Computer Programs

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

NAME OR DESIGNATION OF PROGRAM, COMPUTER, DESCRIPTION OF PROBLEM OR FUNCTION, METHOD OF SOLUTION, RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM, TYPICAL RUNNING TIME, UNUSUAL FEATURES OF THE PROGRAM, RELATED AND AUXILIARY PROGRAMS, STATUS, REFERENCES, MACHINE REQUIREMENTS, LANGUAGE, OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED, OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS, NAME AND ESTABLISHMENT OF AUTHORS, MATERIAL, CATEGORIES

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Program name | Package id | Status | Status date |
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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.

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.

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.

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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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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NESC0528/01

File name | File description | Records |
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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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- 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.