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Title Scaling Analysis for the Direct Reactor Auxiliary Cooling System for AHTRs
Publication Date
Degree MS
Discipline/Department Nuclear Engineering
Degree Level masters
University/Publisher The Ohio State University
Abstract The Advanced High Temperature Reactor (AHTR) is one of the advanced rector concepts that have been proposed for Gen IV reactors. The AHTR combines four main proven nuclear technologies, namely, the liquid salt of molten salt reactors, the coated particle fuel (TRISO particle) of high-temperature gas-cooled reactors, the pool configuration and passive safety system of sodium-cooled fast reactors, and the Brayton power cycle technology. The Direct Reactor Auxiliary Cooling System (DRACS) is a passive heat removal system that has been proposed for AHTR. The DRACS features three coupled natural circulation/convection loops relying completely on buoyancy as the driving force. In the DRACS, two heat exchangers, namely, the DRACS Heat Exchanger (DHX) and the Natural Draft Heat Exchanger (NDHX) are used to couple these natural circulation/convection loops. In addition, a fluidic diode is employed to restrict parasitic flow during normal operation of the reactor and to activate the DRACS in accidents. While the DRACS concept has been proposed, there are no actual prototypic DRACS systems for AHTRs built and tested in the literature. In this report, a detailed modular design of the DRACS for a 20-MWth FHR is first developed. As a starting point, the DRACS is designed to remove 1% of the nominal power, i.e., the decay power being 200 kW. FLiBe with high enrichment in Li-7, and FLiNaK have been selected as the primary and secondary salts, respectively. A 16-MWth pebble bed core proposed by University of California at Berkeley (UCB) is adopted in the design. Shell-and-tube heat exchangers, based on Delaware Method have been designed for the DHX and NDHX. A vortex diode that has been tested with water is adopted in the present design. Finally, pipes with inner diameter of 15 cm are selected for both the primary and secondary loops. The final DRACS design features a total height less than 13 m. Following the prototypic DRACS design is the detailed scaling analysis for the DRACS, which will provide guidance for the design of scaled-down DRACS test facilities. Based on the Boussinesq assumption and one-dimensional formulation, the governing equations, i.e., the continuity, integral momentum, and energy equations are non-dimensionalized by introducing appropriate dimensionless parameters, including the dimensionless length, temperature, velocity, etc. The key dimensionless numbers, i.e., the Richardson, friction, Stanton, time ratio, Biot, and heat source numbers that characterize the DRACS system, are obtained from the non-dimensional governing equations. Based on the dimensionless numbers and non-dimensional governing equations, similarity laws are proposed. In addition, a scaling methodology has also been developed, which consists of the core scaling and loop scaling. Due to the importance of the core heat transfer in establishing the DRACS steady state, core scaling is started with, from which the convection time ratio is obtained. The loop scaling is accomplished by utilizing the convection time ratio obtained from the core…
Subjects/Keywords Nuclear Engineering; AHTR; DRACS; prototypic design; scaling
Contributors Sun, Xiaodong (Advisor)
Language en
Rights unrestricted ; This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.
Country of Publication us
Format application/pdf
Record ID oai:etd.ohiolink.edu:osu1357312725
Repository ohiolink
Date Retrieved
Date Indexed 2016-12-22
Grantor The Ohio State University

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…2011 ......................................................Graduate Fellow, Nuclear Engineering Program, The Ohio State University 2011 to present ..............................................Graduate Research Associate, Nuclear Engineering Program…

The Ohio State University Publications 1. X. Wang, Q. Lv, X. Sun, R.N. Christensen, T.E. Blue, G. Yoder, D. Wilson, and P. Sabharwall, “A Modular Design of a Direct Reactor Auxiliary Cooling System for AHTRs,” Transaction of the American Nuclear…