|Radium bottles in Setagaya home may have been there for over 50 years |
Oct. 15, 2011 - 06:46AM JST( 49 )The hotspot in western Tokyo was first discovered by a civil group AFP
A radiation hotspot in Tokyo’s Setagaya Ward is not linked to the Fukushima nuclear crisis, Japanese authorities concluded Friday after finding dozens of old bottles of radium powder likely used for luminous paint.
As researchers carry out more stringent tests to map how far contamination has spread from the crippled Fukushima Daiichi nuclear power plant, local media had widely suspected the radiation hotspot was created by fallout from the plant.
But researchers inspecting the area and a nearby house discovered a decaying wooden box containing dozens of glass bottles under the floorboards, where the radiation levels hit more than 30 microsieverts per hour—an alarming level.
“Radium 226 was found in the bottles, and it is not an isotope created in uranium fission. This hotspot has nothing to do with the Fukushima nuclear accident,” said an official from the science and technology ministry.
“Some of the bottles were bearing signs indicating they were used for luminous painting, but it’s difficult to identify what they were for exactly. They are so old,” he said, adding that the bottles may have been in the house for more than 50 years.
Radium 226 is also used for medical purposes, he said.
The hotspot in western Tokyo was first discovered by a civil group measuring radiation levels in the capital, 220 kilometers from Fukushima, amid concerns about the spread of radiation from the crippled nuclear plant.
On Thursday, researchers had found radiation levels of up to 3.35 microsieverts per hour in the vicinity of the site, before the bottles were found.
Based on the Japanese science ministry’s criteria, that is equivalent to an annual dose of 17.6 millisieverts. A public evacuation is mandated if the figure reaches the equivalent of 20 millisieverts per year.
“No one lives in the house now, and just walking by near the house would have posed no health impact on neighbors,” the official said.
The origin of the bottles will likely remain a mystery, as he said the owner of the house and recent residents were unaware of it.
A man bought the land and built the house in 1953. He sold it to a relative of the current owner in 1960, ward officials said. The current owner said his family had no idea the bottles were underneath the floorboards.
Radiation fears are a daily fact of life in many parts of Japan following the earthquake and tsunami-sparked meltdowns at the Fukushima plant, with reported cases of contaminated water, beef, vegetables, tea and seafood.
Meanwhile, NHK on Friday reported that a citizens’ group in Funabashi City in Chiba, east of Tokyo, had detected radiation levels of up to 5.82 microsieverts per hour at a local park, compared to official readings of 1.55 microsieverts per hour at the site.
Variable winds, weather and topography result in an uneven spread of contamination, experts say, and radioactive elements tend to concentrate in places where dust and rain water accumulate such as drains and ditches.
The March 11 earthquake triggered a tsunami that tore into Japan’s northeast coast, leaving 20,000 people dead or missing, and sparking meltdowns and explosions at the Fukushima nuclear power plant.
The subsequent release of radiation forced the evacuation of tens of thousands from a 20-km radius from the plant and spots beyond.