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NESC0528 PREP/KITT

PREP KITT, System Reliability by Fault Tree Analysis
PREP, Min Path Set and Min Cut Set for Fault Tree Analysis, Monte-Carlo Method
KITT, Component and System Reliability Information from Kinetic Fault Tree Theory

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1. NAME OR DESIGNATION OF PROGRAM:  PREP/KITT
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2. COMPUTERS
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Program name Package id Status Status date
PREP-KITT NESC0528/01 Tested 01-DEC-1973

Machines used:

Package ID Orig. computer Test computer
NESC0528/01 IBM 370 series IBM 370 series
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3. DESCRIPTION OF PROBLEM OR FUNCTION

The PREP/KITT computer program  package obtains system reliability information from a system fault tree. The PREP program finds the minimal cut sets and/or the minimal path sets of the system fault tree. (A minimal cut set is a smallest set of components such that if all the components are simultaneously failed the system is failed. A minimal path set is a smallest set of components such that if all of the components are simultaneously functioning the system is functioning.) The KITT programs determine  reliability information for the components of each minimal cut or path set, for each minimal cut or path set, and for the system. Exact, time-dependent reliability information is determined for each component and for each minimal cut set or path set. For the system,  reliability results are obtained by upper bound approximations or by a bracketing procedure in which various upper and lower bounds may be obtained as close to one another as desired. The KITT programs can handle independent components which are nonrepairable or which have a constant repair time. Any assortment of nonrepairable components and components having constant repair times can be considered. Any inhibit conditions having constant probabilities of  occurrence can be handled. The failure intensity of each component is assumed to be constant with respect to time. The KITT2 program can also handle components which during different time intervals, called phases, may have different reliability properties.
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4. METHOD OF SOLUTION

The PREP program obtains minimal cut sets by either direct deterministic testing or by an efficient Monte Carlo algorithm. The minimal path sets are obtained using the Monte Carlo  algorithm. The reliability information is obtained by the KITT programs from numerical solution of the simple integral balance equations of kinetic tree theory.
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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

The PREP program will obtain the minimal cut and/or path sets for any tree with up to 2000 components and 2000 logical gates. All gates of the fault tree  must be and and or gates, and no gate may have more than 7 inputs consisting of both components and other gates. PREP can obtain at most 1000 minimal cut sets with a maximum of 19 components per set,  and can obtain at most 500 minimal path sets with a maximum of 29 components per set. KITT1 will obtain reliability information for up to 500 minimal cut or path sets containing a total of at most 400 distinct components and inhibit conditions. KITT2 will obtain reliability information for up to 500 minimal cut or path sets containing a total of at most 350 distinct components and inhibit conditions. KITT2 can obtain reliability information for each of 50  different phases per component.
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6. TYPICAL RUNNING TIME

On the IBM360/75 running time is about 0.06 second for a ten-component tree without repair.
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7. UNUSUAL FEATURES OF THE PROGRAM

The KITT programs obtain exact reliability quantities as functions of time rather than the single point obtained by most other programs.
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8. RELATED AND AUXILIARY PROGRAMS:
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9. STATUS
Package ID Status date Status
NESC0528/01 01-DEC-1973 Tested at NEADB
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10. REFERENCES

W. E. Vesely, Analysis of Fault Trees by Kinetic Tree
Theory, IN-1330, October 1969.
NESC0528/01, included references:
- W.E. Vesely and R.E. Narum:
  The User's Manual for the PREP and KITT Codes
  IN-1349
- W.E. Vesely:
  Single Precision Modifications to the KITT-1 and KITT-2 Fault Tree
  Codes
  Idaho Nuclear Corporation Memorandum, WEV-54-70 (December 9, 1970)
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11. MACHINE REQUIREMENTS:  350K bytes on the IBM360
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12. PROGRAMMING LANGUAGE(S) USED
Package ID Computer language
NESC0528/01 FORTRAN-IV
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13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:     OS/360   MVT
(IBM360).
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14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS:
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15. NAME AND ESTABLISHMENT OF AUTHORS

                 W. E. Vesely and R. E. Narum
                 EG&G Idaho, Inc.
                 P. O. Box 1625
                 Idaho Falls, Idaho  83401
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16. MATERIAL AVAILABLE
NESC0528/01
File name File description Records
NESC0528_01.001 TREBIL SOURCE PROGRAM (F4) + INPUT DATA 985
NESC0528_01.002 MINSET SOURCE PROGRAM (F4+ASSEMBLER) 756
NESC0528_01.003 KITT-1 SOURCE PROGRAM (F4) + INPUT DATA 932
NESC0528_01.004 PREP-KITT-1 JOB CONTROL LANGUAGE 25
NESC0528_01.005 KITT-2 SOURCE PROGRAM (F4) + INPUT DATA 1103
NESC0528_01.006 TREBIL OUTPUT LIST 137
NESC0528_01.007 MINSET OUTPUT LIST 35
NESC0528_01.008 KITT-1 OUTPUT LIST 442
NESC0528_01.009 KITT-2 OUTPUT LIST 543
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17. CATEGORIES
  • G. Radiological Safety, Hazard and Accident Analysis
  • P. General Mathematical and Computing System Routines

Keywords: accidents, failures, fault tree analysis, probability, reliability, system failure analysis.