SKETCH-N 1.0: Solve Neutron Diffusion Equations of Steady-State and Kinetics Problems.

**AUXILIAR PROGRAMS**

PVM library is used for the interface module of the code. The interface module requires PVM be installed on the computer. The PVM is a public domain software available from NETLIB http://www.epm.ornl.gov/pvm/pvm_home.html.

Japan Atomic Energy Agency, 2-4 Shirakata-Shirane, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195 Japan through the OECD Nuclear Energy Agency Data Bank, Issy-les-Moulineaux, France.

Fortran 77 and 90; PC Windows NT/Windows, UNIX Workstations (C00808MNYCP00).

The polynomial, semi-analytic and analytic nodal methods based on the nonlinear iteration procedure are used for spatial discretization 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 pre-conditioner is applied in the both iterative methods. The flux-weighting homogenization procedure is used for partially-rodded nodes to minimize the 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, synchronizes the 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).

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.

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 with the J-TRAC (TRAC-PF1) and TRAC-BF1 codes.

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.

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.

A workstation under UNIX, Windows NT or Windows.

UNIX, Windows NT. The package is distributed as received from the NEADB.

**10.a) Included
Documentation:**

- Vyacheslav G. Zimin, “SKETCH-N: A Nodal Neutron Diffusion Code for Solving Steady-State and Kinetics Problem,” Vol. I, Model Description (2000).

- Vyacheslav G. Zimin, “SKETCH-N: A Nodal Neutron Diffusion Code for Solving Steady-State and Kinetics Problem,” Vol. II, User's Guide (Sept. 2000).

**10.b) Background References:**

- Vyacheslav G. Zimin and Hisashi Ninokata, “Nodal Neutron Kinetics Code SKETCH-N for LWR Analysis,” Proc. 1998 Annual Meting of AESJ, Osaka, 1998, March 26-28, G15.

- Vyacheslav G. Zimin, Hideaki Asaka, Yoshinari Anoda and Masaki Enomoto, “Coupling of the Transient Analysis Code J-TRAC with 3D Neutron Kinetics Code SKETCH-N,” Proc. 1999 Annual Meeting of AESJ, Hiroshima, March 22-24, I8.

- Vyacheslav G. Zimin, Hideaki Asaka, Yoshinari Anoda, Masaki Enomoto, “Verification of J-TRAC Code With 3D Neutron Kinetics Model SKETCH-N for PWR Rod Ejection Analysis,” Proc. of the 9th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH 9), San Francisco, California, October 3-8, 1999.

- Hideaki Asaka, Vyacheslav G. Zimin, Tadashi Iguchi and Yoshinari Anoda, “Coupling of the Thermal-Hydraulic TRAC Codes with 3D Neutron Kinetics Code SKETCH-N (2000)”, Proc. of the OECD/CSNI Workshop on Advanced Thermal-Hydraulic and Neutronics Codes, Current and Future Applications, Barcelona, Spain, 10-13 April, 2000, vol2 pp.1-15.

- Vyacheslav G. Zimin, Hisashi Ninokata, Leonid R. Pogosbekyan, “Polynomial and Semi-Analytic Nodal Methods for Nonlinear Iteration Procedure,” Proc. of the Int. Conf. on the Physics of Nuclear Science and Technology (PHYSOR-98), October 5-8, 1998, Long Island, New York, American Nuclear Society vol. 2, pp. 994-1002.

- Vyacheslav G. Zimin, Hideaki Asaka, Yoshinari Anoda, Elja Kaloinen, RiittaKyrki-Rajamaki. “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.

This package consists of one DVD-ROM with the SKETCH-N 1.0
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, along with the
documentation listed above.

November 2013.

**KEYWORDS:** KINETICS,
NEUTRON DIFFUSION EQUATION, NODAL METHOD, NONLINEAR, THREE-DIMENSIONAL,
TRANSIENTS