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The design of fusion devices often includes water as primary coolant of the first wall/blanket system and a potential accident scenario is the steam/water injection from the primary circuit into the magnets' cryogenic chamber (cryostat). An important question to be answered for the above scenario is whether the pressure suppression created by the cryogenic surfaces is sufficient to prevent cryostat damage. The computer codes used for the assessment of ITER safety were validated in the past years against the EVITA (Experimental Vacuum Ingress Test Apparatus) experiment at CEA-Cadarache, which was designed for the simulation of the physical phenomena occurring during a coolant ingress into the cryostat, namely ice formation on a cryogenic structure, heat transfer coefficient between walls and fluid, flashing, two-phase critical flow. The paper presents the results obtained by the CONSEN computer program for seven post-test calculations of the EVITA facility relating to the cryogenic experiments carried out in 2004 and 2005, in which the kinetics of the ice layer formation was analysed. The comparison with the experimental data has been performed and the main agreements and differences are remarked. [ABSTRACT FROM AUTHOR]

Highlights: [•] The CONSEN code for thermal-hydraulic transients in fusion plants is introduced. [•] A magnet induced confinement bypass accident in ITER has been simulated. [•] A comparison with previous MELCOR results for the accident is presented. [ABSTRACT FROM AUTHOR]

In many scientific areas, non-stochastic simulation models such as finite element simulations replace real experiments. A common approach is to fit a meta-model, for example a Gaussian process model, a radial basis function interpolation, or a kernel interpolation, to computer experiments conducted with the simulation model. This article deals with situations where more than one simulation model is available for the same real experiment, with none being the best over all possible input combinations. From fitted models for a real experiment as well as for computer experiments using the different simulation models, a criterion is derived to identify the locally best one. Applying this criterion to a number of design points allows the design space to be split into areas where the individual simulation models are locally superior. An example from sheet metal forming is analyzed, where three different simulation models are available. In this application and many similar problems, the new approach provides valuable assistance with the choice of the simulation model to be used. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The Paks nuclear power plant is equipped with pressurized water reactors of the VVER-440/213 type. These plants have a number of special features, namely, six-loop primary circuit, horizontal steam generators, loop seal in both hot and cold legs, safety injection tank set-point pressure higher than secondary pressure, etc. As a consequence of the special design solutions, the transient behavior of such a reactor system is different from the usual pressurized water reactor system behavior. To study the transient behavior of these plants, the PMK-2 integral-type facility, a thermal-hydraulic model of the Paks nuclear power plant, was designed and constructed. A short description of the specific design solutions of the VVER-440/213-type plants is given with the modeling aspects and similarity criteria applied to the design of the PMK-2 facility. Since the startup of the facility in 1985, 48 experiments have been performed primarily in an international framework with the participation of several experts from European and overseas countries to study one- and two-phase natural circulation, loss-of-coolant accidents, special plant transients, and experiments in support of the accident management measures. The results of several experiments illustrate the system effects of special design solutions and the effectiveness of bleed-and-feed accident management measures. A brief commentary on the thermal-hydraulic system code validation is provided, and conclusions are offered. [ABSTRACT FROM AUTHOR]