NEA-1577 SKETCH-N

1. NAME OR DESIGNATION OF PROGRAM:  SKETCH-N 1.0.

3. DESCRIPTION OF PROGRAM OR FUNCTION

The SKETCH-N code solves neutron diffusion equations in x-y-z geometry for steady-state and neutron kinetics problems. The code can treat an arbitrary number of neutron energy groups and delayed neutron precursors.

4. METHODS

The polynomial, semi-analytic and analytic nodal methods based on the nonlinear iteration procedure can be used for spatial discretisation of diffusion equations. The time integration of the neutron kinetics problem is performed by a fully implicit scheme with an analytical treatment of the delayed neutron precursors. The steady-state eigenvalue problems are solved by inverse iterations with Wielandt shift, the Chebyshev adaptive acceleration procedure is used for the neutron kinetics problem. The block symmetric Gauss-Seidel preconditioner is applied in the both iterative methods. The flux-weighting homogenisation procedure is used for partially-rodded nodes to minimize a rod cusping effect. Simple one-phase model of the thermal-hydraulics of fuel assembly is included in the code. The code also has an interface module for a coupling with transient analysis codes such as TRAC. The interface module performs a data exchange between the codes, synchronises a time stepping and maps the neutronics data onto thermal-hydraulics spatial mesh and vice versa. The interface module is based on the message-passing library PVM (Parallel Virtual Machine).

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

The code can treat the neutron diffusion problems in Cartesian geometry Few-group macro cross-sections and their dependencies are provided by a c ode user. The code does not have fuel burn-up modeling capabilities. An external thermal-hydraulics code is generally required for the calculation of the "real-life" problems.

6. TYPICAL RUNNING TIME

The running time of the full-core case C1 of the PWR NEACRP rod ejection benchmark (2 neutron energy groups, 6 groups of the delayed neutron precursors, 884x18 neutronics nodes, 910 time steps) is 68 minutes on Sun UltraSPARC I (143 MHz) with an internal thermal hydraulics model.

7. UNUSUAL FEATURES

Dimensions of a problem are specified as parameters in the include files, the code should be recompiled when the problem dimensions are changed. The code has PVM-based interface module developed for a coupling with transient thermal-hydraulics codes. The interface model has been used for a coupling of the SKETCH-N code wit the J-TRAC (TRAC-PF1) and TRAC-BF1 codes.

8. RELATED OR AUXILIARY PROGRAMS:  PVM library is used for the interface module of the code.

- Zimin, V.G. and H. Ninokata
Nodal Neutron Kinetics Code for LWR Analysis, 1998 Annual Meting of AESJ
Osaka, 1998, March 26-28, G15
- Zimin, V.G., Ninokata, H., Pogosbekyan L.
(1998).  Polynomial and Semi-Analytic Nodal Methods for
Nonlinear Iteration Procedure.
Proc. of the Int. Conf. on the Physics of Nuclear Science and Technology
(PHYSOR), October 5-8, 1998, Long Island, New York, American Nuclear Society
vol. 2, pp. 994-1002.
- Zimin, V.G. H.Asaka, Y. Anoda and M. Enomoto
Coupling of the Transient Analysis Code J-TRAC with 3D
Neutron Kinetics Code SKETCH-N,
1999 Annual Meting of AESJ, Hiroshima, March 22-24, I8
- Zimin V. G., H. Asaka, Y. Anoda and M. Enomoto
(1999).  Verification of the J-TRAC Code with 3D Neutron
Kinetics Model SKETCH-N for PWR Rod Ejection Analysis
Proc. of the 9 International Topical Meeting on Nuclear Reactor Thermal
Hydraulics (NURETH 9), San Francisco, California
October 3-8, 1999, CD-ROM American Nuclear Society
- Asaka H., V. Zimin, T. Iguchi, S. Ohmizu and Y. Anoda
(2000).  Coupling of the Thermal-Hydraulic TRAC
Codes with 3D Neutron Kinetics Code SKETCH-N
Proc. of the OECD/CSNI Workshop on Advanced Thermal-Hydraulic and Neutronics
Codes, Current and Future Applications, Barcelona, Spain, 10-13 April, 2000
- Zimin V. G., H. Asaka, Y. Anoda, E. Kaloinen, R. Kyrki-Rajamaki
(2000). Analysis of NEACRP 3D BWR Core Transient Benchmark
Proc. of the 4th Intl. Conf. on Supercomputing in Nuclear Application (SNA 2000)
September 4-7, 2000, Tokyo, Japan, CD-ROM
- Zimin. V.G
(2000)  SKETCH-N: A Nodal Neutron Diffusion Code for Solving Steady-State and
Kinetics Problem. Vol. I, Model Description
- Zimin. V.G
(2000)  SKETCH-N: A Nodal Neutron Diffusion Code for Solving Steady-State and
Kinetics Problem. Vol. II, User's Guide

11. HARDWARE REQUIREMENTS:  A workstation under UNIX, Windows NT or Windows.

13. SOFTWARE REQUIREMENTS:  UNIX, Windows NT.

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

The interface module requires PVM installed on a computer. The PVM is a public domain software available from NETLIB http://www.epm.ornl.gov/pvm/pvm_home.html

The code has been verified by solving the steady-state and neutron kinetics benchmark problems. The coupled J-TRAC/SKETCH-N code system has been verified against NEACRP PWR rod ejection and rod withdrawal benchmark. NEACRP BWR cold water injection benchmark has been used for verification of the TRAC-BF1/SKETCH-N system.

15. NAME AND ESTABLISHMENT OF AUTHORS

H. Asaka, V. G. Zimin
JAEA
2-4 Shirakata-Shirane
Tokai-mura,
Naka-gun
Ibaraki-ken 319-1195
Japan

Source code
Sample input and output files for LWR Benchmarks
Steady-state 2D four-group Koeberg PWR Benchmarks
3D NEACRP PWR rod ejection benchmark case A1
3D NEACRP BWR cold water injection benchmark
Electronic documentation and papers