Radiation Levels at Fukushima Daiichi Fall; Radiation and Sieverts Explained

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Researched by Industrial Info Resources East Asia (Kofu-shi, Japan)--The Japanese Nuclear and Industrial Safety Agency has reported that radiation levels have fallen steadily over the past 12 hours at the Fukushima Daiichi nuclear power station. As of Wednesday, March 16, at 5:00 p.m. JST, equipment at the main plant gate of Fukushima Daiichi detected radiation levels of 752 microSieverts per hour. This is equivalent to 0.000752 Sieverts or 0.752 miliSieverts. A Sievert is the International System of Units derivation of dose equivalent, which is the measure of effects of ionizing radiation on tissue.

1 Sievert (Sv) = 1,000 milliSieverts (mSv) = 1,000,000 microSieverts (μSv)

MicroSieverts are the current unit of measure used to describe radiation levels emitted from Fukushima Daiichi nuclear power station.

Single-dose examples include the following:

• One banana: 0.0001 milliSieverts
• Mammogram: 5 milliSieverts
• Chest CT Scan: 6 to 18 milliSieverts

Hourly dose examples include the following:

• Highest radiation recorded at Unit 2 of Fukushima Daiichi: 8 milliSieverts per hour
• Highest radiation recorded at Fukushima Daiichi main plant gate: 11 millilSieverts per hour
• Standard dose in relation to Chernobyl Unit 4 and its fragments after explosion: 10 to 300 Sieverts per hour

Yearly dose examples include the following:

• Residing in close proximity to a nuclear power station: 0.0001 to 0.01 milliSieverts per year
• Residing in close proximity to a coal-fired power station: 0.0003 milliSieverts per year
• Smoking 1.5 packs of cigarettes per day: 13 milliSieverts per year
• Lowest clearly carcinogenic level: 100 milliSieverts per year

An information breakdown similar to this one was broadcast to the Japanese public via television shortly following the first mention of any trouble at Fukushima Daiichi nuclear power station.

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