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NESC0889 RAS.

RAS, Fault Tree Analysis, Reliability, Minimal Cut Sets for Common Cause Failure

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1. NAME OR DESIGNATION OF PROGRAM:  RAS.
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2. COMPUTERS
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Program name Package id Status Status date
RAS NESC0889/02 Tested 01-JUN-1982

Machines used:

Package ID Orig. computer Test computer
NESC0889/02 CDC 7600 CDC 7600
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3. DESCRIPTION OF PROBLEM OR FUNCTION

The Reliability Analysis Sys- tem, RAS, is an integrated package of computer programs for the quantification of fault trees. In particular, RAS has the capability of performing phased mission analysis. A phased mission is a task to be performed by a system during which the logic model and/or the component failure mode characteristics change at predetermined times. RAS is capable of finding minimal cut sets from fault trees and of calculating reliability characteristics for the basic events, the minimal cut sets, and the top event of a fault tree. In addi- tion, mission cut set cancellation and four methods of bounding mis- sion unreliability have been incorporated into RAS.
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4. METHOD OF SOLUTION

RAS is based upon the MPCUS, POCUS, KITT1, SRTPRN, and COMCAN programs. A new FATRAM algorithm for determining  minimal cut sets is included in RAS. MOCUS is used to determine the  minimal cut sets from a fault tree. POCUS and KITT1 are used to cal- culate reliability characteristics for the basic events, the cut sets, and the top event of a fault tree. SRTPRN sorts minimal cut sets into groups according to the importance of the cut sets. COMCAN is used, in common cause failure analysis, to search basic events in minimal cut sets for shared secondary failure event susceptibilities or common linking conditions among components.
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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM:  Maximum of -, 5 distinct phases per mission
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6. TYPICAL RUNNING TIME

NESC executed the sample problem in less than 1 second of CP time on a CDC7600 and less than 3 seconds of CP time  on a CDC6600.
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7. UNUSUAL FEATURES OF THE PROGRAM:
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8. RELATED AND AUXILIARY PROGRAMS

RAS contains the POCUS, SRTPRN, MOCUS (NESC Abstract 653), KITT1 (NESC Abstract 528), and COMCAN (NESC Abstract 704) computer programs.
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9. STATUS
Package ID Status date Status
NESC0889/02 01-JUN-1982 Tested at NEADB
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10. REFERENCES

- Dale M. Rasmuson, Neldon H. Marshall, and Gary R. Burdick,
  Users's Guide for the Reliability Analysis System (RAS),
  TREE-1168, September 1977.
- RAS, NESC No. 889.C176, RAS Tape Description and Implementation
  Information,
  National Energy Software Center Note 81-62, June 8, 1981.
- J.B. Fussell, F.B. Henry, and N.H. Marshall,
MOCUS: A Computer Program to Obtain Minimal Sets from Fault Trees,    ANCR-1156, August 1974.
- W.E. Vesley and R.E. Narum,
  PREP and KITT: Computer Codes for the Automatic Evaluation of a
  Fault Tree,
  IN-1349, August 1970.
- C.A. Dolan,
  SRTPRN: A Program to Sort and Prune Fault Tree Cut Sets,
  TREE-1012, December 1976.
- G.R. Burdick, N.H. Marshall, and J.R. Wilson,
  COMCAN: A Computer Program for Common Cause Analysis,
  ANCR-1314, June 1976.
NESC0889/02, included references:
- Dale M. Rasmuson, Neldon H. Marshall, and Gary R. Burdick:
  Users's Guide for the Reliability Analysis System (RAS)
  TREE-1168 (September 1977)
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11. MACHINE REQUIREMENTS

If the program is segmented, 42,000 (octal) words of small core memory (SCM) and 10 (octal) words of large core  memory (LCM) are required for execution on a CDC7600. For the CDC 6600, 135,000 (octal) words of central memory and 10 (octal) words of Extended Core Storage (ECS) are required. Without segmentation, additional memory will be required.
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12. PROGRAMMING LANGUAGE(S) USED
Package ID Computer language
NESC0889/02 FORTRAN-IV
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13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:  SCOPE 2.1 (CDC 7600), NOS/BE (CDC CYBER176,CDC6600).
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14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

Subroutines FAPFIM, FABEND, FTBIN, FTBMXJ and FTBMEM are written in  COMPASS assembly language.
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15. NAME AND ESTABLISHMENT OF AUTHOR

             D.M. Rasmuson*, N.H. Marshall,
             and G.R. Burdick
             EG&G Idaho, Inc.
             P.O. Box 1625
             Idaho Falls, Idaho 83415
* Contact
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16. MATERIAL AVAILABLE
NESC0889/02
File name File description Records
NESC0889_02.002 RAS INFORMATION 39
NESC0889_02.003 RAS JCL FOR SAMPLE CASE 25
NESC0889_02.004 RAS SOURCE (FORTRAN-4) 11233
NESC0889_02.005 INEL ENV. ROUTINES FOR SCOPE 2.1 535
NESC0889_02.006 INEL ENV. ROUTINES FOR NOS/BE 566
NESC0889_02.007 RAS INPUT FOR SAMPLE CASE 91
NESC0889_02.008 COMCAN SUSCEPTIBILITY TABLES 28
NESC0889_02.009 SEGLOAD DIRECTIVES 16
NESC0889_02.010 RAS OUTPUT OF SAMPLE CASE 802
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17. CATEGORIES
  • G. Radiological Safety, Hazard and Accident Analysis

Keywords: LMFBR reactors, failures, fault tree analysis, reliability, safety, system failure analysis.