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5. Limits to bow-tie quantification
5.1 Input data inaccuracies
When quantifying a bowtie, it is important to bear in mind that the probabilities of hazardous phenomena estimated by the calculation should be considered as orders of magnitude, not exact values. For this reason, the values obtained by quantifying a bowtie are often rounded off to take into account the error linked to uncertainties in the input data. For example, announcing a probability of occurrence equal to 7.56 × 10 –5 would not make much sense in view of the relative uncertainties involved:
the frequency allocated to the feared event ;
failure probabilities assigned to mitigation barriers ;
...
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Limits to bow-tie quantification
Example of a quantified bow tie
Bibliography
Standards and norms
- Analyse par arbre de panne (AAP) - NF EN 61025 -
Regulations
Arrêté ministériel du 29 septembre 2005 relatif à l'évaluation et à la prise en compte de la probabilité d'occurrence, de la cinétique et de l'intensité des effets et de la gravité des conséquences des accidents potentiels dans les études de dangers des IC soumises à autorisation (Ministerial Order of September 29, 2005 on the assessment and consideration of the probability of occurrence, the kinetics and intensity of effects...
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