Long term monitoring and evaluation of the excavation damaged zone induced around the wall of the shaft applying optical fiber sensor (Cooperative research)

Hata, Koji*; Niunoya, Sumio*; Uyama, Masao*; Nakaoka, Kenichi*; Fukaya, Masaaki*; Aoyagi, Kazuhei; Sakurai, Akitaka; Tanai, Kenji

JAEA-Research 2020-010, 142 Pages, 2020/11

JAEA-Research-2020-010.pdf:13.74MB
JAEA-Research-2020-010-appendix(DVD-ROM).zip:149.9MB

In the geological disposal study of high-level radioactive waste, it is suggested that the excavation damaged zone (EDZ) which is created around a tunnel by the excavation will be possible to be one of the critical path of radionuclides. Especially, the progress of cracks in and around the EDZ with time affects the safety assessment of geological disposal and it is important to understand the hydraulic change due to the progress of cracks in and around EDZ. In this collaborative research, monitoring tools made by Obayashi Corporation were installed at a total of 9 locations in the three boreholes near the depth of 370 m of East Shaft at the Horonobe Underground Research Laboratory constructed in the Neogene sedimentary rock. The monitoring tool consists of one set of "optical AE sensor" for measuring of the mechanical rock mass behavior and "optical pore water pressure sensor and optical temperature sensor" for measuring of groundwater behavior. This tool was made for the purpose of selecting and analyzing of AE signal waveforms due to rock fracture during and after excavation of the target deep shaft. As a result of analyzing various measurement data including AE signal waveforms, it is able to understand the information on short-term or long-term progress of cracks in and around EDZ during and after excavation in the deep shaft. In the future, it will be possible to carry out a study that contributes to the long-term stability evaluation of EDZ in sedimentary rocks in the deep part of the Horonobe Underground Research Laboratory by evaluation based on these analytical data.

Study on plutonium burner high temperature gas-cooled reactor in Japan; Introduction scenario, reactor safety and fabrication tests of the 3S-TRISO fuel

Ueta, Shohei; Mizuta, Naoki; Fukaya, Yuji; Goto, Minoru; Tachibana, Yukio; Honda, Masaki*; Saiki, Yohei*; Takahashi, Masashi*; Ohira, Koichi*; Nakano, Masaaki*; et al.

Nuclear Engineering and Design, 357, p.110419_1 - 110419_10, 2020/02

https://doi.org/10.1016/j.nucengdes.2019.110419

The concept of a plutonium (Pu) burner HTGR is proposed to incarnate highly-effective Pu utilization by its inherent safety features. The security and safety fuel (3S-TRISO fuel) employs the coated fuel particle with a fuel kernel made of plutonium dioxide (PuO) and yttria stabilized zirconia (YSZ) as an inert matrix. This paper presents feasibility study of Pu burner HTGR and R&D on the 3S-TRISO fuel.

Study on engineering technologies in the Mizunami Underground Research Laboratory (FY 2014); Development of recovery and mitigation technology on excavation damage (Contract research)

Fukaya, Masaaki*; Hata, Koji*; Akiyoshi, Kenji*; Sato, Shin*; Takeda, Nobufumi*; Miura, Norihiko*; Uyama, Masao*; Kaneda, Tsutomu*; Ueda, Tadashi*; Hara, Akira*; et al.

JAEA-Technology 2016-002, 195 Pages, 2016/03

JAEA-Technology-2016-002.pdf:46.3MB
JAEA-Technology-2016-002-appendix(CD-ROM).zip:16.11MB

The researches on examination of the plug applied to the future reflood test was conducted as a part of (5) development of technologies for restoration and/on reduction of the excavation damage relating to the engineering technology in the MIU (2014), specifically focused on (1) plug examination (e.g. functions, structure and material) and the quality control methods and (2) analytical evaluation of rock mass behavior around the plug through the reflood test. As the result, specifications of the plug were determined. These specifications should be able to meet requirements for the safety structure and surrounding rock mass against predicted maximum water pressure, temperature stress and seismic force, and for controlling the groundwater inflow, ensuring the access into the reflood gallery and the penetration performance of measurement cable. Also preliminary knowledge regarding the rock mass behavior around the plug after flooding the reflood gallery by installed plug was obtained.

Study on engineering technologies in the Mizunami Underground Research Laboratory (FY 2013); Development of recovery and mitigation technology on excavation damage (Contract research)

Fukaya, Masaaki*; Hata, Koji*; Akiyoshi, Kenji*; Sato, Shin*; Takeda, Yoshinori*; Miura, Norihiko*; Uyama, Masao*; Kaneda, Tsutomu*; Ueda, Tadashi*; Toda, Akiko*; et al.

JAEA-Technology 2014-040, 199 Pages, 2015/03

JAEA-Technology-2014-040.pdf:37.2MB

The researches on engineering technology in the Mizunami Underground Research Laboratory (MIU) project consists of (1) development of design and construction planning technologies, (2) development of construction technology, (3) development of countermeasure technology, (4) development of technology for security, and (5) development of technologies for restoration and/or reduction of the excavation damage. The researches on engineering technology such as verification of the initial design were being conducted by using data measured during construction as a part of the second phase of the MIU plan. Examination about the plug for reflood test in the GL-500m Access/Research Gallery-North as part of the development of technologies for restoration and/or reduction of excavation damage were carried out. Specifically, Literature survey was carried out about the plug, based on the result of literature survey, examination of the design condition, design of the plug and rock stability using numerical simulation, selection of materials for major parts, and grouting for water inflow from between rock and plug, were carried out in this study.

Stabilization of simulated radioactive lead waste and simulated low level radioactive liquid waste using reformed sulfur (Joint research)

Sone, Tomoyuki; Sasaki, Toshiki; Miyamoto, Yasuaki; Yamaguchi, Hiromi; Inoue, Haruka*; Kihara, Tsuyoshi*; Takei, Yoshihisa*; Tatekawa, Takaiki*; Fukaya, Masaaki*; Iriya, Keishiro*; et al.

JAEA-Technology 2008-032, 25 Pages, 2008/03

JAEA-Technology-2008-032.pdf:5.54MB

Reformed sulfur (RS) is superior in water interception and acid resistance compared with cement. Therefore solidified wastes with RS should have the high resistance to leaching. Unconfined compressive strength test and leaching test using solidified simulated wastes containing lead contaminated with radioactive nuclides (Lead waste) with RS and solidified simulated low level radioactive liquid waste (LLLW) with RS were conducted to examine the applicability of reformed sulfur solidification method (RSSM) as solidification technique of Lead waste and LLLW. The results of these studies show that RSSM is effective technique for stabilization of lead compared with cement solidification method because solidified lead with RS has much stronger resistance to leaching of lead than solidified lead with cement. It also show that the applicability of RSSM as solidification technique of the waste containing lead oxide and LLLW is low because the resistance to leaching of solidified lead oxide with RS and of solidified simulated LLLW with RS were equal to or lower than those of solidified products with cement respectively.

None

Seno, Muneaki*; Ito, Kenji*; Ambo, Noriaki*; Fukaya, Masaaki*

PNC TJ1561 96-001, 367 Pages, 1996/02

PNC-TJ1561-96-001.pdf:14.79MB

None

Research and development of CAE system for geological disposal, 2

Kurihara, Yuji*; Tokunaga, Masahiro*; Miyazaki, Kiyoshi*; Makabe, Y.*; Fukaya, Masaaki*; Ono, O.*; Namiki, Kazuto*

PNC TJ1201 92-001, 151 Pages, 1992/02

PNC-TJ1201-92-001.pdf:5.61MB

None

Conceptual design study of small-sized high temperature gas-cooled reactor for developing countries, 2; Nuclear and thermal design

Goto, Minoru; Inaba, Yoshitomo; Fukaya, Yuji; Ohashi, Hirofumi; Tachibana, Yukio; Nakano, Masaaki*; Tanabe, Kenichi*

no journal, , 

Japan Atomic Energy Agency (JAEA) has started a conceptual design of a small-sized HTGR with 50 MW thermal power (HTR50S). It is a first-of-a-kind commercial or demonstration plant of a small-sized HTGR to be deployed in developing countries in the 2020s. The design policy of the HTR50S is to construct it without development of new technologies as possible, which require additional demonstration tests, to suppress the construction cost and deploy it in 2020s. Accordingly, the nuclear and thermal design of the HTR50S was performed by upgrading the proven design technology of the High Temperature Engineering Test Reactor (HTTR). We challenged to increase the power density and decrease the number of the fuel enrichments compared with the HTTR. Additionally, we challenges the nuclear and thermal design for effective utilization of uranium by utilizing high burn-up fuel and axial fuel shuffling.

Influence of pore water vaporization on re-saturation process in Full-Scale EBS test by the Thermo-Hydro-Mechanical coupled analysis

Sato, Shin*; Yamamoto, Shuichi*; Ono, Hirokazu; Tanai, Kenji; Fukaya, Masaaki*; Shimura, Tomoyuki*; Niunoya, Sumio*

no journal, , 

no abstracts in English

Evaluation of swelling deformation using buffer material swelling sensor on the full-scale in-situ engineered barrier system experiment

Kimura, Shun; Nakayama, Masashi; Kinota, Kimihiro; Tanai, Kenji; Niunoya, Sumio*; Shimura, Tomoyuki*; Fukaya, Masaaki*

no journal, , 

Swelling deformation of buffer material has been measured using buffer material swelling sensor on the full-scale in-situ engineered barrier system experiment. The sensor consists of strain gauges and is installed between the buffer material and backfill. This study reports the calculation result of the swelling deformation from measured strain values.