MPs.
  • Four representative locations at increasing distance from #FNPP1:
    • KitaIbaraki (~73km)
    • Takahagi (~84km)
    • Southern Hitachi (~100km)
    • and Mito, Ibaraki capital (~130km).

For reference, I’ve also added:

Also, please keep in mind that:

  • although in general it’s worse to be closer, there are many other factors (wind and air-streams, rain, closeness to the sea, etc.) that play an important role on spreading contamination.
  • the vast majority of Ibaraki’s population (nearly 3 million) lives South from Hitachi / Mito.

Here are the graphs.

Regularly updated

Last month

Notes:
  • Small peak in Ibaraki/Takahagi on 6/14 was not observed in Tokyo, nor in the NPP, so it must be related to local meteorologic conditions.

-> Top

Evolution since the Accident

You can appreciate how:
  • Tokyo only went pass European usual background radioactivity for 3 or 4 hours during the hydrogen explosions at #FNPP1
  • The first rain brought down to earth quite a bit of what was released to the air during those explosions, but otherwise radioactivity decreases smoothly day after day
  • Most graphs halve in about 8 days on the early stages, indicating that most of the radioactive isotopes that escaped during those explosions were short-lived Iodine 131 (~8 days half life)
  • [3/30] Avg of all Ibaraki MPs reaches orange point level on EU’s map (< 0.3 uSv/h)
  • [4/10] Avg of all Ibaraki MPs reaches green point level on EU’s map (< 0.2 uSv/h)
  • [4/12] Hitachi & Takahagi become an orange point on EU’s map (< 0.3 uSv/h)
  • [4/15] KitaIbaraki also becomes an orange point on EU’s map (< 0.3 uSv/h)
  • [4/19] Takahagi becomes a green point on EU’s map (< 0.2 uSv/h) after very unstable weather with strong rain
  • [4/21] Max radioact in Ibaraki becomes an orange point on EU’s map (<0.3 uSv/h ); The whole prefecture fits now within regular radioactivity levels in Europe !
  • [5/11] KitaIbaraki becomes a green point on EU’s map (< 0.2 uSv/h).
  • [5/24] Max radioact in Ibaraki becomes a green point on EU’s map (< 0.2 uSv/h).
  • [5/30] Mito, Ibaraki capital city, becomes a blue point on EU’s map (< 0.1 uSv/h).

-> Top

Historical Series

1st Month after quake (3/14 to 4/13)

Notes:
  • Absorbed dose level registered in KitaIbaraki before the quake was 0.05 uSv/h
  • Periodic absorbed dose rate increases in northern locations (KitaIbaraki, Takahagi) are due to early morning wind direction changes after sunrise (blowing towards the sea at night, back to the shore after sunrise)
  • [3/30] Avg of all Ibaraki MPs reaches orange point level on EU’s map (< 0.3 uSv/h)
  • [4/10] Avg of all Ibaraki MPs reaches green point level on EU’s map (< 0.2 uSv/h)
  • [4/12] Hitachi & Takahagi become an orange point on EU’s map (< 0.3 uSv/h)

-> Top

2nd Month after quake (4/11 to 5/11)

Notes:
  • [4/11 17-18h] Short after today’s large replica (M7.1; stopped #FNPP1 cooling systems for 50min) you can see small bumps on most graphics. At the same time, very strong rain and wind arrived to Kantou area. Given the fact that monitoring posts around the plant do not show such temporary increase in radioactivity, what you see here is most likely to be the effect of the very heavy rain and wind.
  • [4/19 17-18h] Again very unstable weather and strong rain had a noticeable influence on radioactivity readings, with several MPs reporting sharp decreases at this time.
  • [4/15] KitaIbaraki becomes an orange point on EU’s map (< 0.3 uSv/h)
  • [4/19] Takahagi becomes a green point on EU’s map (< 0.2 uSv/h) after very unstable weather with strong rain
  • [4/21] Max radioact in Ibaraki becomes an orange point on EU’s map (<0.3 uSv/h ); The whole prefecture fits now within regular radioactivity levels in Europe !

-> Top

3rd Month after quake (5/11 to 6/11)

You can appreciate how:
  • [5/24] Max radioact in Ibaraki becomes a green point on EU’s map (< 0.2 uSv/h).
  • [5/30] Mito, Ibaraki capital city, becomes a blue point on EU’s map (< 0.1 uSv/h).

-> Top

Advertisements
  1. Lucian Bolokan
    April 10, 2011 at 03:18

    thanks for interessting info

  2. Veronica
    April 11, 2011 at 05:52

    I’ve meaning to do this for days. You’ve done my work for me. Thank you 🙂

  3. Roy Craft
    April 11, 2011 at 11:19

    Glad I was directed to this blog from NEI. Thanks for the great work.

  4. April 17, 2011 at 00:49

    You need to open a radiation consulting office. Excellent work!

  5. interested person
    May 16, 2011 at 15:05

    Thanks for the graphs and the work you have done. It helps to understand what is going on instead out of the mainstream media.

  6. September 19, 2013 at 09:13

    hey are you still updating this? It would be interesting to see the readings after the recent typhoon and leakages.

    • September 25, 2013 at 21:55

      I stopped updating this once TEPCO started providing timely information in decent fashion.
      You can find all the information you want in their website (here).
      All reactors have been stable for about two years now, and that’s nothing a typhoon whatsoever will change. The challenge now is decommissioning in a safe yet shortest and cheapest possible way, and the next step will be the withdrawal of fuel assemblies from Unit4 spent fuel pool in November.

  7. September 24, 2013 at 13:16

    Wow, that’s interesting. I remember once being in the rain in Tokyo sharing an umbrella. If I would have realized, I would certainly have my own big one! Thanks for the info.

    • September 25, 2013 at 21:51

      If you were in Tokyo it wouldn’t have mattered at all weather you had an umbrella or not.
      Nor you nor anyone of the nearly 30 million people living there received any dose beyond natural background radiation around the globe.

      • September 26, 2013 at 02:58

        I know of a few people who became sick from radiation, including myself, while living in Tokyo. My girlfriend became sick and had her urine tests sample positive for both cesium and iodine-131 and she lived in Tokyo. A friend of a friend was told by a doctor that she could not have children for 10 years. Yet many others don’t have any of the symptoms of radiation sickness. To say no one of the 30 million received any dose beyond natural background when there have been hot spots found all around Tokyo is not very logical.

  1. April 8, 2011 at 20:17
  2. May 16, 2011 at 05:02

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: