Nuclear waste: in Japan, a sensitive project in an earthquake-prone region

On the island of Hokkaido, a contested project plans to bury 19,000 tons of radioactive waste 300 m underground. In a region subject to the risk of earthquakes.

Yugo Ono, geologist and professor emeritus at the University of Hokkaido, considers that it is risky to bury radioactive waste in an area subject to seismic movements.

Ouest-France Johann FLEURI. Published on 03/11/2022 at 06h30

On the island of Hokkaido, Numo is carrying out stage 1 of the investigation, which began in 2020. The radioactive waste management company is studying the location, soils, seismic history of the area and calculating budgets. Residents and the city council will be asked to vote on whether to proceed with the project and move to Phase 2. The vote, scheduled for November, has been postponed.

Stored for over a thousand years

The 19,000 tons of nuclear waste that could eventually be buried on site, between 300 m and 3 km below the surface of the ground, are extracts of liquid waste, which after several treatments, remain highly radioactive and must be stored for more than a thousand years, to no longer present a danger to humans. The burial project, the first of its kind in the archipelago, consists of placing them in stainless steel tubes, so that they can be stored as vitrified waste. Numo plans to store 40,000 of these containers underground.

Soil and water table

An underground project that seems risky in a country subject to earthquakes. At Numo, we believe that “the degree of danger is under control”. In the event of a major earthquake, “the containers will follow the movement of the earth”. But Yugo Ono, a geologist and professor emeritus at Hokkaido University, does not share this opinion. “Buried, the waste could pollute the soil and groundwater in the event of a strong earthquake,” he says.

Risks

“The geology of the region, composed of volcanic rocks, is unsuitable for such a project, says the scientist. The soil is very affected by seismic activity. In the case of a major earthquake in Suttsu, “the radioactivity will spread into the water table,” he says. The waste would be stored at a depth of 300 meters, while “seismic activity can be felt up to 10 kilometers down.” Under pressure, the expert is certain: “The tanks will break.”

Another method

Rather than burial, “the only method of storing radioactive waste for Japan today is in steel containers, covered with 2 meters of concrete, within the walls of nuclear power plants. According to Yugo Uno, “this is the safest method, which we master best and it is not so expensive”. But this system requires that the containers be changed every fifty years at the most because the steel will be attacked by radioactivity. “Every twenty years would be better for maximum safety.”

https://www.ouest-france.fr/monde/japon/dechets-nucleaires-au-japon-un-projet-sensible-dans-un-sol-expose-au-risque-sismique-34ad2578-2cfb-11ed-b51f-5704b8d091a6?fbclid=IwAR3r-anXr64CKVoDgPV_t3Gye0cbGKoJdpBepWuTCEZe8WwQQrlTF9L8B1k