Probability of loss of assured safety in systems with multiple time-dependent failure modes: Representations with aleatory and epistemic uncertainty

Property values associated with the failure of individual links in a system with multiple weak and strong links

“…In a prior publication [18], representations for PLOAS are developed for systems in which the failure time CDF for a single WL or SL is based on the following assumed properties of that link for a time interval mn mx t t t   , where mn t and mx t define the endpoints of the time interval considered for analysis:…”

“…Representations for the probability of loss of assured safety (PLOAS) for weak link (WL)/strong link (SL) systems [1-6] involving multiple time-dependent failure modes in the presence of both aleatory and epistemic uncertainty [7][8][9][10][11][12][13][14][15][16][17] are developed and illustrated in Ref. [18]. As described in Ref.…”

“…As described in Ref. [18], loss of assured safety (LOAS) occurs under accident conditions (e.g., a fire) when SL failures place the overall system in a potentially operational mode before deactivation of the overall system as a result of WL failures. In the following, representations are developed and illustrated for the distribution of link property values at the time of link failure in the presence of aleatory uncertainty in link properties.…”

“…However, an over concentration on the final outcome of a complex analysis can lead to (i) loss insights and understanding with respect to the overall analysis and (ii) a possible failure to recognize errors that are present in the analysis. For these reasons, this report and the two indicated following reports deal with internal analysis results and additional summary results that can provide additional information in an analysis of a WL/SL system, including (i) times and property values at which individual links fail [18], (ii) times and property values at which systems of WLs or SLs fail [46], (iii) SL property values at which LOAS occurs [46], (iv) time and property value margins related to the occurrence of LOAS [46], and (v) a variety of verification procedures including comparisons of LOAS related results obtained with quadrature-based procedures and sampling-based procedures [46; 47].…”

IUPAC/CITAC Guide: Classification, modeling and quantification of human errors in a chemical analytical laboratory (IUPAC Technical Report)

“…Any expert is also a human being and the elicitation process (by which the expert is prompted to provide error likelihood, severity, and other estimates) is influenced by aleatory and epistemic uncertainty [40], intrapersonal conflicts [41], etc. Therefore, the evaluation of variability of the error quantification scores and relative risks due to the inherent expert's hesitancy is important also.…”