NESC1063 SEISIM1.

1. NAME OR DESIGNATION OF PROGRAM:  SEISIM1.

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.

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.

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

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.

NEA-DB executed the test case included in this package  on a CDC CYBER 830 computer in 36 seconds of CPU time.

7. UNUSUAL FEATURES OF THE PROGRAM:

8. RELATED AND AUXILIARY PROGRAMS:

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.

- Laurence L. George et al.:
  SEISIM - Systematic Evaluation of Important Safety Improvement
  Measures: User Manual.
  UCID-20496  (July 1985)

11. MACHINE REQUIREMENTS

121,000 (octal) words of SCM and 553,000 (octal) words of LCM are required for execution.

Main storage requirements for executing the test case on a CDC CYBER 830 are : 161,562 (octal) words (CM); 552,460 (octal) words (LCM).

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:  SCOPE 2.1.5.

NOS2.5.1 (CDC CYBER 830).

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.

15. NAME AND ESTABLISHMENT OF AUTHORS

          L.L. George, S.B. Guarro, P.G. Prassinos,
               and J.E. Wells
          Lawrence Livermore National Laboratory

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