• Nuclear Engineering and Technology
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• 제55권11호
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• pp.4077-4082
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• 2023

Large areas must be rapidly screened to monitor radiation in marine environments. For this purpose, this study developed a mobile real-time gamma-ray measurement system for shipboard use and evaluated its performance. The system was developed to measure engine or generator cooling water by installing a canister inside the ship. The minimum detectable activity of the system is about 0.8 Bq/L for a 60 s measurement period, and real-time data transmission and remote control are possible. The system was tested in the field and is currently being installed and operated on ships in service. Such a ship-based real-time gamma-radiation measurement system is suitable for a wide range of marine radiation surveillance applications and is expected to be rapidly deployed.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2022년도 춘계학술대회
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• pp.459-461
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• 2022

본 논문에서는 실내 환경에서 검출되는 방사능을 측정하기 위한 계측 시스템을 제시한다. 일반 가정, 작업장, 연구소 등 다양한 공간에서 발생되는 방사능을 측정하고 이에 대한 예방을 위함이다. 다중 방사능 센서를 이용해서 여러 공간을 동시에 측정한다. 측정된 방사능 데이터는 지그비를 통해서 실시간으로 PC로 전달하여 모니터링하는 시스템이다. 소량의 방사능이라고 하더라고 만성 피폭으로부터의 예방을 위해 연구소 또는 작업장 같은 방사능 노출이 예상되는 곳은 필수적으로 설치되어야 한다고 생각된다.

• 대한방사선기술학회지:방사선기술과학
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• 제47권3호
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• pp.183-195
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• 2024

Additional functional upgrades to the large-area compton camera (LACC) measurement device that can provide characteristics evaluation information (nuclear species and radioactivity) and two-dimensional or three-dimensional distribution imaging information of radioactive materials existing in surface or internal of concrete structures are required in terms of work stability and efficiency in order to apply to actual decommissioning sites such as nuclear power plants or medical cyclotron facilities by using this measurement device. To this purpose, the technology that allows radiation workers to intuitively and visually check the distribution of radioactive materials in advance by matching the two-dimensional distribution imaging information of radioactive materials obtained through the LACC measurement device and visual imaging of the measurement zone (10 m × 5 m) was developed. In addition, the separate system that can automatically adjust the position (height) in units of the measurement area size (0.7 m × 0.3 m × 0.8 m) of the LACC measurement device was developed and the integrated management system for characteristics evaluation information and two-dimensional or three-dimensional distribution imaging information obtained per unit of measurement for radioactive materials was developed. These functional upgrades related to LACC measurement device can improve work efficiency and safety when measuring radioactivity of concrete structures and enable the establishment of appropriate decommissioning strategies using radioactivity measurement information for decommissioning nuclear power plants or medical cyclotron facilities.

• Journal of Radiation Protection and Research
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• 제23권2호
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• pp.65-74
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• 1998

저 준위방사능 계측에서 가장 기본적으로 요구되는 것이 최적 측정시간의 결정이다. 최적화된 계측전략으로 측정시간을 결정하기 위하여 측정시간을 고정하는 방법, 측정값을 고정하는 방법, 시료와 자연계수율 또는 기준준위를 비교하여 측정하는 방법을 비교 검토하는 결정식을 도출하였다. 이 계측전략에서 기기에 주어진 측정조건 즉, 검출기의 효율, 측정기의 용량, 측정기의 최대 및 평균 자연계수율과 관련기준 즉, 기준준위, 검출한계 등을 만족하는 측정시간이 결정된다. 계측전략은 측정시 주어진 조건에서 방사능 존재확인과 정량분석에 대한 시료의 최적 측정시간의 결정을 편리하게 함으로써 일상의 저준위방사능 측정에 유용하게 사용될 것이다.

• 방사선산업학회지
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• 제17권4호
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• pp.471-479
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• 2023

In In-situ radioactivity measurement techniques, efficiency calibration models use predefined models to simulate a sample's geometry and radioactivity distribution. However, simplified efficiency calibration models lead to uncertainties in the efficiency curves, which in turn affect the radioactivity concentration results. This study aims to develop an efficiency calibration optimization methodology to improve the accuracy of in-situ gamma radiation measurements for byproducts from industrial facilities. To accomplish the objective, a drive mechanism for rotational measurement of an byproduct simulator and a sample was constructed. Using ISOCS, an efficiency calibration model of the designed object was generated. Then, the sensitivity analysis of the efficiency calibration model was performed, and the efficiency curve of the efficiency calibration model was optimized using the sensitivity analysis results. Finally, the radiation concentration of the simulated subject was estimated, compared, and evaluated with the designed certification value. For the sensitivity assessment of the influencing factors of the efficiency calibration model, the ISOCS Uncertainty Estimator was used for the horizontal and vertical size and density of the measured object. The standard deviation of the measurement efficiency as a function of the longitudinal size and density of the efficiency calibration model decreased with increasing energy region. When using the optimized efficiency calibration model, the measurement efficiency using IUE was improved compared to the measurement efficiency using ISOCS at the energy of ²²⁸Ac (911 keV) for the nuclide under analysis. Using the ISOCS efficiency calibration method, the difference between the measured radiation concentration and the design value for each simulated subject measurement direction was 4.1% (1% to 10%) on average. The difference between the estimated radioactivity concentration and the design value was 3.6% (1~8%) on average when using the ISOCS IUE efficiency calibration method, which was closer to the design value than the efficiency calibration method using ISOCS. In other words, the estimated radioactivity concentration using the optimized efficiency curve was similar to the designed radioactivity concentration. The results of this study can be utilized as the main basis for the development of regulatory technologies for the treatment and disposal of waste generated during the operation, maintenance, and facility replacement of domestic byproduct generation facilities.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2003년도 가을 학술논문집
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• pp.562-571
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• 2003

발전용원자로에서 뱃치방식으로 환경으로 배출된 액체유출물 내에 함유된 방사능 평가 결과에 오차를 유발하는 시료채취, 제조, 방사능 계측, 유출물 배출체적 측정 등 다양한 인자를 분석하였다. 환경배출 방사능 평가에 포함된 많은 인자들은 단일 측정에 의해 얻어지고 환경배출 방사능의 참값을 알 수 없음에 따라, 평가결과의 오차를 예측하는 것은 원칙적으로 불가능하다. 이에 따라 1993년 ISO가 권고한 측정의 불확도 표현지침에 근거하여 액체폐기물 배출방사능에 대한 불확도 평가모델을 수립하고 가상적인 조건에 대한 액체유출물 환경배출 방사능 평가결과의 불확도를 평가하였다. 그 결과, 액체유출물을 통한 환경배출 방사능 평가결과에 불확도를 유발하는 인자의 상대적인 기여도는 배출폐액의 체적, 시료의 체적, 총방사능 계측값의 순서를 갖는 것으로 나타났다. 또한 개별 변수의 확률분포와 특성값을 토대로 몬테칼로 모사법을 적용하여 최종 환경배출 방사능 평가결과의 확률분포를 해석함으로써, 지금까지 단일 값을 평가 및 보고되었던 발전용 원자로의 액체상 방사성물질 환경배출량이 실제로는 일정한 확률분포를 갖고 있음을 확인하였다.

• 핵의학기술
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• 제16권2호
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• pp.99-105
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• 2012

Purpose : This study is designed to compare two parameters reflecting $^{18}F$-FDG uptake, SUV and radioactivity, for diagnosis of thyroid cancer in dual time $^{18}F$-FDG PET/CT imaging and to find which parameter is more useful to decide whether the tumor is malignant or not. Materials and Methods : We performed retrospective study for 40 patients. All patients are diagnosed as primary thyroid cancer and examined $^{18}F$-FDG PET/CT. First, we got the dispersion of scattering beam of neck and lung apex to set a background and compared each dispersion, mean value, standard deviation of maxSUV and radioactivity. Also, mean maxSUV, ${\Delta}maxSUV$, ${\Delta}maxBq$/ml(%) and radioactivity between groups according to lesion's size based on biopsy are compared with independent-sample t-test. Results : the values that were from maxSUV and radioactivity measurement technique were compensated and calculated to practical values for mean comparison and patients were divided to two groups based on tumor size, Group1 ($size{\leq}1$ cm, n=21), Group2 (size>1 cm, n=19) for accurate comparison. In Group1, maxSUV (semi-quantitative analysis) was increased from $5.64{\pm}5.85$ (1.89~17.84) at first image to $5.90{\pm}5.01$ (1.95~18.22) at second image and radioactivity (Bq/ml) (quantitative analysis) showed similar increase from $5.93{\pm}6.38$ (2.50~16.75) at first image to $6.01{\pm}5.25$ (2.66~16.58) at second image. In Group2, TFmaxSUV was $10.54{\pm}14.36$ (2.54~33.89) in true first image, TSmaxSUV was $9.85{\pm}12.88$ (2.62~26.20) in true second image separately. The maxSUV showed a significant difference in the mean comparison between the two groups (p=0.035) But, mean radioactivity (Bq/ml) was $5.93{\pm}6.38$ (4.81~40.99) in true first image, $6.01{\pm}5.25$ (4.51~36.93) in true second image and didn't show a significant difference statistically (p=0.126) Conclusion : In diagnosis of thyroid tumor, SUV and radioactivity depending on $^{18}F$-FDG uptake showed high similarity with coefficient of determination (R2=0.939) and malignant evaluation results using dual time also showed similar aspect. Radioactivity for evaluation of malignant tumor didn't show better specificity or sensitivity than maxSUV.

• 한국방사선학회논문지
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• 제15권4호
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• pp.533-538
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• 2021

갑상샘 섭취율 측정을 위해 과산화테크네슘을 사용하고 있다. 대퇴부의 배후방사능 측정 시 무릎에서 골반 쪽으로 10 cm 위의 위치에서 검출기와 대퇴부의 거리를 20 cm, 25 cm 위치에서 병원들마다 서로 다른 거리에서 측정하고 있다. 두 거리에서 갑상샘 섭취율 측정을 정량 분석하여 갑상샘 섭취율을 구함에 있어서 유효성의 차이를 연구 하고자 하였다. 결과로써 50명의 대퇴부 20 cm에서 측정한 평균 갑상샘 섭취율은 3.532±4.312%로 나타났으며 25 cm에서 측정한 평균 갑상샘 섭취율은 3.680±4.304%로 나타났다. 갑상샘 섭취율 검사 결과를 통하여 20 cm 거리에서 측정된 대퇴부의 배후방사능 값이 상대적으로 25 cm 거리에서 측정된 배후방사능 값 보다 높게 측정되어 결과적으로 갑상샘 섭취율이 0.148% 낮게 나왔으며 배후방사능 측정을 위한 일정한 거리에서의 측정이 중요하다고 판단된다.

• 한국압력기기공학회 논문집
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• 제19권1호
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• pp.20-26
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• 2023

The defected baffle former bolts of Kori unit 1 were withdrawn to analyze the cause of damage and gamma-ray measurement is being scheduled. Prior to that, in order to calculate the specific radioactivity value of the baffle former bolt, a radioactivity calculation method considering the actual operation history of the nuclear power plant is introduced and the calculation results are shown. In particular, the radioactivity calculation method considering the operation history is obtained by defining the monthly contribution factor from the actual monthly operation history. As a result, the results considering operation history are 16-28% lower than the general radioactivity calculation results. These results can contribute to establish a reasonable but economical strategy when planning nuclear power plant decommissioning.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1999년도 추계학술발표회요약집
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• pp.332.2-332
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• 1999