Thermal Bonding of Light Water Reactor Fuel Using Nonalkaline Liquid-Metal Alloy

Performance evaluation and post-irradiation examination of a novel LWR fuel composed of U0.17ZrH1.6 fuel pellets bonded to Zircaloy-2 cladding by lead bismuth eutectic

“…9 measured on unirradiated material. However, the irradiated end sample is in fair agreement with values reported previously (9). Further investigation into the properties of the LM provides some insight into the potential mechanisms that can describe the observations made during post irradiation examination discussed here.…”

“…Primarily, there appears to be an unwanted physical or chemical reaction occurring between the LM and both the cladding and to a much lesser extent fuel matrix. Such reactions have been observed previously in the literature [9] for lead-bismuth eutectic and Zircaloy-4 tubing in which contact between the two materials at 672K for 1000 hrs resulted of ~8% loss of the tube wall thickness. Similar exposure with lead-tin-bismuth eutectic reduced the loss to only 0.3%.…”

“…Many improvements are required in the choice and design of the cladding material and/or LM. Previous studies have indicated that using lead-tinbismuth eutectic in place of lead bismuth could reduce some of the potential materials incompatibility issues observed in the current experiment [9]. It is hypothesized that the formation of a ZrSn 2 layer at the interface of the LM and the cladding is the reason for this increase in compatibility.…”

“…The extensive loss of the cladding thickness near the midplane of the fuel into inner LM suggests that more zirconium loss was observed than would have expected for dissolution to the levels just discussed. Previous experiences with Zr LBE systems reveal corrosion can easily be detected when the temperature during operation is 400 °C or higher [9]. It is known from corrosion tests that Zircaloy-2 is not attacked by LBE at 350 °C but dissolved rapidly at 450 °C [19].…”

Advanced Moderation Module for High-Temperature Micro-Reactor Applications

“…reaction bond coating) are also designed and pursued to produce an external in-situ scale on the metal or alloy itself that serves as a diffusion barrier. However, such forms of barriers do not provide any flexibility towards stress generated from thermal cycling, which often leads to surface cracks and eventual spallation [39]. Broadly, coating provides more flexibility in its application requirements and can be tuned to generate the most efficient structures to withstand thermal stress and reduce H2 permeability.…”