Dozens of bags containing waste polluted with radioactive substances are still missing in Fukushima Prefecture, three weeks after they were swept away from storage areas in floods triggered by Typhoon Hagibis.

Of the 90 bags originally lost, 36 remain missing. The Environment Ministry, prefectural officials and others are conducting extensive searches but so far they have not had much luck.

In many municipalities in the prefecture, a lot of radioactive waste, including soil, was generated through decontamination work after the 2011 nuclear disaster at Tokyo Electric Power Company Holdings Inc.’s Fukushima No. 1 power plant. Numerous bags containing the waste are kept outdoors in temporary storage areas around the prefecture.

Heavy rains from the 19th typhoon of the year flooded storage space in many locations, sweeping away 44 bags in Kawauchi, 30 in Tamura, 15 in Nihonmatsu and one in Iitate.

By the end of October, 50 bags had been recovered. The contents had leaked from half of them. “We had far heavier rains than we expected. We did not cover bags of radioactive waste,” said an official of the Tamura Municipal Government.

The ministry and other organizations have mobilized 20 to 30 workers to look for the missing bags, wading into rivers when necessary and using drones to search areas that cannot physically be entered.

An aerial survey was conducted by helicopter on Oct. 23. On Friday, 29 workers searched the Furumichi River and areas along it in Tamura. Four bags were collected, but their contents had been lost.

“There has been no confirmation of any environmental impact due to the loss of the bags,” a ministry official said.

“We’ll continue searching in cooperation with local municipalities.”