Data released about plutonium found in soil outside Fukushima plant - 2nd Oct 2011

Data released about plutonium found in soil outside Fukushima plant - 2nd Oct 2011

Plutonium, a highly toxic radioactive substance, found in soil in places even several dozen kilometers away from the stricken Fukushima No. 1 Nuclear Power Plant had a maximum concentration equivalent to 11 and 31 percent of the levels within the premises of the plant, plant operator Tokyo Electric Power Co. said.On Friday the government released data showing varieties of plutonium were detected at six locations in Fukushima Prefecture as far as Iitate village around 45 kilometers northwest of the Fukushima complex.
The government data showed the maximum concentration of plutonium 239 and plutonium 240 combined was 15 becquerels per square meter measured in the city of Minamisoma.
TEPCO said this radioactivity level is equivalent to 0.23 becquerel per kilogram of soil -- or about 31 percent of the maximum 0.75 becquerel detected within the plant's premises.
Plutonium 239 requires 24,000 years for half of its substance properties to decay. The half-life of plutonium 240 is 6,600 years.
Plutonium 238, with a half-life of about 88 years, found in the town of Namie had a maximum concentration of 4 becquerels per square meter. This is equal to 0.062 becquerel per kilograms of soil, or about 11 percent of the 0.54 becquerel measured within the plant compound, according to TEPCO. Source