NESC9700 AVPROG.
AVPROG, Monte-Carlo Simulation of System Availability
NAME OR DESIGNATION OF PROGRAM, COMPUTER, DESCRIPTION OF PROGRAM OR FUNCTION, METHOD OF SOLUTION, RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM, TYPICAL RUNNING TIME, UNUSUAL FEATURES OF THE PROGRAM, RELATED AND AUXILIARY PROGRAMS, STATUS, REFERENCES, MACHINE REQUIREMENTS, LANGUAGE, OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED, OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS, NAME AND ESTABLISHMENT OF AUTHORS, MATERIAL, CATEGORIES
[ top ]
[ top ]
To submit a request, click below on the link of the version you wish to order.
Only liaison officers are authorised to submit online requests. Rules for requesters are
available here.
| Program name | Package id | Status | Status date |
|---|---|---|---|
| AVPROG | NESC9700/01 | Tested | 18-MAY-1987 |
Machines used:
| Package ID | Orig. computer | Test computer |
|---|---|---|
| NESC9700/01 | IBM 3033 | IBM 3084 |
[ top ]
3. DESCRIPTION OF PROGRAM OR FUNCTION
AVPROG is a large-scale simulation program used to estimate steady-state availability of a system, typically a large production unit. The system is modeled as a success logic flow block diagram of equipment affecting the production output. AVPROG simulates system operation over a specified time period using Monte Carlo techniques. System components are failed and restarted using numerous types of distributions that are available. Among the distributions available are the exponential and the lognormal. AVPROG computes availability based on averages from a number of simulation cases (batches) for the specified production time interval. It also ranks unavailability contributors to permit investigation of design modifications that have the greatest impact on availability.
Input to AVPROG consists of system geometry (as defined on logic diagrams), mean time between failures, mean time to restore (MTTR), and mean plant delta (MPD) for each logic block. MTTR is defined to include access time, equipment preparation time, actual replace time, cleanup time, and time to restore the equipment and associated subsystem to normal operation. MPD is defined as additional time to restore full production after theequipment in the logic block has been restored.
AVPROG is a large-scale simulation program used to estimate steady-state availability of a system, typically a large production unit. The system is modeled as a success logic flow block diagram of equipment affecting the production output. AVPROG simulates system operation over a specified time period using Monte Carlo techniques. System components are failed and restarted using numerous types of distributions that are available. Among the distributions available are the exponential and the lognormal. AVPROG computes availability based on averages from a number of simulation cases (batches) for the specified production time interval. It also ranks unavailability contributors to permit investigation of design modifications that have the greatest impact on availability.
Input to AVPROG consists of system geometry (as defined on logic diagrams), mean time between failures, mean time to restore (MTTR), and mean plant delta (MPD) for each logic block. MTTR is defined to include access time, equipment preparation time, actual replace time, cleanup time, and time to restore the equipment and associated subsystem to normal operation. MPD is defined as additional time to restore full production after theequipment in the logic block has been restored.
[ top ]
4. METHOD OF SOLUTION
AVPROG uses Monte Carlo simulations to estimate availability based on time histories of production developed from failure and restore data for each logic block (on the logic diagram representing the system operation) and from specified additional restore time data for the failed system.
AVPROG uses Monte Carlo simulations to estimate availability based on time histories of production developed from failure and restore data for each logic block (on the logic diagram representing the system operation) and from specified additional restore time data for the failed system.
[ top ]
[ top ]
6. TYPICAL RUNNING TIME
Execution time is dependent on the number of blocks in the system, the number of batches, and the simulation time (years) for each batch. A problem, consisting of 49 blocks run at 10 batches for 5000 years each, produced an average of 13,446 failures per batch with a standard deviation of 0.0000015 and took 2.75 minutes of CPU time. A much more complicated problem with 1048 blocks run for 10 batches for 500 years produced an average of 70,749 failures per batch with a standard deviation of 0.000014 and required almost 129 minutes of CPU time.
Execution time is dependent on the number of blocks in the system, the number of batches, and the simulation time (years) for each batch. A problem, consisting of 49 blocks run at 10 batches for 5000 years each, produced an average of 13,446 failures per batch with a standard deviation of 0.0000015 and took 2.75 minutes of CPU time. A much more complicated problem with 1048 blocks run for 10 batches for 500 years produced an average of 70,749 failures per batch with a standard deviation of 0.000014 and required almost 129 minutes of CPU time.
NESC9700/01
NEA-DB executed the test case included in this package on an IBM 3084 computer in one second of CPU time.[ top ]
7. UNUSUAL FEATURES OF THE PROGRAM
AVPROG is unique in its ability to handle MPD in a parallel logic configuration. AVPROG can handle K-out-of-N parallel configurations where the components are not identical. It can also handle weighted and normalized parallel configurations. In considering parallel configurations in the logic diagram, all components are assumed to be operating normally and not on standby. The output shows not only the system availability, but also the contribution of each block to system unavailability, ranked in order of size of the contribution.
AVPROG is unique in its ability to handle MPD in a parallel logic configuration. AVPROG can handle K-out-of-N parallel configurations where the components are not identical. It can also handle weighted and normalized parallel configurations. In considering parallel configurations in the logic diagram, all components are assumed to be operating normally and not on standby. The output shows not only the system availability, but also the contribution of each block to system unavailability, ranked in order of size of the contribution.
[ top ]
[ top ]
10. REFERENCES
- AVPROG, NESC No. 9700.3033B, AVPROG Tape Description,
National Energy Software Center Note 87-86, August 28, 1987.
- AVPROG, NESC No. 9700.3033B, AVPROG Tape Description,
National Energy Software Center Note 87-86, August 28, 1987.
NESC9700/01, included references:
- AVPROG: Availability Analysis Procedures Manual.Y/PO-87-1 (August 1,1983)
- AVPROG: User's Manual.
Y/PO-87-02, Rev. 1 (July 25, 1985)
[ top ]
NESC9700/01
To run the test case on an IBM 3084, 380K bytes of main storage are required.[ top ]
[ top ]
[ top ]
NESC9700/01
| File name | File description | Records |
|---|---|---|
| NESC9700_01.001 | Information file | 67 |
| NESC9700_01.002 | AVPROG source (FORTRAN) | 2669 |
| NESC9700_01.003 | Subroutines (ASSEMBLER) | 330 |
| NESC9700_01.004 | Input data for sample problem | 34 |
| NESC9700_01.005 | Printed output of sample problem | 138 |
Keywords: Monte Carlo method, availability, production, simulation, systems analysis.