• Nuclear Engineering and Technology
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• 제54권4호
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• pp.1449-1455
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• 2022

A radiotracer investigation was carried out in a Thermal Stratification Test Facility (TSTF) with objectives of investigating the dispersion and diffusion of radionuclide and effectiveness of the thermocline to minimize the radionuclide content in the hot water layer. Technetium-99m (^99mTc) as sodium pertechnetate was used as a radiotracer in the investigation. Qualitative analysis showed that a thermocline is formed within the TSTF and is effective in preventing the transport of radionuclide from bottom section to the top section of the facility. It was found that the radiotracer injected at the bottom of the pool took about 17.4 h to disperse from bottom to the top of the facility. The results of the investigation helped in understanding the effectiveness of hot water layer and thus to minimize the pool top radiation levels.

• Nuclear Engineering and Technology
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• 제54권12호
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• pp.4684-4692
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• 2022

Radionuclide identification is an important part of the nuclear material identification system. The development of artificial intelligence and machine learning has made nuclide identification rapid and automatic. However, many methods directly use existing deep learning models to analyze the gamma-ray spectrum, which lacks interpretability for researchers. This study proposes an explainable radionuclide identification algorithm based on the convolutional neural network and class activation mapping. This method shows the area of interest of the neural network on the gamma-ray spectrum by generating a class activation map. We analyzed the class activation map of the gamma-ray spectrum of different types, different gross counts, and different signal-to-noise ratios. The results show that the convolutional neural network attempted to learn the relationship between the input gamma-ray spectrum and the nuclide type, and could identify the nuclide based on the photoelectric peak and Compton edge. Furthermore, the results explain why the neural network could identify gamma-ray spectra with low counts and low signal-to-noise ratios. Thus, the findings improve researchers' confidence in the ability of neural networks to identify nuclides and promote the application of artificial intelligence methods in the field of nuclide identification.

• 한국환경과학회지
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• 제27권6호
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• pp.425-436
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• 2018

To establish initial response scenarios for nuclear accidents around the Kori nuclear power plants, the potential for radionuclide diffusion was estimated using numerical experiments and statistical techniques. This study used the numerical model WRF (Weather Research and Forecasting) and FLEXPART (Flexible Particle dispersion model) to calculate the three-dimensional wind field and radionuclide dispersion, respectively. The wind patterns observed at Gijang, near the plants, and at meteorological sites in Busan, were reproduced and applied to estimates of seasonally averaged wind fields. The distribution of emitted radionuclides are strongly associated with characteristics of topography and synoptic wind patterns over nuclear power plants. Since the terrain around the power plants is complex, estimates of radionuclide distribution often produce unexpected results when wind data from different sites are used in statistical calculations. It is highly probable that in the summer and autumn, radionuclides move south-west, towards the downtown metropolitan area. This study has clear limitations in that it uses the seasonal wind field rather than the daily wind field.

• Journal of Radiation Protection and Research
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• 제22권3호
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• pp.183-193
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• 1997

원전 작업자 피폭관리와 안전성 평가 및 최종적으로 처분허가를 위하여 폐기물 내의 핵종 및 농도를 파악하여야만 한다. 이온교환 수지 및 필터는 그 부피는 작으나 원전 운전중 발생하는 폐기물 내 방사능의 대부분을 차지하고 있다. 본 연구의 목적은 냉각수 정화 계통내의 수지 및 필터 내에 누적되어 있는 방사성 핵종의 양을 예측할 수 있는 방법을 개발하는 것이다. 핵종누적량을 계산하기 위하여 평균제염계수 대신 순간제염계수를 사용하였으며 포트란언어를 사용하여 프로그램을 작성하여 누적량을 계산하였다. 본 예측기법의 검증을 위하여 미국 Rancho-Seco 발전소의 측정자료를 이용하였으며 실험을 통한 계측자료를 검증에 이용하였다. 순간제염계수를 이용한 본 방법의 계산이 평균제염계수를 이용한 것보다 오차가 작았다. 이 방법을 실제 적용하기 위해서는 운전지침에 의하여 주기적으로 계측한 제염제수와 핵종농도 자료만으로도 핵종누적량 계산이 가능하다. 그러나, 특히 발전소 운전상황이 급격하게 변할 때에는, 정확한 누적량 평가를 위하여 제염계수 및 방사성 핵종농도의 측정주기가 짧아져야 한다.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2003년도 가을 학술논문집
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• pp.322-327
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• 2003

It is important to know the accurate radionuclide inventory of radioactive waste for the reliable management. However, estimation of radionuclide concentrations in drummed radioactive waste is difficult and unreliable because of difficulties of direct detection, high cost, and radiation exposure of sampling personnel. In order to overcome these difficulties, scaling factors (SFs) have been used to assess the activities of radionuclides that could not be directly analyzed. A radionuclide assay system has been operated at KORI site since 1996 and consolidated scaling factor method has played a dominant role in determination of radionuclides concentrations. However, some problems are still remained such as uncertainty of estimated scaling factor values, inaccuracy of analyzed sample values, and disparity between the actual and ideal correlation pairs and the others. Therefore, it needs to improve the accuracy of scaling factor values. The scope of this paper is focused on the improvement of accuracy and representativeness of calculated scaling factor values based on statistical techniques. For the selection of reliable activity determination method, the accuracy of estimated SF values for each activity determination method is compared. From the comparison of each activity determination methods, it is recommended that SF determination method should be changed from the arithmetic mean to the geometrical mean for more reliable estimation of radionuclide activity. Arithmetic mean method and geometric mean method are compared based on the data set in KORI system.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2004년도 학술논문집
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• pp.174-174
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• 2004

It is necessary to perform the radionuclide inventory assessment for the disposal of low and intermediate radioactive waste containers. The $\gamma$ nuclide analyzer can be used for the assessment of containers. However, if the radioactivity in the containers is extremely low or high, radionuclide inventory of the containers can not be evaluated properly. Also, gamma scanning method is time consuming and has economical burden to the utilities.(omitted)

• 대한핵의학회지
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• 제23권1호
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• pp.89-93
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• 1989

Single pass radionuclide cardiac angiography was performed in 67-year old woman due to dyspnea and chest discomfort. The study showed markedly dilated ascending aorta and collateral ciculations from left sudclavian vein, and confirmed aortic aneurysm with partial obstruction of superior vena cava.

• 대한핵의학회지
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• 제23권2호
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• pp.183-188
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• 1989

Esophageal transit of radionuclide was quantitatively analyzed in 29 patients with dermatomyositis-polymyositis. Fourteen patients (48.3%) showed retention of tracer in oropharynx. The mean value of percent retention of oropharynx was $15.5{\pm}16.6%$. Esophageal dysfunction was found in 19 patients (65.5%). Among them 4 showed mild, 12 showed moderate and 3 showed severe esophageal dysfunction. Dysphagia was found in 11 patients (37.9%), which was closely related to percent retention of oropharynx.Quantitative analysis of esophageal transit of radionuclide seemed to be a useful technique for evaluation of dysphagia in patients with dermatomyositis-polymyositis.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1995년도 춘계학술발표회논문집(2)
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• pp.769-774
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• 1995

In this study, a transport model was developed in order to analyze and predict the transport behaviors of radionuclides mediated by pseudo-colloid in the fractured rock media. It was resulted that the transport of Pu-239 was faster than Ni-63 because pseudo-colloid formation constant of Pu-239 was greater than that of Ni-63. Also, the effect of pseudo-colloid formation on the transport of a radionuclide was shown to be very significant when the apparent pseudo colloid formation constant, $K_{ap}(m^{3}/kg)$, was greater than 100. Thus, it can be concluded that acceleration of radionuclide migration may be occurred because the pseudo-colloid formation of radionuclides increases the amount of mobile components in the solution and consequently decreases the amount of radionuclides adsorbed on the stationary solid medium.

• Nuclear Medicine and Molecular Imaging
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• 제40권2호
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• pp.96-105
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• 2006

Molecular imaging has its root in nuclear medicine and gene therapy monitoring. Therefore, recent progress in the development of non-invasive imaging technologies, particularly nuclear medicine, should allow molecular imaging to play a major role in the field of gene therapy. These tools have recently been validated in gene therapy models for continuous quantitative monitoring of the location, magnitude, and time-variation of gene delivery and/or expression. This article reviews the use of radionuclide imaging technologies as they have been used in imaging gene delivery and gene expression for gene therapy applications. The studios published to date lend support that noninvasive imaging tools will help to accelerate pre-clinical model validation as well as allow for clinical monitoring of human gene therapy.