Bottom Line:
- Average contamination in Tokyo region soil is 30,032 Bq/m²
- Tokyo City tested out at 61,713 Bq/m² on May 14, 2011
Note: This is not current to August, 2011 so values have likely changed. Let us hope for the better but one has ample reason to suspect that these values will only increase.
Radioactive survey of Tokyo soil
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Tchernobyl zoning values for Cs137 are “politic” values. they exceed “normal safety values”. AIEA official values recommend evacuation zone if Cs137 > 15 Ci km2 (555.000 bq/m2). Note in other hand that Cs137 is only a part of radioactivity realy deposit. For a official Bibliography you can go to http://aipri.blogspot.com/2011/08/les-valeurs-radiologiques-officielles.html
http://siteresources.worldbank.org/INTBELARUSINRUSSIAN/Resources/446826-1103101286215/environm_eng_8.pdf
The most contaminated area immediately closest to the Chernobyl plant has been declared a 1,700 km2 exclusion zone from which all persons were evacuated in 1986 and the lands taken out of economic activity save for basic safety and maintenance, forest fire fighting and scientific research activities, where there are no inhabitants. Specifically, where surface deposition of radioactive isotopes exceeded 15 Curies (Ci)/km2, or 555 kilobecquerels (kBq)/m2, evacuation was obligatory.
http://www-pub.iaea.org/MTCD/publications/PDF/Pub1122_scr.pdf
http://www.arpansa.gov.au/pubs/rps/rps7.pdf
http://www.iaea.org/ns/rasanet/projects/chernobyl/livingadvice.htm
http://ec.europa.eu/energy/nuclear/radioprotection/doc/studies/emergency_planning_en.pdf
http://www-pub.iaea.org/MTCD/publications/PDF/SS-115-Web/Start.pdf
http://www.un.org/ha/chernobyl/docs/report.pdf
http://www.nea.fr/html/rp/chernobyl/c03.html
According to recent reports, the Okutama area west of Tokyo showed high radioactive readings. If this is true, then the main tokyo water supply from “Lake Okutama” will become contaminated as the radioactivity leaches into the soil, streams, and ground water that feeds into the lake.
You’re right.