Cynod [electronic resource] : A Neutronics Code for Pebble Bed Modular Reactor Coupled Transient Analysis
- Washington, D.C. : United States. Office of the Assistant Secretary for Nuclear Energy, 2008.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
- Additional Creators:
- Idaho National Laboratory, United States. Office of the Assistant Secretary for Nuclear Energy, and United States. Department of Energy. Office of Scientific and Technical Information
- Restrictions on Access:
- Free-to-read Unrestricted online access
- 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 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.
- Report Numbers:
- E 1.99:inl/con-08-14160
- Other Subject(s):
- Published through SciTech Connect.
4th International Topical Meeting on High Temperature Reactor Technology,Washington D.C.,09/28/2008,10/01/2008.
Abderrafi M. Ougouag; Hans D. Gougar; Hikaru Hiruta; Javier Ortensi.
- Funding Information:
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