Fukushima rated INES level 7

[Kyodo News] Japan raises nuke accident severity level to highest 7 from 5

My summary:

  • The rating is based on the amount of radiation released
  • Cumulative radiological release estimated at 370 PBq (NISA), 630 PBq (NSC)
  • NSC had earlier estimated rate of radiological release of 10 PBq/hour, over "several" hours
  • These activities are in terms of 131I "equivalent" (see INES User's Manual Appendix I)
  • Estimated cumulative doses of up to: >100 mSv (within 20 km exclusion zone), 50 mSv (20-30 km "stay indoors" zone), >1 mSv up to 60 km northwest, 40 km south-southwest
  • Unclear if this is outdoors dose (I assume it is)

Here's the NISA press release:

[NISA] INES Rating on the Events in Fukushima Dai-ichi Nuclear Power Station by the Tohoku District - off the Pacific Ocean Earthquake

It gives these estimates of the radiological discharge:

For comparison, I've dug up a more comprehensive estimates for the discharge from the Chernobyl disaster. Keep in mind that the dispersal mechanisms are different -- there's no core fire at Fukushima.

http://titania.sourceoecd.org/vl=2140418/cl=16/nw=1/rpsv/~4292/v3n1/s1/p1l

Posted by Author at 11:22 PM

1 comment:

  1. Thanks uvdiv. I expect a lot of song and dance about the level change, which actually doesn't mean much. Useful comparison to the ~10000PBq of Chernobyl, the majority of which fell on land.

    For clarity, I'd add that most of the 20km zone did not receive 100mSv, and likewise only selected areas outside that received 50mSv.

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