In excess of 496,000 cu. meters of low-level radioactive waste would need to be disposed of through burial if every nuclear reactor in the country is decommissioned, according to government officials.

It is the first time a specific volume for radioactive waste stemming from reactor decommissioning has been disclosed, the officials from the Natural Resources and Energy Agency, under the Ministry of Economy, Trade and Industry, said Friday.

The hunt for a disposal site for the waste is ongoing.

The total covers 48 commercial reactors operated by nine regional utilities and Japan Atomic Power Co., as well as eight slated for decommissioning: the six units at Tokyo Electric Power Co.’s disaster-hit Fukushima No. 1 plant, and reactors 1 and 2 at the Hamaoka plant run by Chubu Electric Power Co. in Shizuoka Prefecture.

In addition to high-level radioactive waste represented by the spent nuclear fuel, low-level waste must be buried for disposal and kept apart from residential settlements for up to 400 years.

To pass the costs of reactor decommissioning on to electricity users, power companies estimate the volume of low-level radioactive waste that needs to be disposed of and submit the figures to the Natural Resources and Energy Agency.

Of the low-level waste, pressure vessels, which contain nuclear fuel in reactors, and fuel control rods are among the most dangerous. They are categorized as L1 waste, which must be buried deeper than 50 meters and managed for an estimated 300 to 400 years.

According to estimates by the power companies, reactors 1 through 4 at Kansai Electric Power Co.’s Oi nuclear plant in Fukui Prefecture would generate the largest amount of L1 class waste, at 936 cu. meters. Units 1 to 7 reactors at Tepco’s Kashiwazaki-Kariwa plant in Niigata Prefecture came in second, at 849 cu. meters.

The total amount of L1 waste from all 56 reactors, including the eight scheduled for decommissioning, comes to 7,613 cu. meters.

Radioactive waste designated as L2 has a lower radioactive concentration and includes filters and waste fluid, while even lower-ranked L3 waste includes concrete.

Tepco’s Kashiwazaki-Kariwa plant is predicted to produce the largest volume of L2 and L3 waste.

The total amount of L2 waste at all 56 reactors is estimated at 95,652 cu. meters; for L3 waste, the figure stands at 393,174 cu. meters.

Postponing a decision on where to bury such waste in turn delays decommissioning work or means the waste will need to be stored temporarily on the premises of nuclear power stations.

Once new reactors under construction enter into operations, including at Electric Power Development Co.’s Oma plant in Aomori Prefecture, Japan’s mountain of nuclear waste will only continue to grow.