NEA-0615 RELOSS.
RELOSS, Reliability of Safety System by Fault Tree Analysis
NAME OR DESIGNATION OF PROGRAM, COMPUTER, DESCRIPTION OF PROBLEM 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 AUTHOR, MATERIAL, CATEGORIES
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| Program name | Package id | Status | Status date |
|---|---|---|---|
| RELOSS | NEA-0615/01 | Tested | 20-FEB-1981 |
Machines used:
| Package ID | Orig. computer | Test computer |
|---|---|---|
| NEA-0615/01 | CDC 7600 | CDC 7600 |
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3. DESCRIPTION OF PROBLEM OR FUNCTION
Program RELOSS is used in the reliability/safety assessment of any complex system with predetermined operational logic in qualitative and (if required) quantitative terms. The program calculates the possible system outcomes following an abnormal operating condition and the probability of occurrence, if required. Furthermore, the program deduces the minimal cut or tie sets of the system outcomes and identifies the potential common mode failures.
Program RELOSS is used in the reliability/safety assessment of any complex system with predetermined operational logic in qualitative and (if required) quantitative terms. The program calculates the possible system outcomes following an abnormal operating condition and the probability of occurrence, if required. Furthermore, the program deduces the minimal cut or tie sets of the system outcomes and identifies the potential common mode failures.
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4. METHOD OF SOLUTION
The reliability analysis performed by the program is based on the event tree methodology. Using this methodology, the program develops the event tree of a system or a module of that system and relates each path of this tree to its qualitative and/or quantitative impact on specified system or module outcomes. If the system being analysed is subdivided into modules the program assesses each module in turn as described previously and then combines the module information to obtain results for the overall system.
Having developed the event tree of a module or a system, the program identifies which paths lead or do not lead to various outcomes depending on whether the cut or the tie sets of the outcomes are required and deduces the corresponding sets.
Furthermore the program identifies for a specific system outcome, the potential common mode failures and the cut or tie sets containing potential dependent failures of some components.
The reliability analysis performed by the program is based on the event tree methodology. Using this methodology, the program develops the event tree of a system or a module of that system and relates each path of this tree to its qualitative and/or quantitative impact on specified system or module outcomes. If the system being analysed is subdivided into modules the program assesses each module in turn as described previously and then combines the module information to obtain results for the overall system.
Having developed the event tree of a module or a system, the program identifies which paths lead or do not lead to various outcomes depending on whether the cut or the tie sets of the outcomes are required and deduces the corresponding sets.
Furthermore the program identifies for a specific system outcome, the potential common mode failures and the cut or tie sets containing potential dependent failures of some components.
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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM
The present dimensions of the program are as follows. They can however be easily modified:
Maximum number of modules (equivalent components): 25
Maximum number of components in a module: 15
Maximum number of levels of parentheses in a logical statement: 10
Maximum number of system outcomes: 3
Maximum number of module outcomes: 2
Maximum number of points in time for which quantitative analysis is required: 5
Maximum order of any cut or tie set: 10
Maximum order of a cut or tie of any module outcome: 3
Maximum order of a cut or tie set of any system outcome in terms of (equivalent) components: 5
Maximum order of a cut or tie set of any system outcome in terms of individual components (used only if the system is divided into modules): 5
Maximum number of special conditions considered for a common mode failure analysis: 5
Maximum number of probability laws: 30
Maximum number of pairs of modules sharing components: 10
The present dimensions of the program are as follows. They can however be easily modified:
Maximum number of modules (equivalent components): 25
Maximum number of components in a module: 15
Maximum number of levels of parentheses in a logical statement: 10
Maximum number of system outcomes: 3
Maximum number of module outcomes: 2
Maximum number of points in time for which quantitative analysis is required: 5
Maximum order of any cut or tie set: 10
Maximum order of a cut or tie of any module outcome: 3
Maximum order of a cut or tie set of any system outcome in terms of (equivalent) components: 5
Maximum order of a cut or tie set of any system outcome in terms of individual components (used only if the system is divided into modules): 5
Maximum number of special conditions considered for a common mode failure analysis: 5
Maximum number of probability laws: 30
Maximum number of pairs of modules sharing components: 10
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7. UNUSUAL FEATURES OF THE PROGRAM
Program RELOSS relates qualitatively and quantitatively a single initiating event to various system outcomes using the event tree methodology. The necessary input information being deduced from line diagrams of the system, engineering description of its operational logic and general design information, makes the program very versatile because it can be used to relate directly to engineering design without recourse to an intermediate reliability appreciation of the system. It can be also used to identify the critical failure modes of complex systems by deducing the minimal cut or tie sets of the various system outcomes of interest.
Program RELOSS relates qualitatively and quantitatively a single initiating event to various system outcomes using the event tree methodology. The necessary input information being deduced from line diagrams of the system, engineering description of its operational logic and general design information, makes the program very versatile because it can be used to relate directly to engineering design without recourse to an intermediate reliability appreciation of the system. It can be also used to identify the critical failure modes of complex systems by deducing the minimal cut or tie sets of the various system outcomes of interest.
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10. REFERENCES
- R.N. Allan, I.L. Rondiris, D.M. Fryer, C. Tye:
Computational Development of Event Trees in Nuclear Reactor
Systems
Second National Reliability Conference (March 1979), Birmingham
(available from Institute of Quality Assurance, London).
- I.L. Rondiris:
Reliability Evaluation of Nuclear Power Plants,
PhD Thesis, University of Manchester (1978).
- R.N. Allan, I.L. Rondiris, D.M. Fryer, C. Tye:
Computational Development of Event Trees in Nuclear Reactor
Systems
Second National Reliability Conference (March 1979), Birmingham
(available from Institute of Quality Assurance, London).
- I.L. Rondiris:
Reliability Evaluation of Nuclear Power Plants,
PhD Thesis, University of Manchester (1978).
NEA-0615/01, included references:
- R.N. Allan and I.L. Rondiris:Users Manual for RELOSS (Reliability of Safety Systems)
PhD Thesis, University of Manchester (April 1979)
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14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS
If
found necessary, the following overlay structure can be used:
Root segment: Main program
Primary Overlay 1: RDATA, CPREV, TIMEPR, FNLWE, FNL, PROBDF,
CONVRT, SIMPLE
Primary Overlay 2: CMFSUB, REVISE, BACK
Primary Overlay 3: MCUT2, RENUB, CMSC
Primary Overlay 4: COMROW, SYSTEM, MODULE, PROB, CUT, COMCUT,
NEWCUT, MINCUT, EVMAP, CHECK, PROBCUT, CTEST,
TEST, SPLIT
The above overlay structure gives a storage saving of 14.5%.
If
found necessary, the following overlay structure can be used:
Root segment: Main program
Primary Overlay 1: RDATA, CPREV, TIMEPR, FNLWE, FNL, PROBDF,
CONVRT, SIMPLE
Primary Overlay 2: CMFSUB, REVISE, BACK
Primary Overlay 3: MCUT2, RENUB, CMSC
Primary Overlay 4: COMROW, SYSTEM, MODULE, PROB, CUT, COMCUT,
NEWCUT, MINCUT, EVMAP, CHECK, PROBCUT, CTEST,
TEST, SPLIT
The above overlay structure gives a storage saving of 14.5%.
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NEA-0615/01
| File name | File description | Records |
|---|---|---|
| NEA0615_01.001 | INFORMATION FILE | 13 |
| NEA0615_01.002 | INFORMATION FILE | 13 |
| NEA0615_01.003 | SOURCE | 4853 |
| NEA0615_01.004 | S.P. INPUT | 109 |
| NEA0615_01.005 | S.P. OUTPUT | 1176 |
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- G. Radiological Safety, Hazard and Accident Analysis
- K. Reactor Systems Analysis
- P. General Mathematical and Computing System Routines
Keywords: fault tree analysis, reactor operation, reactor safety, reliability, safety.