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PSR-0465 EVNTRE.

EVNTRE, Code System for Event Progression Analysis for PRA

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1. NAME OR DESIGNATION OF PROGRAM:  EVNTRE
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2. COMPUTERS
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Program name Package id Status Status date
EVNTRE PSR-0465/01 Arrived 06-MAY-2002

Machines used:

Package ID Orig. computer Test computer
PSR-0465/01 DEC VAX 8650
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3. DESCRIPTION OF PROGRAM OR FUNCTION

EVNTRE is a generalized event tree processor that was developed for use in probabilistic risk analysis of severe accident progressions for nuclear power plants. The general nature of EVNTRE makes it applicable to a wide variety of analyses that involve the investigation of a progression of events which lead to a large number of sets of conditions or scenarios.
EVNTRE efficiently processes large, complex event trees. It can assign probabilities to event tree branch points in several different ways, classify pathways or outcomes into user-specified groupings, and sample input distributions of probabilities and parameters. PSTEVNT, a postprocessor program used to sort and reclassify the 'binned' data output from EVNTRE and generate summary tables, is included.
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4. METHODS

EVNTRE processes event trees that are cast in the form of questions or events, with multiple choice answers for each question. Split fractions (probabilities or frequencies that sum to unity) are either supplied or calculated for the branches of each question in a path-dependent manner. EVNTRE traverses the tree, enumerating the leaves of the tree and calculating their probabilities or frequencies based upon the initial probability or frequency and the split fractions for the branches taken along the corresponding path to an individual leaf. The questions in the event tree are usually grouped to address specific phases of time regimes in the progression of the scenario or severe accident. Grouping or binning of each path through the event tree in terms of a small number of characteristics or attributes is allowed. Boolean expressions of the branches taken are used to select the appropriate values of the characteristics of
interest for the given path. Typically, the user specifies a cutoff tolerance for the frequency of a pathway to terminate further exploration. Multiple sets of input to an event tree can be processed by using Monte Carlo sampling to generate approximate mapping from input to output.
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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

A preprocessor program supplied can be used to replace a PARAMETER statement if array sizes require adjustment.
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6. TYPICAL RUNNING TIME

Central processing time can vary from a few minutes to several hours depending on the size and complexity of the problem. The size of the event tree, the amount of sampling done where uncertainties exist, and the extent of branching and calculation of branch probabilities in the event tree are some of the conditions which can add to the processing time. NESC executed the EVNTRE sample problem in approximately 45 CPU minutes, and the PSTEVNT sample problem in approximately 9 CPU minutes on a DEC VAX6220.
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7. UNUSUAL FEATURES
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8. RELATED OR AUXILIARY PROGRAMS
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9. STATUS
Package ID Status date Status
PSR-0465/01 06-MAY-2002 Masterfiled Arrived
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10. REFERENCES
PSR-0465/01, included references:
- J.M. Griesmeyer and L.N. Smith
A Reference Manual for the Event Progression Analysis Code (EVNTRE)
NUREG/CR-5174, SAND88-1607 (September 1989)
- S.J. Higgins
A User's Manual for the Postprocessing Program PSTEVNT
NUREG/CR-5380, SAND88-2988 (November 1989)
- L.Reed
EVNTRE, NESC No. R1132, EVNTRE Tape Description and Implementation Information
NESC Note 91-66 (April 26, 1991)
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11. HARDWARE REQUIREMENTS

EVNTRE was developed for VAX computers. Memory requirements depend on the particular problems being solved. EVNTRE, as currently dimensioned, requires 850 Kbytes of virtual
memory. PSTEVNT requires 1400 Kbytes of memory.
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12. PROGRAMMING LANGUAGE(S) USED
Package ID Computer language
PSR-0465/01 FORTRAN-77
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13. SOFTWARE REQUIREMENTS

This software runs under VMS 4.5; VMS 5.3 and requires a FORTRAN 77 compiler.
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14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS
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15. NAME AND ESTABLISHMENT OF AUTHORS

Contributed by:
                Radiation Safety Information Computational                                                 Center
                Oak Ridge National Laboratory
                Oak Ridge, Tennessee, U. S. A.

Developed by:   Sandia national Laboratories,
                Albuquerque, New Mexico
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16. MATERIAL AVAILABLE
PSR-0465/01
EVNTRE.EXE  executable file containing the following :
EVNTRE.FOR Fortran Source file
UFUN.FOR Function UFUN Fortran Source
PB1.DAT Peach Bottom Sample Input
PB2.DAT Peach Bottom Sample Input
PB3.DAT Peach Bottom Sample Input
PB4.DAT Peach Bottom Sample Input
PB5.DAT Peach Bottom Sample Input
PB.OUT Peach Bottom Sample Problem Output
CONV.FOR Data Conversion Program Source
EVNT.FOR EVNTSUB Utility Source
EVNT1.DAT EVNTSUB Sample Input
EVNT2.DAT EVNTSUB Sample Input
EXEC.COM EVNTRE Execution Command Procedure
ECHO.OUT Sample Problem Output
PBBIN.OUT Sample Problem Output
PSTEVNT.FOR PSTEVNT FORTRAN Source
UWGT.FOR Function UWGT Fortran Source
PST1.DAT PSTEVNT Sample Input
PST2.DAT PSTEVNT Sample Input
PST3.DAT PSTEVNT Sample Input
PST4.DAT PSTEVNT Sample Input
PST5.DAT PSTEVNT Sample Input
PST6.DAT PSTEVNT Sample Input
PST7.DAT PSTEVNT Sample Input
PSTEVNT.COM OSTEVNT Execution Command Procedure
POSTLHS.COM PSTEVNT Execution Command Procedure
PST1.OUT PSTEVNT Sample Problem Output
PST2.OUT PSTEVNT Sample Problem Output
PST3.OUT PSTEVNT Sample Problem Output
PST4.OUT PSTEVNT Sample Problem Output
PST5.OUT PSTEVNT Sample Problem Output
PST6.OUT PSTEVNT Sample Problem Output
PST7.OUT PSTEVNT Sample Problem Output
Readme.rsi  Information file
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17. CATEGORIES
  • GR. Probabilistic Risk Assessment

Keywords: risk assessment.