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RISS 인기검색어
- 검색키워드
- 저자 : Jichang Ryu (검색결과 6 건)
- 무료
- 기관 내 무료
- 유료
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Application of Bayesian Statistics to Infer Radioactivity of Uranium Wastes
Jichang Ryu,Junghwan Hong,Jungsuk Park,Gyuseong Cho 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.1
A method of quantitatively analyzing radioactivity of uranium waste in the In-situ measurement using Bayesian inference was proposed. When applying the traditional efficiency calibration method, which uses standard sources or Monte Carlo simulation, the radioactivity error is large depending on the degree of spread of the radioactive contamination especially in large sample such as a 200 L drum. In addition, the existing method has a limitation in that it is difficult to reflect the uncertainty according to the location of the source. In this preliminary study, to overcome the limitations of the existing method, a Bayesian statistical-based radioactivity quantitative analysis model was proposed that can increase the accuracy of analysis even in situations where radioactive contamination of uranium waste is non-uniformly distributed. As a result of evaluating the simulated waste with the proposed Bayesian method, the accuracy was improved more than about 6 times compared to the classical efficiency calibration method.
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Development of High Intensity Focused Ultrasonic to Decontaminate Complex Metal Wastes
Jichang Ryu,Junghwan Hong,Chanjun Park,Jungsuk Park,Unhak Seong,Jungcheol Shin 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.1
High-intensity focused ultrasonic (HIFU) decontamination technology to decontaminate complex metal radioactive waste was developed and verified. Ultrasonic decontamination technology is a method widely used in this field, but its energy strength is weak, so it cannot be applied to fixed contamination. The HIFU developed in this study can eliminate a wide range of fixed contamination due to the advantage of maintaining a high frequency while having hundreds of times the energy intensity compared to conventional general ultrasonic method. In addition, there is a merit in that there is no work that generates a lot of secondary wastes such as chemical decontamination method or threatens the safety of workers. In particular, high ultrasonic energy is transmitted to curved parts and inside pipes that cannot be decontaminated with blasting method, so various types of metal wastes can be treated with the HIFU method. In this study, the performance of the HIFU was verified for zirconium chips, and the radioactivity after decontamination was reduced to less than MDA in all subjects.
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유지창(Jichang Yoo),정정용(Jungyong Jung),김창기(Changkee Kim),민병선(Byungsun Min),류백능(Baekneung Ryu) 한국추진공학회 2011 한국추진공학회 학술대회논문집 Vol.2011 No.5
본 연구에서는 바인더로 HTPE)/BuNENA를 적용하고 산화제로는 AP와 AN, 금속 연료로 Al을 사용한 HTPE 둔감 추진제 2종에 대한 연소속도, 점화지연시간, 민감도 및 둔감특성을 HTPB 추진제와 비교 고찰하였다. 민감도는 HTPB 추진제와 HTPE 추진제가 유사하게 나타났으며, 점화지연시간은 HTPE 추진제가 2~3배 크게 나타났고, 둔감성에서는 HTPB 추진제가 EIDS 완속가열시험 기준을 만족시키지 못한 반면 HTPE 추진제는 기준에 부합하였다. In this study, 2 kinds of HTPE insensitive propellants composed of HTPE/BuNENA binder, AP, AN and Al were investigated for combustion characteristics, ignition delay time, sensitivity and insensitive properties compared with HTPB propellant. HTPE propellant showed almost same sensitivity results as HTPB propellant, showed 2~3 times higher value than the value of HTPB propellant, ignition delay time respectively, and met the standard criteria, while HTPB propellant failed.
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Self-attenuation Correction of U-235 in Metal Ingot Using MCNP and Gamma Spectroscopy
Sunwoo Lee,Changhyun Ryu,Jungsuk Park,Junghwan Hong,Jichang Ryu,Kwangpyo Kim 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.1
Some of the metal waste generated from KEPCO NF is being disposed of in the form of ingots. An ingot is a metal that is melted once and then poured into a mold to harden, and it is characterized by a uniform distribution of radioactive material. When measuring the uranium radioactivity in metal ingot with HPGe detector, 185.7 keV of U-235 is used typically because most gamma rays emitted at U-235 are distributed in low-energy regions below 200 keV. To analyze radioactivity concentration of U-235 with HPGe detector more accurately, self-attenuation due to geometrical differences between the calibration source and the sample must be corrected. In this study, the MCNP code was used to simulate the HPGe gamma spectroscopy system, and various processes were performed to prove the correlation with the actual values. First an metal ingottype standard source was manufactured for efficiency calibration, and the GEB coefficient was derived using Origin program. And through the comparison of actual measurements and simulations, the thickness of the detector’s dead layers were defined in all directions of Ge crystal. Additionally instead of making an metal ingot-type standard source every time, we analyzed the measurement tendency between commercially available HPGe calibration source (Marinelli beaker type) and the sample (metal ingot type), and derived the correction factor for geometry differences. Lastly the correction factor was taken into consideration when obtaining the uranium radioactivity concentration in the metal ingot with HPGe gamma spectroscopy. In conclusion, the U-235 radioactivity in metal ingot was underestimated about 25% of content due to the self-attenuation. Therefore it is reasonable to reflect this correction factor in the calculation of U-235 radioactivity concentration.
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Manseok Do,Jungyoon Han,Myoungjun Kim,Jichang Ryu,Junghwan Hong,Jungcheol Shin,Unhak Seong 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.2
Despite its advantages such as safety, unnecessary pretreatment, and decontamination of waste with complex geometry, conventional ultrasonic decontamination technology has been only used to remove loose contaminants, oil and grease, not fixed contaminants due to the limitations in increasing the intensity in the high frequency range. Thus, ultrasound has been used as an auxiliary method to accelerate chemical decontamination of radioactive wastes or chemicals were added to the solution to increase the decontamination efficiency. The recently developed high-intensity focused ultrasound (HIFU) decontamination technology overcomes these limitations by combining multiple frequencies of ultrasonic waves in a specific arrangement, making it possible to remove most fixed contaminants, including radioactive micro particles less than 1 micrometer within half an hour. KEPCO NF and EnesG developed mobile HIFU decontamination equipment and successfully demonstrated the decontamination effect on various radionuclides found in nuclear power plants by treating radioactive metal waste to the level below free release criteria. The mobile HIFU decontamination equipment used in the demonstration can be operated anywhere where water is supplied, including controlled area in nuclear power plants, and is expected to be used widely for decontamination and free release of metal radioactive wastes.
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