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Nakayama, Masashi
JAEA-Data/Code 2020-009, 98 Pages, 2020/09
JAEA-Data-Code-2020-009.pdf:6.06MB
JAEA-Data-Code-2020-009-appendix1(DVD-ROM).zip:172.11MBJAEA-Data-Code-2020-009-appendix2-1(DVD-ROM).zip:468.85MBJAEA-Data-Code-2020-009-appendix2-2(DVD-ROM).zip:102.94MBJAEA-Data-Code-2020-009-appendix2-3(DVD-ROM).zip:141.88MBJAEA-Data-Code-2020-009-appendix2-4(DVD-ROM).zip:141.6MB
Japan Atomic Energy Agency (JAEA) has developed a low alkaline cement, named as HFSC (Highly Fly-ash contained Silicafume Cement), in order to decrease the effect on geological environment of cementitious material. HFSC was used experimentally as the shotcrete (140m, 250m and 350m depth gallery) and lining concrete (GL-374m to GL-380m of east access shaft) in construction part of Horonobe URL. In order to evaluate the effect of HFSC on the surrounding rock and groundwater, concrete and rock cores were periodically sampled from the site where the in-situ construction test was conducted, and various analyzes were conducted. Ordinary Portland Cement (OPC) was used for part of 140m depth gallery, and the same analysis as HFSC was conducted, in order to compare the effect of OPC and HFSC. This report summarizes the results of analyzes conducted on core samples from 2009 to 2018.
Nakayama, Masashi; Niunoya, Sumio*; Miura, Norihiko*; Takeda, Nobufumi*
JAEA-Research 2017-016, 62 Pages, 2018/01
JAEA-Research-2017-016.pdf:19.99MB
The Horonobe URL Project has being pursued by JAEA to enhance the reliability of relevant disposal technologies through investigations of the deep geological environment within the host sedimentary formation at Horonobe, Hokkaido. The URL Project consists of 2 major research areas, "Geoscientific Research" and "Research and Development on Geological Disposal Technologies", and proceeds in 3 overlapping phases, over a period of around 20 years. Phase III (Investigations in the underground facilities) investigation was started in 2010 FY. The in-situ experiment for performance confirmation of engineered barrier system (EBS experiment) had started 2013 at GL-350 m gallery, and heating by electric heater in simulated overpack had started in January, 2015. One of objectives of the EBS experiment is acquiring data concerned with THMC coupled behavior. These data will be used in order to confirm the performance of engineered barrier system. This report shows consideration of concrete-type plug composition. The low alkaline cement developed by JAEA, called HFSC, was used for the plug. HFSC has used in construction test at the gallery as shotcrete in Horonobe URL.
Nakayama, Masashi; Niunoya, Sumio*; Minamide, Masashi*
Genshiryoku Bakkuendo Kenkyu (CD-ROM), 23(1), p.25 - 30, 2016/06
In Japan, any high-level radioactive waste repository is to be constructed at over 300m depth below surface. Tunnel support is used for safety during the construction and operation, and shotcrete and concrete lining are used as the tunnel support. Concrete is a composite material comprised of aggregate, cement and various additives. Low alkaline cement has been developed for the long term stability of the barrier systems whose performance could be negatively affected by highly alkaline conditions arising due to cement used in a repository. Japan Atomic Energy Agency (JAEA) has developed a low alkaline cement, named as HFSC (Highly fly-ash contained silicafume cement), containing over 60wt% of silica-fume (SF) and coal ash (FA). JAEA is presently constructing an underground research laboratory (URL) at Horonobe for research and development in the geosciences and repository engineering technology. HFSC was used experimentally as the shotcrete material in construction of part of the 350m deep gallery in Horonobe URL in 2013. The objective of this experiment was to assess the performance of HFSC shotcrete in terms of mechanics, workability, durability, and so on. HFSC used in this experiment is composed of 40wt% OPC (Ordinary Portland Cement), 20wt% SF, and 40wt% FA. This composition was determined based on mechanical testing of various mixes of the above components. Because of the low OPC content, the strength of HFSC tends to be lower than that of OPC in normal concrete. The total length of tunnel constructed using HFSC shotcrete is about 112m at 350m deep drift. The workability of HFSC shotcrete was confirmed by this experimental construction. In this report, we present detailed results of the in-situ construction test.
Nakayama, Masashi; Okamoto, Reiko*; Shirase, Mitsuyasu*
no journal, ,
In Japan, high-level radioactive waste repository will be constructed in a stable host rock formation more than 300m underground. Tunnel support is used for safety during the construction and operation, and shotcrete and concrete lining are used as the tunnel support. Low alkaline cement has been developed for the long term stability of the barrier systems whose performance could be negatively affected by highly alkaline conditions arising due to cement used in a repository. JAEA has developed a low alkaline cement, named as HFSC (Highly fly-ash contained silicafume cement), containing over 60wt% of silica-fume and coal ash. HFSC was used experimentally as the shotcrete material in construction of part of the 140m, 250m and 350m deep gallery in Horonobe URL. JAEA has been carrying out the investigation about interaction among cement, rock and groundwater using core samples of shotcrete and rock. In this report, the effect on surrounding rock and groundwater from shotcrete using HFSC is described through comparison with that from shotcrete using OPC.
