• Nuclear Engineering and Technology
• /
• 제53권4호
• /
• pp.1304-1310
• /
• 2021

Two-phase flow, especially gas-liquid two-phase flow, has a wide application in industrial field. The diagnosis of two-phase flow parameters, which directly determine the flow and heat transfer characteristics, plays an important role in providing the design reference and ensuring the security of online operation of two-phase flow system. Computer tomography (CT) is a good way to diagnose such parameters with imaging method. This paper has proposed a novel image reconstruction method for thermal neutron CT of two-phase flow with improved simulated annealing (ISA) algorithm, which makes full use of the prior information of two-phase flow and the advantage of stochastic searching algorithm. The reconstruction results demonstrate that its reconstruction accuracy is much higher than that of the reconstruction algorithm based on weighted total difference minimization with soft-threshold filtering (WTDM-STF). The proposed method can also be applied to other types of two-phase flow CT modalities (such as X(𝛄)-ray, capacitance, resistance and ultrasound).

• Nuclear Engineering and Technology
• /
• 제55권9호
• /
• pp.3213-3228
• /
• 2023

As an important part of the digital reactor, the pin-by-pin wise fine coupling calculation is a research hotspot in the field of nuclear engineering in recent years. It provides more precise and realistic simulation results for reactor design, operation and safety evaluation. CORCA-K a nodal code is redeveloped as a robust pin-by-pin wise neutronics and thermal-hydraulic coupled calculation code for pressurized water reactor (PWR) core. The nodal green's function method (NGFM) is used to solve the three-dimensional space-time neutron dynamics equation, and the single-phase single channel model and one-dimensional heat conduction model are used to solve the fluid field and fuel temperature field. The mesh scale of reactor core simulation is raised from the nodal-wise to the pin-wise. It is verified by two benchmarks: NEACRP 3D PWR and PWR MOX/UO₂. The results show that: 1) the pin-by-pin wise coupling calculation system has good accuracy and can accurately simulate the key parameters in steady-state and transient coupling conditions, which is in good agreement with the reference results; 2) Compared with the nodal-wise coupling calculation, the pin-by-pin wise coupling calculation improves the fuel peak temperature, the range of power distribution is expanded, and the lower limit is reduced more.

• Journal of Radiation Protection and Research
• /
• 제12권2호
• /
• pp.19-27
• /
• 1987

황산망간 용액조장치의 $^{56}Mn\;{\gamma}$선 검출효율을 결정하는데 $^{56}Mn$용액의 방사능을 절대측정하는 것은 필수적이다 $^{56}Mn$시료를 제작하기 위하여 99.99%의 순도를 갖는 Mn금속조각 13.718mg되는 시료를 한국에너지연구소 TRIGA MARK-II 원자로의 중성자선속이 약 $10^{13}n/cm^2{\cdot}s$되는 열중성자장에서 12분간 조사시켰다. 중성자 방사화된 $^{56}Mn$금속시료를 0.1N-HCI 용액 50ml 용해시켜서 $^{56}Mn$시료를 제작하여 $4{\pi}{\beta}-{\gamma}$ 동시계수기술로 방사능을 측정한 결과 불확도 0.366%를 갖는 값으로서 1987년 10월 15일 0 시를 기준하여 408.070kBq/mg을 얻었다.

• 한국작물학회지
• /
• 제53권2호
• /
• pp.161-170
• /
• 2008

Interest is growing in applying simulation models for the South Texas conditions, to better assess crop water use and production with different crop management practices. The Environmental Policy Integrated Climate (EPIC) model was used to evaluate its application as a decision support tool for irrigation management of com (Zea mays L.) in South Texas of the U.S. We measured actual crop evapotranspiration (ETc) using a weighing lysimeter, soil moisture using a neutron probe, and grain yield by field sampling. The model was then validated using the measured data. Simulated ETc using the Hargreaves-Samani equation was in agreement with the lysimeter measured ETc. Simulated soil moisture generally matched with the measured soil moisture. The EPIC model simulated the variability in grain yield with different irrigation regimes with $r^2$value of 0.69 and root mean square error of $0.5\;ton\;ha^{-1}$. Simulation results with farm data demonstrate that EPIC can be used as a decision support tool for com under irrigated conditions in South Texas. EPIC appears to be effective in making long term and pre-season decisions for irrigation management of crops, while reference ET and phenologically based crop coefficients can be used for inseason irrigation management.

• Journal of Radiation Protection and Research
• /
• 제23권3호
• /
• pp.123-138
• /
• 1998

개인피폭선량 평가용 열형광선량계인 UD802 선량재에 대한 X-선장, 감마선장, 베타선장 및 중성자선장의 순수선장과 X-선장/감마선장, 베타선장/감마선장 및 중성자장/감마선장의 혼합선장에서의 반응특성을 조사하였으며 소자반응이 확률적으로 분포하는 성질을 이용한 개인피폭선량 평가 방법을 개발하였다. 선량계 특성조사를 위한 기준조사는 한국원자력안전기술원의 X-선장, 베타선장 및 감마선장을 이용하였으며 중성자선장은 미국 PNL에 의뢰하여 수행하였다. 특성조사 결과 광자 선장에 대한 소자1과 소자2는 에너지에 대한 의존성이 매우 적어 선량당량의 계산시 매우 유용한 자료로 사용되어질 수 있으며 소자3과 소자4는 저에너지 및 중에너지의 광자선장에 대해 매우 민감한 변화를 보이고 있다. 소자1/소자3 및 소자1/소자4의 반응비는 베타선장과 중성자선장에 대하여 에너지의존성이 큰 반응비를 나타내며, 소자3/소자2의 반응비는 중성자선장에 대해서만 1이하의 값을 나타내고 있다. 저에너지 및 중에너지 광자선장에 대한 에너지 분별은 소자3/소자2 및 소자3/소자4의 반응비로서 가능함을 확인하였다. 본 연구에서 개발한 확률분포 분석법의 적용가능성을 보이기 위하여 Panasonic UD716AGL/UD802 판독시스템에 적용하여 ANSI N13.11-1993에 따른 성능검증을 수행하였다. 성능검증 결과 모든 범주에 대하여 성능지수, ${\mid}B{\mid}+S$가 최대 0.232의 성능이 확인되었다. 특히 일부 소자의 비정상적 반응에 대해서도 최적의 피폭선량평가를 수행하고 있음이 확인되었으며, 실험실에서 재현될 수 없는 실제 방사선작업 환경에서의 선량평가 수행시, 본 논문에서 제시한 선량평가방법을 적용할 경우 계획된 피폭과 예상하지 못한 방사선장에 대한 피폭을 구분할 수 있어 보다 심도 있는 피폭선량평가 및 방사선관리가 가능할 것으로 판단된다.