The Ministry of Economy, Trade and Industry has crafted a map highlighting areas around Japan the government deems appropriate for constructing final disposal sites for high-level radioactive waste from nuclear power plants. The government called the move a first step in the effort toward disposal of the waste — provisions for which have been lacking even as the nation proceeded with nuclear power generation for decades.

It is not clear, however, whether the effort will move forward as hoped. The process to produce the map essentially involved only insiders from the so-called nuclear village, and questions have been raised as to how scientifically reliable it is. The government needs to keep the process for identifying candidate sites open and transparent to win the public’s understanding and trust in the effort.

Spent nuclear fuel is reprocessed to extract uranium and plutonium, which can be used again as fuel. High-level radioactive waste consists of liquid that is produced during reprocessing. Such waste will be vitrified in glass and put in metal canisters. Since this waste emits strong radiation over a long period of time, the canisters containing it will be surrounded by clay to serve as a buffer. Under a law passed in 2000, vitrified high-level nuclear waste in canisters must be buried in bedrock at least 300 meters deep, away from human settlements, and stored for up to 100,000 years.

The map unveiled by METI is illustrated in four colors — pale green, deep green, gray and orange. Pale and deep green areas represent areas where the underground disposal of high-level radioactive waste is deemed possible due to the absence of such obstacles as volcanoes, active geological faults and soft ground. They account for roughly 65 percent of the nation’s land and some 1,500 — or more than 80 percent — of the nation’s municipalities. Deep green areas, lying up to 20 km from a coastline, are deemed desirable from the viewpoint of transportation of the radioactive waste. They cover some 30 percent of Japan’s land and about 900 municipalities.

Areas considered inappropriate for hosting a site are marked in red or gray, covering slightly over 30 percent of the nation’s land. Red areas are characterized by the presence of volcanoes and active faults. Areas where coal mines and oil fields exist, or exploration for underground resources may be done in the future, are in gray.

One problem with the map is that the safety of building disposal sites in areas marked pale or deep green will not be scientifically guaranteed, since there will be limits to predicting future movements of geological layers due to unknown faults or the size and timing of volcanic eruptions. In using the map to explore possible candidate sites, the government needs to publicly share the risks of such unforeseeable developments.

Transparency in the process of producing the map is also questionable. The standard for classifying national land into four categories was set behind closed doors by a government panel whose members were chosen by METI officials. It is not known whether the standard has been reviewed by other experts.

Uncertainties hang over nuclear power in general. The government’s pursuit of the nuclear fuel cycle, in which spent fuel from power plants is reprocessed to be used again, remains elusive. Most of Japan’s reactors remain idle following the 2011 catastrophe at the Fukushima No. 1 plant, making it difficult to assess the volume of high-level nuclear waste that needs to be disposed of in the future.

In the past, the national government waited for municipalities interested in hosting a high-level nuclear waste disposal site to come forward. After none did so, the government adopted a new policy in 2015 that it would take the lead in finding a site — by highlighting scientifically feasible areas and asking multiple municipalities for surveys to determine prospective candidates. The administration of Prime Minister Shinzo Abe has been pushing the process to find a waste disposal site as it seeks to reactivate the idled reactors. Disclosing the map is part of the process. However, it has not been made known how the government will proceed with the next step — identifying candidate sites for surveys among the vast areas highlighted as feasible in the map. If the government at this stage unilaterally names candidate municipalities, major confusion will likely follow that will divide local residents and officials.

Disposing of high-level radioactive waste is an issue that cannot be averted given that the nation is engaged in nuclear power generation. But the government, which has long pursued nuclear power as a national policy, and companies that run nuclear power plants must not forget that they are ultimately responsible for producing the nuclear waste. The government needs to make the process toward disposal open and transparent — and scientifically trustworthy — sparing no effort to win the public’s understanding and support at each step of the way.

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