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Condensation is a phenomenon widely studied for many years. However, the experimental data fragmentation and wide application of simplified theoretical models prevent the consolidation and development of the condensation phenomenon model corresponding to the known reality in all aspects. Both the experimental data and the models are obtained and developed in order to meet the practical needs of the industry first and foremost -- only the most widely used regimes have attracted researchers' attention. However, because fundamental research is very difficult the objectives were usually limited to the optimization of the processes, and other practical tasks. One of not adequately understood and analysed regime is stratified two-phase flow with surface instability induced by direct phase interaction in the interface. This paper presents water temperature profiles measured in stratified co-current two-phase flow (steam--water) inside a short and narrow rectangular channel. Measurements were made at x/h = 9.4; 14.8; 20.4; 39.2 (166, 312, 458, 932 mm) from the beginning of the channel, using a nonintrusive thermography method. The thermography method allows with high resolution and low data uncertainty (±2 °C) measuring the water temperature right at the channel sidewall. The different flow conditions were created in the channel by changing velocities of flowing phases (water 0.014, 0.028 and 0.056, and steam 6, 8, 10 and 12 m/s) and supply water temperature (25 °C). It was found that between different regimes the vertical temperature profiles measured from the interface to the bottom of the channel changed not equally and smoothly. In the tested case the water layer can be virtually divided into 4 zones by height where water temperature changes differently. It was also found that because of the 'condensation-turbulence self-induction' the steam flow momentum transfer to water turbulence occurred not only at the interface (depth of ~1 mm) but reached much deeper. By increasing the velocity of steam and at a constant rate of water flow the starting points of 'condensation-turbulence self-induction' move closer to the beginning of direct vapour--water contact. [ABSTRACT FROM AUTHOR]

The rapid condensation event is mostly considered a dangerous and undesirable side effect in thermal-hydraulic systems. This work demonstrates a different viewpoint, where condensation implosion is employed to perform mechanical work. Previous experimental study of the condensation implosion event, briefly presented in this article, showed that condensation implosion can be induced intentionally. These results were used as the basis for further investigations. In this work, a concept of the thermal-hydraulic system has been developed, where condensation-implosions-generated pressure difference could be used as a driving force. Numerical study has been performed to investigate the operation of the developed conceptual thermal-hydraulic system. A thermal-hydraulic computer code RELAP5 was selected for modeling the system operation. The RELAP5 code was found not able to predict the condensation implosion; therefore, a modified heat transfer model was implemented into the code. This modification allowed simulating the condensation implosion artificially in the thermal-hydraulic system and modeling the system response to the event. Final results show that a proposed circulation principle is possible and such a thermal-hydraulic system can operate. [ABSTRACT FROM AUTHOR]

After closing Unit 1 of the Ignalina NPP, a decision was made to transfer the spent fuel to Unit 2 for further use. For that purpose, a container which can transport up to six RBMK-1500 type assemblies was designed. From the point of radiation safety, it is important that the dose rate on any surface of the container does not exceed 2000 μv/h [1]. The initial fuel enrichment, burn up depth and cooling time most strongly affect the spent fuel isotopic composition and thus directly influence the radiation characteristics of the container. In this article, the evaluation of dose rate applying the SCALE code system (USA) is presented and performed and a comparison with the MCNP code and experimental results is made. [ABSTRACT FROM AUTHOR]