Spent nuclear fuel (SNF) will likely continue to be stored in dry storage canisters for a longer time than initially planned. Degradation mechanisms such as chloride-induced stress corrosion cracking ...can cause defects and cracks in the canister walls leading to the loss of the inert environment, which may increase the likelihood of internal component corrosion. One of the simplest methods to detect a leak in an SNF canister is to monitor the temperature distribution on its outer surfaces. This method has been successfully demonstrated for vertical canisters. However, it has not been extensively applied to horizontal canisters. The objective of this paper is to use computational fluid dynamics (CFD) simulations to determine if leakage of the inert gas from the 61-BT canister (and replacement by air) can be practically detected by measuring temperatures on the canister’s external surfaces. CFD simulations that model conduction, radiation, and natural convection heat transfer in the 61-BT canister inserted in a horizontal storage module are conducted. Simulations for helium and air gas backfills, pressures, seasonal and daily ambient temperatures, and SNF decay heat are conducted. The results showed that the depressurization of the inner gas from the initial pressure to the ambient value does not significantly affect the temperature distribution on the canister's outer surfaces. However, the replacement of the helium gas by air can be effectively detected by measuring the temperature difference between the side and ends of the canister’s outer surfaces. This difference changes from 20° to 8°C for a storage period from 0 to 40 years, respectively. Therefore, this method can be used for more than 40 years of storage.
Hydrogen (H2) detectors are important tools to ensure the safety in H2 production/storage/transportation/use and also monitor many H2-related physiochemical processes in industrial or medical ...practices. Ideal H2 detectors should not only have high detection performance (e.g., high sensitivity and selectivity) but also possess low power-consumption, high compactness, simple fabrication using low-cost materials, and ease of instrumentation that can be easily handled and operated. In this work, nanoporous composites by simply reducing palladium (Pd) precursors to the surface of halloysite nanotubes (HNTs) were developed and optimized for the development of a resistive H2 detector. The detector was prepared by depositing solution droplets of Pd/HNT with an optimal mass concentration on an interdigitated microelectrode surface of 1 cm × 1 cm and then drying it at 65 °C. The developed H2 detector exhibited reliable H2 detection, achieving low limit H2 detections of 27 ppb and <10 ppm in both N2 and air, respectively. It also presented high selectivity, differencing H2 from other interfering gases such as CO2 and CH4, and demonstrated stability in its response from room temperature to 50 °C. We attribute the characteristics of the detector performance to the nature of Pd/HNT composites (large surface, high porosity, specific reaction of Pd to H2, etc.). Given its high detection performance, simple resistance read-out, and ease of fabrication, it is believed that the developed detector will have broad applications in the H2 energy industry and many other H2-related industrial and medical procedures.
