Review of Leak Rates and Control in High-Temperature Fluid Applications

Continued interest in molten halide salts and liquid metals for use in advanced nuclear reactors has prompted the development of increasingly complex thermal-hydraulic test systems at a wide array of institutions. Given the high cost of failures in these systems, the adoption of proven design practices is critical. However, much of the relevant knowledge authored by experienced engineers, particularly concerning high-temperature fluid leakage, resides in obsolete or inaccessible literature. This work synthesizes historical insights into leakage phenomena and provides guidance for contemporary high-temperature system design. A review of articles and their perspective on leak rates, joints, significant leak events, the results of leaks, and recovery from leaks is presented. From this literature, gas leak rates of 2.10×10−9 to 1.05×10−8 Pa·m3/s have been reported as acceptable by both molten salt and liquid-metal engineers. These gas leak rates are a reasonable target during system acceptance testing, increasing the likelihood of long-term, leak-free, high-temperature operation.