8 YEARS SINCE DISASTER: Gov’t to mull long-term storage of tritium-tainted water

4 August 2019

A government subcommittee will launch full-fledged discussions based on the premise of long-term storage of tritium-contaminated wastewater from Tokyo Electric Power Co.'s crippled Fukushima Daiichi nuclear plant, panel chairman Ichiro Yamamoto said Aug. 3. It is tasked with examining how to dispose of water containing tritium, a radioactive substance which remains intact in the current process of purification.

Yamamoto, vice president of Nagoya University of Arts and Sciences, made the comment after inspecting the plant. He showed sympathy for calls for long-term storage but pointed out that it is not a permanent solution because of the limit to the capacity of tritium-containing water tanks which can be installed on the plant premises. He thus indicated the panel's continuation of arguments over methods of permanent disposal.

The visit by the subcommittee's delegation was the first in about two years since July 2017. Its nine members toured part of an area set aside for the installation of additional tritium-tainted water tanks and a site for the planned construction of facilities for storing waste materials, among other places.

"We have to consider storing tritium-containing water," Yamamoto told reporters after the tour, showing his intention to sort out conditions for realizing long-term storage on the plant premises. "Various equipment and storage space are necessary," he said. "We will discuss how to make storage space available while allowing for these factors," he added, indicating that the panel will scrutinize how to make available land which can be used for storage.

On the other hand, Yamamoto referred to the need for determining a future disposal method, saying, "We cannot store wastewater eternally. When this area is cleaned up (after completion of plant decommissioning), we would like to eliminate (tritium-tainted) water as well."

At a public hearing held in August last year, one participant after another called for long-term storage of tritium-containing water instead of releasing it into the Pacific Ocean. At the next subcommittee session on Aug. 9 based on the outcome of the inspection, discussions are expected to focus on whether the plant premises can accommodate additional tanks exceeding the maximum capacity of 1.37 million tons currently planned by the utility and on how long the storage can be continued, among other topics.

Tetsu Nozaki, head of the Fukushima Prefectural Federation of Fisheries Cooperative Associations opposing the dumping of tritium-tainted water into the sea, appreciated Yamamoto's view. "We are grateful to see the subcommittee discuss long-term storage on land while heeding fishermen's calls," Nozaki said. "But we remain opposed to the ocean release as an ultimate method of disposal."

In a report drawn up in 2016, a government working party listed five alternative methods of treating tritium-tainted water: geological injection, release into the ocean, atmospheric release as vapor, atmospheric release after conversion to hydrogen, and underground burial. The subcommittee had held 12 meetings as of last December on the basis of the report.

■Deciding disposal method inevitable
Tritium-contaminated wastewater arises at nuclear reactors at home and abroad, and is released into the sea after dilution in many cases. Toyoshi Fuketa, chairman of the Nuclear Regulation Authority, sees ocean release as "the sole choice" but, in reality, it has not won the understanding of residents in Fukushima Prefecture.

About 1.15 million tons of treated wastewater, including tritium-containing water, are kept at the plant. The utility plans to increase total tank capacity to 1.37 million tons by the end of next year. If newly contaminated water stemming from the inflow of underground water stands at the fiscal 2018 level of 170 tons per day, additionally installed tanks will theoretically be full within 2022. Even if wastewater is to be stored for a long period, discussions over an ultimate disposal method cannot be postponed.

(Translated by Kyodo News)