Many local governments are troubled over how to handle waste containing radioactive cesium, including sludge discharged from water and sewage treatment plants, and ash.
According to surveys by the Health, Labor and Welfare Ministry and The Yomiuri Shimbun, more than 120,000 tons of such radioactive waste is being stored in Tokyo and 13 prefectures in the Tohoku and Kanto regions.
Although the government aims to establish a new law to create a government-led framework to dispose of the waste, it is uncertain whether this will resolve the problem quickly.
About 180 tons of sludge was being stored at a disposal site in Fukushima city as of Wednesday. Sludge is discharged when river water and sewage is purified at treatment plants–water treatment plants discharge sludge containing mostly earth and sand, while sludge from sewage treatment plants contains domestic wastewater and excrement.
Therefore, most of the sludge is incinerated to reduce its volume, after which it is buried or recycled into materials for cement.
At the disposal site in Fukushima’s Horikawacho district, sandbags weighing one ton each were recently piled up inside an outdoor tank about 5 meters deep and surrounded by concrete walls 15 centimeters thick.
The bags were filled with dehydrated sludge containing radioactive cesium. Workers in protective suits lifted the bags into the tank with a crane.
The quantity of the radioactive sludge was increasing by about 14 tons a day, and according to workers, the 10 tanks at the site will be full by the end of the year.
Separately from the bags, about 5,000 tons of sludge containing higher levels of radioactive substances were being stored untouched in tanks. This is because 446,000 becquerels of cesium per kilogram were detected in the sludge in May, and about 300,000 becquerels at a later date.
The government presented a preliminary guideline for handling such radioactive waste in June. It asked local governments to take measures to block radiation rays if radioactivity exceeds 100,000 becquerels, but it does not give directions as to final disposal methods.
An official of the city government said: “Many residents have expressed fears about the effects of radioactive rays and complained about the odor. We want the government to indicate how we should handle the waste as soon as possible.”
The guideline stipulates that if the radioactivity is less than 100,000 becquerels, waste can be temporarily stored at so-called controlled landfill sites, at which hazardous substances will not leak into soil.
But little progress has been made in securing such disposal sites to accommodate radioactive waste.
At a water purification center in Maebashi, 41,000 becquerels of radioactivity were detected in ash in May. The center is storing 190 tons of radioactive waste.
However, there is no controlled disposal site in Gunma Prefecture that fulfills the guideline’s requirement for how far such a site must be from residential areas.
A city government official said, “All we can do now is store the waste.”
About 30,000 becquerels of radioactivity was detected at a plant operated by the Tochigi prefectural government for recycling sewage waste in Utsunomiya. The plant’s storage facilities will be full of ash and vitreous slag by the end of August.
The prefectural government has consulted with 23 municipalities from which sludge and ash are brought to the plant. It is considering returning radioactive waste to sewage treatment sites or private-sector garbage disposal sites in the municipalities for storage.
But a senior official of one of the city governments that has a disposal site said, “Unless the time limit for storage is known, no disposal site will agree to accept [the waste].”
The guideline stipulates that if the radiation level is less than 8,000 becquerels, waste can be permanently disposed of by burying it at controlled landfill sites.
But this measure has been implemented only at a few locations, including Tokyo wards with disposal sites facing Tokyo Bay.
An official of a Tokyo-based waste disposal company with a controlled landfill site in Chiba Prefecture said: “We’re examining whether longtime landfill storage [of radioactive waste] could cause unknown problems. Even if waste clears the government’s guideline, we can’t accept it unconditionally.”
Such sludge and ash had been recycled into cement materials and fertilizer, but the processes have been stalled since the accident at Fukushima No. 1 nuclear power plant.
A law for regulating nuclear reactors and other facilities stipulates that if the radiation level in finished products is less than 100 becquerels, sludge and ash with radioactive substances can be mixed into materials for cement.
However, companies producing the recycled materials have become nervous. They will not accept sludge or ash unless the radiation level at the time of delivery is less than 100 becquerels.
The companies are especially reluctant to accept ash, which contains higher levels of radioactivity than sludge.
Taiheiyo Cement Corp., the nation’s largest cement producer, resumed in June accepting dehydrated sludge at its plant in Saitama Prefecture, but it has not accepted ash.
Some local governments. such as Saitama and Chiba prefectures, are considering storing radioactive waste in the form of sludge without incinerating it.