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Lee B.,Korea Institute of Geoscience and Mineral Resources | Hamm S.-Y.,Pusan National University | Jang S.,Korea Rural Community Corporation | Cheong J.-Y.,Korea Radioactive Waste Management Corporation | Kim G.-B.,Korea Water Resources Corporation
Geosciences Journal | Year: 2014

Climate change has resulted in a gradual increase in the surface temperature and significantly variable precipitation in different regions of the world. Linear regression of the groundwater levels in Korea between 2000 and 2010 revealed a decreasing trend with a slope of -29.2 mm/yr; -29.6 mm/yr in the wet season and -32.0 mm/yr in the dry season. Mann-Kendall and Sen's tests were carried out using the groundwater levels and groundwater temperatures at 78 locations in South Korea between 2000 and 2010. The groundwater levels showed a trend in ~50% of the 78 groundwater level datasets, of which ~70% exhibited a decreasing trend at the 95% confidence level. This decreasing trend in the groundwater levels appears to be related to a change in the precipitation in South Korea because more abundant rainfall in the wet season each year does not contribute significantly to groundwater recharge, whereas less rainfall that occurs in the dry season can cause a decrease in the groundwater level. Linear regression of the groundwater temperatures revealed a slope of 0.1006 °C/yr between 2000 and 2010 with a gentler slope (0.08 °C/yr) in summer (June-September), showing that the increase in surface temperature has an impact on increasing the groundwater temperature. In this situation of climate change in Korea, the paradigm of groundwater management strategy needs to be altered properly. © 2014 The Association of Korean Geoscience Societies and Springer-Verlag Berlin Heidelberg.

Park J.B.,Korea Radioactive Waste Management Corporation | Kim C.-W.,Korea Hydro and Nuclear Power Co. | Kim S.-H.,FNC Technology | Kim J.Y.,FNC Technology
Annals of Nuclear Energy | Year: 2012

As part of the following-up action pertaining to the construction and operation permit for the first stage of the LILW (Low- and Intermediate-Level Radioactive Waste) repository, the preparation for a large-scale in situ experiment is underway by the Korea Radioactive Waste Management Corporation (KRMC) for a realistic assessment of the characteristics of gas generation after the post-closure phase of a repository. In this paper, we discuss a method of determining the representative composition of simulated dry active waste and a related fabrication plan for this material. After a comparison with experimental gas generation results from Finland, dry active waste content was chosen for a large-scale gas generation experiment. Six different types of materials and details on their simulated dry active waste contents are derived with the total mass and density for both a 200 L and a 320 L drum. © 2011 Elsevier Ltd. All rights reserved.

Cheong J.-Y.,Korea Radioactive Waste Management Corporation | Hamm S.-Y.,Pusan National University | Lee J.-H.,Pusan National University | Lee K.-S.,Korea Basic Science Institute | And 2 more authors.
Environmental Earth Sciences | Year: 2012

The nitrate of groundwater in the Gimpo agricultural area, South Korea, was characterized by means of nitrate concentration, nitrogen-isotope analysis, and the risk assessment of nitrogen. The groundwaters belonging to Ca-(Cl + NO 3) and Na-(Cl + NO 3) types displayed a higher average NO 3 - concentration (79.4 mg/L), exceeding the Korean drinking water standard (<44.3 mg/L NO 3 -). The relationship between δ 18O-NO 3 - values and δ 15N-NO 3 - values revealed that nearly all groundwater samples with δ 15N-NO 3 - of +7.57 to +13.5‰ were affected by nitrate from manure/sewage as well as microbial nitrification and negligible denitrification. The risk assessment of nitrate for groundwater in the study area was carried out using the risk-based corrective action model since it was recognized that there is a necessity of a quantitative assessment of health hazard, as well as a simple estimation of nitrate concentration. All the groundwaters of higher nitrate concentration than the Korean drinking water standard (<44.3 mg/L NO 3 -) belonged to the domain of the hazard index <1, indicating no health hazard by nitrate in groundwater in the study area. Further, the human exposure to the nitrate-contaminated soil was below the critical limit of non-carcinogenic risk. © 2011 Springer-Verlag.

Kim J.,FNC Technology | Jung H.,Korea Radioactive Waste Management Corporation | Ha J.-C.,Korea Radioactive Waste Management Corporation | Kim E.-H.,Seoul National University
Annals of Nuclear Energy | Year: 2013

In order to simulate gas migration at an underground disposal facility, the characteristics of a medium such as the gas threshold pressure and gas permeability need to be measured in advance. In this study, the gas threshold pressure and gas permeability of silo concrete specimens for a Korean LILW (Low- and Intermediate-Level Waste) disposal facility were measured. The concrete specimens had the same composition as the concrete used in the construction of the silo. The gas threshold pressure was measured by injecting a constant gas flow into cross sections of the specimens. To measure the gas permeability, selected pressures were applied to the specimens and the apparent permeability was calculated using the Hagen-Poiseuille equation. The intrinsic permeability was calculated with the Klinkenberg empirical equation. The gas threshold pressure and gas permeability ranged from 30 to 40 bar and from 10-17 to 10-18 m2, respectively. © 2012 Elsevier Ltd. All rights reserved.

Baik M.H.,Korea Atomic Energy Research Institute | Kim S.S.,Korea Atomic Energy Research Institute | Lee J.K.,Korea Atomic Energy Research Institute | Lee S.Y.,Korea Atomic Energy Research Institute | And 2 more authors.
Journal of Radioanalytical and Nuclear Chemistry | Year: 2010

Sorption experiments for radionuclides such as 14C, 99Tc, 137Cs, 90Sr, 63Ni, and 241Am were conducted using two different groundwaters (GM-1 and SS-5) and solid materials (granodiorite and fracture-filling material) sampled from the Wolsong low- and intermediate-level radioactive waste (LILW) repository, Gyeongju, Korea. The distribution coefficients of the radionuclides, K d's, were obtained and their sorption properties were discussed for each radionuclide. For all sorbing radionuclides, the Kd values for the fracture-filling material were observed to be higher than those for granodiorite regardless of the groundwater. The Kd values were increased in the sequence 99Tc < 14C < 90Sr < 137Cs < 63Ni < 241Am regardless of sorbent types implying that the sorption of radionuclides onto geological media is affected by their chemical behavior in accordance with geochemical environments. Anionic radionuclides such as 14C and 99Tc showed very low Kd values both for the granodiorite and fracture-filling material. The mineralogical composition of the geological media and groundwater conditions was also observed to be important in the sorption of sorbing radionuclides, especially in the case of strongly sorbing radionuclides. © 2009 Akadémiai Kiadó, Budapest, Hungary.

Yoon J.-H.,Korea Radioactive Waste Management Corporation | Choi W.-S.,Korea Atomic Energy Research Institute | Lee S.,Korea Atomic Energy Research Institute | Seo K.-S.,Korea Atomic Energy Research Institute
Nuclear Engineering and Technology | Year: 2011

In Korea, although the concept of dry storage system for PWR spent fuels first emerged in the early 1990s, wet storage inside nuclear reactor buildings remains the dominant storage paradigm. Furthermore, as the amount of discharged fuel from nuclear power plants increases, nuclear power plants are confronted with the problem of meeting storage capacity demand. Various measures have been taken to resolve this problem. Dry storage systems along with transportation of spent fuel either on-site or off-site are regarded as the most feasible measure. In order to develop dry storage and transportation system safety analyses, development of design techniques, full scale performance tests, and research on key material degradation should be conducted. This paper deals with two topics, structural analysis methodology to assess cumulative damage to transportation packages and the effects of an aircraft engine crash on a dual purpose cask. These newly emerging issues are selected from among the many technical issues related to the development of transportation and storage systems of spent fuels. In the design process, appropriate analytical methods, procedures, and tools are used in conjunction with a suitably selected test procedure and assumptions such as jet engine simulation for postulated design events and a beyond design basis accident.

Kim J.,FNC Technology | Jung H.,Korea Radioactive Waste Management Corporation | Ha J.-C.,Korea Radioactive Waste Management Corporation
Nuclear Engineering and Design | Year: 2013

After closure of an underground disposal facility, it would be saturated with ground water and gases would be generated by various mechanisms. As the generated gases are accumulated, internal pressure of the concrete silo would increase and integrity of the silo could be damaged by overpressure. Therefore, an effective gas permeable seal is necessary to prevent the overpressurization of the concrete silo. For designing the gas permeable seal, experimental study and computer modeling on the gas migration through the concrete should be performed. In this study, in order to obtain the specific characteristics of the concrete silo which are necessary for computer modeling, gas entry pressure and gas permeability of the concrete silo were measured by using specimens which have a same composition with the concrete silo. The results of this study could be utilized to the simulation of gas migration and design of the gas permeable seal for a LILW disposal facility in Korea. © 2013 Elsevier B.V. All rights reserved.

Lee D.-G.,Hyundai Engineering | Park J.-H.,Hyundai Engineering | Lee Y.-H.,Hyundai Engineering | Baeg C.-Y.,Korea Radioactive Waste Management Corporation | Kim H.-J.,Korea Radioactive Waste Management Corporation
Nuclear Engineering and Technology | Year: 2013

A full-sized model for the horizontally oriented metal cask containing 21 spent fuel assemblies has been considered to evaluate the internal natural convection behavior within a dry shield canister (DSC) filled with helium as a working fluid. A variety of two-dimensional CFD numerical investigations using a turbulent model have been performed to evaluate the heat transfer characteristics and the velocity distribution of natural convection inside the canister. The present numerical solutions for a range of Rayleigh number values (3×106~3×107) and a working fluid of air are further validated by comparing with the experimental data from previous work, and they agreed well with the experimental results. The predicted temperature field has indicated that the peak temperature is located in the second basket from the top along the vertical center line by effects of the natural convection. As the Rayleigh number increases, the convective heat transfer is dominant and the heat transfer due to the local circulation becomes stronger. The heat transfer characteristics show that the Nusselt numbers corresponding to 1.5×106 < Ra < 1.0×107 are proportional to 0.5 power of the Rayleigh number, while the Nusselt numbers for 1.0×107 < Ra < 8.0×107 are proportional to 0.27 power of the Rayleigh number. These results agreed well with the trends of the experimental data for Ra>1.0×107.

Ko J.-H.,Hyundai Engineering | Park J.-H.,Hyundai Engineering | Jung I.-S.,Hyundai Engineering | Lee G.-U.,Hyundai Engineering | And 2 more authors.
Nuclear Engineering and Technology | Year: 2014

Korea expects a shortage in storage capacity for spent fuels at reactor sites. Therefore, a need for more metal and/or concrete casks for storage systems is anticipated for either the reactor site or away from the reactor for interim storage. For the purpose of interim storage and transportation, a dual purpose metal cask that can load 21 spent fuel assemblies is being developed by Korea Radioactive Waste Management Corporation (KRMC) in Korea. At first the gamma and neutron flux for the design basis fuel were determined assuming in-core environment (the temperature, pressure, etc. of the moderator, boron, cladding, UO2 pellets) in which the design basis fuel is loaded, as input data. The evaluation simulated burnup up to 45,000 MWD/MTU and decay during ten years of cooling using the SAS2H/ OGIGEN-S module of the SCALE5.1 system. The results from the source term evaluation were used as input data for the final shielding evaluation utilizing the MCNP Code, which yielded the effective dose rate. The design of the cask is based on the safety requirements for normal storage conditions under 10 CFR Part 72. A radiation shielding analysis of the metal storage cask optimized for loading 21 design basis fuels was performed for two cases; one for a single cask and the other for a 2x10 cask array. For the single cask, dose rates at the external surface of the metal cask, 1m and 2m away from the cask surface, were evaluated. For the 2x10 cask array, dose rates at the center point of the array and at the center of the casks’ height were evaluated. The results of the shielding analysis for the single cask show that dose rates were considerably higher at the lower side (from the bottom of the cask to the bottom of the neutron shielding) of the cask, at over 2mSv/hr at the external surface of the cask. However, this is not considered to be a significant issue since additional shielding will be installed at the storage facility. The shielding analysis results for the 2x10 cask array showed exponential decrease with distance off the sources. The controlled area boundary was calculated to be approximately 280m from the array, with a dose rate of 25mrem/yr. Actual dose rates within the controlled area boundary will be lower than 25mrem/yr, due to the decay of radioactivity of spent fuel in storage. © 2014, Korean Nuclear Society. All rights reserved.

Cho C.-H.,Korea Radioactive Waste Management Corporation | Kim T.-M.,Korea Radioactive Waste Management Corporation | Seong K.-Y.,Korea Radioactive Waste Management Corporation | Kim H.-J.,Korea Radioactive Waste Management Corporation | Yoon J.-H.,Korea Radioactive Waste Management Corporation
Annals of Nuclear Energy | Year: 2011

As a part of an effort to determine the ideal storage solution for pressurized water reactor (PWR) spent nuclear fuel, a cost assessment was performed to better quantify the competitiveness of several storage types. Several storage solutions were chosen for comparison, including three dry storage concepts and a wet storage concept. The net present value (NPV) and the levelized unit cost (LUC) of each solution were calculated, taking into consideration established scenarios and facility size. Wet storage was calculated to be the most expensive solution for a 1700 MTU facility, and metal cask storage marked the highest cost for a 5000 MTU facility. Sensitivity analyses on discount rate, metal cask price, operation and maintenance cost, and facility size revealed that the system price is the most decisive factor affecting competitiveness among the storage types.

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