• Nuclear Engineering and Technology
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• 제51권2호
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• pp.588-599
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• 2019

This research presents a structural design of high-level waste (HLW) container using ultra-high performance fiber reinforced concrete (UHP-FRC) material. The proposed design aims to overcome the drawbacks of the existing concrete containers which are heavy, difficult to fabricate, and expensive. In this study, the dry storage container (DSC) that commonly used at Canadian Nuclear facilities is selected to present the proposed design. The design has been performed such that the new UHP-FRC alternative has a structural stiffness equivalent to the existing steel-concrete-steel container under various loading scenarios. Size optimization technique is used with the aim of maximizing stiffness, and minimizing the cost while satisfying both the design stresses and construction requirements. Then, the integrity of the new design has been evaluated against accidental drop-impact events based on realistic drop scenarios. The optimization results showed: the stiffness of the UHP-FRC container (300 mm wall thick) is being in the range of 1.35-1.75 times the stiffness of existing DSC (550 mm wall thick). The use of UHP-FRC leads to decrease the container weight by more than 60%. The UHP-FRC container showed a significant enhancement in performance in comparison to the existing DSC design under considered accidental drop impact scenarios.

• Nuclear Engineering and Technology
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• 제53권11호
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• pp.3704-3710
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• 2021

The characteristics of the external radiation on the surface of the casks for spent nuclear fuel (SNF) storage by dry method are investigated for the case when the spatial distribution of SNF in the basket changes due to the destruction of the fuel rod claddings. The surface areas are determined, where the changes in fluxes of neutrons, produced by ²⁴⁴Cm actinide, and γ-quanta, produced by long-lived isotopes, are maximum in the result of the decrease in the height of the SNF area. Concrete (VSC-24) and metal (SC-21) casks are considered as examples. The procedure of periodic measurement of the dose rate of neutrons or γ-quanta at the specified points of the cask surface is proposed for identifying the fuel rod cladding destruction. Under normal operation, the decrease in the dose rate produced by neutrons as the function of SNF storage duration is determined by the half-life of ²⁴⁴Cm, and for γ-quanta - by the half-lives of long-lived SNF isotopes. Consequently, a stepwise change in the dose rate of neutrons or γ-quanta, detected by the measurements, as compared to the previous one, would indicate the destruction of the fuel rod claddings.

• Nuclear Engineering and Technology
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• 제55권10호
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• pp.3898-3906
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• 2023

The paper notes that the most common way of handling spent nuclear fuel (SNF) of power reactors is its temporary long-term dry storage. At the same time, the operation of the dry spent fuel storage facilities almost never use the modern capabilities of information systems in safety control and collecting information for the next studies under implementation of aging management programs. The author proposes a structure of an information system that can be implemented in a dry spent fuel storage facility with ventilated storage containers. To control the thermal component of spent fuel storage safety, a database structure has been developed, which contains 5 tables. An algorithm for monitoring the thermal state of spent fuel was created for the proposed information system, which is based on the comparison of measured and forecast values of the safety criterion, in which the level of heating the ventilation air temperature was chosen. Predictive values of the safety criterion are obtained on the basis of previously published studies. The proposed algorithm is an implementation of the information function of the system. The proposed information system can be used for effective thermal monitoring and collecting information for the next studies under the implementation of aging management programs for spent fuel storage equipment, permanent control of spent fuel storage safety, staff training, etc.

• 한국압력기기공학회 논문집
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• 제16권1호
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• pp.110-116
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• 2020

As the management plan for domestic spent nuclear fuel is delayed, the storage of the operating nuclear power plant is approaching saturation, and the Kori 1 Unit that has reached its end of operation life is preparing for the dismantling plan. The first stage of dismantling is the transfer of spent nuclear fuel stored in storage at plants. The spent fuel management process leads to temporary storage, interim storage, reprocessing and permanent disposal. In this paper, the technical issues to be considered when transporting spent fuel in this process are summarized. The spent fuels are treated as high-level radioactive waste and strictly managed according to international regulations. A series of integrity tests are performed to demonstrate that spent fuel can be safely stored for decades in a dry environment before being transferred to an intermediate storage facility. The safety of spent fuel transport container must be demonstrated under normal transport conditions and virtual accident conditions. IAEA international standards are commonly applied to the design of transport containers, licensing regulations and transport regulations worldwide. In addition, each country operates a physical protection system to reduce and respond to the threat of radioactive terrorism.

• 한국작물학회지
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• 제45권5호
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• pp.305-309
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• 2000

Ultra-drying [＜5.0% seed moisture content (SMC)] storage technique is a cost-effective storage method for oily seeds. To decide proper ultra-drying condition for soybean seeds, drying rate was compared three silica gel to seed ratios, two seed sizes with varietal difference, two kinds of container, and three seed amounts per container under :t 23$\pm$1$^{\circ}C$. When the relative humidity (RH) was reduced at the rate of less than 0.1 % a day, silica gel was replaced with dry one by 47 days. Higher silica gel to seed ratios (3:1 and 2:1) dried faster than lower ratio (1:1) until 28 days, but not after 43 days of drying. Also, large seeded variety was dried faster than small seeded variety. Kinds of container and seed amounts per container didn't show differences in drying of soybean seeds. After completion of ultra-drying, percentage germination by standard germination test (SGT) was not different among silica gel to seed ratios, kinds of container, and seed amounts per container, except among seed sizes (varieties). Before SGT, soybean seeds were premoistened using saturated ${CaCl}_2$ for 48 hours and ${NH}_4$Cl for 24 hours in desiccators. To compare germinability between ordinary-dried seeds and ultra-dried seeds, the seeds of seven soybean varieties, which were varying in size from 8.1 to 34.9 g per 100 seeds, were dried using same amount of silica gel under 23$\pm$1$^{\circ}C$. After completion of 76 days of drying, SMCs were reduced to 3.13-3.45% from 7.86-8.82%. SMC after completion of drying was not correlated with 100-seed weight (r=0.556). Before germination tests, soybean seeds were premoistened using saturated salt solutions. Percentage germination was higher with ultra-dried seeds than ordinary-dried seeds in SGT and higher with ordinary-dried seeds than ultra-dried seeds in AAT at the beginning of storage and after 6 months storage, but general trend of percentage germination was not observed among varieties classified by 100-seed weight. From these results, we concluded that further studies are needed to improve ultra-drying storage method for soybean seeds.

• 방사성폐기물학회지
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• 제21권4호
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• pp.503-516
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• 2023

A transfer cask serves as the container for transporting and handling canisters loaded with spent nuclear fuels from light water reactors. This study focuses on a cylindrical transfer cask, standing at 5,300 mm with an external diameter of 2,170 mm, featuring impact limiters on the top and bottom sides. The base of the cask body has an openable/closable lid for loading canisters with storage modules. The transfer cask houses a canister containing spent nuclear fuels from lightweight reactors, serving as the confinement boundary while the cask itself lacks the confinement structure. The objective of this study was to conduct a structural analysis evaluation of the transfer cask, currently under development in Korea, ensuring its safety. This evaluation encompasses analyses of loads under normal, off-normal, and accident conditions, adhering to NUREG-2215. Structural integrity was assessed by comparing combined results for each load against stress limits. The results confirm that the transfer cask meets stress limits across normal, off-normal, and accident conditions, establishing its structural safety.

• Animal Bioscience
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• 제36권5호
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• pp.797-809
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• 2023

Objective: Many scientists have investigated solutions to reduce microbiological risks in dry-aged meat after the dry-aging technology was revived for high quality and value-added premium meat product in the market. This study aimed to investigate the effect of scoria powder in onggi (Korean earthenware) on the meat quality of pork loins during 21 days of dry aging and to elucidate its mechanism of action. Methods: The pork loins were randomly divided into three groups: aged in vacuum-packaging, onggi containing red clay only (OR), and onggi containing 30% red clay and 70% scoria powder (OS). Microbial analyses (total plate count and Lactobacillus spp.) and physicochemical analyses (pH, shear force, volatile basic nitrogen [VBN], water activity, 2-thiobarbituric acid reactive substances, water content, water holding capacity, cooking loss, and color analysis) of aged meat were conducted. Far-infrared ray emission, quantification of immobilized L. sakei and microstructure of onggi were investigated to understand the mechanism. Results: On day 21, the meat aged in OS exhibited lower pH, shear force, VBN, and water activity than those aged in OR, along with an increase in the number of Lactobacillus spp. OS had a smaller pore diameter than OR, implying lower gas permeability, which could promote the growth of L. sakei. Conclusion: OS improved the microbiological safety and storage stability of pork loin during dry aging by increasing number of Lactobacillus spp. possibly due to low permeability of OS.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 춘계학술발표대회 논문집
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• pp.68-73
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• 2011

An experimental study was conducted to investigate the thermal performance of a medium-temperature heat pipe against the charge amount of working fluid. The container and the wick of the heat pipe were made of stainless steel and the working fluid was Dowtherm-A for medium-temperature applications around $250^{\circ}C$. The diameter and length of the heat pipe were 25.4 mm and 1 m, respectively. The maximum thermal load was 1 kW and the working fluid charge ratio varied from 372% to 420%. The results showed that the thermal resistance ranged from 0.12 to $250^{\circ}C/W$ and the effective thermal conductance ranged from 7,703 to $8,898 W/m{\cdot}K$. Dry-out occurred for the heat pipe with 372% fill-charge at the heat load of 950 W, while the other heat pipes with higher charge amount did not encounter dry-out up to 1060 W.

• Nuclear Engineering and Technology
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• 제54권2호
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• pp.601-607
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• 2022

In recent years, monitoring of spent nuclear fuel inside dry cask storage has become an important area of national security. Muon tomography is a useful method for monitoring spent nuclear fuel because it uses high energy muons that penetrate deep into the target material and provides a 3-D structure of the inner materials. We designed a muon tomography system consisting of four 2-D position sensitive detector and characterized and optimized the system parameters. Each detector, measuring 200 × 200 cm², consists of a plastic scintillator, wavelength shifting (WLS) fibers and, SiPMs. The reconstructed image is obtained by extracting the intersection of the incoming and outgoing muon tracks using a Point-of-Closest-Approach (PoCA) algorithm. The Geant4 simulation was used to evaluate the performance of the muon tomography system and to optimize the design parameters including the pixel size of the muon detector, the field of view (FOV), and the distance between detectors. Based on the optimized design parameters, the spent fuel assemblies were modeled and the line profile was analyzed to conduct a feasibility study. Line profile analysis confirmed that muon tomography system can monitor nuclear spent fuel in dry storage container.

• 한국환경과학회지
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• 제30권8호
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• pp.703-708
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• 2021

To improve the environmental management and resources, in this study, we aimed to investigate the effect of adding oyster shell powder to Hanwoo manure on its characteristics and microbial composition during the storage period. Additives were deposited on top of the manure surface at the rate of 0, 0.5, and 1% of oyster shell powder per 200 g of Hanwoo manure in a plastic container with three replicates; however, untreated manure litter served as the control. Manure characteristics (dry matter, organic matter and crude ash) and microbial composition (lactic acid bacteria, yeast, Bacillus subtilis, Salmonella, and E.coli) were evaluated at day 0, 2, 4, and 8. Manure characteristics exhibited an effect on dry matter, organic matter, and crude ash at day 2 and 8 (p<0.05), and not for day 0 and 4 (p>0.05). With the exception of yeast content at day 4 of storage, lactic acid bacteria, yeast, Bacillus subtilis, Salmonella, and E.coli exhibited no significant differences in all conditions during the storage period. Conclusively, addition of 1% oyster shell powder to Hanwoo manure resulted in slightly better manure characteristics; however, its microbial composition remained unchanged.