• Tunnel and Underground Space
• /
• v.19 no.6
• /
• pp.507-516
• /
• 2009

In cases of high-level radioactive waste repositories, heat load is apparent by radioactive waste decay. The safety of a waste repository would be influenced by changing circumstances caused by heat transfer through rock. Thus, a ventilation system is necessary to secure the waste repository. The first priority for building an appropriate ventilation system is completing a computer simulation research with thermal rock properties and a heat transfer coefficient. In this study, the heat transfer coefficient in KURT was calculated using the measurement of inner circumstance factors that include dry bulb and wet bulb temperature, rock surface temperature, and barometric pressure. The heater that is 2 m in length and 5 kw in capacity heats the inside of rock in the research module by $90^{\circ}C$. As a result of determining the heat transfer coefficient in the heating section, the changes of heat transfer coefficient were found to be a maximum of 7.9%. The average heat transfer coefficient is approximately 4.533 w/$m^2{\cdot}K$.

• Explosives and Blasting
• /
• v.35 no.3
• /
• pp.31-54
• /
• 2017

In the countries operating nuclear reactors, the development of high-level radioactive waste(HLW) disposal technique is considered as an urgent and important issue for sustainable utilization of nuclear energy. In Korea, in which a low and intermediate radioactive waste repository is already operating, the construction of an underground research laboratory for in situ validation studies became a matter of interest with increasing concerns on the management of HLW. In order to construct and to operate an underground HLW repository safely in deep underground, the stability of rock mass should be guaranteed. As an important factor on rock stability, excavation damaged zone (EDZ) has been studied in many underground research laboratories in foreign countries. For accurate evaluation of the characteristics and effects of EDZ under disposal condition, it is required to use reliable investigation method based on the analysis of previous studies in similar conditions. In this study, status of foreign underground research laboratories in other countries, approaches for investigation the characteristics, size, and effect of EDZ, and major findings from the researches were surveyed and reported. This will help the accomplishment of domestic researches for developing HLW management techniques in underground research laboratory.

• Tunnel and Underground Space
• /
• v.13 no.2
• /
• pp.153-168
• /
• 2003

The objective of this present study is to understand long term(500 years) thermohydromechanical interaction behavior in the vicinity of a repository cavern on the joint location and repository depth variations. The model includes a saturated discontinuous granitic rock mass, PWR spent nuclear fuel in a disposal canister surrounded with compacted bentonite inside a deposition hole, and mixed bentonite backfilled in the rest of the space within a repository cavern. It is assumed that two joint sets exist within the model. Joint set 1 includes joints of 56$^{\circ}$ dip angle, spaced at 20 m, and joint set 2 is in the perpendicular direction to joint set 1 and includes joints of 34$^{\circ}$ dip angle, spaced at 20 m. In order to understand the behavior change on the joint location variations, 5 different models of 500m in depth are analyzed, and additional 3 different models of 1000 m in depth are analyzed to understand the effect of depth variation.

• Nuclear Engineering and Technology
• /
• v.22 no.1
• /
• pp.36-44
• /
• 1990

A safety assessment computer code CALM (Computer program of Assessment for LILW Management) is developed for the theoretical prediction of long-term safety of low-and intermediate-level radioactive waste disposal. CALM is composed of three submodels, which are the resaturation model, the geosphere migration model, and the radiation dose model. For the verification of its usefulness, the safety assessment of an assumed waste repository is performed. The results show that the computer code, CALM developed through this study can be a useful tool for the safety assessment of low- and intermediate-level radioactive waste repository.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.10 no.1
• /
• pp.55-62
• /
• 2012

As an alternative of the high-level radioactive waste disposal in the subsurface repository, a deep borehole disposal is reviewed by several nuclear advanced countries. In this study, the state of the art on the borehole disposal researches was reviewed, and the possibility of borehole disposal in Korean peninsula was discussed. In the deep borehole disposal concept radioactive waste is disposed at the section of 3 - 5km depth in a deep borehole, and it has known that it has advantages in performance and cost due to the layered structure of deep groundwater and small surface disposal facility. The results show that it is necessary to acquisite data on deep geologic conditions of Korean peninsula, and to research the engineering barrier system, numerical modeling tools and disposal techniques for deep borehole disposal.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.11 no.4
• /
• pp.293-301
• /
• 2013

Borehole Disposal Concept (BDC) was initiated by the South African Nuclear Energy Corporation (NECSA) with the view to improve the radioactive waste management practices in Africa. At a time when geological disposal of radioactive waste is being considered, the need to protect ground water from possible radioactive contamination and the investigation of radionuclides migration through soil and rocks of zone of aeration into ground water has becomes very imperative. This is why the Borehole Disposal Concept (BDC) is being suggested to address the problem. The concept involves the conditioning and emplacement of disused sealed radioactive sources in an engineered facility of a relatively narrow diameter borehole (260 mm). Tanzania is operating a Radioactive Waste Management Facility where a number of spent sealed radioactive sources with long and short half lives are stored. The activity of spent sealed radioactive sources range from (1E-6 to 8.8E+3 Ci). However, the long term disposal solution is still a problem. This study therefore proposing the country to adopt the BDC, since the repository requires limited land area and has a low probability of human intrusion due to the small footprint of the borehole.

• Tunnel and Underground Space
• /
• v.10 no.4
• /
• pp.553-558
• /
• 2000

Since 1977, KAERI has conducted the fundamental R&D on the permanent disposal of potential HLW repository in Korea. The first ten year project is divided into three short-term phase studies. The first phase study which shall be finished in March of 2000, has the prime target to develop the disposal concept of HLW. Throughout this study the preliminary and generic disposal repository system has been introduced. The potential repository is proposed to be emplaced into crystalline rocks which is the most common rock types in Korea. The proposed depth of the repository is between 300 to 700 meter. The numerical code, MASCOT-K was developed to asserts the long term safety of the proposed repository concept. Based on this conceptual design preliminary safely assessment was performed. Results show that for the given disposal system the potential radioactive release it well below the regulatory limit.

• Nuclear industry
• /
• v.29 no.7
• /
• pp.21-24
• /
• 2009

2009년 경주 윌성 지역에 건설 중이던 중 저준위 방사성폐기물 처분장(이하 방폐장) 건설의 완공이 지하 동굴 굴진 공사중 연약 암반이 발견된 것과 관련하여 애초 계획보다 30개월 지연된다고 지식경제부와 방사성폐기물공단이 발표하였다. 경주 주민들은 이에 대해 방폐장 건설의 안전성에 의혹을 제기하면서 진상조사를 할 것을 요구하였고 지경부는 한국지질학회에 의뢰하여 진상조사단을 구성하여 지연 사유를 조사하도록 하였으며 조사 결과 발표회가 개최되었다. 그러나 이에 만족하지 않고 추가 조사 등을 요구하는 지역 주민들의 요구에 의해 '방폐장 현안사항 해결을 위한 지역 공동협의회'가 구성되었으며 이들이 구성한 '방폐장 안전성 검증조사단'이 방폐장 안전성 확인을 위해 현재 조사 활동을 수행하고 있다.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1996.05c
• /
• pp.589-594
• /
• 1996

도서지역에서의 해수침입에 의한 해수-담수 경계면의 예측은 담수의 이용측면에서 뿐만 아니라 방사성폐기물 영구처분장과 같은 시설을 지하동굴을 이용하여 건설할 경우 설계개념의 설정 및 처분시설의 성능평가 측면에서도 중요한 사항이다. 해수침입의 예측에 널리 사용되어 온 Ghyben-Herzberg 근사식을 자연수위면의 경사가 급한 도서 지하매짙에 적용할 경우 야기되는 문제점을 지적하고, 보다 신뢰성이 향상된 방법인 염분 이동식에 근거한 수치해를 이용하여 해수-담수 경계면을 예측하였다. 경사도가 다른 두 가지 가상 처분시스템에 대한 정상상태에서의 해수침입 해석 결과, Ghyben-Herzberg 근사식은 담수지역에서의 수직 수두구배가 작은 경우에만 적용되며 국내에서 방사성폐기물 처분부지로 고려하였던 굴업도와 같은 작은 도서의 지하매질에서의 해수-담수 경계면 예측시 오류를 범할 수 있으므로 단순 적용은 피해야 할 것으로 판단되었다.

• Tunnel and Underground Space
• /
• v.13 no.2
• /
• pp.138-152
• /
• 2003

Three-dimensional computer modeling using FLAC3D had been carried out fur evaluating the thermal-mechanical stability of a high-level radioactive waste repository excavated in several hundred deep location. For effective modeling, a FISH program was made and the geological conditions and rock properties achieved from the drilling sites in Kosung and Yusung areas were used. Sensitivity analysis fer the stresses and temperatures from the modeling designed utilizing fractional factorial design was carried out. From the sensitivity analysis, the important design parameters and their interactions could be determined. From this study, it was found that deposition hole spacing is the most important parameter on the thermal and mechanical stability. The second and third most important parameters were disposal tunnel and buffer thickness.