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IAEA1238 MOCA.

MOCA, Criticality of VVER Reactor Hexagonal Fuel Assemblies

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1. NAME OR DESIGNATION OF PROGRAM:  MOCA.
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2. COMPUTERS
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Program name Package id Status Status date
MOCA IAEA1238/01 Tested 08-SEP-1994

Machines used:

Package ID Orig. computer Test computer
IAEA1238/01 PC-80286 PC-80486
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3. DESCRIPTION OF PROGRAM OR FUNCTION

Criticality problem in neutron  transport for hexagonal fuel assembly in VVER nuclear reactor. The assembly is assumed to be either arranged in an infinite hexagonal array or placed in vacuum. The problem is solved in three- dimensional geometry, using standard energy group formalism and assuming that effective scattering cross sections are presented as Legendre polynomial expansions. The code evaluates ten different physical quantities, e.g. multiplication factor, neutron flux per energy group and spatial zone, integrated over angle and power in any zone of the assembly.
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4. METHOD OF SOLUTION

Monte Carlo method of successive generations is applied. Computation proceeds according to an analog random process. The code is organized into three blocks:
In the first block, the input data are converted to quantities for use in the Monte Carlo calculation. An initial neutron distribution is calculated, which corresponds to a fission spectrum  uniform in spatial and angular variables.
The main calculations are carried out in the second block (subroutine PROC2). This block is subdivided into geometrical and physical parts. Neutron tracks in individual zones and groups as well as probabilities for the formation of secondary neutrons are calculated.
In the third block (subroutine PROC3), the results are evaluated statistically. Effective multiplication coefficients, the neutron flux per group and zone, and respective errors are computed. These quantities serve as a basis for the evaluation of other quantities. The results are either printed or stored for future evaluations.
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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

In the PC version of the program, the maximum number of neutrons is 1000, the maximum number of energy groups is 4, and the maximum number of material compositions is 15. Angular expansion of scattering cross sections is allowed up to P10. These restrictions can easily be removed by increasing input parameters and array dimensions. (See pp 8-14 of th manual.)
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6. TYPICAL RUNNING TIME

No general estimate was made. Running time for the sample problem on an 80386-based desktop computer with 80387 math coprocessor is 90 minutes.
IAEA1238/01
Sample case DATA about 35 seconds with the Microsoft version and 16 the Lahey version. The sample case on the report UJV 6487 R took about 18 minutes on both versions.
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7. UNUSUAL FEATURES OF THE PROGRAM:  None noted.
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8. RELATED AND AUXILIARY PROGRAMS:
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9. STATUS
Package ID Status date Status
IAEA1238/01 08-SEP-1994 Tested at NEADB
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10. REFERENCES:
IAEA1238/01, included references:
- Jan Kyncl:
  The Code MOCA
  UJV 6487 R (March 1983).
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11. MACHINE REQUIREMENTS:  80387 math coprocessor.
IAEA1238/01
NEA-DB tested the program on a PC DELL 40486 (33-MHz) with 8 MB of RAM.
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12. PROGRAMMING LANGUAGE(S) USED
Package ID Computer language
IAEA1238/01 FORTRAN-77
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13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:  MS-DOS 3.30; OS/2.
IAEA1238/01
MS-DOS 6.2 with compilers MS-FORTRAN 5.1, and Lahey F77L-EM/32 FORTRAN 77 VERSION 5.20.
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14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

In case of compilation problems, the code may be split, e.g. by subroutine.
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15. NAME AND ESTABLISHMENT OF AUTHORS

        Jan KYNCL
        Nuclear Research Institute
        250 68 REZ
        Czech Republic
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16. MATERIAL AVAILABLE
IAEA1238/01
File name File description Records
IAEA1238_01.001 Information file 169
IAEA1238_01.002 Microsoft executable 0
IAEA1238_01.003 Lahey executable 0
IAEA1238_01.004 Source file AZIRN.FOR 12
IAEA1238_01.005 Source file CTI.FOR 6
IAEA1238_01.006 Source file EXPRNF.FOR 15
IAEA1238_01.007 Source file FLTRNF.FOR 8
IAEA1238_01.008 Source file GTISO.FOR 15
IAEA1238_01.009 Source file MAIN.FOR 19
IAEA1238_01.010 Source file OPFILE.FOR 14
IAEA1238_01.011 Source file PIS.FOR 6
IAEA1238_01.012 Source file PROC1.FOR (Microsoft version) 600
IAEA1238_01.013 Source file PROC11.FOR 123
IAEA1238_01.014 Source file PROC2.FOR (Microsoft version) 890
IAEA1238_01.015 Source file PROC3.FOR 595
IAEA1238_01.016 Source file RANDU.FOR 10
IAEA1238_01.017 Source file SFLRAF.FOR 5
IAEA1238_01.018 Source file PROC1.LAH (Lahey version) 620
IAEA1238_01.019 Source file PROC2.LAH (Lahey version) 911
IAEA1238_01.020 Input data (case on disk) 50
IAEA1238_01.021 Input data (case on report) 50
IAEA1238_01.022 Output data for input DATA 711
IAEA1238_01.023 Output data for input DATA2 (Ms. version) 585
IAEA1238_01.024 Output data for input DATA2 (Lh. version) 696
IAEA1238_01.025 DOS file-names 24
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17. CATEGORIES
  • C. Static Design Studies

Keywords: Monte Carlo method, criticality, fuel assemblies, hexagonal lattices, neutron transport equation, three-dimensional.