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NESC0674 SAFTAC

SAFTAC, Monte-Carlo Fault Tree Simulation for System Design Performance and Optimization

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1. NAME OR DESIGNATION OF PROGRAM:  SAFTAC
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2. COMPUTERS
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Program name Package id Status Status date
SAFTAC NESC0674/01 Tested 01-DEC-1976

Machines used:

Package ID Orig. computer Test computer
NESC0674/01 IBM 370 series IBM 370 series
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3. DESCRIPTION OF PROBLEM OR FUNCTION

SAFTAC is a Monte Carlo fault
tree simulation  program that provides  a systematic  approach for
analyzing  system   design,  performing  trade-off   studies,  and
optimizing system changes or additions.
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4. METHOD OF SOLUTION

SAFTAC   assumes   an   exponential   failure
distribution  for  basic  input  events and  a  choice  of  either
Gaussian distributed or constant repair  times.  The program views
the system represented by the fault tree as a statistical assembly
of  independent  basic  input events,  each  characterized  by  an
exponential  failure distribution  and,  if  used, a  constant  or
normal repair distribution.
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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

The   program   is
dimensioned to  handle 1100  basic input  events and  1100 logical
gates.  It can  be redimensioned to handle up to  2000 basic input
events and 2000 logical gates within the existing core memory.
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6. TYPICAL RUNNING TIME

Running time  is dependent  upon the  fault
tree  size and  structure  and the  degree  of  resolution in  the
quantitative evaluation desired.
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7. UNUSUAL FEATURES OF THE PROGRAM

The    fault   tree    technique
provides analysis flexibility which ranges from equipment analysis
to  over-all  plant  analyses incorporating  all  the  influencing
elements on a total-system basis.   The deductive approach used in
this technique  is useful  for evaluating  design consistency  and
reliability,   for    judging   alternatives,    for   determining
acceptability of  trade-offs, and  for analyzing  multiple failure
combinations and  common mode  failures in  complex systems.   The
fault tree  method allows analyses to  consider the rate  at which
failures or events are detected  after they occur (detection time)
and the rates at which they  are restored to normal (repair time).
The fault tree method is concerned with assuring that all critical
activities are identified and eliminated or controlled.  A system,
when defined in terms of  the all encompassing analysis capability
of fault tree analysis, is a  composite of operational and support
equipment,  personnel,  facilities  and software  which  are  used
together  as  an  entity  and are  capable  of  performing  and/or
supporting an operational role.
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8. RELATED AND AUXILIARY PROGRAMS

SAFTAC is an  improved version of
an earlier program.  See reference 5.
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9. STATUS
Package ID Status date Status
NESC0674/01 01-DEC-1976 Tested at NEADB
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10. REFERENCES

- P.A. Crosetti:
  Fault Tree Simulation Computer Program
  DUN-7697 (June 1971).
- P.A. Crosetti and R.A. Bruce:
  Commercial Application of Fault Tree Analysis, Ninth Reliability
  and Maintainability Conference
  Annals of Reliability and Maintainability, Vol. 9, p. 230 (1970).
- P.A. Crosetti:
  Fault Tree Analysis with Probability Evaluation
  DUN-SA-157 (November 3, 1970).
- P.A. Crosetti:
  Fault Tree Analysis for Reactor Systems
  DUN-SA-165 (February 25, 1971).
- P.A. Crosetti:
  Computer Program for Fault Tree Analysis
  DUN-5508 (April 1969).
NESC0674/01, included references:
- P.A. Crosetti:
  Fault Tree Simulation Computer Program
  DUN-7697  (June 1971)
- Description of Subroutine DOY
  Excerpt from: CSCX RJE/CRJE Reference, Vol. 2; Library Elements
  E00003-02-00 (April 1971).
- Notes on the IBM Version of STAFAC
  (November 22, 1976).
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11. MACHINE REQUIREMENTS

300K bytes for compilation,  140K bytes for
running the sample problem on an IBM370.
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12. PROGRAMMING LANGUAGE(S) USED
Package ID Computer language
NESC0674/01 FORTRAN-IV
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13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:  CSCX  or  EXEC2
(UNIVAC1108), OS/360,370 (IBM360,370).
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14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

   The
CALL OVERFL(K000FX)  statement on UNIVAC1108 execution  causes the
overflow  condition  to be  set  for  K000FX=1; for  K000FX=2  the
condition is not set.
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15. NAME AND ESTABLISHMENT OF AUTHORS

   1108          P. A. Crosetti
                 United Nuclear Industries, Inc.
                 P. O. Box 490
                 Richland, Washington  99352
   360           L. Garcia de Viedma
                 NEA Data Bank
                 B. P. 9
                 Batiment 45
                 91190 Gif-sur-Yvette, France
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16. MATERIAL AVAILABLE
NESC0674/01
File name File description Records
NESC0674_01.001 PROGRAM SOURCE - FORTRAN IV 769
NESC0674_01.002 JCL 12
NESC0674_01.003 SAMPLE PROBLEM DATA 11
NESC0674_01.004 SAMPLE PROBLEM OUTPUT LIST 404
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17. CATEGORIES
  • G. Radiological Safety, Hazard and Accident Analysis
  • P. General Mathematical and Computing System Routines

Keywords: Monte Carlo method, fault tree analysis, probability, reliability, system failure analysis.