Time filter

Source Type

Hung Z.-Y.,National Tsing Hua University | Huang Y.-K.,National Tsing Hua University | Pei B.-S.,National Tsing Hua University | Hsu W.-S.,National Tsing Hua University | Chen Y.-S.,Institute of Nuclear Energy Research
Kerntechnik | Year: 2015

The accident that occurred at the Fukushima Daiichi Nuclear Power Plant is a reminder of the danger of hydrogen explosion within a reactor building. Sufficiently high hydrogen concentration may cause an explosion that could damage the structure, resulting in the release of radioisotopes into the environment. In the first part of this study, a gas diffusion experiment was performed, in which helium was used as the working fluid. An analytical model was also developed using the GOTHIC code and the model predictions of the helium distribution were found to be in good agreement with the experimentally measured data. In the second part of the study, a model of the Mark HI containment of the Kuosheng Plant in Taiwan was developed, and was applied to a long-term station blackout (SBO) accident similar to that of the Fukushima plant. The hydrogen generation was calculated using the Modular Accident Analysis Program and was used as the boundary condition for the GOTHIC containment model. The simulation results revealed that the hydrogen concentration at the first floor of the wetwell in the containment reached 4% 9.7 h after the accident. This indicated the possibility of dangerous conditions inside the containment. Although active hydrogen ignitors are already installed in the Kuosheng plant, the findings of this study indicate that it may be necessary to add passive recombiners to prolong an SBO event. © Carl Hanser Verlag, München © Carl Hanser Verlag GmbH & Co. KG.

Hsiao T.-Y.,National Tsing Hua University | Hsiao T.-Y.,Institute of Nuclear Energy Research | Lin C.,National Tsing Hua University
Progress in Nuclear Energy | Year: 2012

Once an event in a pressurized water reactor (PWR) occurs and the operator has identified it, the system may then be returned to safe operational status. Usually, monitoring the thermal state of the reactor, e.g.; the temperature and pressure of the reactor cooling system (RCS), allows the operator to recognize an event in progress. In this study, the temperature difference between hot and cold legs and the pressure of the steam generator (SG) are also adopted as the parameters relative to identification. The event data are generated by the best estimated model RELAP5. The cumulative distribution function (CDF) is constructed and the cumulative probability from 0.05 to 1.00, with 0.05 increments, are chosen for identification. Considering the measurement noise, the probabilistic approach is adopted. The random value is added to the simulated data, and then a 95% confidence interval is obtained. To identify an event, eighty data points, i.e.; twenty data points for each parameter and four parameters for each event, should match the stored data. Since the identification procedure is simple, the process is very fast. This method will be beneficial in the context of executing an emergency operating procedure more effectively. © 2012 Elsevier Ltd. All rights reserved.

Tseng Y.-S.,Institute of Nuclear Energy Research | Wang J.-R.,Institute of Nuclear Energy Research | Lin C.-H.,Institute of Nuclear Energy Research | Shin C.,National Tsing Hua University
American Society of Mechanical Engineers, Power Division (Publication) POWER | Year: 2010

Chinshan Nuclear Power Plant (CSNPP) is a two-unit BWR4 plant with 1804MWt power per unit. Taipower Co., the owner of the plant is preparing the life extension procedure to extend the CSNPP operation time. In order to meet the life extension requirement, many issues need to be solved before life extension licensing, such as the spent nuclear fuel management, structure aging etc. For the spent nuclear fuel management, ROC Atomic Energy Council (ROCAEC) certified method is employed to analyze the thermal behaviors of Dry Storage System (DSS). This method uses ANSYS coupled with RELAP5-3D to solve the thermal characteristic and successfully accomplish the licensing procedure of the Chinshan Nuclear Dry Storage Project. However, further validation results demonstrate that the coupled method still exists uncertainty and deficiency. In this study, a new Computational Fluid Dynamics (CFD) numerical model for spend nuclear fuel (NSF) dry storage system (DSS) has been developed to improve the accuracy of DSS thermal analysis results. Its accuracy has been validated by comparing the temperature predictions with the experimental results of VSC-17 DSS. It has been found that the thermal behaviors and physical phenomena in the DSS could be predicted with good agreement for the measurements. Moreover, the uncertainty and reasonableness of results in previous method can be improved by the new thermal analyses methodology. Copyright © 2010 by ASME.

Cheng C.-C.,National Yang Ming University | Guan S.-S.,Institute of Nuclear Energy Research | Yang H.-J.,Institute of Nuclear Energy Research | Chang C.-C.,Taipei Medical University Hospital | And 3 more authors.
Journal of Biomedical Science | Year: 2016

Background: Hypoxia in tumor niche is one of important factors to start regeneration of blood vessels, leading to increase survival, proliferation, and invasion in cancer cells. Under hypoxia microenvironment, furthermore, steadily increased hypoxia-inducible factor-1aα (HIF-1aα) is observed, and can increase vascular endothelial growth factor (VEGF) expression and promote angiogenesis. Zinc protoporphyrin (ZnPP), a heme oxygenase-1 (HO-1) inhibitor, is potential to inhibit tumor proliferation and progression. However, the mechanism of ZnPP in inhibition of tumor is not completely clear. We hypothesize that ZnPP may modulate HIF-1aα through inhibiting HO-1, and then inhibit angiogenesis and tumor progression. This study aimed to dissect the mechanism of ZnPP in tumor suppression. Results: We observed the amount of VEGF was increased in the sera of the colorectal cancer (CRC) patients (n = 34, p < 0.05). Furthermore, increased VEGF expression was also measured in colorectal cancer cells, HCT-15, culturing under mimicking hypoxic condition. It suggested that hypoxia induced VEGF production from cancer cells. VEGF production was significantly reduced from HCT-15 cells after exposure to HIF-1aα inhibitor KC7F2, suggesting that HIF-1aα regulated VEGF production. Moreover, we observed that the HO-1inhibitor ZnPP inhibited the expressions of HIF-1aα and VEGF coupled with cell proliferations of HCT-15 cells, suggesting that ZnPP blocked HIF-1aα expression, and then inhibited the consequent VEGF production. In the xenograft model, we also observed that the animals exposed to ZnPP displayed much smaller tumor nodules and less degree of angiogenesis with decreased expression of the angiogenesis marker, aαvβ3 integrin, compared to that in normal control. Conclusions: This study demonstrated that VEGF level in serum was elevated in the patients with CRC. The HO-1 inhibitor, ZnPP, possessed the properties of anti-tumor agent by decreasing HIF-1aα levels, blocking VEGF production, impairing tumor angiogenesis, and inhibiting tumor growth. © 2016 Cheng et al.

Tseng Y.-S.,Institute of Nuclear Energy Research | Wang J.-R.,Institute of Nuclear Energy Research | Tsai F.P.,Cool Tec Co. | Cheng Y.-H.,National Tsing Hua University | Shih C.,National Tsing Hua University
Annals of Nuclear Energy | Year: 2011

This study numerically investigated the thermal performance of a new tube-type dry-storage system (DSS) with 61 BWR spent nuclear fuels (SNFs) by utilizing the Computational Fluid Dynamics (CFD) code FLUENT. Through a minimized and necessary assumption of modeling process (e.g.; the lumped model of fuel assembly), a geometry model was employed to solve the problem of conjugate heat transfer coupled with thermal radiation. The simulation results show that the maximum temperature is 333 °C, and the minimum temperature margins are 81.5 °C and 12.3 °C for the fuel assembly and concrete structure, respectively. The results further demonstrate that the new tube-type DSS meets the thermal requirements in the NUREG-1536 guidelines and the temperature limitation of structure material. Finally, the CFD simulation can be a powerful tool for thermal-hydraulic analysis, which can provide useful information for design improving, such as the accuracy temperature values, location of hot spots in each component and the flow field characteristics.

Discover hidden collaborations