Methodology for reliability-oriented recalculation and assessment of existing nuclear structures with extended service life. Sub-project: Methodology for probabilistic evaluation

With respect to a possible extension of the service lifetime of civil structures in nuclear installations, particularly interim storage facilities, the question on the basis for an adequate assessment arises. Such structures are generally not assessed with respect to their failure probability or reliability. However, the underlying parameters for structural failure (e.g., actions or material properties) have uncertainties. Thus, the assessment of the existing civil structures regarding their extended lifetimes should be reliability-based. For some types of structures (e.g. bridges), national regulations do exist for reassess-ment. In some European countries, similar guidelines etc. have been provided consider-ing the particularities of individual building types. Comparable guides for nuclear civil structures do not exist up to now. Special features, other than in general civil engineering, to be considered for the assessment are e.g. the following: service life period, large cross-sections, large permanent loads, consequences of the structural failure, specific actions, target reliability.