Our Unit 2 Rough Estimation Of Radiation Levels In Containment

These estimations are very rough calculations. They give an idea about how high the radiation in the pedestal below the reactor could be. These numbers are very rough and not normally something we post on the website. They are worth sharing to give people an idea how incredibly high the radiation inside containment is.

We took the radiation sampling TEPCO did during their March 27 scope of unit 2. From there we extrapolated some distance based assumptions to guess at the increases in radiation. The concrete pedestal is about 2 meters of thick concrete. That provides quite a bit of shielding for whatever may be inside the pedestal one year later.

 

Our very rough guess is the radiation in the pedestal could be:  the corium in the pedestal an estimated    5 GSv/hr.
Enough to cook a hot dog in .0000001 nano seconds.

**Peter ran some additional calculations and came up with the following:
Rad levels in unit 2, kilo (10exp3), mega (10exp6 equals a million), GIGA (10exp9) and tera (10exp12).
“I myself figured 10 teraSv/h based on 30 half-thicknesses and the inverse square law for a point source. Note that most increase in this estimate stems from the assumption that the source is behind the concrete and does not include the possibility of fuel having escaped into the drywell.”

Taking both rough calculations we have somewhere between 5 gigaSv/h to 10 teraSv/h in the pedestal region of unit 2. 

For some comparison at Chernobyl, the control room after the explosion was 300 Sv/hr – providing a lethal dose in 1-2 minutes. At 22 years later, levels inside the reactor hall were approximately 34 Sv/hr – a lethal dose in 10-20 minutes.

The situation inside the reactors at Fukushima is still very dangerous even though workers have managed to go inside parts of the buildings.
Asahi Shimbun explains this may delay or require changes to the long term decommissioning road map.

This article would not be possible without the extensive efforts of the SimplyInfo research team
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