• Applied Biological Chemistry
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• 제18권2호
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• pp.56-60
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• 1975

완두유묘의 자엽 및 뿌리조직중 탄소-14 방사능을 Liquid scintillation counter로 신속히 측정하는 새로운 방법에 관하여 실험하였다. 식물조직을 액체공기에 처리하여 분쇄한 다음 Gel phosphor에 헌탁시켜, Liquid scintillation counter로 측정하였다. 이시료에 다시 내부표준물질을 가한 다음 계측효율을 구하여 Apparent absolute activity를 얻었다. 이렇게 얻은 헌탁시료의 절대방사능은 자기 흡수현상 때문에, 따로 Flask combustion 방법으로 구한 절대방사능 보다는 낮았으나, 항상 비례하였다. 따라서 동일한 실험조건하에서 상술한 비율을 얻으면, 완두조직중 탄소-14의 점대방사능은, 비교적 간편한 헌탁측정(suspension counting) 만으로 가능하였다. 본방법은 완두 외에 다른 식물조직중 탄소-14 분석에도 쓰일 수 있다.

• Nuclear Engineering and Technology
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• 제35권2호
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• pp.165-170
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• 2003

We developed an improved 3-PM liquid scintillation counting (3-PM LSC) method in which three detectors can be displaced to back and forth directions, and a data acquisition system being able to provide the values for all parameters required for the method. The detectors are entirely located in a 20-mm lead chamber of an inner diameter of 500 mm. A saw-toothed gear ties up all detectors so as to move them uniformly, up to 50 mm with unit of 1 mm. The data acquisition system was designed in an integrated circuit to perform the necessary works such as fast amplification, discrimination, coincidence and logic analysis. It generates values of nine parameters among twelve's generated in the 3-PH LSC method. The dead time of each counting channel is of extending type, valving from 10 to 100 $mutextrm{s}$. We measured the TDCR values with an unquenched liquid scintillation source 1"C by displacing the detectors with a step of 2.5 mm away from counting vial. Their values were derived on the range from 0.9 to 0.6. The extent is three times wider than those regions observed by applying the defocalization technique.ique.

• 분석과학
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• 제15권1호
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• pp.20-25
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• 2002

추출크로마토그래피와 액체섬광계수기를 이용하여 기존의 방사성 스트론튬 분석법 단점을 해결하는 신속하고 신뢰성 있는 $^{89}Sr$ 과 $^{90}Sr$ 분석법을 개발하였다. 옥살산 공침혹은 양이온 교환수지로 방해원소를 제거한 후 Sr-spec 컬럼을 사용하여 스트론튬만을 순수분리한 후, 액체섬광계수기를 사용하여 $^{89}Sr$에서 방출하는 첼렌코프광을 측정하였고 spectrum unfolding 방법으로 $^{90}Sr$을 정량하였다. 본 연구에서 개발된 방사성 스트론튬 분석법을 환경 표준시료 (IAEA-375, Soil) 및 액체 폐기물시료에 적용하여 분석법의 유효성을 검증하였다.

• Journal of Radiation Protection and Research
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• 제21권2호
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• pp.91-98
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• 1996

알파방출핵종 존재하에 베타방출핵종인 $^{241}Pu$ 최적 분석조건을 검토하였다. 펄스파고 분석기법을 이용하여 PSA 준위를 설정하였다. $^{241}Pu$ 표준선원을 이용하여 figure of merit가 최대가 되도록 $^{241}Pu$ counting channel를 조정하였고 계측효율이 최대가 되도록 형광체 부피를 설정하였다. 최적화된 $^{241}Pu$ 분석법을 토양과 이끼등의 환경시료에 적용하여 $^{241}Pu$ 방사능농도를 측정하였고. $^{241}Pu/^{239,\;240}Pu$ 방사능 비율로부터 우리나라의 일부 토양 및 이끼에 침적된 Pu의 근원을 규명하였다.

• 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.

• Journal of Korean Society for Atmospheric Environment
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• 제10권E호
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• pp.299-302
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• 1994

At a nuclear power plant, environmental radioactivity monitoring is routine work for the radiation safety management For the environmental monitoring of tritium($^3$H) activity in water sampled liquid scintillation counting( LSC) method is applied to measure low- energy beta activity from tritium in the samples. The $^3$H activity is measured using the BECKMAN 5801 system at the KRISS( Korea Research Institute of Standards and Science) for evaluating the lower limits of detection( LLD) of $^3$H measurement and the measuring capability of low-level $^3$H activity at four nuclear Power Plant sites. The LSC systems used for low-level $^3$H activity measurements at the nuclear Power Plants are confirmed to satisfy throughout an intercomparison study under the experimental arrangements by the KRISS.

• Nuclear Engineering and Technology
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• 제36권2호
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• pp.121-126
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• 2004

3-PM liquid scintillation counting using the geometry-efficiency variation technique has been applied to the activity measurement of $^{204}T1$, which decays to $^{204}Hg\;and\;^{204}Pb\;by\;{\beta}^-$ and E.C., respectively. The TDCR values K have been derived over a wide range, 0.78 < K < 0.97, by displacing the detectors up to 50 mm away from an unquenched liquid scintillation sample $^{204}Tl$. The derived plots of the logic sums of double coincidences $N_D(K)$ very K vary linearly in the observed regions. The fractions of losses due to electron capture decay have been taken into account by employing a PENELOPE Monte Carlo simulation. The calibrated activity is 102.3 kBq at a reference date of July 1st, 2002 (UT) with a combined uncertainty of $0.63\%$. This is consistent with the value determined by means of the CIEMAT/NIST method at KRISS.

• Journal of Pharmaceutical Investigation
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• 제25권3호
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• pp.223-226
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• 1995

A new method to study water uptake into biodegradable polymer was developed. Polymer was gently mixed with the tritiated buffer and the radioactivity level of the polymer due to water uptake was measured by liquid scintillation counting. The rate of water uptake was estimated from the plot of the amount of water in the device as a function of time. The technique used in this study is particularly useful for estimating water uptake of biodegradable polymers which were difficult to study by other techniques such as weight gain used for hydrogel.

• Journal of Radiation Protection and Research
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• 제20권2호
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• pp.103-115
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• 1995

계측이 간단하며 화학적 분리가 필요 없는 액체섬광계수법을 이용하여 일부 지하수 및 온천수중 $^{222}Rn$의 최적 분석조건을 검토하였다. $^{222}Rn$의 분석을 위한 최적 파형분석(PSA) 준위는 Optiphase HiSafe3 형광체 (Cocktail)에서 110, 그리고 톨루엔계열 형광체 (Toluene-based cocktail)에서는 90이었다. $^{222}Rn$의 계측효율은 Optiphase HiSafe3 형광체를 이용한 경우 ${\alpha}$영역에서의 계수효율은 유리용기는 282.2%, 테프론용기에서는 271.6%였으며, 톨루엔계열 형광체를 이용한 경우에는 유리용기와 테프론 용기에서 각각 262.3%, 247,5%였다. Optiphase HiSafe3 형광체와 테프론용기를 사용하여 60분간 계측하는 경우 ${\alpha}$-선 피크영역에서 $^{222}Rn$의 검출하한치는 $0.30Bq/{\iota}$였다. 또한, 본 연구에서 검토한 분석법은 일부 지하수 및 온천수중 $^{222}Rn$의 분석에도 응용되었다.

• Journal of Radiation Protection and Research
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• 제18권2호
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• pp.17-25
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• 1993

액체섬광 계수기에 대한 $^3H,\;^{14}C,\;^{36}Cl$의 베타선 스펙트럼의 시뮬레이션을 Monte Carlo 법으로 수행하였다. 베타선의 손실에너지는 'continuous slowing down approximation(CSDA)' 모형으로부터 구하였다. 순 베타방출 핵종이 균일하게 용해되어 있는 섬광용액은 $1.25cm{\times}3.5cm$의 원통형 geome try로 가정하였다. $^{14}C,\;^{36}Cl$에 대한 계산결과는 계수효율의 경우 실험 값과 2%의 범위 내에서 잘 일치하였으나 $^3H$에 대해서는 상당한 편차를 나타내었다. 이는 저 에너지 베타선에 대한 섬광용액 자체의 quenching 효과에 기인하는 것으로 판단된다.