• Nuclear Engineering and Technology
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• 제54권7호
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• pp.2748-2754
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• 2022

Because existing reactant coolant system (RCS) leakage detection mechanisms are insensitive to small leaks, a real-time, direct detection system with a detection threshold below 0.5 gpm·hr^-1 was studied. A beta-ray detection system using a silicon detector with good energy resolution for beta rays and a low gamma-ray response was proposed. The detection performance in the leakage condition was evaluated through experiments and simulations. The concentration of ¹⁶N in the coolant corresponding to a coolant leakage of 0.5 gpm was calculated using the analytic method and ORIGEN-ARP. Based on the concentration of ¹⁶N and the measurement of the silicon detector with ⁹⁰Sr/⁹⁰Y, the beta-ray count rate was estimated using MCNPX. To evaluate the effect of gamma rays inside the containment building, the signal-to-noise ratio (SNR) was calculated. To evaluate the count rate ratio, the radiation field inside the containment building was simulated using MCNPX, and response evaluation experiments were performed using beta and gamma rays on the silicon detector. The expected beta-ray count rate at 0.5 gpm leakage was 7.26 × 10⁵ counts/sec, and the signal-to-background count rate ratio exceeded 88 for a transport time of 10 s, demonstrating its suitability for operation inside a reactor containment building.

• Preventive Nutrition and Food Science
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• 제3권4호
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• pp.339-343
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• 1998

Gamma-irradiated chicken at dose levels of 0.1 to 10 kGy was subjected to detection of radiation-induced hydrocarbons whether irradiated or not. The hydrocarbons extracted from chicken fat were separated by florishil column chromatography and identified with GC-FID and GC/MS methods. Eight kinds of hydrocarbons were identified from irradiated chicken, among which 1, 7-hexadecadiene and 8-heptadencene were detected as major compounds , Remarkably radiation-induced hydrocarbons in irradiated chiken were detected at 0.5kGy and over. The concentration of radiation-induced hydrocarbons was relatively constant during 16 weeks.

• 한국정보통신학회논문지
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• 제19권4호
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• pp.1024-1030
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• 2015

현재 해운물류의 안전과 보안이 국제적으로 강화되고 있다. 그로 인해 국내에서는 해운물류의 안전과 보안을 위한 기술에 대한 연구가 진행되고 있다. 관련한 기술 중에 컨테이너 검색의 강화에 따라 휴대용 방사선 검출장치의 필요성이 증가하고 있다. 본 논문에서는 Cortex-A9을 기반으로 한 휴대용 방사선 검출 장치의 구현에 관한 연구와 소모 전력을 감소시켜 시스템의 사용시간을 향상시키는 연구를 제안하고자한다. 휴대용 방사선 검출장치의 구성은 아날로그 보드와 디지털 플랫폼 그리고 센서 모듈로 크게 구성된다. 아날로그 보드의 각 단에서 사용되는 전원이 다양하다. 다양한 전원을 사용하기 위해 스위칭 레귤레이터를 사용하는데 이로써 스위칭 노이즈가 발생해 결과에 오차를 발생시킨다. 이를 줄이고 소모 전력을 감소시키는 기법에 대한 연구를 제안하였다.

• Nuclear Engineering and Technology
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• 제43권6호
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• pp.567-572
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• 2011

A sensitivity analysis of the methods used to evaluate the transport properties of a CdZnTe detector was performed using two different radiations (${\alpha}$ particle and gamma-ray) emitted from an $^{241}Am$ source. The mobility-lifetime products of the electron-hole pair in a planar CZT detector ($5{\times}5{\times}2\;mm^3$) were determined by fitting the peak position as a function of biased voltage data to the Hecht equation. To verify the accuracy of these products derived from ${\alpha}$ particles and low-energy gamma-rays, an energy spectrum considering the transport property of the CZT detector was simulated through a combination of the deposited energy and the charge collection efficiency at a specific position. It was found that the shaping time of the amplifier module significantly affects the determination of the (${\mu}{\tau}$) products; the ${\alpha}$ particle method was stabilized with an increase in the shaping time and was less sensitive to this change compared to when the gamma-ray method was used. In the case of the simulated energy spectrum with transport properties evaluated by the ${\alpha}$ particle method, the peak position and tail were slightly different from the measured result, whereas the energy spectrum derived from the low-energy gamma-ray was in good agreement with the experimental results. From these results, it was confirmed that low-energy gamma-rays are more useful when seeking to obtain the transport properties of carriers than ${\alpha}$ particles because the methods that use gamma-rays are less influenced by the surface condition of the CZT detector. Furthermore, the analysis system employed in this study, which was configured by a combination of Monte Carlo simulation and the Hecht model, is expected to be highly applicable to the study of the characteristics of CZT detectors.

• 한국축산식품학회지
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• 제30권2호
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• pp.232-235
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• 2010

This study examined the photostimulated luminescence (PSL) detection method suggested by the Korean Food and Drug Administration to assess whether the method can be used to identify irradiated spices in restructured pork patties, which served as a model system for processed meat products. Red and black pepper powders were irradiated at 0, 5.0, 7.5, and 10 kGy, and pork patties were formulated with the spice at irradiated pepper concentrations of 0.1% and 0.5%. PSL was then used to estimate amounts of light derived from the spice itself and pork patties. The results of PSL analysis showed that red and black pepper powders were determined as positive and presumptive positive, respectively, when irradiated at more than 7.5 kGy. However, when used in pork patties, all samples were negative for irradiation. Thus, PSL may not be useful in detecting irradiated ingredients used in processed meat products.

• Journal of Radiation Protection and Research
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• 제45권2호
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• pp.76-80
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• 2020

Background: To improve the measurement accuracy of liquid-scintillation counting for activity standardization, it is necessary to significantly reduce the background caused by thermal noise or after-pulses. We have therefore improved a movable 3 photomultiplier (3PM)-γ coincidence-counting method using the logical sum of three double coincidences for β events. Materials and Methods: We designed a new data-acquisition system in which β events are obtained by counting the logical sum of three double coincidences. The change in β-detection efficiency can be derived by moving three photomultiplier tubes sequentially from the liquid-scintillation vial. The validity of the method was investigated by activity measurement of ¹³⁴Cs calibrated at the Korea Research Institute of Standards and Science (KRISS) with 4π(PC)β-γ(NaI(Tl)) coincidence counting using a proportional counter (PC) for the β detector. Results and Discussion: Measurements were taken over 14 counting intervals for each liquidscintillation sample by displacing three photomultiplier tubes up to 45 mm from the sample. The dead time in each β- and γ-counting channel was adjusted to be a non-extending type of 20 ㎲. The background ranged about 1.2-3.3 s^-1, such that the contributions of thermal noise or after-pulses were negligible. As the β-detection unit was moved away from the sample, the β-detection efficiencies varied between 0.54 and 0.81. The result obtained by the method at the reference date was 396.3 ± 1.7 kBq/g. This is consistent with the KRISS-certified value of 396.0 ± 2.0 kBq/g within the uncertainty range. Conclusion: The movable 3PM-γ method developed in the present work not only succeeded in reducing background counts to negligible levels but enabled β-detection efficiency to be varied by a geometrical method to apply the efficiency extrapolation method. Compared with our earlier work shown in the study of Hwang et al. [2], the measurement accuracy has much improved. Consequently, the method developed in this study is an improved method suitable for activity standardization of β-γ emitters.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2016년도 추계학술대회
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• pp.202-205
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• 2016

전 세계적으로 해운물류 안전 보안체계가 강화됨에 따라 국가물류보안 체계 구축을 위한 해운물류안전 보안 핵심기술 개발이 이루어지고 있다. 이러한 국제적 정서에 발맞추어, 국내에서도 감마선 핵종을 검출할 수 있는 휴대용 방사선 검출 장치에 대한 관심이 높아지고 있다. 본 논문에서는 방사선 검출에 대한 검사 장비의 성능을 높이려고 온도 보정 Algorithm을 적용한 Digital 휴대용 방사선 검출기 구현에 대한 연구를 제안하고자 한다.

• Journal of Radiation Protection and Research
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• 제25권4호
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• pp.197-205
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• 2000

실리콘 PIN 다이오드 검출기를 이용하여 전자선량계(PED)를 설계 및 제작하고, 전자신호회로의 성능과 방사선 검출 반응특성을 평가하였다. 전자회로의 성능검사에서는 방사선에 의한 검출기의 신호가 신호처리회로에서 양호하게 출력되었으며, $^{137}Cs$ 감마 방사선을 이용한 방사선조사 시험결과 선량계의 반응도 및 분산계수는 각각 1.85 cps/$Gy{\cdot}h^{-1}$ 및 19.3%로 측정되어 전자선량제의 성능기준을 만족하는 것으로 나타났다. 본 전자선량계의 시작품은 향후 전자회로의 성능향상과 작동 프로그램을 보완 및 개선함으로써 개인 방사선 모니터링에 활용될 것으로 기대된다.

• Journal of Radiation Protection and Research
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• 제24권3호
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• pp.171-184
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• 1999

본 논문에서는 저준위 환경방사능 측정시 이용되는 검출한계에 대한 기본개념 및 수식을 통계학적 이론을 기초로 서술하였다. 방사능을 정확하게 검출할 신뢰도를 95%로 설정하여 알파 베타 및 감마선 측정기에 대한 검출한계치값을 계산하였다. 또한 환경 방사능 계측에 많이 사용되는 방사능 핵종에 대해 최소 검출 방사능 농도값을 검출한계치 개념을 근거로 계산하여 저준위 환경 방사능 분석시 환경방사능 측정결과에 대한 신뢰도 평가에 활용 가능 하도록 하였다.

• Journal of Radiation Protection and Research
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• 제27권1호
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• pp.51-57
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• 2002

반도체 검출기를 이용하여 Hybrid 전치증폭기를 갖는 전자식 개인선량계를 설계 제작하고, 방사선 검출 반응특성과 기계적 및 주변 환경 요건에 따른 각종 성능을 평가하였다. $^{137}Cs$ 감마 방사선을 이용한 방사선 조사 시험결과 감도는 $3.8\;cps/Gy{\cdot}h^{-1}$이고, $10{\mu}Sv{\sim}4Sv$ 범위의 선량당량 조사시 선량계의 지시값은 오차 8%이하에서 선형성이 잘 유지되었다. 방향의존성을 ${\pm}60^{\circ}$ 이내에서 4%이하이며, ISO 기준선장에 의한 에너지 반응영역은 $60{\sim}1,250\;keV$로 나타났으며, IEC 61526에 의한 선량계의 성능검사시 9개 영역의 시험항목에 대한 국제기준을 만족하였다.