Leakage rate prediction through cracked concrete elements: A literature review

Concrete is a durable structural material and is vital for the design of containment buildings that house nuclear reactor units. During a potential accident, this physical barrier protects the outside environment by preventing pressurized gases with radioactive materials from escaping the inner building volume. Under extreme circumstances (e.g. beyond design basis events), this solid shield can crack, and the resulting leakage may pose a risk to public safety and the surrounding area. To minimize the impact of such events, the leakage rate passing through this boundary must be accurately quantified. This paper summarizes the experiments, results, models, and research gaps pertaining to the quantitative prediction of gas leakage rate through cracked concrete elements. Publications considered in this paper span the research conducted from 1972 to 2024. Despite the multitude of experiments and proposed prediction models, the numerical assessment of the leak-tightness for concrete containment buildings remains a formidable task as predictions exhibit noticeably large variability and are, in general, inaccurate. Based on the comprehensive literature review, it is identified that new prediction models need to be developed which account for the complex roughness effects of crack patterns, crack formation due to hydration heat-induced shrinkage, drying shrinkage, and creep, in addition to the localized impacts of many embedded components. • Reviews leakage rate studies for cracked concrete from 1960 to 2024. • Compares leakage models against extensive experimental data. • Finds large variability and inaccuracy in existing predictions. • Identifies key gaps: roughness, shrinkage, creep, and crack patterns. • Calls for new models to improve leak-tightness assessment of containments.