atw 2018-09v3

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<strong>atw</strong> Vol. 63 (<strong>2018</strong>) | Issue 8/9 ı August/September References 468 AMNT <strong>2018</strong> | YOUNG SCIENTISTS' WORKSHOP | | Fig. 3-1. Overview of whole Nodalisation of the IPR-R1 (left) and 13 core channels (right) generated by the software for input deck generation. Power [kW] | | Tab. 3-2. Thermal hydraulic data IPR-R1. Core inlet temperature (Position 3) [°C] Core outlet temperature (Position 3) [°C] There is good agreement between the published RELAP calculations in [REI2009] and the calculated ATHLET data. 4 Summary A new method based on a heuristic approach for modelling selected research reactor types in thermal hydraulic analysis codes is presented. This new approach allows a fast and reliable generation of the input deck’s fundamental elements despite limited technical documentation. Focusing on one MTR and one TRIGA design, the main steps of developing process and the characteristics of the new method are highlighted. This includes the Core inlet temperature (Position 8) [°C] Core outlet temperature (Position 3) [°C] Calculation 51 20.87 27.97 20.87 23.94 Reference [REI2009] 50 20.95 26.95 22.95 24.95 abstraction and modularisation of research reactor plant designs as well as the conception of type-specific nodalisation. At the end of this paper, an exemplary MTR and TRIGA research reactor is presented, generated by the developed software. Focusing on the stationary conditions, there is a good agreement between the calculated and experimental data. This proves the basic functionality of the developed modelling system by generating a realistic plant model for TRIGA and MTR type. In future work, the nodalisation for both research reactor designs will be reviewed and tested against a range of safety transients and accidents. ABD2008A ABD2008B ABD2015 I.D. Abdelrazek, E.A. Villarino: ETRR-2 Nuclear Reactor: Facility Specification; Coordinated Research Project on Innovative Methods in Research Reactor Analysis, organised by IAEA, October 2008. I.D. Abdelrazek, E.A. Villarino: ETRR-2 Nuclear Reactor: Experimental Results Coordinated Research Project on Innovative Methods in Research Reactor Analysis, organised by IAEA, October 2008. I.D. Abdelrazek, et al.: Thermal hydraulic analysis of ETRR-2 using RELAP5 code, Kerntechnik 80, 2015. ATH2016 G. Lerchl et.al.: ATHLET 3.1A User’s Manual, GRS-P-1/Vol.1, Ref.7, March 2016. IAEA2005 IAEA2016 IAEA2016B REI2009 RRDB<strong>2018</strong> Authors IAEA: Research reactor utilization, safety, decommissioning, fuel and waste management, ISBN 92-0-113904-7, IAEA 2005. IAEA: Safety of Research Reactors, IAEA Safety Standards Series No. SSR-3, Vienna Austria, 2016, ISSN 1020-525X. IAEA: History, development and future of TRIGA research reactors, Technical Report Series No. 482, ISBN 978-92-0- 102016-1, IAEA 2016. P. A. L. Resi, et al.: Assessment of a RELAP5 model for the IPR-R1 TRIGA research reactor, International Nuclear Atlantic Conference – INAC 2009, ISBN: 978-85-99141-03-8. IAEA: Research Reactor Database, Website URL: https://nucleus.iaea.org/RRDB/ RR/ReactorSearch.aspx?rf=1 (01.02.<strong>2018</strong>). Vera Koppers Prof. Dr.-Ing. Marco K. Koch Responsible Professor Ruhr-Universität Bochum (RUB) Universitätsstraße 150 44801 Bochum, Germany | | Fig. 3-2. Core inlet (left) and core outlet (right) temperature. AMNT <strong>2018</strong> | Young Scientists' Workshop Heuristic Methods in Modelling Research Reactors for Deterministic Safety Analysis ı Vera Koppers and Marco K. Koch

<strong>atw</strong> Vol. 63 (<strong>2018</strong>) | Issue 8/9 ı August/September Development and Validation of a CFD Wash-Off Model for Fission Products on Containment Walls Katharina Amend and Markus Klein The research project aims to develop a CFD model to describe the run down behavior of liquids (wall films, transition of film flow into a discrete number of rivulets, droplets) and the resulting wash-down of fission products on surfaces in the reactor containment. Numerical experiments allow for a deeper physical understanding, which is the basis for an improved semi-empirical modeling. This paper presents a three-dimensional numerical simulation for water running down inclined surfaces coupled with an aerosol wash-off model and the resulting particle transport using the software package OpenFOAM. The wash-off model is based on the procedure used in AULA (German: Abwaschmodell für unlösliche Aerosole, wash-off of insoluble aerosol particles) in the lumped parameter code COCOSYS [1]. A parameter variation was conducted and the simulation results are compared to the laboratory experiments performed by Becker Technologies [2]. 1 Introduction The desired goal is the prevention of environmental contamination with radioactive particles after a core meltdown in a light water reactor. The containment in a nuclear reactor building prevents high pressure radioactive steam from escaping in the event of an emergency. During such a critical accident in a light water ­reactor, most of the fission products enter the containment building in the form of soluble and insoluble aerosols. These particles might deposit on walls and installation surfaces. Condensing steam that is also released into the containment can wash down even insoluble particles into the containment sump. In previous studies [3, 4] the understanding of the run down behavior of water, the formation of film flow, rivulets or droplets, was the main subject of interest. This study investigates the wash-off of insoluble particles based on the run down behavior of water on inclined plates and the developing flow patterns using CFD simulations. 2 Laboratory experiments The laboratory tests are part of the THAI AW3 test program [5]. They investigate the aerosol wash-down behavior of non-soluble silver from inclined walls by steam condensate. Trapezoidal plates (plain stainless steel or decontamination paint coating) with different inclinations are loaded with dry silver aerosol. At the uppermost part water enters the plate via a tubular distributor with a given flow rate. The water flows down the plate, washes off part of the particles and is finally collected in cups, which get exchanged after a specified time period. The samples are put into a cabinet dryer and the remaining aerosol mass is weighed to quantify the wash-off. Pictures taken during the experiments show the flow patterns and run down behavior of the water on the plates, see Figure 1. Two kinds of silver aerosol particles are used: a fine silver powder and coarse silver powder. The fine ­silver powder is specified with a particle diameter of 0.7-1.2 μm for 99.9 % of the particles and as averaged par ticle diameter of the undisturbed powder d p = 1 μm can be assumed. It has a bulk density of ρ bulk = 1.1 g/(cm 3 ) and a specific surface of A sp = 2.5 m 2 /g. For the coarse silver powder the specification of particle diameter is 1.5 – 2.5 μm (99.9 %). Here the averaged particle diameter is d p =2 μm, the bulk density is also ρ bulk = 1.1 g/(cm 3 ) and the specific surface A sp = 1.21 m 2 /g. 3 Simulation of the water field In previous studies the simulation of the flow field with three different inclinations, namely 2°, 10° and 20°, and with empirical contact angle field and filtered randomized initial contact angle distribution (FRICAF) were presented [4, 6]. The computational domain is a trapezoidal geometry (length = 1.215 m, small base = 0.09 m, large base = 0.475 m, Figure 2), as used in the laboratory experiments [5]. | | Fig. 1. Pictures of lab tests [5] with 2° inclination and a mass flow rate of 11 g/s after 2 min and 15 min. | | Fig. 2. Schematic of computational domain of inclined trapezoidal plate, dimensions in mm. The simulations are carried out with the software package Open- FOAM using the standard two-phase solver InterFoam. The Navier-Stokes equations for isothermal and incompressible multiphase flow are solved and the phase interface is captured by the Volume-of-Fluid method. The time step is adjusted such that the maximum Courant number is below 0.4 to ensure a sufficient level of accuracy. The time is discretized via Euler implicit. The inlet is extending over the entire upper boundary with a Young Scientists' Workshop Awarded Katharina Amend was awarded with the 2 nd price of the 49 th Annual Meeting on Nuclear Technology (AMNT <strong>2018</strong>) Young Scientists' Workshop. 469 AMNT <strong>2018</strong> | YOUNG SCIENTISTS' WORKSHOP AMNT <strong>2018</strong> | Young Scientists' Workshop Development and Validation of a CFD Wash-Off Model for Fission Products on Containment Walls ı Katharina Amend and Markus Klein