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NESC1063 SEISIM1.

SEISIM-1, Seismic Probabilistic Risk Assessment

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1. NAME OR DESIGNATION OF PROGRAM:  SEISIM1.
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2. COMPUTERS
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Program name Package id Status Status date
SEISIM-1 NESC1063/01 Tested 27-APR-1988

Machines used:

Package ID Orig. computer Test computer
NESC1063/01 CDC 7600 CDC CYBER 830
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3. DESCRIPTION OF PROGRAM OR FUNCTION

SEISIM1 calculates the probabilities of seismically induced failures for components and systems and propagates these calculations to determine the probability of accident sequences and the resulting total risk, which is quantified as an expected value of radiation release and exposure from a given nuclear power plant. SEISIM1 was developed as  a fundamental tool for the systems analysis portion of the NRC's Seismic Safety Margins Research Program (SSMRP). The SSMRP provides  a complete, self-contained methodology to assess and quantify the risk to nuclear power plants from seismic events and seismically induced failures.
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4. METHOD OF SOLUTION

Accident sequence and system failure probabilities are computed from cut-set probabilities, utilizing three alternative approximation schemes, which represent the probabilities as unions of cut sets. All cut-set probabilities containing response-dependent basic events are converted to multinormal integrals, which are calculated using numerical integration. SEISMI1 computes each release sequence probability by multiplying the initiating event and accident sequence probabilities by the probabilities of earthquake and containment failure. Release  category probabilities are computed by adding the probabilities of all release sequences associated with that release category.
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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

Maxima of -
   5000 cut sets
   2000 basic events
    200 accident sequences
    200 response quantities
     50 unique fragility functions
     13 basic events per cut set
     10 release categories
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6. TYPICAL RUNNING TIME

NESC executed the sample problem, which consists of two initiating events, 12 accident sequences, three logical component groups, and 91 basic events, in 4 CP seconds on a  CDC7600.
NESC1063/01
NEA-DB executed the test case included in this package  on a CDC CYBER 830 computer in 36 seconds of CPU time.
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7. UNUSUAL FEATURES OF THE PROGRAM:
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8. RELATED AND AUXILIARY PROGRAMS:
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9. STATUS
Package ID Status date Status
NESC1063/01 27-APR-1988 Tested at NEADB
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10. REFERENCES

- SEISIM1, NESC No. 1063, SEISIM1 Tape Description and
  Implementation Information,
  National Energy Software Center Note 86-76, July 14, 1986.
- J.E. Wells, L.L. George, and G.E. Cummings,
  Seismic Safety Margins Research Program Phase I Final Report -
  Systems Analysis (Project VII),
  NUREG/CR-2015 (UCRL-53021), Vol. 8, November 1981.
- P.D. Smith, D.L. Bernreuter, M.P. Bohn, T.Y. Chuang, G.E.
  Cummings, R.D. Dong, J.J. Johnson, R.W. Mensing, and J.E. Wells,
  An Overview of Seismic Risk Analysis for Nuclear Power Plants,
  UCID-18680, September 11, 1980.
NESC1063/01, included references:
- Laurence L. George et al.:
  SEISIM - Systematic Evaluation of Important Safety Improvement
  Measures: User Manual.
  UCID-20496  (July 1985)
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11. MACHINE REQUIREMENTS

121,000 (octal) words of SCM and 553,000 (octal) words of LCM are required for execution.
NESC1063/01
Main storage requirements for executing the test case on a CDC CYBER 830 are : 161,562 (octal) words (CM); 552,460 (octal) words (LCM).
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12. PROGRAMMING LANGUAGE(S) USED
Package ID Computer language
NESC1063/01 FORTRAN-IV
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13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:  SCOPE 2.1.5.
NESC1063/01
NOS2.5.1 (CDC CYBER 830).
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14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

SEISIM1 requires as input, files created by other programs developed as part of the SSMRP project. In particular, the SMACS program (NESC 9706) provides the response data for SEISIM1. SEISIM1 calls subroutines MDNOR and MDNRIS from proprietary International Mathematical and Statistical Library, Inc. (IMSL); these routines are not included.
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15. NAME AND ESTABLISHMENT OF AUTHORS

          L.L. George, S.B. Guarro, P.G. Prassinos,
               and J.E. Wells
          Lawrence Livermore National Laboratory
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16. MATERIAL AVAILABLE
NESC1063/01
File name File description Records
NESC1063_01.001 Information file 66
NESC1063_01.002 JCL and control information 28
NESC1063_01.003 SEISIM source program 3884
NESC1063_01.004 Sample problem input INFILE 20
NESC1063_01.005 Sample problem input LUFILE 25
NESC1063_01.006 Sample problem input REFILE 260
NESC1063_01.007 Sample problem input CRFILE 71
NESC1063_01.008 Sample problem input FRFILE 31
NESC1063_01.009 Sample problem input LCFILE 63
NESC1063_01.010 Sample problem input IEFILE 18
NESC1063_01.011 Sample problem input ASFILE 144
NESC1063_01.012 IMSL SUBROUTINES 9
NESC1063_01.013 Sample problem output 1517
NESC1063_01.014 Sample problem output OUTP 269
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17. CATEGORIES
  • G. Radiological Safety, Hazard and Accident Analysis

Keywords: nuclear power plants, risk assessment, safety, seismic effects, systems analysis.