INVESTIGATING THE RELATION BETWEEN COMMON CAUSE COUPLING FACTORS AND AGEING

Usually, probabilistic safety analyses are using the assumption of the constant component failure rate, and the assumption that the probability associated to common cause failure (CCF) will be constant in time. Still, as ageing phenomena could have some influence on components or systems performances, is probable that it could influence the probability of occurrence of CCFs also. This paper is devoted to investigation of the most important CCFs initiating factors from point of view of relation to ageing phenomena. The connections between CCF potential and ageing phenomena, as the influence of the individual prevention factors against CCF were evaluated. A questionnaire has been developed on this topic and all the inputs provided were summarized, compared and commented. The analysis has not been limited only to the list of negative factors that would increase the CCF potential, it has included also positive factors representing the prevention and correction measures applied with the aim to avoid occurrence and recurrence of CCF events, whether related to ageing or not. Two main topics were discussed: a) the strength of relation between the individual CCF coupling factors (contributing to total CCF potential) and ageing phenomena; b) the effect of CCF prevention measures on the coupling factors versus ageing relation (estimated for those CCF coupling factors that were evaluated as coincident with ageing phenomena, with at least medium level of coincidence).

NITOI Mirela;  HOLY J.;  DINU Irina Paula; 

2013-06-12

Institute for Nuclear Research

JRC82346

http://www.jnrd-nuclear.ro/index.php/archive?layout=edit&id=81,    https://publications.jrc.ec.europa.eu/repository/handle/JRC82346,