A government task force on nuclear disaster on June 16 decided to allow sludge containing 8,000 becquerels per kilogram or less of radioactive cesium to be buried in sites that will not be used as residential areas or agricultural fields.
A government task force on nuclear disaster on June 16 decided to allow sludge containing 8,000 becquerels per kilogram or less of radioactive cesium to be buried in sites that will not be used as residential areas or agricultural fields.
Sewage sludge contaminated with radioactive materials from the crippled Fukushima No. 1 nuclear power plant, operated by Tokyo Electric Power Co., has been found in 13 prefectures, including Fukushima and Tokyo.
The new policy will also apply to radioactivity contaminated sludge from waterworks.
The problem surfaced on May 1 when Fukushima Prefecture announced highly radioactive cesium was detected in sewage at sewage treatment facilities in Koriyama in the prefecture.
The task force on May 12 said sludge containing 100,000 becquerels per kilogram of radioactive substance "can be left temporarily." But the announcement met strong opposition from municipalities as being "too ambiguous."
The new guidelines announced on June 16 said that sludge containing 8,000 becquerels per kilogram or less of radioactive cesium can be buried after waterproof processing if the site is not used for residential or farming purposes; sludge containing 8,000 to 100,000 becquerels can be buried if the radioactivity dose of an individual is controlled under legal limits--less than 10 microsieverts a year; and sludge containing 100,000 becquerels or more per kilogram of radioactive substances should be stored at radiation-shielded facilities.
As for the legally permitted distance between a treatment facility and a residential site, the guidelines called for at least 70 meters for a facility that will process 100,000 becquerels or less of radioactive materials per kilogram and at least 50 meters for a facility that will handle sludge containing 70,000 becquerels or less of radioactive substances per kilogram. There will be no requirement on a facility that will handle sludge with 8,000 becquerels or less levels of radioactivity, the guidelines said.
With the Sewage Service Law in Japan requiring the reuse of sludge, 80 percent of sludge is being used to produce cement.
The task force said in May that if the radiation level of sludge is 100 bequerels or less per kilogram, reuse is permissible. However, significant number of related companies have refused to accept the sludge.
There is no change in the latest guidelines on the standards of cement production from sludge.
Taiheiyo Cement Corp. announced in its website on June 15 that it has started accepting sludge containing low-level radioactive substances.
The company's IR public relations group said, "Accepting sewage sludge is a social requirement. We sell products after checking and confirming the radiation level under the permissible limit."
However, some construction companies are likely to refuse using the recycled cement.
An official at the Ministry of Land, Infrastructure, Transport and Tourism said, "If a company refuses to use cement with a permissible level of radioactivity, the company can be said to be part of spreading harmful rumors. We would like to correctly convey the new standards."