Quarry sourced crushed stones from hot-zone city of Namie
FUKUSHIMA — High levels of radiation have been detected on the first floor of a newly built condominium complex in Nihonmatsu, Fukushima Prefecture, the municipal government said.
Crushed stones used in the building’s concrete foundation came from the exclusion zone around the Fukushima No. 1 nuclear plant, local government officials said.
A quarry firm said Monday it shipped some 5,280 tons of crushed stones from Namie, Fukushima Prefecture, to 19 contractors after the nuclear crisis started last March 11, including some 1,065 tons distributed to a concrete maker that provided the material for the Nihonmatsu building’s foundations.
The firm is investigating its shipments to determine if crushed stones contaminated with radiation also were used in other buildings.
The city of Nihonmatsu detected 0.9 to 1.24 microsieverts of radiation per hour inside the first-floor condominium unit, which is higher than the radiation level outside, which was between 0.7 to 1 microsieverts at places 1 meter above ground around the building. On the second and third floors, the inside readings were 0.1 and 0.3 microsievert.
The city conducted the checks after a junior high school girl living on its first floor logged an exposure reading of 1.62 millisieverts during a three-month period from September, the local authority said.
The Ministry of Economy, Trade and Industry has not imposed radiation restrictions on crushed stones used in concrete or curbed their shipments.
Although the quarry stopped taking stones from Namie, those picked up before the disaster had been stored under simple roofs or were exposed to weather.
The radiation at the Namie stone collection site stands at around 20 microsieverts per hour, the prefecture said.
The head of the quarry said: “I never imagined the crushed stones were radioactive when I shipped them. I feel very sorry for those who have been involved.”
Chief Cabinet Secretary Osamu Fujimura said Monday the government will closely study the distribution routes that the crushed stones took, but he also said that the annual radiation exposure in the condo will not reach 20 millisieverts — the level at which evacuation would be required.
The three-story structure has 12 condos, with two of the four units on the first floor occupied by nuclear evacuees from Minamisoma and Namie.
Fukushima Prefecture officials will look for other places to accommodate the families living on the first floor, officials said.