RSICC CODE PACKAGE PSR-493

1. NAME AND TITLE

SHC: Seismic Hazard Characterization of 69 Nuclear Plant Sites East of the Rocky Mountains.

2. CONTRIBUTORS

Lawrence Livermore National Laboratory, California, through the OECD Nuclear Energy Agency Data Bank, Issy-Les Molineaux, France.

3. CODING LANGUAGE AND COMPUTER

Fortran 77; CRAY2 (P00493CY00000).

4. NATURE OF PROBLEM SOLVED

SHC was developed as part of the Eastern United (EUS) Seismic Hazard Characterization (SHC) Project to design an SHC methodology for the region east of the Rocky Mountains in a form suitable for probabilistic risk assessment and to apply that methodology to 69 site locations, some of them with local soil conditions. The method developed uses expert opinions to obtain the input to the analysis. SHC contains four modules which calculate the seismic hazard at a site located in a region of diffuse seismicity, where the seismicity is modeled by area sources. SHC integrates the opinions of 11 seismicity and five ground-motion experts. The PRDS module generates the discrete probability density functions of the distances to the site for the various seismic source zones. These probability distributions are used by the COMAP module to generate the set of all alternative maps and the discrete probability density of the seismic zonation maps for each expert. The third module, ALEAS, uses these maps and their weights to calculate the best estimate and constant percentile hazard distribution resulting from the choice of a given seismicity expert for all ground-motion experts. This module can be used alone to perform a seismic hazard analysis as well as in conjunction with the other modules. The fourth module, COMB, combines the best-estimate and constant-percentile hazard over all seismicity experts, using the set of weights calculated by ALEAS, to produce the final probability distribution of the hazard for the site under consideration so that the hazard analysis can be performed for any location in the EUS. Local geological site characteristics are incorporated in a generic fashion, and the data are developed in a generic manner.

5. METHOD OF SOLUTION

SHC uses a seismic-source approach utilizing statistical and geological evidence to define geographical regions with homogeneous Poisson activity throughout the zone, described by a magnitude-recurrence relationship. The seismic hazard methodology is based on a probability model of the occurrence and distribution of earthquakes and the attenuation of the ground motion from a source to a site. It also includes modeling of local site effects, such as soil types. The earthquake location is assumed to be uniformly distributed throughout the zone, and the ground-motion model expresses the decay with distance of the median value of a ground-motion parameter. In addition, the methodology incorporates the uncertainty in all parameters into the results. The uncertainty in the hazard is estimated by a Monte Carlo simulation process in which all levels of confidence are normalized and treated as probability values. It includes a probability distribution of the maps for each seismicity expert, distributions for the uncertainty in each of seismicity parameters, and distribution of the ground-motion models for each of the ground-motion experts.

6. RESTRICTIONS OR LIMITATIONS

Maxima of 150 zones per combination, 100 combinations, 96 zones, 50 simulations per attenuation expert, 50 zone clusters for alternative boundaries, 35 zones per cluster, 30 maps, 30 zones per map, 21 distances per distribution of a zone, 20 zones in a circle of influence, 20 efficients per attenuation model, 11 seismic experts, 10 accelerations, 9 frequencies, 7 attenuation models per expert, 6 attenuation experts for ALEAS, 5 attenuation experts for COMBS, 5 return periods, 4 regions.

7. TYPICAL RUNNING TIME

NESC executed the sample problem in approximately 3 CP minutes on a Cray Y-MP.

8. COMPUTER HARDWARE REQUIREMENTS

SHC was operable on Cray computers.

9. COMPUTER SOFTWARE REQUIREMENTS

SHC was written in Fortran 77 to run under CTSS on a Cray2. The software was submitted to NESC in February 1989. This release was tested at NESC in November 1991 under UNICOS 6.1 on a Cray Y-MP. A Fortran 77 compiler is required to compile and run the code. SHC was not tested when it was transferred to RSICC and released in November 2001.

10. REFERENCES

a) Included in documentation:

SHC, NESC No. 1121.CRA2, "SHC Cray Version Tape Description and Implementation Information," National Energy Software Center Note 92-32 (December 9, 1991).

D.L. Bernreuter, J.B. Savy, R.W. Mensing and J.C. Chen, "Seismic Hazard Characterization of 69 Nuclear Plant Sites East of the Rocky Mountains: Methodology, Input Data and Comparisons to Previous Results for Ten Test Sites," NUREG/CR-5250 (UCID-21517) Vol. 1 (January 1989).

b) Background references:

11. CONTENTS OF CODE PACKAGE

Included are the referenced documents in 10.a and one DS/HD diskette with a self-extracting, compressed archive which includes the CRAY-2 source, sample problem, and data files.

12. DATE OF ABSTRACT

November 2001.

KEYWORDS: SEISMIC; REACTOR SAFETY; PROBABILITY SAFETY ANALYSIS