Tono Mine
Activities and Closure Process

Excavation at the Tono Mine began in 1972 to study uranium deposits. From 1986, geoscience research—focusing on solute transport in sedimentary rock—was carried out.

Closure planning of Tono Mine started in FY2004, and actual closure activities began in FY2010. Backfilling of mine drifts, including three shafts, was completed in FY2014.
In FY2015 and FY2016, surface facilities were removed and land leveling was completed, except for the muck disposal area.
Voluntary environmental monitoring, in addition to legal requirements, continued for five years after the backfilling. In 2019, external experts confirmed that no issues were found, and monitoring was concluded.
Currently, mine site management and environmental monitoring are being conducted.