March 28, 2011
The health ministry has instructed the operator of water purification plants nationwide to temporarily stop taking in rainwater to prevent contamination in tap water following radiation leaks from the crippled Fukushima Daiichi nuclear plant, ministry officials said Sunday.
While calling on the plants to ensure stable supply of tap water, the Ministry of Health, Labor and Welfare also proposed covering pools of the plants with tarps to keep out rainwater or to use powdered activated carbon that can help get rid of radioactive materials.
The instruction by the ministry came after radiation levels beyond Japan’s regulated standard were found in tap water at multiple purification plants in Fukushima and other prefectures including Tokyo, 220 kilometers southwest of the plant.
Radioactive materials emitted to the atmosphere from the nuclear plant apparently fell down to earth with the rain. Radiation levels in water fall over time after it stops raining.
The Tokyo metropolitan government said its test showed that radioactive iodine was undetectable Sunday in water at the Kanamachi purification plant in the capital’s Katsushika Ward, where water with radiation levels considered to be unsafe for infants was found Tuesday.
The undetectable level means that the reading of radioactive iodine per kilogram of water sampled was 20 becquerels or less.
At the Kanamachi plant, the level of radioactive iodine has been falling since Tuesday when it was 210 becquerels, exceeding the central government’s limit of 100 becquerels for safe consumption by infants but below the 300 becquerels limit for adults.
Radioactive iodine was also undetected at the Ozaku purification plant in Hamura in the suburbs of Tokyo the same day while 27 becquerels was marked at the Asaka plant in Asaka, Saitama Prefecture, north of Tokyo.
Another government survey over the weekend showed that radiation levels in Yamagata Prefecture, next to Fukushima, returned to a normal state, even falling below a maximum level hit before the massive quake.
The maximum radiation level marked in Yamagata came to 0.074 microsievert from 5 p.m. Saturday to 9 a.m. Sunday, down from 0.089 observed between Friday and Saturday. A human is exposed to radiation of 50 microsieverts in one X-ray chest examination.
The maximum radiation level detected in Tokyo, Tochigi and Ibaraki prefectures also continued to fall.
This article was posted: Monday, March 28, 2011 at 4:52 am