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[en] The steam condensation on the inside wall of containment and film evaporation on the outside wall of containment are very important phenomena during passive containment cooling system (PCS) heat removal process. The GOTHIC8.0 code was used to simulate condensation and evaporation heat removal processes in this paper. The code prediction results were compared and evaluated based on experimental data of condensation and evaporation tests. The results show that the condensation model in GOTHIC can simulate steam condensation heat transfer process quite well. The film evaporation rate from GOTHIC model is lower than that from evaporation test. Although GOTHIC model is conservative to analyze containment response during design benchmark accident, it is suggested that further work should focus on making code development to better simulate film evaporation phenomenon. (authors)
[en] Computational and design studies of the arrangement of an autonomous power unit with a nuclear reaction in a sparsely populated location characterized by weak soil are presented. A variant of a possible arrangement of the reactor taking account of the requirements of the facility is shown. The radioactive emission around the reactor and the distribution of heat emission in the soil, for picking and determining the number of cooling elements, are calculated. A technical solution that provides for the installation of a nuclear reactor in soft ground is proposed.
[en] This publication documents the results achieved by participants of an IAEA coordinated research project (CRP) related to hydrogen production using nuclear energy. The IAEA has previously developed the Hydrogen Economic Evaluation Programme (HEEP) that supports the analysis of various options for future hydrogen economies. HEEP is the first of its kind software and has been distributed freely to IAEA Member States. The CRP participants performed a generic benchmark analysis for various scenarios of hydrogen production and against other codes built on different platforms and models. The research report highlights various aspects of nuclear hydrogen production based not only on national but also international trends. It considers important technical aspects of coupling nuclear reactors to hydrogen plants and the challenges for nuclear hydrogen production compared to steam or solar energy produced hydrogen. Major accomplishments achieved by Member States are presented in the summary section of this report. A detailed description of the activities and outcomes through the implementation of the CRP can be found in the individual country reports available on the CD-ROM attached to this publication.
[en] A transient analysis code TAPIRS was developed to analyze the behavior of the heat pipe cooled space reactor power system based on the SAIRS models. Three typical accidents are analyzed using TAPIRS. The results show that the fuel temperature is below a safe limit under the control drum failure, the AMTEC failure and partial loss of the heat transfer area of radiator. This demonstrates that the reactor system is with the characteristics of self-stabilization ability under accident conditions. (authors)
[en] To increase heat transfer performance of dry cooling system, direct contact heat exchangers were considered. There is no thermal resistance by wall structure and it is easy to get large surface area. On the other hand the conventional system uses fin structure and heat transfer performance is reduced due to thermal conduction in the fins. In most cases, increasing heat transfer performance is able to be obtained by increasing Reynolds number. In this study, many types of direct contact heat exchangers were analyzed and the optimum heat exchanger type having high heat transfer performance and low pressure loss of the system was selected. In summary, the best type for direct contact heat exchanger is falling oil film along vertical strings. It is important to consider not only heat transfer performance of the heat exchanger but also frictional pressure loss. The range of Reynolds number in the direct contact heat exchangers are generally 100 to 10,000. Within this range, whole correlations used for this study are proven, thus the results are reliable. This study shows that straight flow of air on the flat surface is the best option for direct contact heat exchanger. The heat transfer performance on the wavy surface is high due to turbulence, but the frictional pressure loss is much large.
[en] To establish a lunar base, the problem of energy supply needs to be solved first. The nuclear reactor power system has the advantages of high power, long service life and environmental resistance ability. It is an ideal energy solution option for lunar base and other deep space exploration missions. The brief analysis of the current status of energy that can be used for the lunar base was carried out. The design idea of 40 kWe nuclear reactor power system for lunar base was proposed. After the preliminary optimization design, process and overall design parameters of the system were given. Finally, the system scheme was analyzed and demonstrated from the aspects of reactor physics, shielding, thermodynamics and structure. The results show that the system scheme is reasonable and feasible. It can meet the requirements of safety and lifetime. (authors)
[en] Nuclear energy is categorized as the most economic and sustainable energy by IAEA. However, demand and needs for safety and reliability of nuclear industry are increasing after FUKUSHIMA. Especially, reliable data on the stability of nuclear fuel in a reactor and spent fuel is necessary for safety analysis of nuclear reactor and spent fuel. In this study standard reference data were developed and uploaded to the database of national standard reference center. The standard reference data produced in NFDC will be helpful for increasing reliability and stability evaluation of nuclear fuel and spent fuel
[en] Highlights: • CFD method is used to predict natural circulation under swing motions. • CFD method can avoid using land-based correlations to swing system. • Pseudo-steady mass flux amplitude increases linearly with swing angles. • Swing phase difference significantly changes the pseudo-steady parameters. - Abstract: In nuclear power systems, the natural circulation loop will startup to remove the residual heat after losing the power for the forced circulation. The natural circulation will startup if the driving force caused by the density difference is large enough to overcome the resistance of the loop, however, the system will encounter additional forces, including the transport force and the Coriolis force, which may change the driving force and break the stability of natural circulation. In this work, the CFD model for a natural circulation loop was developed to study the dynamic startup performances and the pseudo steady-state operations under swing conditions. Using CFD methodology can avoid employing the correlations for wall friction and heat transfer using in system code, which may be not applicable for swing systems. Based on the CFD analysis, parametric studies were carried out, including swing period, maximum swing angle, heat power, swing center and the swing phase difference. The swing angle, swing period, swing phase difference and heated power can significantly affect the thermohydraulics and stability of the natural circulation systems, while the swing radius has little influence. This work proved that CFD methodology may be qualified for analyzing the natural circulation system under swing conditions.
[en] PCCS (Passive Containment Cooling System) comprised of heat exchanger tubes were devised for iPOWER (innovative Power Reactor) concept design. To guarantee the cooling performance of the PCCS, the condensation heat transfer needs to be accurately calculated. The relation between diameter of PCCS heat exchanger and condensation heat transfer coefficient has been investigated in the present study and the heat exchanger design was selected based on the JNU (Jeju National University) experiment. A curvature effect correction factor was derived by Popiel and Dehbi used the parameter when proposing his generalized condensation heat transfer coefficient correlations. In this study, the condensation phenomena simulations were performed to derive the curvature effect correction factor applicable to the condensation phenomena. Based on the CFD analysis results, Bird correction factor was selected as a parameter for condensation phenomena. The fitting equation was introduced which shows good agreement with CFD results. The modified correlation can be expected to be applicable as a curvature effect correction factor when deriving generalized condensation heat transfer coefficient correlations. For the further works, as validation of modified curvature effect correction factor, quantitative comparison between the modified curvature effect correction factor and the experimental results of curvature effect on condensation will be conducted.
[en] Research work was performed to implement the Ukrainian study under Task 2 of the SYNERGIES collaborative project, including research on the possibility of wide deployment of nuclear reactors for non-electric applications (heat production) and assessment of nuclear energy development based on the Generation IV reactors. Proposals are made for international cooperation in the development of the nuclear energy system (NES) of Ukraine in the medium- and long-term using Generation III+ and Generation IV reactors. Neither of these scenarios were considered during the GAINS project.