A Review and interpretation of iodine-129 in Earth's surface layers; Towards evaluating the long-term stability of geological environments

Mitsuguchi, Takehiro; Okabe, Nobuaki*; Kokubu, Yoko; Matsuzaki, Hiroyuki*

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 31(2), p.96 - 110, 2024/12

https://doi.org/10.3327/jnuce.31.2_96

Geological disposal of high-level radioactive waste requires not only selecting sites appropriate for the waste repository, where its isolation ability would not be damaged by natural phenomena for several tens of thousands of years, but also rationally constructing the disposal system depending on site-specific geological environments and their anticipated long-term variability. Recently, elemental/isotopic compositions of underground fluids (deep groundwaters, hot/cold spring waters, brines associated with oil and natural gas reservoirs, and so on) in Japan have been studied for evaluating the long-term stability of the geological environments of this country. Iodine and its radioactive isotope I (half-life = 15.7 million years) are included in the subjects of the study. The current review paper provides overviews of (i) the iodine content and iodine-129/127 ratio (I/I ratio) of various materials in Earth's surface layers, (ii) relevant sample pretreatments and measurements, and (iii) I/I data of the underground fluids in Japan, then gives (iv) some interpretations of the fluid I/I data, along with their problems and uncertainties, and (v) some implications towards evaluating the long-term stability of geological environments.

Assessment report of research and development activities in FY2021; Activity of "Research and Development on Geological Disposal of High-level Radioactive Waste" (Post- and pre-review report)

Geological Disposal Research and Development Department

JAEA-Evaluation 2022-007, 81 Pages, 2022/11

JAEA-Evaluation-2022-007.pdf:2.06MB
JAEA-Evaluation-2022-007-appendix(CD-ROM).zip:37.06MB

Japan Atomic Energy Agency (JAEA) consulted the advisory committee, "Evaluation Committee on Research and Development (R&D) Activities for Geological Disposal of High-Level Radioactive Waste", for post- and pre-review assessment of R&D activities on high-level radioactive waste disposal in accordance with "General Guideline for the Evaluation of Government Research and Development (R&D) Activities" by the Cabinet Office, Government of Japan, "Guideline for Evaluation of R&D in Ministry of Education, Culture, Sports, Science and Technology" and JAEA's "Regulation on Conduct for Evaluation of R&D Activities". In response to JAEA's request, the Committee reviewed mainly the progress of the R&D project on geological disposal, the relevance of the project outcome and the efficiency of the project implementation during the period of the current and next plan. This report summarizes the results of the assessment by the Committee with the Committee report attached.

Synthesized research report in the second mid-term research phase, Mizunami Underground Research Laboratory Project, Horonobe Underground Research Laboratory Project and Geo-stability Project (Translated document)

Hama, Katsuhiro; Sasao, Eiji; Iwatsuki, Teruki; Onoe, Hironori; Sato, Toshinori; Fujita, Tomoo; Sasamoto, Hiroshi; Matsuoka, Toshiyuki; Takeda, Masaki; Aoyagi, Kazuhei; et al.

JAEA-Review 2016-014, 274 Pages, 2016/08

JAEA-Review-2016-014.pdf:44.45MB

We synthesized the research results from the Mizunami/Horonobe Underground Research Laboratories (URLs) and geo-stability projects in the second midterm research phase. This report can be used as a technical basis for the Nuclear Waste Management Organization of Japan/Regulator at each decision point from siting to beginning of disposal (Principal Investigation to Detailed Investigation Phase).

The Primary evaluation of the impacts of naturaI phenomena on the safety functions of the geological disposal system; An Example study on site generic phase

Makino, Hitoshi; ; Miyahara, Kaname

JNC TN8400 2000-033, 74 Pages, 2000/11

JNC-TN8400-2000-033.pdf:9.19MB

Natural phenomena is one of the potential factors perturbing the long-term stability of the geological environment, and for natural phenomena, it is necessary to consider uncertainties relevant to time, frequency and effect. Therefore it will be important to have information about the potential impacts of natural phenomena on the safety functions of geological disposal system in the future by assuming that natural phenomena perturbs the safety functions of the geological disposal system. In this report, we have considered 4 natural phenomena, 'uplift, subsidence and denudation', 'climatic and sea-level changes', 'earthquakes and fault movement' and 'volcanism', which had been extracted by investigation in foreign countries and by considering the characteristics of Japan as natural phenomena which may perturb the long-term stability of the geological environment. And we have considered mainly typical effects of naturaI phenomena on geological environment and investigated the typical impacts of those natural phenomena on the safety functions of the geological disposal system. On perturbation scenarios, the maximum of total doses have been less than regulatory guidelines in foreign countries in all situations except the cases assuming that a new fault, which causes significant pathway of groundwater flow and nuclide migration, intersects the waste packages. In the case, the maximum of total doses may reach the same level as regulatory guidelines in foreign countries or natural radiation exposure in Japan depending on fault generation time or grandwater flow rate through the fault. And, on isolation failure scenarios, it has been implied that nuclide mass/flux originated from geological disposal is comparable level with nuclide mass/flux in natural environment. These results could give useful information about the potential impacts of natural phenomena on the safety functions of geological disposal system, and also could show the potential importance of ...

None

; ; Shimizu, Kazuhiko; Miyahara, Kaname; ; Seo, Toshihiro; Fujita, Tomoo

JNC TN1410 2000-008, 100 Pages, 2000/10

JNC-TN1410-2000-008.pdf:4.23MB

no abstracts in English

Investigation on sealing technique in geological disposal

Toida, Masaru*; Masumoto, Kazuhiko*; ; Okutsu, Kazuo*;

JNC TJ8400 2000-020, 68 Pages, 2000/02

JNC-TJ8400-2000-020.pdf:9.45MB

For the geological disposal of high level radioactive wastes, after placement of the wastes, it is necessary to close off (to be called "sealing" hereafter) the underground potential passages (disposal pits, disposal tunnels, main and connecting tunnels and access tunnels) with an effective combination of engineered barriers such as buffers, backfiling materials, plugs and grout. It is necessary to ensure the long-term durability to isolate disposed wastes in the system. The results of the research works this year are as follows ; (1)The objectives are to discuss the design of tunnel sealing experiments at URL site. The results of research were about (a)tracer experiment and numerical analysis (b)evaporation measurement (c)presentation at the coordination meeting. (2)The discussion was about the equipment of inclined compaction methods and bearing capacity of rock against pressures for the concrete plugs.

None

Kagawa, Akio

JNC TN8200 2000-001, 40 Pages, 1999/10

JNC-TN8200-2000-001.pdf:0.79MB

None

Research efforts on the long-term stability of the geological environment; Uplift and denudation research as an example

Kawamura, Makoto*; Nishiyama, Nariaki; Jia, H.*; Koizumi, Yukiko*; Ishikawa, Taiki*; Umeda, Koji*

no journal, , 

As part of its research and development into geological disposal technology for high-level radioactive waste, the Toki Geochronological Institute is conducting fundamental research into the long-term stability of the geological environment. In developing uplift and erosion survey and evaluation techniques, the research and development is focused on the development of uplift and erosion evaluation methods using thermochronology and geothermobarometry, the advancement of uplift and erosion rate estimation techniques based on multi-dating of emergent landforms, and the advancement of topographic analysis and comprehensive survey techniques to be reflected in modeling of long-term changes in the geological environment. This report will introduce the current status of the advancement of topographic analysis and comprehensive survey techniques to be reflected in modeling of long-term changes in the geological environment as an example.

Geosphere stability project, 3; Provenance analysis techniques

Tokuyasu, Kayoko; Yasue, Kenichi; Komatsu, Tetsuya; Tamura, Itoko; Horiuchi, Yasuharu

no journal, , 

We have carried out the research and development of provenance analysis techniques to elucidate the mountain-building stage using quartz ESR signals in sediments. The R&D was conducted using the Tokai Formation including Toki Sand and Gravel Formation distributed over the Tono area. In the northern part of the area, bedrocks consist of sedimentary rocks, Nohi Rhyolite and Sanyo Granite, whereas consist of Ryoke Granites in the southern part. Samples of sediments were taken from the quarry located between the Tsukechi River and Atera fault. Basement rock samples were also taken in and around the quarry. Outcrop observation indicates that the provenance of sediments changed between the lower and upper parts. Quartz grains for ESR measurements were extracted from all samples. As a result, granitic rocks of Sanyo belt were not exposed to the drainage basin during the deposition of the lower part between 3.9 and 2.0 Ma, then the granitic rocks were exposed during the deposition of upper part after about 2.0 Ma. We conclude that it is possible to estimate the sediment provenance using ESR properties.

Geosphere Stability Project, 2; Analysis on effects of uncertainties of GEMs for evaluation of long-term variability of groundwater flow conditions

Onoe, Hironori; Matsuoka, Toshiyuki; Komatsu, Tetsuya; Yasue, Kenichi*; Iwatsuki, Teruki; Takeuchi, Ryuji; Kato, Tomoko; Sasao, Eiji

no journal, , 

JAEA have been developing the Geological-Evolutionary Models (GEMs) taking into account of long-term change of the geological environment in order to evaluate the geosphere stability. This paper summarized the current status of Research and development activities with analysis on effects of uncertainties of GEMs for evaluation of long-term variability of groundwater flow conditions.