skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Cynod: A Neutronics Code for Pebble Bed Modular Reactor Coupled Transient Analysis

Abstract

The Pebble Bed Reactor (PBR) is one of the two concepts currently considered for development into the Next Generation Nuclear Plant (NGNP). This interest is due, in particular, to the concept’s inherent safety characteristics. In order to verify and confirm the design safety characteristics of the PBR computational tools must be developed that treat the range of phenomena that are expected to be important for this type of reactors. This paper presents a recently developed 2D R-Z cylindrical nodal kinetics code and shows some of its capabilities by applying it to a set of known and relevant benchmarks. The new code has been coupled to the thermal hydraulics code THERMIX/KONVEK[1] for application to the simulation of very fast transients in PBRs. The new code, CYNOD, has been written starting with a fixed source solver extracted from the nodal cylindrical geometry solver contained within the PEBBED code. The fixed source solver was then incorporated into a kinetic solver.. The new code inherits the spatial solver characteristics of the nodal solver within PEBBED. Thus, the time-dependent neutron diffusion equation expressed analytically in each node of the R-Z cylindrical geometry sub-domain (or node) is transformed into one-dimensional equations by means of the usualmore » transverse integration procedure. The one-dimensional diffusion equations in each of the directions are then solved using the analytic Green’s function method. The resulting equations for the entire domain are then re-cast in the form of the Direct Coarse Mesh Finite Difference (D-CMFD) for convenience of solution. The implicit Euler method is used for the time variable discretization. In order to correctly treat the cusping effect for nodes that contain a partially inserted control rod a method is used that takes advantage of the Green’s function solution available in the intrinsic method. In this corrected treatment, the nodes are re-homogenized using axial flux shapes reconstructed based on the Green’s function method. The performance of the new code is demonstrated by applying it to a delayed supercritical problem and a to the OECD PBMR400 rod ejection benchmark problem. The latter makes use of the coupled CYNOD-THERMIX/KONVEK codes. A final improvement to the code is the subject of a companion paper: a heterogeneous TRISO fuel particle model was devised and incorporated into the code and used to provide an enhanced Doppler treatment. The new code is currently being coupled to the RELAP5-3D code for thermal-hydraulics. The full length paper will include extensive summaries of the equations and algorithm, descriptions of the sample and benchmark problems and details of the results. It is shown, in inter-code comparisons, that the new code correctly predicts the transient behaviors of the test problems.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Idaho National Laboratory (INL)
Sponsoring Org.:
DOE - NE
OSTI Identifier:
950982
Report Number(s):
INL/CON-08-14160
TRN: US0902097
DOE Contract Number:  
DE-AC07-99ID-13727
Resource Type:
Conference
Resource Relation:
Conference: 4th International Topical Meeting on High Temperature Reactor Technology,Washington D.C.,09/28/2008,10/01/2008
Country of Publication:
United States
Language:
English
Subject:
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; BENCHMARKS; CONTROL ELEMENTS; DIFFUSION EQUATIONS; FUEL PARTICLES; GEOMETRY; KINETICS; NEUTRON DIFFUSION EQUATION; OECD; PEBBLE BED REACTORS; REACTOR TECHNOLOGY; SAFETY; SIMULATION; THERMAL HYDRAULICS; TRANSIENTS; CYNOD; pebble bed modular reactor

Citation Formats

Hikaru Hiruta, Abderrafi M. Ougouag, Hans D. Gougar, and Javier Ortensi. Cynod: A Neutronics Code for Pebble Bed Modular Reactor Coupled Transient Analysis. United States: N. p., 2008. Web. doi:10.1115/HTR2008-58255.
Hikaru Hiruta, Abderrafi M. Ougouag, Hans D. Gougar, & Javier Ortensi. Cynod: A Neutronics Code for Pebble Bed Modular Reactor Coupled Transient Analysis. United States. doi:10.1115/HTR2008-58255.
Hikaru Hiruta, Abderrafi M. Ougouag, Hans D. Gougar, and Javier Ortensi. Mon . "Cynod: A Neutronics Code for Pebble Bed Modular Reactor Coupled Transient Analysis". United States. doi:10.1115/HTR2008-58255. https://www.osti.gov/servlets/purl/950982.
@article{osti_950982,
title = {Cynod: A Neutronics Code for Pebble Bed Modular Reactor Coupled Transient Analysis},
author = {Hikaru Hiruta and Abderrafi M. Ougouag and Hans D. Gougar and Javier Ortensi},
abstractNote = {The Pebble Bed Reactor (PBR) is one of the two concepts currently considered for development into the Next Generation Nuclear Plant (NGNP). This interest is due, in particular, to the concept’s inherent safety characteristics. In order to verify and confirm the design safety characteristics of the PBR computational tools must be developed that treat the range of phenomena that are expected to be important for this type of reactors. This paper presents a recently developed 2D R-Z cylindrical nodal kinetics code and shows some of its capabilities by applying it to a set of known and relevant benchmarks. The new code has been coupled to the thermal hydraulics code THERMIX/KONVEK[1] for application to the simulation of very fast transients in PBRs. The new code, CYNOD, has been written starting with a fixed source solver extracted from the nodal cylindrical geometry solver contained within the PEBBED code. The fixed source solver was then incorporated into a kinetic solver.. The new code inherits the spatial solver characteristics of the nodal solver within PEBBED. Thus, the time-dependent neutron diffusion equation expressed analytically in each node of the R-Z cylindrical geometry sub-domain (or node) is transformed into one-dimensional equations by means of the usual transverse integration procedure. The one-dimensional diffusion equations in each of the directions are then solved using the analytic Green’s function method. The resulting equations for the entire domain are then re-cast in the form of the Direct Coarse Mesh Finite Difference (D-CMFD) for convenience of solution. The implicit Euler method is used for the time variable discretization. In order to correctly treat the cusping effect for nodes that contain a partially inserted control rod a method is used that takes advantage of the Green’s function solution available in the intrinsic method. In this corrected treatment, the nodes are re-homogenized using axial flux shapes reconstructed based on the Green’s function method. The performance of the new code is demonstrated by applying it to a delayed supercritical problem and a to the OECD PBMR400 rod ejection benchmark problem. The latter makes use of the coupled CYNOD-THERMIX/KONVEK codes. A final improvement to the code is the subject of a companion paper: a heterogeneous TRISO fuel particle model was devised and incorporated into the code and used to provide an enhanced Doppler treatment. The new code is currently being coupled to the RELAP5-3D code for thermal-hydraulics. The full length paper will include extensive summaries of the equations and algorithm, descriptions of the sample and benchmark problems and details of the results. It is shown, in inter-code comparisons, that the new code correctly predicts the transient behaviors of the test problems.},
doi = {10.1115/HTR2008-58255},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2008},
month = {9}
}

Conference:
Other availability
Please see Document Availability for additional information on obtaining the full-text document. Library patrons may search WorldCat to identify libraries that hold this conference proceeding.

Save / Share: