Noda city (Noda-shi on the map) is located in Chiba prefecture, at the northern doorstep of Tokyo.
Noda City announced on January 24 that more than 15,550 Becquerels of radioactive cesium exceeded the criteria of designated waste (more than 8,000 bq per 1 kilogram) from the rooftop sludge of Municipal Nittsuka Elementary School. It is the first time that sludge exceeded the standard value in the city. The city already removed the sludge, in accordance with procedures as specified waste based on the Special Measures Law.
In response to the high radiation dose measurements found in Kashiwa city public property site this month, the city started inspection of sludge etc. and dose measurement at 300 public facilities. The country’s decontamination standard is 0.23 microsieverts per hour with a measurement height of 1 meter (50 centimeters for children-related facilities), but the city has independently set the measurement height to be a more severe 5 cm. There are no places that have exceeded city standards so far.
Meanwhile, on the 14th and 15th, they measured sludge on the roof of 12 elementary and junior high schools that were the subjects of solar panel roofing projects. As a result, they found doses exceeding city standards at five schools, up to 0.85 micro-Sievert was measured. City removed the sludge and checked radioactive cesium concentration. Only the sludge of Yotsuka-sho, had concentration of cesium exceeding the standard value of designated waste.
The removed sludge is temporarily stored at a temporary storage place surrounded by containers on the city hall premises. Approximately 5 cubic meters of targeted waste is treated, and four schools sludge which cesium concentration was found within the standard value were treated as general waste.
Translated from Japanese by Hervé Courtois