June 6, 2018

Deposit Tritiated Water in Large Tanks for 100 Years or Longer
Citizens’ Commission on Nuclear Energy (CCNE)
1. Recent Moves
Large volumes of radioactive water are accumulated at the Fukushima Daiichi nuclear
accident site, as groundwater flowing into the reactor and turbine buildings mixes with thecooling water that surrounds nuclear fuel debris. This is treated using equipments to remove
radioactive substances and then stored in makeshift water tanks as “treated water,” but it stillcontains tritium, which the equipments cannot remove. The stored “treated water” hasaccumulated over the past seven years to the point that total volume exceeds one million
cubic meters, and the site is jam-packed with rows of 1,000 m3 tanks. As a result, space tobuild more tanks is running out in less than three years1. Thus the authorities involved arereportedly making every effort to create a favorable atmosphere so that the society would
accept release of the water into the ocean.
This problem has been recognized at an early stage, with the government (Agency of
Natural Resources and Energy, METI) organizing a “Tritiated Water Task Force” under theCommittee on Countermeasures for Contaminated Water Treatment and publishing the“Tritiated Water Task Force Report” in June 20162.
At a meeting to exchange views with representatives of municipalities within Fukushima
Prefecture at the end of 2017, Toyoshi Fuketa, who chairs Japan’s Nuclear Regulation
Authority (NRA), expressed his view that from a scientific standpoint there would be noproblem with releasing the treated water into the ocean and that TEPCO should decide on adischarge method within the year3. At a regular press conference on January 17, Chairman
Fuketa expressed concern that if the decision to discharge the water delayed further, “thedecommissioning of the Fukushima Daiichi reactors would come to a standstill.”4
A telephone poll on Fukushima prefectural residents conducted last February 24 and 25 by
Asahi Shimbun Publishing Co. and Fukushima Broadcasting Co., asking whether or not theresidents agreed that the treated water accumulated in the tanks at the Fukushima Daiichi
nuclear power station should be diluted and released into the ocean. The results showed 67%
1“Treated contaminated water – time for a decision draws near,” Nihon Keizai Shimbun, Feb. 23, 2018 (inJapanese).
2“Tritiated Water Task Force Report,” June 2016.
http://www.meti.go.jp/earthquake/nuclear/osensuitaisaku/committtee/tritium_tusk/pdf/160603_01.pdf(Japanese) http://www.meti.go.jp/english/earthquake/nuclear/decommissioning/pdf/20160915_01a.pdf(English) An edition with commentary, “Regarding the Tritiated Water Task Force Report,” Nov. 11, 2016
http://www.meti.go.jp/earthquake/nuclear/osensuitaisaku/committtee/takakusyu/pdf/001_03_00.pdf(Japanese) and others.
3“TEPCO urged to discharge or dispose of treated water,” The Denki Shimbun, Jan. 16, 2018 (in Japanese).
4“Judgment required for release of Fukushima Daiichi treated water,” The Denki Shimbun, Jan. 18, 2018 (inJapanese).
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opposed, far outnumbering the 19% in favor5.

2. Controversy over Toxicity
Because exposure to tritium occurs internally at the cellular level and is frequently
simultaneous with exposure to other radioactive substances, epidemiological judgment on its
effects on human health is yet to be established. The prescribed concentration limit foroceanic releases is 60,000 becquerel per litter (Bq/L)6, but this by no means assures provedsafety. There are huge differences even in regulatory standards for drinking water, with theWHO saying 10,000 Bq/L; the Canadian government, 7,000 Bq/L (but the Ontario Drinking
Water Advisory Council recommending 20 Bq/L)7; and 100 Bq/L in EU8.

3. Evaluating Options for Dealing with Tritiated Water
The above-mentioned “Tritiated Water Task Force Report” refers to five groups ofdisposal technology and describes conceptual designs and estimated costs for each. None ofthem, however, appears to us a good solution.
The Citizens’ Commission on Nuclear Energy (CCNE) published a special report lastDecember titled, “Settlement After 100+ years of Shielded Isolation” (revised edition 2017,in Japanese)9. In this report, tritiated water is proposed to be stored in durable large-volume
tanks until thorough investigations and verifications are carried out, rather than rushing todischarge it to the ocean in the middle of the scientific disagreement on the radio-toxicity oftritium.
In concrete terms, if 10 large tanks of the type currently used at Japan’s oil stockpile baseswith a capacity of 100,000 tons each were built and the tritiated water kept in them for 123years, the total amount of tritium in the tanks is assured to be reduced to less than 1/1000th ofthe current amount, because tritium has a radioactive half-life of 12.3 years [i.e. 10 times ofthat yielding (1/2)10 = 1/1024]. This amount would be less than the minimum annual amountof oceanic discharge of tritium from the entire Fukushima Daiichi nuclear station during theeight years prior to the March 2011 accident there. What we have proposed is to carry out
such long-term storage and wait for sufficient decay of radioactivity. Given a unit
construction cost of about 3.0 billion yen and assuming an extra tank is built for conducting
internal inspections every 20 years, 11 units would come to about 33.0 billion yen, which
5“66％ ‘feel anxious’ about radioactive substances - Fukushima Prefecture poll,” The Asahi Shimbun,
March 3, 2018 (in Japanese).
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Notification No. 187 of the Ministry of Economy, Trade and Industry, “Notification establishing doselimits, etc., based on the stipulations of regulations regarding the establishment, operation, etc. ofcommercial nuclear power reactors,” March 21, 2001 (in Japanese). This gives a concentration limit of 60
Bq/cm3 for tritiated water in Attached Table 2 (i.e., 60,000 Bq/L).
7“Report and Advice on the Ontario Drinking Water Quality Standard for Tritium”, May 21, 20098
Canadian Nuclear Safety Commission, “Tritium in Drinking Water”, August 20, 2009http://nuclearsafety.gc.ca/eng/resources/health/tritium/tritium-in-drinking-water.cfm
9Released on Nov. 11, 2017, p. 7 http://www.ccnejapan.com/?p=7900
2differs little from the 34.5 billion yen cost of the plant’s “ice wall.” Further, the provenengineering at Japan’s oil stockpile bases can be applied to design specifications such as
construction of dikes around the tanks in case of total leaks. If further reduction ofradioactivity is deemed necessary and new storage tanks must be built to replace old ones atthe end of their service life, further decay on the order of 1/1000th can be expected bydepositing in new tanks for another 123 years.
Regarding safety in the case of earthquakes, building dikes—the same as the currently
implemented method—is a realistic approach for protection in case leaks occur. Regarding
where to build the tanks, we think it would be possible to use the site reserved forconstruction of Units 7 and 8 at the Fukushima Daiichi nuclear station. Moreover, thevolumetric efficiency of large tanks per unit site area is far higher than that of the smaller
1,000-ton capacity tanks which currently store the tritiated water, so if those smaller tanks
are dismantled in order and new large tanks built in turn, we think it would be possible toreplace the existing tanks in the area where they now stand.

4. Conclusion
Not everything has been elucidated regarding the toxicity of tritiated water. A fundamental
lesson learned from the many years of dealing with serious industrial pollution cases in thiscountry is that toxic substances should not be scattered across the environment, but should becentrally managed and detoxified to the utmost before being released into the environment.
The above proposal by the CCNE has a well-proved industrial basis, both in terms ofengineering and economy. It is, therefore, the most stable and safe solution.
As mentioned above, a poll in Fukushima found 67% of the residents opposed to sea
discharge, and under such circumstances, it would be utterly unacceptable from an ethicalstandpoint for the Government and TEPCO, who should bear responsibility and liability forthe nuclear accident, to make a unilateral decision and release the radioactive water into theocean.

For enquiries regarding the above matters, contact:
Citizens’ Commission on Nuclear Energy (CCNE),

c/o the Takagi Fund for Citizen Sciencerd

3 Fl. Arai Bldg., 4-15 Honshio-cho, Yotsuya, Shinjuku-ku, Tokyo 160-0003
TEL/FAX: 03-3358-7064

E-MAIL: email@ccnejapan.com URL: www.ccnejapan.com

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