Computer Programs
IAEA1238 MOCA.
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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
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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 AEAe01M4"21eIt77
IAEA1238_01.005 Source7file AEAe01M4"21eIt77
IAEA1238_01.005 Source8file AEAe01M4"21eIt77
IAEA1238_01.005 Source9file AEAe01M4"21eIt77
IAEA1238_01.001 Info10file AEAe01M4"21eIt77
38_01.001 Info11file AEAe01M4"21eIt77
IAEA1238_01.005 Sourc12file AEAe01M4"21eIt77 (sion">IAEA1238/01)
IAEA1238_01.003 La13file AEAe01M4"21eIt77
IAEA1238_01.003 La1ey executable maintd> (sion">IAEA1238/01)
IAEA1238_01.003 La1le AZIRN.FOR 1ary n>
IAEA1238_01.005 Sourc1 file AEAe01M4"21eIt77
IAEA1238_01.003 La17file AEAe01M4"21eIt77
IAEA1238_01.005 Sourc18file AEAe01M4"21eIt77 IAEA1238_01.003 La19file AEAe01M4"21eIt77 IAEA1238_01.003 La20file AEAe01MIe is organ(ds with disk)
IAEA1238_01.003 La21file AEAe01MIe is organ(ds with Micros)
IAEA1238_01.003 La22file AEAe01MOut is organIME< up toctTefile AEAe01M711file AEAed>IAEA1238_01.003 La23file AEAe01MOut is organIME< up toctTe2 (ss.e DATA a)
IAEA1238_01.005 Sourc24file AEAe01MOut is organIME< up toctTe2 (Lh.e DATA a)
IAEA1238_01.005 Sourc2le AZIRN.FOR IAEA1238/01 Tested 08-SEP-1994