Development of a fullyconsistent reduced order model to study instabilities in boiling water reactors
Abstract
A simple nonlinear Reduced Order Model to study global, regional and local instabilities in Boiling Water Reactors is described. The ROM consists of three submodels: neutronkinetic, thermalhydraulic and heattransfer models. The neutronkinetic model allows representing the time evolution of the three first neutron kinetic modes: the fundamental, the first and the second azimuthal modes. The thermalhydraulic model describes four heated channels in order to correctly simulate outofphase behavior. The coupling between the different submodels is performed via both void and Doppler feedback mechanisms. After proper spatial homogenization, the governing equations are discretized in the timedomain. Several modifications, compared to other existing ROMs, have been implemented, and are reported in this paper. One novelty of the ROM is the inclusion of both azimuthal modes, which allows to study combined instabilities (inphase and outofphase), as well as to investigate the corresponding interference effects between them. The second modification concerns the precise estimation of socalled reactivity coefficients or C{sub mn}{sup *V,D}  coefficients by using direct crosssection data from SIMULATE3 combined with the CORE SIM core simulator in order to calculate Eigenmodes. Furthermore, a nonuniform twostep axial power profile is introduced to simulate the separate heat production in the single and twophase regions,more »
 Authors:

 Chalmers Univ. of Technology, Div. of Nuclear Engineering, Dept. of Applied Physics, SE412 96 Gothenburg (Sweden)
 Publication Date:
 Research Org.:
 American Nuclear Society, Inc., 555 N. Kensington Avenue, La Grange Park, Illinois 60526 (United States)
 OSTI Identifier:
 22105593
 Resource Type:
 Conference
 Resource Relation:
 Conference: PHYSOR 2012: Conference on Advances in Reactor Physics  Linking Research, Industry, and Education, Knoxville, TN (United States), 1520 Apr 2012; Other Information: Country of input: France; 14 refs.
 Country of Publication:
 United States
 Language:
 English
 Subject:
 21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; CROSS SECTIONS; DOPPLER EFFECT; FEEDBACK; FORSMARK1 REACTOR; HEAT PRODUCTION; HEAT TRANSFER; INSTABILITY; ITERATIVE METHODS; KINETICS; NEUTRONS; NONLINEAR PROBLEMS; REACTIVITY COEFFICIENTS; REACTOR STABILITY; SIMULATION; THERMAL HYDRAULICS; TIME DEPENDENCE
Citation Formats
Dykin, V., and Demaziere, C. Development of a fullyconsistent reduced order model to study instabilities in boiling water reactors. United States: N. p., 2012.
Web.
Dykin, V., & Demaziere, C. Development of a fullyconsistent reduced order model to study instabilities in boiling water reactors. United States.
Dykin, V., and Demaziere, C. Sun .
"Development of a fullyconsistent reduced order model to study instabilities in boiling water reactors". United States.
@article{osti_22105593,
title = {Development of a fullyconsistent reduced order model to study instabilities in boiling water reactors},
author = {Dykin, V. and Demaziere, C.},
abstractNote = {A simple nonlinear Reduced Order Model to study global, regional and local instabilities in Boiling Water Reactors is described. The ROM consists of three submodels: neutronkinetic, thermalhydraulic and heattransfer models. The neutronkinetic model allows representing the time evolution of the three first neutron kinetic modes: the fundamental, the first and the second azimuthal modes. The thermalhydraulic model describes four heated channels in order to correctly simulate outofphase behavior. The coupling between the different submodels is performed via both void and Doppler feedback mechanisms. After proper spatial homogenization, the governing equations are discretized in the timedomain. Several modifications, compared to other existing ROMs, have been implemented, and are reported in this paper. One novelty of the ROM is the inclusion of both azimuthal modes, which allows to study combined instabilities (inphase and outofphase), as well as to investigate the corresponding interference effects between them. The second modification concerns the precise estimation of socalled reactivity coefficients or C{sub mn}{sup *V,D}  coefficients by using direct crosssection data from SIMULATE3 combined with the CORE SIM core simulator in order to calculate Eigenmodes. Furthermore, a nonuniform twostep axial power profile is introduced to simulate the separate heat production in the single and twophase regions, respectively. An iterative procedure was developed to calculate the solution to the coupled neutronkinetic/thermalhydraulic static problem prior to solving the timedependent problem. Besides, the possibility of taking into account the effect of local instabilities is demonstrated in a simplified manner. The present ROM is applied to the investigation of an actual instability that occurred at the Swedish Forsmark1 BWR in 1996/1997. The results generated by the ROM are compared with real power plant measurements performed during stability tests and show a good qualitative agreement. The present study provides some insight in a deeper understanding of the physical principles which drive both corewide and local instabilities. (authors)},
doi = {},
url = {https://www.osti.gov/biblio/22105593},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2012},
month = {7}
}