SWAT: Step-Wise Burnup Analysis Code System to Combine SRAC-95 Cell Calculation Code and ORIGEN2.

**AUXILIARY PROGRAM**

LIBMAK: Auxiliary code prepares one-grouped cross section data files for ORIGEN2.

TABMAK: Auxiliary code reads the burnup calculation results of the ORIGEN2 code and prepares input files of the SRAC95 and ORIGEN2 codes for the next burnup step.

Japan Research Institute, Ltd., Energy Technology Department, Tokyo, Japan.

Japan Atomic Energy Research Institute, Tokaimura, Nakagun, Ibaraki-ken, Japan.

Fortran 77 and C; Sun, HP, Fujitsu, Hitachi, & Linux PC (C00714MNYCP01).

SWAT solves the general criticality problems, especially for burnup credit issues by driving codes CCC-716/SRAC95 and CCC-371/ORIGEN2.1 or ORIGEN2. A modified version of ORIGEN2 is included in this package, but SRAC is not included.

SWAT is an automated driver code system on which development began in 1992. At that time, SWAT was constructed by combining the source programs of SRAC and ORIGEN2. To overcome the problem associated with code updates, SWAT chose to use an operating system to execute SRAC95 and ORIGEN2 so that SWAT will be independent of development and modification of SRAC95 and ORIGEN2.1.

ORIGEN2(82) or ORIGEN2.1 are used for burnup calculations using the matrix exponential method. A decay library and updated photon library of activation products are included in this distribution. SWAT uses SRAC95 for neutron spectrum calculation in 107 groups using the collision probability method for given geometry and isotopic composition. One- or two-dimensional cell geometries are supported in SRAC95. Several data libraries are included in the SRAC-95 package. This is an updated version of the earlier code.

In calculating the problem-dependent cross section in SWAT, the total burnup history is divided into “burnup steps.” Power, boric acid concentration, temperature of each region, and void ratio of coolant are given as history data. For each burnup step, the neutron spectrum and effective cross section are evaluated by SRAC95 using the information given in previous burnup calculations and cell geometry information. The calculation model used in SWAT is not fixed. Geometry options for the collision probability method in SRAC95 can be selected by the user.

Collision probability method; 1D and 2D Sn for cell calculations; and 1D, 2D and 3D diffusion for core were used in SRAC95.

The SWAT package does not contain SRAC; it can be obtained through NEA Data Bank (NEA‑0842/03) or RSICC (CCC-716). SRAC should be installed and tested on your system before installing SWAT. Restriction on the complexity of the problem in SRAC: 20 regions for a continuous energy resonance absorption calculation and 16 steps for cell burnup.

Runtime depends on the number of energy group, geometry option, and with or without burnup calculation.

The code has been tested on SUN, HP, and Linux-PC computers.

SWAT can be run on several Unix operating systems. A Fortran 77 compiler is required. The developers also tested it on a PC running Linux and FreeBSD with g77. RSICC tested SWAT on a Linux-PC computer. No executables are included.

**a. included in the
RSICC document **

K. Suyama, “SWAT Installation Guide,” informal English report (March 14, 2003).

K. Suyama, T.Kiyosumi, and H. Mochizuki, *Revised SWAT—The
Integrated Burnup Code System*, JAERI-DATA/Code 2000-0027 (In Japanese)
(2000).

K. Suyama, T.Kiyosumi, and H. Mochizuki, “Revised SWAT—The Integrated Burnup Code System,” (In Japanese) (2006) Update.

**b. background
information:**

K. Suyama and H. Mochizuki, “Revised Burnup Code System
Swat: Description And Validation Using Postirradiation Examination Data,” *Nuclear
Technology,* Vol. 138, pp. 97 (May 2002).

K. Tsuchihashi, Y. Ishiguro, K. Kaneko, and M. Ido, *Revised
SRAC Code System,* JAERI 1302 (1986) (in English but for old version SRAC).

Teruhiko Kugo, Keichiro Tsuchihashi, Hiroshi Akie, and
Hideki Takano, *SRAC-EWS (Engineering WorkStation) Version of the SRAC Code*,
JAERI JW282 (1994).

K. Tsuchihashi, H. Takano, K. Horikami, and Y. Ishiguro, *SRAC:
JAERI Thermal Reactor Standard Code System for Reactor Design and Analysis*,
JAERI 1285 (1983).

Included on a CD are the referenced documents, the source, scripts, modified ORIGEN2 source code, and SWAT test cases.

April 2003; September 2011.

**KEYWORDS:** BURNUP; ISOTOPE INVENTORY; FISSION
PRODUCT INVENTORY; FUEL MANAGEMENT