High radiation doses were reported Thursday in spots in Tokyo and neighboring Chiba Prefecture, both over 200 kilometers away from the crippled Fukushima Daiichi nuclear plant, with their readings found to exceed current dose levels in some evacuation zones around the plant.
Airborne radiation of up to 3.35 microsieverts per hour was recorded Thursday along a sidewalk in a residential area in Tokyo’s Setagaya Ward in an inspection commissioned by the ward, and a citizens’ group detected up to 5.82 microsieverts close to the ground at a children’s theme park in Funabashi, Chiba Prefecture, local officials said
After learning of the findings at the H.C. Andersen Park, officials in Funabashi began checking radiation levels in the park and the affected area was made off limits by its operator. The contaminated spot is located where accumulated rain water flows into and is not normally accessed by park visitors.
Setagaya officials said the higher radiation level could have resulted from an accumulation of rainwater due to the location’s sunken geological formation. But they could not explain why radiation readings taken at a height further above the ground were higher than close to the surface where mud and dust gather.
The officials said they have used water and other methods in attempt to decontaminate the spot, which was discovered after a resident alerted authorities, but radiation levels have shown little improvement even after the cleaning.
In Setagaya, radiation of up to 3.35 microsieverts per hour was recorded Thursday at a height of 1 meter along the sidewalk in the Tsurumaki district, ward officials said.
The ward officials took samples of tree leaves over a home’s board fence in the area concerned to investigate what type of radioactive material is involved.
They are also trying to work out how to decontaminate the sidewalk, which is regularly used by pupils at a primary school. The area has been cordoned off as a precautionary measure.