Government Must Fundamentally Review Geological Radwaste Disposal Policy

By Ban Hideyuki (CNIC Co-Director)

 

1. Background — Shift from marine dumping to geological disposal

In the 1950s and 1960s, Japan’s high-level radwaste disposal policy was marine dumping. In 1972, however, the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter (“London Convention”) was established (Japan ratified it in 1980), and the country was urged to shift its high-level radwaste disposal method from the conventional deep-seabed dumping to geological disposal within its borders.

 

In 1992, the Japan Atomic Energy Agency (then Power Reactor and Nuclear Fuel Development Corporation) released a document entitled “Research and Development on Geological Disposal of High-Level Radioactive Waste 1991” (First Progress Report). The Second Progress Report was released in 1999, based on which the Specified Radioactive Waste Final Disposal Act (“Final Disposal Act”) was put into effect in 2000. As specified in the Act, the Nuclear Waste Management Organization of Japan (NUMO) was established as the body responsible for selecting sites, building facilities, and carrying out the disposal.

The Final Disposal Act specifies that the site-location selection process should consist of three stages: a “literature review,” a “preliminary survey,” and an “in-depth investigation.” The Act states that each time one of these stages is completed, NUMO must listen to and respect the opinions of the of the municipalities and governor of the prefecture where the area is located before proceeding to the next stage. The national government interprets the Act as stating that if the response of a municipal head in the area is negative, NUMO will not proceed to the next stage. In 2002, NUMO started to openly invite applications from municipalities across the country to find candidate repository hosts, and in 2007, Toyo Town in Kochi Prefecture (then headed by mayor Tashima Yasuoki) submitted an application. However, a local opposition movement recalled the mayor, and a rerun election was conducted, ending up with the withdrawal of the application. After this “Toyo Town Incident” in 2007, another approach to finding a candidate town was added, which was to enable the national government to request a prospective municipality to accept a NUMO literature review.

 

2. “Nationwide Map of ‘Scientific Features’ Relevant for Geological Disposal”

In 2017, the Nuclear Energy Subcommittee Radioactive Wastes Working Group, placed under the Electricity and Gas Industry Committee of the METI Advisory Committee for Natural Resources and Energy, released a “Nationwide Map of ‘Scientific Features’ Relevant for Geological Disposal.” In retrospect of how the map was released, the Ministry of Economy, Trade and Industry (METI) was urged to determine a disposal site location by the national government and ruling parties, and prepared a plan to select scientifically prospective areas and to request municipalities in the name of the government to accept a literature review. However, such an approach would radically change the conventional site selection policy, and objections from parties concerned seems to have been quite considerable. As a result, the plan to prepare a map of prospective areas was changed to preparing a map showing scientific features indicating suitability for siting a repository. The Map was prepared based on NUMO’s preliminary survey area selection criteria, combined with transportation limitations.

In November 2020, NUMO began literature reviews in Suttsu Town and Kamoenai Village, both in Hokkaido. Suttsu had applied voluntarily for the review, while Kamoenai had accepted a government request. The results of these literature reviews were expected to be published in about two years, but were yet to be released as of March 2024. The reports will be made available for public inspection and will be used to recommend locations that should proceed to the preliminary survey. The heads of the municipalities that the literature review finds suitable to proceed to the next-stage survey will have an opportunity to express their opinions concerning whether to accept the recommendation or not. Hokkaido has an ordinance that rejects any admission of high-level radioactive waste into the island. In accordance with the ordinance, current Hokkaido Governor Suzuki Naomichi has been maintaining a stance of rejecting any preliminary survey.

If the disposal site search process moves in this direction, the efforts to find a host town will return to the starting point, indicating that the current host town selection approach needs to be reviewed.

 

3. What is “high-level radioactive waste”?

According to Article 2 of the Final Disposal Act, the scope of “high-level radioactive waste” includes vitrified radioactive waste (“class 1 specified radioactive waste”) and transuranic waste (TRU waste) for which geological disposal is suitable (“class 2 specified radioactive waste”). The Act does not regard spent nuclear fuel as radioactive waste; spent nuclear fuel is regarded as a resource. While power operators do not regard spent fuel as a high-value resource, once the fuel is reprocessed into plutonium it is assigned a high value in accounting books.

The radioactive material regulation legislation classifies spent fuel as high-level radioactive material. Likewise, spent MOX fuel, spent fuel from research and test reactors, as well as fuel debris from the Fukushima Daiichi and HIC (high integrity container) waste are defined as high-level radioactive waste (see Table 1).

If the disposal site selection process progresses from a literature review to a preliminary survey and then to an in-depth investigation, the area of the required disposal site size will differ depending on whether direct disposal of spent nuclear fuel is added to the waste to be disposed of, and regulatory means for nonproliferation will be required. This would mean a drastic change in the disposal site design. Accordingly, it is far more reasonable to design a disposal site whose scope includes the direct disposal of spent fuel, as described above.

 

4. Research on direct disposal of spent nuclear fuel

In the Japan Atomic Energy Commission (JAEC) Framework for Nuclear Energy Policy, established in 2005, there is a statement in case of uncertainties:

“3-1-3 (6) Responding to Uncertainties

Since there are uncertain factors such as technical trends and international situations over the long term, we expect that the Government, research and development institutions and operating entities will independently and/or collectively pursue surveys and research concerning direct disposal of spent fuel in an appropriate manner, which enables flexible considerations for policy choices in response to circumstantial changes. (page 34)”

In response to this nuclear energy policy, the METI Geological Disposal Fundamental Research and Development Coordination Committee (today’s Geological Disposal Research and Development Coordination Committee) included a direct spent-fuel disposal plan in the General Plan for Geological Disposal Research and Development (for FY2013 to FY2017) (March 2013). The plan shows the following milestones.

1) In one year (FY2013): Preparation of the “first summary” regarding the feasibility and challenges of direct spent-fuel disposal

2) In three years (by FY2015): Preparation of the “second summary regarding the technical feasibility of direct spent-fuel disposal (for-review version)”

3) In five years (by FY2017): Release of the “second summary (final version)” based on the second summary (for-review version), in which the plan is examined by experts in and outside Japan

The “first summary” scheduled originally for 2013 was released under the name of “Preliminary Assessment of Geological Disposal System for Spent Fuel in Japan: First Progress Report on Direct Disposal” (JAEA-Research 2015-016) in 2015.[1] However, the second summary (for-review version) has not yet been released. During the discussion to review the Framework for Nuclear Energy Policy, which began in 2010, the status of progress of the second summary was never mentioned. It seems that the preparation of the second summary had not yet  started. Nevertheless, the discussion about the review of this Framework failed to be finalized after it was exposed that the METI had a “secret meeting” (a meeting on how to respond to committee members). The JAEC was then organizationally scaled down, and the scope of its work was also reduced.

Thereafter, concerning the research on the direct disposal of spent nuclear fuel, the governmental Fifth and Sixth Basic Energy Plans (2018 and 2021) state concerning the study and research on direct disposal that the government will “promote steady study and research.”

“Concerning the technical reliability of geological disposal, the latest scientific knowledge will be periodically and continuously examined and reflected in the plan, and from the viewpoint of securing a wide variety of options and enabling flexible responses, study and research on the alternative disposal options such as direct disposal of spent fuel should be promoted consistently.”

The above-mentioned Geological Disposal Research and Development Coordination Committee created a five-year comprehensive plan starting from FY2023, which mentions research and development into alternative disposal options, specifically direct disposal and deep borehole disposal of spent nuclear fuel.

The second summary on direct disposal should be prepared, because it is essential to include the direct disposal of spent nuclear fuel as an option for disposal.

 

5. “First Progress Report on Direct Disposal” (2015)

This report deals only with the Base Scenario. As per the Comprehensive Technical Report (NUMO 2021), there should be a Perturbation Scenario, a Rare Event Scenario, and also a Human Intrusion Scenario. The second report is expected to present the assessment and results of each of these scenarios.

In this Base Scenario, two bundles of pressurized water type reactor spent nuclear fuel (burnup: 45,000 megawatt days per tonne of fuel (MWd/t) are sealed in one cask. The total amount to be disposed is 32,000 tons. This amount of spent fuel is equivalent to 40,000 units of vitrified radioactive waste. The thickness of bentonite is 70 centimeters, which is equal to that used for vitrified radioactive waste. The assumed timeline is also the same: an overpack breakdown will occur in 1,000 years, followed by the start of the leak of radioactive substances. The assumed rock type is crystalline schist (granite), and a disposal site is planned to be located on flat land and the groundwater is assumed to be precipitating water. Disposal depth is assumed to be 1,000 meters. The assessment of the vitrified radioactive waste in the crystalline schist is conducted at the same depth. Due to heat generation, disposal bores are required to be distant from each other, and the repository site ground surface area should be six times as large as that for vitrified radioactive waste. Included radioactive substances (the inventory) differ between spent nuclear fuel and vitrified radioactive waste. In the spent nuclear fuel, uranium and plutonium are included as they are, while in vitrified radioactive waste, these two elements have been mostly removed. Therefore, the major nuclides that influence dose evaluation should be different.

The assessment results show that the doses will be highest for the marine fishery operator group, whose exposure doses are estimated to be about 0.7 µSv/y. This estimation is based on the expected time point when radioactive substances will migrate from the disposal site located in a plain field area to the ocean and is higher than the estimated doses for the agriculture worker group and freshwater fishery operator group.

The major nuclide that will influence the doses is assumed to be carbon 14 for both organic and inorganic nuclides. The reason why the doses are expected to increase after 100,000 years is attributed to uranium daughter nuclides (see Figure 1[2])

There are also issues specific to spent nuclear fuel. As an example, in 100 years, the radioactivity of plutonium 241 reduces to about seven thousandths of its original value. While the content of plutonium included originally in the spent nuclear fuel is reduced, the relative amount of plutonium 239 will increase. Such a situation is often dubbed the generation of “plutonium mines.” “It is required to consider security measures and nuclear security-related international requirements even after the facilities are closed, not to mention during the operation of disposal facilities” (“First Progress Report,” p. 4). One of the prospective methods to avoid the generation of plutonium mines is deep borehole disposal.

To dispose of the plutonium powder already stored in Japan, the can-in-canister method, down blending method, and hot isostatic press (HIP) method are being studied. Dr. Edwin Lyman, a member of the Union of Concerned Scientists (UCS), reported on the US-based experimental study of the down blending method at Japan PuPo2017 (International Conference on US-Japan Nuclear Co-operation Agreement and Japan’s Plutonium Policy) organized by Citizens’ Nuclear Information Center in Tokyo. Concerning the HIP method, I received an introduction to this research from Professor Neil Hyatt of the University of Sheffield during my visit to the UK in 2019.

 

6. Statement by 300 geoscientists and joint convention on radioactive waste

On October 30, 2023, 300 geoscientists released a statement: “There is no suitable place for geological disposal in Japan, one of the world’s most tectonically active zones,”[3] demanding a fundamental review of the conventional geological HLW disposal plan. “At present it is impossible to specify a stable place not influenced by earthquakes by predicting bedrock brittleness and ultradeep underground water behavior resulting from crustal changes during the upcoming 100,000 years . . . the conventional policy that takes geological HLW disposal for granted should be reviewed in the light of nuclear plant policy change, including temporary terrestrial HLW storage. The review of the conventional policy should ensure sufficient opportunities for scientists, engineers and experts engaged in geology to express opinions, in cooperation with the Science Council of Japan. In addition, a neutral, open and independent organization should be set up to listen widely to the voices of the people of Japan to lead to a conclusion.”

Even if there is no geological layer that is theoretically available for HLW in the Japanese archipelago, the high-level radioactive waste already generated must be processed and disposed of in this country. This is clearly stated in the preface of the Joint Convention on the Safety of Spent Fuel Management and on the Safety of Radioactive Waste Management[4] (entered into force in June 2001; Japan acceded to the Joint Convention in November 2003): “(xi) Convinced that radioactive waste should, as far as is compatible with the safety of the management of such material, be disposed of in the State in which it was generated.”

It is therefore a must to find a location where the highest possible safety can be secured. The current disposal site selection procedure is, based on the “Nationwide Map of ‘Scientific Features’ Relevant for Geological Disposal,” to select relatively good locations, from about ten locations that apply for the hosting of the site or to which the national government has requested a literature review to be conducted. The method based on the “Nationwide Map of ‘Scientific Features’ Relevant for Geological Disposal” will end up selecting a relatively “good” location, but does not necessarily ensure the highest possible security.

The background that may allow such an approach appears to be that emphasis is placed on the “engineering response” (“artificial barrier”). The safety of geological disposal is regarded as being ensured by the combination of the “artificial barrier” and “natural barrier,” but to ensure safety for 100,000 years, the “natural barrier” should be more strongly emphasized despite the conventional approach.

 

7. An alternative approach proposed by Dr. Chigira Masahiro[5]

In his book, entitled Selection of High-level Radioactive Waste Sites ― Prior Avoidance of Geological Uncertainties (in Japanese), Dr. Chigira argues that the geological areas that are very likely to be screened out as a result of the screening process should be excluded from the beginning. He states that the geology in the Suttsu Town and Kamoenai Village areas consists of water-cooled cataclasite and should be avoided. He writes, in addition, that the areas where there are many rifts and/or a variety of intricate geological conditions should be avoided. Concerning granite, he writes that plutonic granite rock mass deep underground is prospective for HLW disposal use, while it is often seen in the form of columnar joints on the ground surface.

If the conventional policymakers accept this prior avoidance recommendation, the possibility of selecting a safer site selection is higher, but it is unknown if it can be accepted at present. That is because, even if the subterranean structure consists of, as an example, hyaloclastite, NUMO and the government are highly likely to judge that the safety of the location can be secured by engineering.

What response those who are currently engaged in geological disposal can make to this new proposal, different from conventionally discussed methods, is not known, but they must respond to the proposal with serious consideration.

 

8. Recommendations from the Science Council of Japan

In 2010, the JAEC requested the Science Council of Japan (SCJ) to prepare a report on how to develop a consensus about geological disposal and how to communicate information associated with it. In response, the SCJ established “High-level Radioactive Waste Disposal Study Committee,” which consisted of members who were experts in a variety of academic fields, including social science and seismology. On September 11, 2012, the SCJ submitted its “Policy Recommendations on High-Level Radioactive Waste Disposal (Response Paper)” to the JAEC. In consideration of the 2011 Fukushima Daiichi NPS explosions, the response paper was very different from what was requested by the JAEC. The paper presented the following recommendations:

1) Fundamentally reviewing the policy on high-level radioactive waste disposal
2) Recognizing the limits to scientific and technical capacities and securing scientific autonomy
3) Rebuilding the policy framework in consideration of temporal safe storage and total inventory management
4) Necessity of building a persuasive policymaking process to ensure fairness in burden sharing
5) Necessity of organizing discussion systems to build popular consensus on multiple stages
6) Being aware that tenacious, long-term commitment is required to reach a solution

Paragraph 1) presents an important indication that the current process is preposterous in its attempt to obtain a consensus to a solution to final disposal without the population’s understanding of nuclear policy. The temporal storage is expected to last a few tens to hundreds of years. The total inventory is required to be managed in two respects: setting an upper limit to the total radioactive waste generated and suppressing waste generation. The SCJ paper demands, during the temporal storage lasting a few hundred years, multi-stage consensus building with stakeholders, and research, investigation, and technology development by independent scientist groups.

The report calculates that the temporal storage would be about 300 years, but the reasons for this duration are not clarified. However, I estimate that the amount of cesium and strontium, which thermally affects the geological disposal of vitrified radioactive waste, would reduce to about one thousandth over this period of time. Currently reprocessed waste is planned to be temporally stored for 300 years, but because vitrified waste is conventionally planned to be stored on the ground surface for more than 50 years, about 200 years’ additional temporal storage may produce an equivalent reduction effect. During the long-term, on-surface storage, every type of high-level radioactive waste should be examined, suitable disposal methods for individual HLW types investigated, and multi-stage consensus building should be engaged in among stakeholders.

Neither JAEC nor METI showed an attitude of seriously examining and referencing the SCJ response paper. Now that the step toward the preliminary survey will be suspended, they should return to the SCJ paper and thoroughly review the conventional radioactive waste disposal policy. (Written in March 2024)


[1] “Preliminary Assessment of Geological Disposal System for Spent Fuel in Japan; First Progress Report on Direct Disposal,” jopss.jaea.go.jp/pdfdata/JAEA-Research-2015-016.pdf.

[2] Japan Atomic Energy Agency. Preliminary Assessment of Geological Disposal System for Spent Fuel in Japan – First Progress Report on Direct Disposal (in Japanese), December 2015, p. 286. jopss.jaea.go.jp/pdfdata/JAEA-Research-2015-016.pdf. Retrieved on May 8, 2024.

[3] Statement: “There is no suitable place for geological disposal in Japan, one of the world’s most tectonically active zones.” (For more details, please refer to article at Report on the 2nd Meeting of the Geological Disposal Technical WG: Experts Against Geological Disposal Attend a Government Working Group

[4] The Joint Convention on the Safety of Spent Fuel Management and on the Safety of Radioactive Waste Management (Joint Convention on Waste) www.nra.go.jp/data/000110080.pdf

[5] Chigira Masahiro: Director, Fukada Geological Institute

 

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