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Projects / Programmes source: ARIS

Thermal-Hydraulic Safety Analyses

Periods
Research activity

Code Science Field Subfield
2.03.00  Engineering sciences and technologies  Energy engineering   
2.13.00  Engineering sciences and technologies  Process engineering   
1.07.00  Natural sciences and mathematics  Computer intensive methods and applications   

Code Science Field
T160  Technological sciences  Nuclear engineering and technology 
T210  Technological sciences  Mechanical engineering, hydraulics, vacuum technology, vibration and acoustic engineering 
T200  Technological sciences  Thermal engineering, applied thermodynamics 
T140  Technological sciences  Energy research 
P240  Natural sciences and mathematics  Gases, fluid dynamics, plasmas 
Evaluation (rules)
source: COBISS
Researchers (21)
no. Code Name and surname Research area Role Period No. of publicationsNo. of publications
1.  21538  PhD Robert Bergant  Energy engineering  Researcher  2002 - 2003  42 
2.  07025  PhD Leon Cizelj  Energy engineering  Researcher  2001 - 2003  963 
3.  12755  PhD Marko Tomaž Čepin  Energy engineering  Researcher  2001 - 2003  558 
4.  15653  PhD Gregor Černe  Systems and cybernetics  Researcher  2001 - 2002  51 
5.  04143  MSc Ljubo Fabjan  Energy engineering  Researcher  2001 - 2003  177 
6.  23083  PhD Janez Gale  Process engineering  Researcher  2003  75 
7.  15816  PhD Andrej Horvat  Energy engineering  Researcher  2001 - 2003  52 
8.  19174  MSc Samo Hrvatin  Energy engineering  Researcher  2001 - 2002  49 
9.  11425  PhD Romana Jordan Cizelj  Energy engineering  Researcher  2001 - 2003  508 
10.  05570  PhD Ivo Kljenak  Energy engineering  Researcher  2001 - 2003  466 
11.  16435  PhD Boštjan Končar  Energy engineering  Researcher  2001 - 2002  367 
12.  18292  PhD Marko Kovač  Materials science and technology  Researcher  2001 - 2003  175 
13.  14572  PhD Matjaž Leskovar  Energy engineering  Researcher  2001 - 2003  435 
14.  02852  PhD Borut Mavko  Energy engineering  Head  2001 - 2003  930 
15.  06631  PhD Iztok Parzer  Energy engineering  Researcher  2001 - 2003  194 
16.  21181  Zoran Petrič  Energy engineering  Researcher  2001 - 2003  15 
17.  08661  PhD Andrej Prošek  Energy engineering  Researcher  2001 - 2003  600 
18.  12165  PhD Mladen Stanojević  Computer science and informatics  Researcher  2001 - 2002  84 
19.  19725  Andrej Sušnik    Researcher  2001 - 2003 
20.  19175  PhD Aljaž Škerlavaj  Process engineering  Researcher  2001 - 2002  81 
21.  12057  PhD Iztok Tiselj  Energy engineering  Researcher  2001 - 2003  468 
Organisations (1)
no. Code Research organisation City Registration number No. of publicationsNo. of publications
1.  0106  Jožef Stefan Institute  Ljubljana  5051606000  90,695 
Abstract
A number of issues dealing with Thermal-Hydraulic Safety Analyses was addressed The uncertainty of a small-break loss-of-coolant accident simulation in a two-loop pressurized water reactor was evaluated using the Code Scaling, Applicability and Uncertainty (CSAU) methodology. The appearance and disappearance of bubbly flow regime in downward flow was studied with the RELAP5 thermal-hydraulic computer code. Subcooled boiling was studied with two different approaches: a two-dimensional Eulerian model, and a three-dimensional Lagrangian model, in which vapor bubbles are tracked individually. A two-fluid interface-tracking model was combined with a "classical" two-fluid model. The resulting model is suitable for problems, where fluids, which are initially separated by a continuous interface, disperse and mix, so that the interface cannot be tracked on the same length scale. Natural convection in a fluid with internal heat generation was modeled with a Large Eddy Simulation method. The simulation revealed that the Rayleigh-Taylor instability is the dominant mechanism, which causes the appearance of turbulent flow regime Hydrogen stratification in a nuclear power plant containment atmosphere during a severe accident was simulated using the MELCOR and CONTAIN computer codes. To model steam explosions, a combined single-multiphase flow model of the premixing phase was developed and used to simulate isothermal premixing experiments, performed in other research centers. Probabilistic Safety Assessment Fault tree analysis was used to improve the requirements specification of safety software. Based on sets theory and first order logical predicates, the requirements specification is stated formally in gates and basic events of the fault tree. A house events matrix was also developed, which upgrades static fault tree analysis into a dynamic tool capable of modeling time requirements. These research activities belong to the framework of the international project "Allowed Outage Time for Test and Maintenance - Optimization for Safety", supported by the International Atomic Energy Agency. A method was developed, which explicitly includes numerical and linguistic information into the assessment of a specific failure rate. The basis of the method is Bayes' theorem, whereas specific data about component operation are included in the model using fuzzy set theory. Structural Safety Analyses Major efforts were devoted to computational simulations of intergranular cracking, with intergranular stress corrosion cracking as observed in Inconel 600 steam generator tubes taken as an example. Detailed simulation models at the grain size level were developed. The random grain structure is represented by an incomplete random tessellation (Voronoi tessellation). The mechanistic consideration of forces and other processes responsible for the initiation and growth of cracks is handled via empirical models.
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