Structural reliability of pre-stressed concrete containments

Abstract

This paper presents probabilistic analysis of structural capacity of pre-stressed concrete containments subjected to internal pressure. The conventional design methods for containments are based on allowable stress codes which ensure certain factor of safety between expected load and expected structural strength. Such an approach may give different values of structural reliability in different situations. In recent years, two international round robin exercises have been conducted aimed at predicting the capacity of lined and unlined pre-stressed concrete containments used in nuclear industry. These exercises involved experimental testing and numerical analysis of the models. The first exercise involved ¼ scale steel-lined Pre-stressed Concrete Containment Vessel (PCCV) which was tested at Sandia National Laboratories (SNL) in USA. The second used an unlined containment being tested by the Bhabha Atomic Research Centre (BARC), Tarapur, India. These studies are essentially deterministic studies that have helped validate the analysis methodology and modelling techniques that can be used to predict pre-stressed concrete containment capacity and failure modes. The paper uses these two examples to apply structural reliability method to estimate the probability of failure of the containment. 2 coefficients of variation of the applied pressure and containment radius are the most important parameters. The variability of the probability of failure is decreased at higher pressures, but the coefficients of variation still play an important role.

Analytic Probabilistic Safety Analysis under Severe Uncertainty

“…In many real systems the components' strengths may be added together, rather than combined in parallel or series. Such an example is given in (Prinja et al 2017). This poses a challenge for analytical methods, as in general normal distributions and log normal distributions cannot be summed easily (except in limited cases such as independently distributed normal random variables).…”

“…In (Prinja et al 2017) probabilistic safety analysis of a concrete containment was presented as part of a round robin international test exercise. Two experimental test cases (Sandia National Laboratories and Bhabha Atomic Research Centre) are described and the probability of failure for each containment is calculated.…”

“…In the United States the nuclear regulator (Budnitz et al 1985) refers to the work of Kennedy who provides many analytic relationships to establish the fragility curve for a containment with a conventional probabilistic treatment (Kennedy et al 1980). The effect of epistemic uncertainty in PSA with conventional probability was considered in (Prinja et al 2017;Sun and Yao 2008).…”

Robust propagation of probability boxes by interval predictor models

“…For this reason, probability boxes are useful in situations where limited data is available to model random variables. An example of such a situation in the nuclear industry is given by [22], and in the aerospace industry by [21]. However, due to their epistemic uncertainty, the propagation of probability boxes through models is more difficult than for conventional random variables, as in general a naïve Monte Carlo propagation with insufficient samples will discard some of the epistemic uncertainty [8,9].…”

Development of Efficient External Multi-Hazard Risk Quantification Methodology for Nuclear Facilities

“…Most importantly, there is a fundamental limitation that the analytical time is quite large because sufficient samples must be extracted for the response R and the capacity C for every single external hazard intensity. An analytical study has been conducted to assess the probabilistic reliability and fragility analyses under specific loads at a level of a single component and a structure in the nuclear industry [22]. However, this study did not extend from the component level fragility to the overall plant level system fragility assessment stage.…”