• Journal of Radiation Protection and Research
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• 제43권4호
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• pp.137-142
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• 2018

Background: Gamma-ray detectors having a thin window of a material with low atomic number can increase the true coincidence summing effects for radionuclides emitting X-rays or gamma-rays. This effect can make efficiency calibration or spectrum analysis more complicated. In this study, a Cu shield was tested as an X-ray filter to neglect the true coincidence summing effect by X-rays and gamma-rays in gamma-ray spectrometry, in order to simplify gamma-ray energy spectrum analysis. Materials and Methods: A Cu shield was designed and applied to an n-type high-purity germanium detector having an $X-{\gamma}$ summing effect during efficiency calibration. This was tested using a commercial, certified mixed gamma-ray source. The feasibility of a Cu shield was evaluated by comparing efficiency calibration results with and without the shield. Results and Discussion: In this study, the thickness of a Cu shield needed to avoid true coincidence summing effects due to $X-{\gamma}$ was tested and determined to be 1 mm, considering the detection efficiency desired for higher energy. As a result, the accuracy of the detection efficiency calibration was improved by more than 13% by reducing $X-{\gamma}$ summing. Conclusion: The $X-{\gamma}$ summing effect should be considered, along with ${\gamma}-{\gamma}$ summing, when a detection efficiency calibration is implemented and appropriate shielding material can be useful for simplifying analysis of the gamma-ray energy spectra.

• Journal of Radiation Protection and Research
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• 제43권3호
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• pp.85-96
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• 2018

Background: A variety of inorganic scintillators have been developed and improved for use in radiation detection and measurement, and in situ gamma-ray spectrometry in the environment remains an important area in nuclear safety. In order to verify the feasibility of promising scintillators in an actual environment, a performance test is necessary to identify gamma-ray peaks and calculate the radioactivity from their net count rates in peaks. Materials and Methods: Among commercially available scintillators, $LaBr_3(Ce)$ scintillators have so far shown the highest energy resolution when detecting and identifying gamma-rays. However, the intrinsic background of this scintillator type affects efficient application to the environment with a relatively low count rate. An algorithm to subtract the intrinsic background was consequently developed, and the in situ calibration factor at 1 m above ground level was calculated from Monte Carlo simulation in order to determine the radioactivity from the measured net count rate. Results and Discussion: The radioactivity of six natural radionuclides in the environment was evaluated from in situ gamma-ray spectrometry using an $LaBr_3(Ce)$ detector. The results were then compared with those of a portable high purity Ge (HPGe) detector with in situ object counting system (ISOCS) software at the same sites. In addition, the radioactive cesium in the ground of Jeju Island, South Korea, was determined with the same assumption of the source distribution between measurements using two detectors. Conclusion: Good agreement between both detectors was achieved in the in situ gamma-ray spectrometry of natural as well as artificial radionuclides in the ground. This means that an $LaBr_3(Ce)$ detector can produce reliable and stable results of radioactivity in the ground from the measured energy spectrum of incident gamma-rays at 1 m above the ground.

• Nuclear Engineering and Technology
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• 제2권4호
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• pp.273-278
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• 1970

국내에서 채광한 자연방사능광물의 분석의뢰를 계기로 이에 관심을 갖고 Uranium와Thorium 의 함유량을 원광으로부터 비파괴적이고 간단한 ${\gamma}$-선 분광법으로 측정 분석하여 보았다. Ge(Li) 측정기를 ${\gamma}$-선 분광에 이용한 결과는 재래식방법에 비하여 분석정도를 훨씬 높일 수 있었으며, 자연방사능측정법과 원자로중성자로 조사시킨 activation법으로 Uranium와 Thorium의 함유량을 분석하였던바 하나의 시료(인천에서 채광)에서는 약 0.5%의 Uranium, 또 다른 시료에서는 2%의 Th와 0.1%의 U이 포함되어 있음이 확인되었다. 우리가 처음 시도한 이 분석법은 경제적이고 간편.신속하게 분석할수 있어 핵연료물질조사에 널러 이용할 수 있음을 입증한다.

• Nuclear Engineering and Technology
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• 제55권8호
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• pp.2927-2934
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• 2023

The influence of the atmospheric radon background on the airborne gamma spectrum can seriously affect researchers' judgement of ground radiation information. However, due to load and endurance, unmanned aerial vehicle (UAV)-borne gamma-ray spectrometry is difficulty installing upward-looking detectors to monitor atmospheric radon background. In this paper, an advanced spectral-ratio method was used to correct the atmospheric radon background for a UAV-borne gamma-ray spectrometry in Inner Mongolia, China. By correcting atmospheric radon background, the ratio of the average count rate of U window in the anomalous radon zone (S5) to that in other survey zone decreased from 1.91 to 1.03, and the average uranium content in S5 decreased from 4.65 mg/kg to 3.37 mg/kg. The results show that the advanced spectral-ratio method efficiently eliminated the influence of the atmospheric radon background on the UAV-borne gamma-ray spectrometry to accurately obtain ground radiation information in uranium exploration. It can also be used for uranium tailings monitoring, and environmental radiation background surveys.

• 분석과학
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• 제14권3호
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• pp.212-220
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• 2001

본 연구는 감마선 분광분석법을 이용하여 환경시료에 함유되어 있는 천연방사성 핵종인 라듐($^{226}Ra$) 및 라돈($^{222}Rn$)의 직접분석법의 개발을 목표로 수행되었다. 감마선 분광분석법에 의한 라듐 및 라돈의 분석에서는 주변환경조건에 따라서 변화의 폭이 큰 대기중의 라돈 및 딸핵종에 의한 백그라운드 영향을 소멸시키거나 보정해 주어야만 한다. 본 고에서는 측정함 내부로 질소가스를 흘려주어 측정함 내부를 질소가스 분위기로 바꾸어 줌으로서 대기중의 라돈 및 딸핵종에 의한 불안정한 백그라운드를 소멸시키고자 하였다. 질소가스를 검출기 주위로 흘려주었을 때, 1 MeV 이하의 에너지 영역에 대해서는 80% 그리고 1 MeV 이상에서는 20~50% 정도까지 백그라운드를 감소시킬 수 있었다. 즉, 검출기 주위를 질소분위기로 바꾸어 줌으로서 백그라운드를 소멸, 안정화시킴으로서 검출감도를 약 10배 향상시킬 수 있었다.

• Journal of Radiation Protection and Research
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• 제43권2호
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• pp.75-84
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• 2018

Background: Gamma-ray spectrometry helps in radiation shielding problems and different applications of radioisotopes. Experimental arrangements including broad beam geometries are widely used. The aim is to investigate and evaluate the ${\gamma}-ray$ spectra via attenuation by environmental materials. Materials and Methods: The photo peak to nominated parts in the ${\gamma}-ray$ spectra and the attenuation coefficients ${\mu}_b/{\rho}$ from broad beam geometries are measured for the materials water, soil, sand and cement at the energies 0.662, 1.25, and 1.332 MeV with a $3{^{\prime}^{\prime}}{\times}3{^{\prime}^{\prime}}$ NaI(Tl) detector. Results and Discussion: The ${\gamma}-ray$ spectra vary according to changes in the effective atomic number $Z_{eff}$ of the attenuator, the photon energy and the solid angle. The peak to total ratios are the most sensitive parts to variations in the experimental conditions and overturn in the region 0.663 MeV to 1.332 MeV. This is indicated as inversion trend. The results are discussed in view of $Z_{eff}$ and the experimental conditions. The intensity build-up is larger at the lower energy and larger scattering angles in agreement with Klein-Nishina formula and other results. The build-up factor B is$${\sim_=}$$1 at high ${\gamma}-energies$ and small scattering angles. Conclusion: The sensitivity to material characteristics decrease gradually from peak: to total, to Compton valley, to Compton plateau ratios. Rigorous collimation is necessary at small energies. Cement, of the largest $Z_{eff}$, is characterized by the maximum broad beam mass attenuation coefficients ${\mu}_b/{\rho}$. The obtained results provide information to decide for the suitable experimental set-up based on aim of the work.

• Nuclear Engineering and Technology
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• 제54권2호
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• pp.423-428
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• 2022

Very low contents (in the range of 10^-9 g/g) of Ir in mantle-derived rock samples (komatiites) were non-destructively determined by INAA coupled with coincidence gamma-ray spectrometry using 16 Ge detectors. Aliquots of the same samples were analyzed by NiS fire-assay ICP-MS for Ir and other platinum group elements. Because the INAA procedure used in this study is non-destructive and is almost free from spectral interference in gamma-ray spectrometry, the INAA values of Ir contents obtained in this study can be highly reliable. Iridium values obtained by ICP-MS were consistent with the INAA values, implying that the ICP-MS values of Ir obtained in this study are equally reliable. Under the present experimental conditions, detection limits were estimated to be 1 pg/g, which corresponds to 0.1 pg for a sample mass of 0.1 g. These levels can be even lowered by an order of magnitude, if necessary, which cannot be achieved by ICP-MS carried out in this study.

• Nuclear Engineering and Technology
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• 제41권10호
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• pp.1307-1314
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• 2009

The isotope ratio of $^{134}Cs/^{137}Cs$ in a spent PWR fuel sample was obtained with a newly developed gamma/neutron combined measuring system at KAERI. Burnup and Pu/U ratio of the spent fuel sample were determined by using the measured isotope ratio and the burnup-isotope ratio correlation equations calculated from the ORIGEN-ARP computer code. The results were compared and evaluated with the chemically determined burnup and Pu/U ratio. As a result of the comparative evaluation, the nondestructively determined burnup and Pu/U ratio values showed a good agreement with the chemically obtained results to within a 4.5% and 0.8% difference, respectively.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2018년도 추계학술논문요약집
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• pp.533-534
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• 2018

• Journal of Radiation Protection and Research
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• 제34권4호
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• pp.170-175
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• 2009

감마선분광분석법을 이용하여 비상시 환경방사능 모니터링을 수행할 경우 스펙트럼 측정시 해당 시료의 종류에 따른 백그라운드 자료 확보와 이를 활용한 체계적인 핵종확인 과정이 선행되어야 한다. 비상시 환경방사능 모니터링을 고려하여 24시간 동안 포집 후 회화시킨 공기부유진 시료를 HPGe 감마선분광분석 시스템으로 계측하여 감마선에너지 스펙트럼을 얻었으며, 그 스펙트럼에서 보이는 피이크들의 핵종을 판별하기 위해 두 가지 방법 - 1) 반감기 추정 2) 핵자료를 이용한 축차우연동시합성피이크 확인 - 으로 접근하였다. 그 결과로서 공기부유진의 감마선에너지스펙트럼에 대한 핵종판별결과 자료를 산출하였다.