Horonobe Underground Research Laboratory Project Investigation report for the 2024 fiscal year

Nakayama, Masashi; Ishii, Eiichi; Aoyagi, Kazuhei; Hayano, Akira; Murakami, Hiroaki; Ono, Hirokazu; Takeda, Masaki; Fukatsu, Yuta; Mochizuki, Akihito; Ozaki, Yusuke; et al.

JAEA-Review 2025-042, 136 Pages, 2025/12

JAEA-Review-2025-042.pdf:12.95MB

The Horonobe Underground Research Laboratory (URL) Project is being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant technologies for geological disposal of high-level radioactive waste through investigating the deep geological environment within the host sedimentary rocks at Horonobe-cho in Hokkaido, north Japan. In the fiscal year 2024, we continued R&D on "Study on near-field system performance in geological environment", "Demonstration of repository design options", and "Understanding of buffering behaviour of sedimentary rock to natural perturbations". These are identified as key R&D on challenges to be tackled in the Horonobe underground research plan for the fiscal year 2020 onwards. Specifically, "full-scale engineered barrier system (EBS) performance experiment" and "solute transport experiment with model testing" were carried out as part of "Study on near-field system performance in geological environment". "Demonstration of engineering feasibility of repository technology" and "evaluation of EBS behaviour over 100C" were addressed for "Demonstration of repository design options". The validation of a method for assessing permeability using the Ductility Index and a method for estimating the state of in-situ ground pressure from hydraulic perturbation tests were investigated as part of the study "Understanding of buffering behaviour of sedimentary rock to natural perturbations". In FY2024, we continued construction of the East Access Shaft and the Ventilation Shaft, and construction of these shafts were completed to a depth of 500 m. After the completion of the East Access Shaft, excavation of the West Access Shaft and 500 m gallery has began. As of the end of FY2024, excavation progress is as follows, the East Access Shaft and the Ventilation Shaft were 500 m depth, the West Access Shaft was 472 m depth, 500 m gallery was 112.9 m, respectively. In the Horonobe International Project (HIP), Management Board and Joint Task Meeting was held at the Horonobe URL in June 2024 to review the progress of construction of galleries and preparations of experiments. Task Meetings to review the implementation plan for in-situ testing and analysis were also held. HIP will be implemented in two phases: Phase 1 (from FY2022 to FY2024) and Phase 2 (from FY2025 to FY2028), the research results of Phase 1 were compiled in FY2024.

NEA Horonobe International Project - HIP Interim report for Phase 1 (February 2023 - March 2025)

Tachi, Yukio; Aoyagi, Kazuhei; Ozaki, Yusuke; Hayano, Akira; Ono, Hirokazu; Takeda, Masaki; Mochizuki, Akihito; Dei, Shuntaro; Minaka, Jumpei; Murakami, Hiroaki; et al.

NEA/NE(2025)20 (Internet), 118 Pages, 2025/11

https://www.oecd-nea.org/jcms/pl_111824/nea-horonobe-international-project-hip-interim-report-for-phase-1-february-2023-march-2025

Horonobe Underground Research Laboratory Project Investigation Program for the Fiscal Year 2025

Nakayama, Masashi; Ishii, Eiichi; Hayano, Akira; Aoyagi, Kazuhei; Murakami, Hiroaki; Ono, Hirokazu; Takeda, Masaki; Mochizuki, Akihito; Ozaki, Yusuke; Kimura, Shun; et al.

JAEA-Review 2025-027, 80 Pages, 2025/09

JAEA-Review-2025-027.pdf:6.22MB

The Horonobe Underground Research Laboratory Project is being pursued by the Japan Atomic Energy Agency to enhance the reliability of relevant technologies for geological disposal of high-level radioactive waste through investigating the deep geological environment within the host sedimentary rocks at Horonobe Town in Hokkaido, north Japan. In the fiscal year 2025, we continue R&D on "Study on near-field system performance in geological environment" and "Demonstration of repository design options". These are identified as key R&D challenges to be tackled in the Horonobe underground research plan for the fiscal year 2020 onwards. In the "Study on near-field system performance in geological environment", we continue to obtain data from the full-scale engineered barrier system performance experiment, and work on the specifics of the full-scale engineered barrier system dismantling experiment. As for "Demonstration of repository design options", the investigation, design, and evaluation techniques are to be systemized at various scales, from the tunnel to the pit, by means of an organized set of evaluation methodologies for confinement performance at these respective scales. Preliminary borehole investigations will be conducted within a 500 m gallery, with the objectives of obtaining rock strength and rock permeability data, as well as surveying the extent of the excavation damaged zone surrounding the test tunnel via tomographic analysis. A planning study for the in-situ construction test will be conducted to investigate the construction of backfill material and watertight plugs. The volume of water inflow associated with the excavation of the 500 m gallery will be observed, and its magnitude will be compared with the range of water inflow predicted in the analysis. The test plan to determine the extent of the excavation damaged zone around the pit, which is planned to be constructed in the 500 m gallery, will be studied to determine the in-situ excavation damaged zone. In addition, the investigation and evaluation methods for the amount of water inflow from fractures and the extent of the excavation damaged zone around the pit will be organized. Concerning the construction and maintenance of the subsurface facilities, excavation of the West Access Shaft and the 500 m gallery will continue. It is anticipated that the construction of the facilities will be completed by the end of the fiscal year 2025. In addition, we continue R&D on the following three tasks in the Horonobe International Project; Task A: Solute transport experiment with model testing, Task B: Systematic integration of repository technology options, and Task C: Full-scale engineered barrier system dismantling experiment.

Development of a test system for evaluating poroelastic parameters of rocks using circumferential strain control

Morita, Mana*; Kiyama, Tamotsu*; Fukuda, Daisuke*; Aoyagi, Kazuhei; Tamura, Tomonori; Yagi, Keisuke*; Kodama, Junichi*

Shigen, Sozai Koenshu (Internet), 12(2), 5 Pages, 2025/09

no abstracts in English

Observational evidence of elastic shear displacement along a minor fault in soft siliceous mudstone

Tamura, Tomonori; Ishii, Eiichi; Aoyagi, Kazuhei; Yagi, Keisuke*

Rock Mechanics and Rock Engineering, 9 Pages, 2025/00

https://doi.org/10.1007/s00603-025-05138-8

Collection of measurement data obtained in the extension of 350 m galleries at the Horonobe Underground Research Laboratory Project

Sakurai, Akitaka; Aoyagi, Kazuhei; Murakami, Hiroaki; Tamura, Tomonori; Fujieda, Daigo; Togase, Kazuki

JAEA-Data/Code 2024-005, 48 Pages, 2024/07

JAEA-Data-Code-2024-005.pdf:6.54MB
JAEA-Data-Code-2024-005-appendix(DVD-ROM).zip:1029.9MB

We currently focus on the three tasks that were identified as "key R&D challenges to be tackled" in the "Horonobe Underground Research Plan for the fiscal year 2020 Onwards". These tasks include "Study on near-field system performance in geological environment", "Demonstration of repository design options", and "Understanding of buffering behaviour of sedimentary rocks to natural perturbations". To implement these tasks, we will excavate shafts and galleries to the 500 m depth. From fiscal year 2023, we will start extension of the 350 m gallery excavating 3 horizontal gallery (Niches No.6, No.7, and Niche of the East Shaft No.1) and excavation of the shaft to the 500 m depth and excavation of 500 m gallery. This report summarizes the measurement data acquired at Niches No.6, No.7, and Niche of the East Shaft No.1 in fiscal year 2023 to accumulate the basic data for carrying out the Observational Construction Program for the excavation of the shaft to the 500 m depth and galleries at the 500 m depth.

Development for advanced solution monitoring and measurement system (ASMS)

Mukai, Yasunobu; Nakamura, Hironobu; Yoshimoto, Katsunobu; Tamura, Takayuki*; Iwamoto, Tomonori*

Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-32-Kai Nenji Taikai Rombunshu (Internet), 9 Pages, 2011/11

JNFL and JAEA are collaboratively developing an advanced solution monitoring and measurement system (ASMS) that is direct Pu measurement NDA system in the solution tank containing plutonium nitrate solution for the improvement of current safeguards subjects to be solved, and for next generation safeguards instrument. The target measurement uncertainty of ASMS is set less than 6% that is equivalent to detection level of partial defect at interim inventory verification by NDA. The ASMS detector was designed based on MCNPX calculation, and then manufactured. As an actual test, the detector was set in a process tank at Plutonium Conversion Development Facility, the calibration tests (known-alpha) for quantitative measurement was conducted. As a result, the total measurement uncertainty for Pu mass is about 3.4% except for the low liquid height region that is satisfied the target value. In addition, the monitoring capability of ASMS was confirmed.

Development and future challenge for Advanced Solution Measurement and Monitoring System (ASMS)

Nakamura, Hironobu; Mukai, Yasunobu; Yoshimoto, Katsunobu; Tamura, Takayuki*; Iwamoto, Tomonori*

Proceedings of INMM 52nd Annual Meeting (CD-ROM), 9 Pages, 2011/07

JNFL and JAEA are collaboratively developing an Advanced Solution Measurement and monitoring System (ASMS) that is direct Pu measurement NDA system in the large scale solution tank containing purified plutonium nitrate for the improvement of current safeguards subjects to be solved, and for next generation safeguards instrument (NGSI). In this report, we summarize the first step results of ASMS development regarding quantitative measurement methodology. In order to establish quantitative measurement, accurate MCNPX modeling and calculations are very important and necessary. After calibration exercise implementation, we successfully obtained calibration constants (slope), and the total measurement uncertainty was about 3% for Pu effective mass for 2 hours measurement except for the low level region. In addition, the image of safeguards by design and collaboration of SMMS are also presented.

Plan and reports of coupled irradiation (JRR-3 and JOYO of research reactors) and hot facilities work (WASTEF, JMTR-HL, MMF and FMF); R&D project on irradiation damage management technology for structural materials of long-life nuclear plant

Matsui, Yoshinori; Takahashi, Hiroyuki; Yamamoto, Masaya; Nakata, Masahito; Yoshitake, Tsunemitsu; Abe, Kazuyuki; Yoshikawa, Katsunori; Iwamatsu, Shigemi; Ishikawa, Kazuyoshi; Kikuchi, Taiji; et al.

JAEA-Technology 2009-072, 144 Pages, 2010/03

JAEA-Technology-2009-072.pdf:45.01MB

"R&D Project on Irradiation Damage Management Technology for Structural Materials of Long-life Nuclear Plant" was carried out from FY2006 in a fund of a trust enterprise of the Ministry of Education, Culture, Sports, Science and Technology. The coupled irradiations or single irradiation by JOYO fast reactor and JRR-3 thermal reactor were performed for about two years. The irradiation specimens are very important materials to establish of "Evaluation of Irradiation Damage Indicator" in this research. For the acquisition of the examination specimens irradiated by the JOYO and JRR-3, we summarized about the overall plan, the work process and the results for the study to utilize these reactors and some facilities of hot laboratory (WASTEF, JMTR-HL, MMF and FMF) of the Oarai Research-and-Development Center and the Nuclear Science Research Institute in the Japan Atomic Energy Agency.

First trial to study the feasibility of direct plutonium mass measurement in a process tank by a new NDA; Advanced solution measurement and monitoring system

Nakamura, Hironobu; Takaya, Akikazu; Mukai, Yasunobu; Hosoma, Takashi; Yoshimoto, Katsunobu; Tamura, Takayuki*; Iwamoto, Tomonori*

Proceedings of INMM 50th Annual Meeting (CD-ROM), 9 Pages, 2009/00

JNFL and JAEA have collaboratively started to develop an ASMS for RRP since 2007 as a trial base. The purpose of the development is to establish quantitative plutonium mass measurement technique directly by NDA of high concentrated pure plutonium nitrate solution in a process tank. If it is established, ASMS provides direct Pu mass measurement and monitoring capability, substitutes for sampling and analysis at IIV, and extends process monitoring to safety purposes. The target of the measurement uncertainty is set less than 6% (1 ) which is equivalent to the detection level of partial defect at IIV by NDA. The principle is similar to the one of NDA for MOX powder, but extended such as introducing variable alpha depends on solution properties. As a first trial, a simple prototype system was constructed and tested at Plutonium Conversion Development Facility of JAEA. Prior to the installation, MCNP calculations for entire cell and tank were performed. Two detectors with a gap were installed just center of the annular tank, then we carried out calibration using plutonium nitrate solution in the range up to 52 kgPu. Consequently, good consistency between calculation and measured singles/doubles count rate were obtained. As a feasibility study, it was necessary to find out subjects to be solved. We would like to present benefits of ASMS, review installation and detector setup and summarize preliminary calibration results.