3.2 R&D on Processing and Disposal Technologies for High-Level Radioactive Waste

JNC will develop safe and reliable technologies for vitrification of the high-level radioactive waste separated from re-usable nuclear materials during reprocessing. The information and experience obtained during the development work will subsequently be transferred to JNFL. JNC will also cooperate in the operation of JNFL's vitrification plant.

Regarding R&D on geological disposal technologies for HLW, JNC will carry out its research activities in accordance with the allocation of roles set out in the Long-Term Nuclear Program. JNC's research projects will contribute to realization of final disposal by NUMO and to the establishment of safety standards, etc. by the government.


3.2.1 Long-Term Perspectives

3.2.1.1 Developing Treatment Technologies for High-Level Radioactive Waste

(1) Vitrification of high-level radioactive waste will continue at the Tokai Vitrification Facility (TVF), providing relevant data on operational procedures and on plant-scale improvements.
(2) Information from the TVF has been provided for the company responsible for designing the vitrification facility at the Rokkasho Reprocessing Plant. JNC will actively support JNFL in carrying out test operation and, later, full operation of the facility.
(3) The vitrified waste stored temporarily at the TVF will be transported to an storage facility to be constructed at a site still to be identified; the waste will then be stored for 30 to 50 years before final disposal.
[1] The siting and construction of the storage facility will be realized systematically in accordance with the operation plan for the Tokai Reprocessing Plant (TRP).
[2] When siting the storage facility, care will be taken to fully coordinate activities with other involved organizations and, at the same time, to gain the understanding and cooperation of the local community.



3.2.1.2 R&D on Geological Disposal Technology for HLW

(1) The Role of JNC

To date, R&D on the geological disposal of HLW has been carried out with JNC as the lead organization. In the future, however, other organizations in Japan will also promote R&D on HLW in accordance with their assigned roles in the Long-Term Nuclear Program.

Activities leading to implementation of final disposal, and the tasks allocated to the different organizations, are set out in the Long-Term Nuclear Program. NUMO, as the implementation entity, will be responsible for developing technologies for the safe implementation of the disposal project, as well as for improvements in the areas of economic performance and efficiency. At the same time, the government and related institutions should actively push forward with R&D projects on safety regulations and repository safety assessment; basic R&D activities will include research on the deep geological environment and development of technologies aimed at enhancing the reliability of geological disposal. Based on past results, JNC should continue its R&D activities with the aim of demonstrating the reliability of geological disposal technologies and establishing advanced safety assessment methods. This will include work in underground research facilities (URLs) and at the Quantitative Assessment Radionuclide Migration Experimental Facility (QUALITY), etc. URLs are considered to serve not only as a place for conducting scientific investigations, but also as resources for enhancing public understanding of R&D activities related to the geological disposal.

According to the report entitled "Securing the Basis for Nuclear Technologies," published by the Nuclear Subcommittee of the Advisory Committee for Energy in June 2001, based on the Long-Term Nuclear Program and the consequent allocation of roles JNC is expected to conduct R&D using URLs and the QUALITY facility. The overall aim is to enhance the reliability of geological disposal technologies and develop advanced safety assessment methodologies through research on the deep geological environment and development of assessment models.

(2) Ways to promote R&D

According to the Long-Term Nuclear Program, JNC will promote R&D based on existing R&D results, using research facilities such as URLs, the Engineering Scale Test and Research Facility (ENTRY) and QUALITY. The URLs are aimed mainly at research on the deep geological environment, while the ENTRY and QUALITY facilities contribute to development of geological disposal technologies and advanced safety assessment methods. JNC will pursue URL programs that play an important role in the R&D mentioned above, as well as in international collaboration projects. Future R&D should be conducted systematically, taking into account the requirements arising in each stage of the implementation schedule, through coordination of activities with the government and related institutions. R&D results will be actively documented and published.

[1] Research on the Deep Geological Environment

JNC will undertake investigations with the aim of obtaining the data required for a comprehensive analysis of the deep geological environment for the purpose of designing an underground disposal facility and assessing its performance. Relevant characterization and evaluation techniques will be developed and improved.

URLs play a key role in this connection. Exploration of the geological environment will be refined in a stepwise manner as the investigation program moves forward. Explorations from the surface (first phase) will be followed by excavation of an exploratory shafts and drifts (2nd phase) and, finally, detailed investigations in an underground facility (3rd phase). In each phase, information on the geological environment relevant to design studies and safety assessment will be collected, evaluated and verified. The exploration techniques used will also be improved and integrated as necessary. In parallel, the applicability of engineering technologies for the design and construction of an underground facility will be verified.

In addition, research on the long-term stability of the geological environment and natural analogue studies in uranium ore bodies will be conducted.

[2] R&D on Geological Disposal

i. Improving the reliability of disposal technologies.

Using the ENTRY facility and the URLs, JNC will acquire data for input to state-of-the-art modeling of the properties and long-term evolution of the engineered barriers. Studies will also be carried out on the applicability of design technologies in the light of actual data on the geological environment.

ii. Development of advanced safety assessment methods

Based on the results of investigations of the deep geological environment, JNC will use the ENTRY and QUALITY facilities to refine safety assessment models and data with a view to establishing integrated safety assessment methodologies.

[3] URL Programs

URL programs are currently underway in Mizunami and Horonobe.

In December 1995, an agreement was concluded among four relevant parties (the local governments of Mizunami, Toki and Gifu Prefecture and PNC (at that time)) concerning the Mizunami URL; the program was initiated in 1996. Site development and sinking of a shaft will start in 2002, with a schedule for completing excavation of a major part of the research shafts and drifts by 2009. In the Mizunami URL, techniques for exploration and characterization of the geological environment and application of basic engineering technologies deep underground will be studied for crystalline rock.

In November 2000, an agreement was concluded among three relevant parties (the local Governments of Hokkaido and Horonobe town and JNC) concerning the Horonobe URL Research Center and an initial survey began in March 2001. The underground facility will be constructed at a depth of 500 m or more; site development and excavation of underground facility will begin in 2005, with the aim of completing a major part of the facility by 2010. In the Horonobe URL Research Center, exploration and characterization techniques for the geological environment, long-term stability and application of basic engineering technologies deep underground will be studied for sedimentary rocks. Verification of the design for the engineered barriers, the complex long-term evolution of the barriers, improvement of models, verification of the applicability of design techniques and safety assessment methods will also form part of the program.

JNC will pursue both URL programs on schedule. By obtaining the acceptance of the local communities, JNC will realize an important aspect of confidence-building in R&D on geological disposal of HLW in Japan.

The URL facilities will also provide a wide range of possibilities for academic research by universities or other research institutes, as well as a place for the public to experience the deep geological environment, thereby improving understanding and acceptance.

[4] International Cooperation

International cooperation will be actively promoted from the perspective of achieving international scientific consensus on assessment methods and results and complementing domestic research. In particular, until a deep geological research facility becomes available in Japan, JNC will accumulate relevant expertise by participating in international collaborative research projects in underground research laboratories in the North America and Europe.

[5] R&D and the publication of results

The results obtained from these R&D projects will be widely published and are expected to make a timely contribution to the disposal program and to the establishment of safety regulations.
i. Techniques will be developed for characterizing the geological environment from the surface to deep underground, based on explorations from the surface. This will take into account requirements relating to the design of the disposal system and safety assessment. (development of methods for characterizing the geological environment; safety assessment methods for the surface exploration phase)
ii. Based on data obtained from investigations during the excavation phase, the results from the surface exploration phase and the evolution of the geological environment during excavation of shafts and drifts will be verified. Refinement of models will also be conducted based on actual geological data.
(improvement of methods for characterizing the geological environment; safety assessment methods for the shafts and drifts excavation phase)
iii. Based on the explorations in the underground facility, geological investigation techniques will be refined, taking into account the requirements of disposal system design and safety assessment. Data will also be collected on the actual geological conditions encountered and the reliability of models will be checked.
(confirming the reliability of methods for geological characterization; safety assessment methods for the exploration phase from the underground facility)



3.2.2 Plans for the Next Five Years

3.2.2.1 Developing HLW Treatment Technologies

(1) Efforts will be made towards developing expertise in operation and maintenance technologies for the vitrification of HLW, including experience gained as part of processing HLW in the TVF. The developed technologies, including plant operation data, will be transferred to JNFL. Efforts will be made to keep the volume of high-level liquid waste in the storage tanks at the same level or lower than at present.
(2) Concerning the storage of vitrified HLW, a plan for the storage of vitrified HLW has been formulated based on studies of transport and storage technologies, as well as on siting conditions. The plan includes a general vision, strategies for ensuring safety and required siting conditions. In the future, JNC will pursue specific measures for storage of vitrified HLW following this basic policy. Efforts will be coordinated with the electricity utilities.



3.2.2.2 R&D on Geological Disposal Technology for HLW

Characterization of the geological environment and development of state-of-the-art safety assessment methodologies during the phase of surface investigations at the URLs will proceed as described below. In the Mizunami URL, investigations in the shafts and drifts excavation phase will also be initiated. To maintain transparency of the R&D activities, results will be actively documented and published.

(1) Research on the Deep Geological Environment

[1] Explorations from the surface (1st phase) and excavation of shafts and drifts (2nd phase) will be initiated at the crystalline rock URL (Mizunami); explorations from the surface (1st phase) at the sedimentary rock URL (Horonobe) will also begin. These programs will reflect experience and expertise gained in URLs in the US and Europe.
[2] Surface exploration techniques developed to date will be applied at the two URL sites to check their suitability. A geological structural model will be developed based on estimating key geological features identified from the surface to deep underground and on measured physical/chemical properties of groundwater and rock.
[3] A program of experiments will be formulated for determining the applicability of design and construction techniques for large-scale facilities deep underground. Their impact on the geological environment, and the recovery of zones affected by excavation of shafts and drifts, will also be evaluated.
[4] Research on natural phenomena will be supplemented by studies on seismic/fault activity, uplift/subsidence, sea-level/climatic changes and volcanic activity. This will contribute to development of methods for evaluating the long-term stability of the geological environment, as described in the Second Progress Report.
In addition, natural analogue studies in uranium ore bodies will be continued with a view to building up relevant expertise and obtaining information for indirectly assessing the long-term safety of geological disposal.

(2) R&D on Geological Disposal

(2-1) Improving the Reliability of Disposal Technologies
[1] With a view to formulating a database on the key characteristics of the engineered barriers, data on corrosion mechanisms and the long-term corrosion rate of overpack materials will be expanded and the reliability of the corrosion lifetime will be verified. Data on the behavior of buffer materials under saline conditions will be obtained for advanced studies on buffer design. The quality assurance information which forms the basis for technical standards will also be developed.
[2] For the long-term behavior of the engineered barriers, data will be collected on long-term deformation and degradation phenomena, the critical conditions required to maintain the performance of the engineered barriers will be studied and the reliability of models will be verified. Thermo-hydro-mechanical-chemical behavior will also be evaluated. In addition, natural analogue studies will be conducted to look at the interactions between engineered barriers and the degradation of engineered barrier materials.
[3] Regarding the performance of engineered components, including the engineered barriers, a sealing performance test and an engineered barrier construction/performance test will be conducted in overseas URLs, taking into consideration possible improvements to the concrete materials used.


(2-2) Development of state-of-the-art safety assessment methods
[1] Regarding the database for assessment of nuclide migration, which includes a thermodynamic database for determining solubility and a sorption/diffusion database, the QUALITY facility will be used to supplement existing data on important nuclides, to obtain data for saline conditions and to provide more information on standardization of data sampling methods.
[2] With a view to verifying existing nuclide migration models, processes to be considered in modeling migration in the geosphere and treatment of heterogeneity will be reviewed in engineering-scale tests in the ENTRY facility and as part of international collaborative research.
[3] To develop phenomenological models of nuclide migration, research will be undertaken in the QUALITY facility on glass/nuclide dissolution, sorption (including ion exchange) and surface complexation, diffusion (including surface diffusion), colloid properties and migration mechanisms and complexation processes between organics and nuclides.
[4] Models for evaluating the effects of natural phenomena, including faulting and volcanic activity, based on information obtained from research on the long-term stability of the geological environment and data on shear response characteristics of the engineered barriers, will be further developed.
[5] Safety assessment methodologies, including uncertainty analysis*, which have been developed for generic studies, will be further improved and developed, mainly for application to specific geological environments; for these environments, the data and information will be obtained from generic (i.e. non-site-specific) URLs incrementally and iteratively, in accordance with the stepwise investigations from ground surface to the underground facility.
[6] A suitably configured computer system for carrying out total system performance analysis will be developed to improve efficiency and to aid quality assurance of the above studies.
* For example, to evaluate uncertainty the methods used to present possible values and their distribution (frequency distribution) will be studied for key parameters of radionuclide migration, including permeability and distribution coefficient.

(3) URL Programs

[1] Mizunami

As part of a program of surface explorations initiated in 1996, investigations will be conducted in boreholes, the geological environment from the surface to deep underground will be modeled and the effects of the underground facility on the geological environment will be evaluated.

Subsequently, as part of the investigation phase during construction, modeling results will be verified by comparing them with actual data. The techniques used for the surface explorations and the modeling of the geological environment will be documented in technical reports. The appropriateness of engineering strategies, including design and construction techniques for the underground facility, will also be confirmed.

[2] Horonobe

The location at which the underground facility will be constructed will be identified as the first step of the surface exploration phase. At the selected location, and in the neighboring region, activities will include data acquisition using geophysical surveys and boreholes, modeling of the geological environment from the surface to deep underground and estimating the effects of constructing an underground facility on the geological environment. Based on the results of these studies, an underground facility will be designed and the program will move on to investigations during construction of the underground facility.

The exploration techniques and modeling studies, as well as the data on the geological environment from the surface to deep underground, will be summarized in technical reports.

(4) International Cooperation

International collaborative research in foreign URLs will be promoted in close cooperation with domestic organizations.
[1] Data on the behavior of the excavation disturbed zone around drifts and the influence of the sealing materials will be obtained in the URL at Pinawa, Canada. The data will be used to confirm safety assessment models.
[2] JNC will join the in-situ experimental program in the Aspo URL, Sweden, with a view to verifying the data and analytical models used for repository design and to improving methods for investigating hydrology and mass transport in the geosphere.
[3] JNC will participate in the in-situ experimental programs at the Grimsel Test Site and the Mont Terri Rock Laboratory, Switzerland, with the aim of verifying the robustness of the analysis model used for nuclide migration in the geosphere.
[4] JNC will promote collaborative research with USDOE laboratories in order to develop methods for systematic investigation of the geological environment and models explaining complex phenomena occurring in the repository near-field. The database on nuclide solubility and sorption will also be expanded.
[5] JNC will follow up possibilities for collaborative research in the URL now under construction in a clay formation at Bure, France; the aim is to verify models of the creep behavior of the rock around a repository and to confirm the geochemical database for sedimentary rock.
In addition, JNC will join international projects such as those run by the Organization for Economic Co-operation and Development/Nuclear Energy Agency (OECD/NEA) and the International Atomic Energy Agency (IAEA) and will promote cooperation with other European and Asian countries, as appropriate.

back