• Journal of Radiation Protection and Research
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• v.40 no.3
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• pp.181-186
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• 2015

Measurement of xenon radioisotopes from nuclear fission is a key element for monitoring underground nuclear weapon tests. $^{131m}Xe$, $^{133}Xe$, $^{133}mXe$ and $^{135}Xe$ in the air can be detected via low background systems such as a beta-gamma coincidence counting system. Radioxenon monitoring is performed through air sampling, xenon extraction, measurement and spectrum analysis. The minimum detectable concentration of $^{135}Xe$ can be significantly variable depending on the sampling time, extraction time and data acquisition time due to its short half-life. In order to optimize the acquisition time with respect to certain experimental parameters such as sampling and xenon extraction, theoretical approach and experiment using SAUNA system were performed to determine the time to minimize the minimum detectable concentration, which the results were discussed.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2007.11a
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• pp.103-104
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• 2007

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2012.05a
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• pp.359-360
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• 2012

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.419-424
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• 2004

Various radiation counters have been using to determine radioactivity of radwastes for disposal. A radiation counting system was set up using a radiation detector chosen in this study and its stability was investigated through the periodic determination of background and counting efficiencies in accordance with a quality control program to increase the confidence level. The average background level for the $\gamma$-spectrometer was 1.59 cps and the average counting level for the standard sample was 45248 Ops within $2{\sigma}$ confidence levels. The average alpha background level for the low background ${\alpha}{\beta}$ counting system was 0.31 cpm and the efficiency for alpha counting was 34.38%. The average beta background level for the ${\alpha}{\beta}$ counting system was 1,30 cpm and the efficiency for beta counting was 46.5%, The background level in the region of 3H and 14C for the liquid scintillation counting system was 2.52 and 3.31 cpm and the efficiency for alpha counting was 58.5 and 95.6%, respectively. The minimum detectable activity for the$\gamma$-spectrometer was found to be 3.2 Bq/$m\ell$ and 3.8 Bq/$m\ell$ for the liquid scintillation counter, and 20.5 and 23.0 Bq/$m\ell$, respectively for the $\alpha$ and $\beta$ counting system.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2010.05a
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• pp.399-400
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• 2010

• Journal of Radiation Protection and Research
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• v.33 no.3
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• pp.121-126
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• 2008

Radioactivities of the stack air effluents from the Advance Fuel Science Building (AFSB) at KAERI have been investigated and evaluated. In this AFSB, nuclear fuels for the HANARO research reactor have been fabricated and the advanced nuclear fuels have been studied. A stack air monitoring system has been continuously operating to monitor the stack air effluents from the facility to protect the environment. As the results of the periodical radioactivity measurement and both the gamma and alpha spectrometry for the millipore filters taken from the stack air monitor from January until March 2008, a trace amount of primordial $^{40}K$ and the short-lived decay products of natural borne $^{222}Rn$ and $^{220}Rn$ have been detected. However, the radioactivities have rapidly decayed to the level below the Minimum Detectable Activity (MDA) of the counting system. Therefore, it was evaluated that no uranium isotopes have been released to the atmosphere from the stack of the AFSB at KAERI.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.3
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• pp.321-328
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• 2019

The detection performances of the NaI(Tl), $LaBr_3$(Ce) and $CeBr_3$ scintillation detectors, which can be used to rapidly evaluate the major artificial radionuclides deposited on the soil surface in a nuclear accident or radiological emergency, were compared. Detection performance was assessed by calculating the minimum detectable activity (MDA). The detection efficiency of each detector for artificial radionuclides was semi-empirically determined using mathematical modelling and point-like sources having certified radioactivity. The background gamma-ray energy spectrum for MDA evaluation was obtained from relatively wide and flat grassland, and the MDA values of each detector for the major artificial radionuclides that could be released in nuclear accidents were calculated. As a result, the relative MDA values of each detector regarding surface deposition distribution at normal environmental radiation level were evaluated as high in the order of the NaI(Tl), $LaBr_3$(Ce), and $CeBr_3$ detectors. These results were compared based on each detector's intrinsic and measurement environment background, detection efficiency, and energy resolution for the gamma-ray energy region of the radionuclide of interest.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05c
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• pp.526-531
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• 1996

국내의 방사성 동위원소 (Radioisotope; RI) 사용기관에서 발생, 수거되어 현재 원자력연구소 저장고 내에 보관중인 폐기물중 가연분을 대상으로 소각실증실험을 수행하였다. 폐기물 발생일을 기준하여 최소 2년이상이 경과한 RI 폐기물을 소각한 결과 폐기물의 부피와 무게를 각각 약 1/250, 1/30로 줄일 수 있었으며, 소각운전중 배출기체의 농도는 환경관련법상의 배출허용기준치 이하, 배출방사선량은 검출기의 측정한계 이하였다. 방사성동위원소 추적자로 I-131 ($Na^{131}$ I형태, 총 2mCi)을 사용한 모의 폐기물을 소각한 결과 대부분의 방사능은 소각재에 잔존하기 보다는 휘발되어 배기체와 함께 거동하며 주로 포대여과기의 여과층에서 잡히는 것으로 나타났다.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.9 no.3
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• pp.141-148
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• 2011

It is clarified in the radioactive waste transfer regulation that the concentration of radioactive waste for the major radio nuclide has to be examined when radioactive waste is guided to the radioactive waste stores. In case of the low level radioactive waste sample, the analytical results of radioactive waste concentration frequently show a value lower than minimum detectable activity (MDA). Since the MDA value basically depends on the amount of a sample, background value, measurement time, counting efficiency, and etc, it would be necessary to increase a sample amount with a intention of minimizing MDA. In order to measure a concentration of $^{129}I$ in low and medium level radioactive waste, $^{129}I$ was collected by using a distillation technique after leaching the simulated radioactive waste sample with a non-volatile acid. The recovery of $^{129}I$ measured was compared with that measured with column elution technique which is a conventional method using an anion-exchange resin. The recovery of inactive iodide by using the distillation method and column elution were found as $86.5{\pm}0.9%$ and $87.3{\pm}2.7%$, respectively. The recovery and MDA value calculated for distillation technique when 100 g of extracted solution of $^{129}I$ was taken, were found to be $84.6{\pm}1.6%$ and $1.2{\times}10^{-4}Bq/g$, respectively. Consequently, the proposed technique with simplified process lowered the MDA value more than 10 times compared to the column elution technique that has a disadvantage of limited sampling amount.

• Journal of Radiation Protection and Research
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• v.22 no.2
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• pp.111-117
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• 1997

Recently, the conclusion of Comprehensive Test Ban Treaty(CTBT) is globally constructing a network system for nuclear test monitoring. The radionuclide experts of the Conference on Disarmament recommended that the detection of nuclear debris in the atmosphere was an essential factor of nuclear test monitoring and proposed the technical requirements. Based on those requirements, atmospheric radionuclide monitoring system to detect nuclear debris generated from the nuclear explosion test was composed. The system is comprised of high volume air sampler(HVAS), filter paper presser and high purity germanium detector(HPGe). Minimum detectable concentrations(MDCs) of the key nuclides requiring in CTBT monitoring strategies are determined by considering of decay time, counting time and flow rate of the high volume air sampler for the rapid explosion and the optimum measurement condition. The results were selected $10{\pm}$2h, $20{\pm}$2h and $850{\pm}50m^3$/h as parameters, respectively. The relation between the natural air-borne radionuclide concentration of $^{212}Pb$ and MDC were calculated which gave effect in the Compton continuum baseline due to those nuclides in the gamma-ray spectroscopy. These results can be used as an actually tool in the CTBT monitoring strategies.