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Japan: 400 mSv per hour What Does That Mean?

March 15, 2011

U.S. Nuclear Regulatory Commission (NRC) regulations require nuclear license applicants to show that their plants can withstand a series of design-basis accidents without releasing radiation that would exceed a given level. In particular, the whole-body dose for someone standing at the site boundary for the worst two hours of the accident cannot exceed 25 rem, or 250 milli-Sieverts (mSv).

The dose rate for such a design-basis accident would be 125 mSv per hour.

In comparison, the dose rate near reactor Unit 3 at Fukushima Dai-Ichi has reportedly reached 400 mSv per hour. The Fukushima accident is therefore now a beyond-design-basis accident, at least in NRC terms.

Source: All Things Nuclear, click here

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  1. aaa
    November 12, 2011 at 7:12 pm

    Its a lot.

    0.1 Sv = cancer risk rises by 1%
    0.4 Sv = fukushima
    0.76 Sv = max dosage of life saving SAR operations
    1 Sv = sickness (here starts deterministic effects)
    3 Sv = effect on internal organs
    5 Sv = LD 50
    10 Sv = no cure, only pain killers
    more then 100 Sv = death within few hours
    800 Sv = instant death

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