Risk to Fukushima 50 Falling

By Bruce Thompson

Japan's Nuclear and Industrial Agency (NISA) released today a summary of the workers whose exposure to radiation has approached the annual limit of 250 milliSieverts (mSv). According to the report:

Exposure of Workers

- April 30 - TEPCO summarized the result of exposure dose measurement of workers engaged in emergency work and whose external exposure dose exceeded 100 mSv at the end of March 2011. According to the summary, the result of exposure dose measurement (the total value of internal and external exposure and the number of personnel) was as follows: 2 persons with 200~250 mSv, 8 persons with 150~200 mSv, and 11 persons with 100~150 mSv.

So as of March 31, 2011, none of the Fukushima 50 had yet reached their maximim annual exposure limit. And only 21 had reached at least 40% of their annual limit. With careful monitoring and crew rotation, that means none of them need ever exceed their annual limits.

The NISA also issued a Frequently Asked Questions (FAQ) sheet to the general public outside the 20 kilometer evacuation zone which effectively sounds the "All Clear". Other than refraining from eating leafy vegetables grown inside the zone, the most they need do is shower, if they get caught out in the rain, and let the water go down the drain as usual. With a mandatory evacuation order inside the 20 km zone, no one other than plant workers is at further risk.