Training Course on Geological Disposal of Radioactive Waste at Mizunami URL Part II. Study About the Geological Environment and HLW Disposal in Korea

2019 ⦽ǎႊᔍᖒ⠱ʑྜྷ⦺⫭ ⇹ĥ⦺ᚁݡ⫭ םྙ᫵᧞Ḳ

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Training Course on Geological Disposal of Radioactive Waste at Mizunami URL

Part II. Study About the Geological Environment and HLW Disposal in Korea

Naon Changa, Yongheum Job, Sangsu Parkc, HyungJin Byund, JiHwan Booe, Wonjae Leef, Jiwoo Leeg,

Hyunseok Leeh, Han Young Jooi, Sol-Chan Hanb, and Chang-Lak Kimf,*

a

Hanyang University, 222, Wangsimni-ro, Seongdong-gu, Seoul, Republic of Korea

b

Korea Advanced Institute of Science and Technology, 291, Daehak-ro, Yuseong-gu, Daejeon, 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

It becomes a serious issue that the on-site spent fuel pool of the nuclear power plants is getting saturated. As this reason, it needs the construction of the High Level radioactive Waste (HLW) repository site or interim storage. Therefore, we study about the domestic geological environment for HLW disposal and proposal of the HLW disposal system in South Korea. It was performed as a part of the

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UDGLRDFWLYH ZDVWH GHHS JHRORJLFDO GLVSRVDO´ supported by KONICOF (Korea Nuclear International Cooperation Foundation). 10 people of students participated the domestic lessons (KINGS, 2019.01.21~2019.01.25) and overseas lessons (JAEA MIU, 2019.01.28 ~2019.02.01) with above program.

2. Geological Environment of Korea

In the HLW repository site, natural barriers play an important role for preventing the releasing of the radionuclides. The geological characteristics (geological distribution, temperature distribution, hydraulic conductivity, earthquake and etc.) effect to the natural barrier and the safety disposal of the HLW directly.

2.1 Geological Distribution

The Geological distribution of Korea is represented in Fig. 1 and Table 1. The plutonic rock painted with an orange in the Fig. 2 occupied largest amount in Korea, about 35.2%. Specially, it is distributed about 25.6% in South Korea. The HLW has to be disposed under the state geological structure. Before construction of the HLW repository site, it needs to estimate the detail volume of the each rock type.

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2019 ⦽ǎႊᔍᖒ⠱ʑྜྷ⦺⫭⇹ĥ⦺ᚁݡ⫭םྙ᫵᧞Ḳ Table 1. Geological Distribution of Korea [1]

Type Feature Proportion

Plutonic

Rock Paleozoic & Mesozoic Era 35.2 % Metamorphic

Rock

Crystalline Rock 8.7 %

Gneiss 21.3 %

Igneous

Rock Intrusion & Eruption 13.6 % Sedimentary

Rock Paleozoic & Mesozoic Era 16.0 % Others Unconsolidated Sediment

& Quaternary Deposit 5.2 %

2.2 Temperature Distribution

The temperature distribution in South Korea is shown in Fig 2 according to the various depth. The

domestic average heat is 71 MW/m2 and it decreases

to the 69 MW/m2 at 300 m underground. It needs that

total amount of the geothermal heat and heat from the HLW is lower than the regulation limit. Therefore, detail data of the geothermal heat as each area have to be collected before construction of the site.

Fig. 2. Estimated temperature distribution at various depth in South Korea [2].

2.3 Hydraulic Conductivity

In the HLW repository site, hydraulic conductivity is considered importantly because the radionuclides leakage follow the groundwater. As shown In South Korea, the hydraulic conductivity with fractured rock aquifers is average 0.076 m/day and with alluvial layers is average 1.26 m/day [3]. However, this result is not suitable for applying HLW disposal due to the depth of the observation hole. The observation is performed about the 200 m underground though HLW repository site is deeper than 200 m. Therefore, it needs to investigate again in the adapt depth.

Fig. 3. Hydraulic conductivity distribution in South Korea (a) fractured rock aquifers, (b) Alluvial layers [3].

3. Necessity of URL in Korea

To construct the HLW repository site, it needs to get more information about geological characteristics than now due to above limitation. Also, the geochemical and radiochemical data for getting a licensing process is needed. These investigations can be carried out in the Underground Research Facility (URL) such as MIU in Japan. Therefore, it is suggested that the construction of URL and detail research have to be preceded before construction of HLW repository site.

ACKNOWLEDGEMENT

This work was supported by a grant from by the Korea Nuclear International Cooperation Foundation.

REFERENCES

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the 9th Asian Geothermal Symposium, Nov. 7-9,

2011

>@ %\HRQJ *RQ &KRL HW DO ³&RQVWUXFWLRQ RI %DVLF Evaluation Criteria for Candidate HLW 5HSRVLWRU\6LWHV´.$(5,&0-1192/2009 (2010).