To Iwaki City
Of Fukushima Prefecture
Fukushima Daiichi & Tokyo
[updated on Dec. 15, 2011]
For most of peoples in the world, the distance between Tokyo and Fukushima Daiichi (220 km or 140 miles) must be very remote and vague. It is almost equal to the distance from Paris to Brussels. Or it is almost equal to the distance from New York to the Three Mile Island Nuclear Generating Station.
So, it is no wonder that some people in the world suspect that Tokyo is under full of radiation coming from Fukushima Daiichi. In terms of the number of atoms emitting radiation, many, many of such atoms are now in per square meters at any part of Tokyo. But, it's effect is so far almost equal to a dosage in New York or Paris.
Yet, I do not recommend Europeans and Americans to casually come to Tokyo nowadays, since even the Japanese politics is going into a tough period around the Kan Cabinet getting so unpopular.
SECTION I: Overview of State of Radiation from Fukushima Daiichi
The typical radiation level now around Fukushima Daiichi is 1.6 micro sieverts, Tokyo 0.062 micro sieverts, Yokohama 0.053 micro sieverts, Nagoya 0.046 micro sieverts, Kyoto 0.039 micro sieverts, etc.
http://atmc.jp/
Measured values of radiation levels at various points in the Fukushima Daiichi Nuclear Plant are mostly less than 50 micro Sieverts. However, the south point of the Main Office Building in the plant shows 400 micro-Sieverts/hour or 0.4 milli Sieverts/hour (300 milli sieverts per month).
http://www.tepco.co.jp/nu/fukushima-np/f1/index-j.html
SECTION II: Details of Explosion Events in Fukushima Daiichi
Operational History of Unit-1
date... time...event
3/11...14:46...scrum
...15:42...emergency diesel generator stopped
...16:36...emergency cooling system unable to inject water
3/12...1:20...pressure of primary containment vessel (PCV) reached 840kPa>2 times of design pressure
...5:30...sudden de-pressuring of primary containment vessel of reactor-1(possible release of radioactive gas)
...10:17...start venting
...15:36...explosion of reactor-1 building
===========================================
Operational History of Unit-2
date... time...event
3/11...14:46...scrum
...15:42...emergency diesel generator stopped
...16:36...emergency cooling system unable to inject water
3/12...1:20...pressure of primary containment vessel (PCV) reached 840kPa>2 times of design pressure
3/13...10:17...start venting
3/14...13:25...loss of cooling capability
...16:34...start pumping sea water
3/15...0:02...venting
...6:10...sound of explosion
...6:20...damage to supression chamber?
3/20...15:15...sea water charge to spent fuel pool (40t)
...15:46...power to power center
3/21...18:22...white smoke
===========================================
Operational History of Unit-3
date... time...event
3/11...14:46...scrum
...15:42...emergency diesel generator stopped
3/13...5:10...emergency cooling system unable to inject water
...5:10...venting
...13:12...start pumping sea water and boron
3/14...5:20...venting
...11:01...explosion
http://www.asahi-net.or.jp/~pu4i-aok/cooldata2/politics/fukushimameltdown.htm
It is not Unit 1 explosion but fire and explosions in Unit 2 and Unit 3 that sprayed radioactive material around Fukushima Prefecture as far as Tokyo.
Day... micro-Sv/h
==============
11-Mar... 0.0376
12-Mar... 0.0384
13-Mar... 0.0383
14-Mar... 0.0377
15-Mar... 0.809
16-Mar... 0.161
17-Mar... 0.0562
18-Mar... 0.0524
For radiation dosages measured in Tokyo in the longer time span from March to May, 2011, refer to the following:
http://www.metro.tokyo.jp/INET/OSHIRASE/2011/05/20l5db00.htm
Note that 1 nGy/h = 0.001 milli Sv/h = 1 micro Sieverts/hour.
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APPENDIX. I
Tokyo Radiation Doses from December 6 to 16, 2011.
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(Who can invoke a hurricane if not the 3/11 Tsunami?
http://www.youtube.com/watch?v=n17eQVsDOvU)