2019 ⦽ǎႊᔍᖒ⠱ʑྜྷ⦺⫭ ⇹ĥ⦺ᚁݡ⫭ םྙ᧞Ḳ
165
Training Course on Geological Disposal of Radioactive Waste at Mizunami URL
Part I. Introduction to MIU and Practical Training in MIU
Yongheum Joa, Naon Changb, Sangsu Parkc, HyungJin Byund, JiHwan Booe, Wonjae Leef, Jiwoo Leeg,
Hyunseok Leeh, Han Young Jooi, Sol-Chan Hana, and Chang-Lak Kimf,*
a
Korea Advanced Institute of Science and Technology, 291, Daehak-ro, Yuseong-gu, Daejeon, Republic of Korea
b
Hanyang University, 222, Wangsimni-ro, Seongdong-gu, Seoul, Republic of Korea
c
Pohang University of Science and Technology, 77, Cheongam-ro, Nam-gu, Pohang-si, Gyeongsangbuk-do, Republic of Korea
d
Ulsan National Institute of Science and Technology, 50, UNIST-gil, Eonyang-eup, Ulju-gun, Ulsan, Republic of Korea
e
Jeju National University, 102, Jejudaehak-ro, Jeju-si, Jeju-do, Republic of Korea
f
KEPCO International Nuclear Graduate School, 658-91, Haemaji-ro, Seosaeng-myeon, Ulju-gun, Ulsan, Republic of Korea
g
Kyung Hee University, 1732, Deogyeong-daero, Giheung-gu, Yongin-si, Gyeonggi-do, Republic of Korea
h
Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul, Republic of Korea
i
Dongguk University, 123, Dongdae-ro, Gyeongju-si, Gyeongsangbuk-do, Republic of Korea
*
clkim@kings.ac.kr
1. Introduction
Disposal in deep geological repositories is internationally considered as the most preferred option for the long-term management of high-level radioactive wastes. Underground research laboratories (URLs) is facilities that are constructed or developed to provide realistic environmental information and test technical issues and materials. URLs play an essential role in the development of the repository systems and assessment of disposal concepts [1].
Fig. 1. Research Facilities of JAEA for Geological Isolation Research and Development [2].
Japan has two URLs in Mizunami and Horonobe with different types of host rock. JAEA has been performing geoscientific research on granite rock at the Mizunami site. In this report on the training
course on geological disposal or radioactive waste at the Mizunami URL (MIU), the technical and scientific facts of MIU and the lessons from the course and the practical issues during the development and operation of the facility are introduced.
2. Brief Description on MIU
The URL project of Japan in two different sites are based on the recommendation by the Japan Atomic Energy Commission that URLs should be constructed at several places [3]. JAEA started MIU project in 1996. MIU locates at Mizunami city, Gifu prefecture. The host rock of MIU is ca. 70 million years-old granite and fresh groundwater flow. Underground facility mainly consists of main and ventilation shafts. The depth of the shafts are 500 m and the distance between shafts is 40 m. Two shafts are connected by the sub-stage at every 100 m depth. Research galleries for experiments are placed at 300 m and 500 m depth. Surface facilities are operating for auxiliary purposes. For example, the drainage water treatment facility manages groundwater discharge due to the high concentration of fluoride.
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2019 ⦽ǎႊᔍᖒ⠱ʑྜྷ⦺⫭⇹ĥ⦺ᚁݡ⫭םྙ᧞Ḳ Fig. 2. Surface and Underground Facilities in MIU.Geological investigation in MIU has been carrying out in three phases. Phase I is a surface-based investigation on the purpose of the understanding the initial condition of the geological environment by borehole and reflection seismic wave. Investigation of Phase II was conducted to understand the short-term evolution and recovery of the geological environment during construction. Geological mapping and sampling are important parts of phase II. Phase III aimed to investigate long-term geological behavior in drifts by monitoring boreholes and in-situ experiments.
3. Practical Training at MIU site
This training course mainly consisted of lectures from researchers working in MIU and the field experiments. The lectures were focused on the procedures, approaches, and results of the geological investigations held in MIU. Geologic, hydrogeologic, hydrogeochemical, and rock mechanical studies in MIU were introduced through a sequence of three phases. In the field experiment, borehole core samples from the underground in MIU were investigated and the borehole logging for finding the fractured zone was performed. Microscopic observation enabled to characterize the filling material and alteration features of the fault zone. In addition, a site visit on the experimental gallery at 300 m provided the insight of understanding the deep geological environment. Groundwater samples
obtained in the gallery at 300 m were used for the measurement of pH, Eh, and ion concentrations.
Fig. 3. Borehole Samples for Geological Mapping.
Fig. 4. Groundwater Monitoring System.
ACKNOWLEDGEMENT
This work was supported by a grant from by the Korea Nuclear International Cooperation Foundation.
REFERENCES
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>@ -DSDQHVH $WRPLF (QHUJ\ &RPPLVVLRQ ³/RQJ-Term Program for Research, Development and Utilization of Nuclear Energy, 1994.