In choosing a high-temperature lubricant for use in the extreme conditions of a nuclear reactor, three properties need to be considered: viscosity, thermal degradation, and oxidation. For nuclear applications, you need a lubricant that maintains the same consistency at both low and high temperatures, will not break down and leave deposits on working surfaces, and won’t oxidize as the temperature increases.
High decomposition temperatures
All of this information can be distilled into a single indicator, and that is the lubricant’s decomposition temperature, i.e., the temperature at which a lubricant ceases to maintain its nature and function. Considering that conditions in nuclear reactors rise above 300°C, the solution would be to find hi-temp lubricants with decomposition temperatures that exceed that number. This isn’t always as straightforward as it seems. The higher the operating temperature gets, the more limited your options are for high-temperature lubricants. Most oils and greases are not viable above 400°C. This makes high-temperature lubricants the only viable option, in particular metal sulfides such as molybdenum disulfide, which maintains high levels of lubricity, extreme resistance to oxidation and thermal stability at temperatures above 600°C.
For the most part, to obtain a high-temperature lubricant that satisfies the nuclear industry’s needs in terms of viscosity/ lubricity, thermal degradation, and oxidation, specialized formulations need to be created, such as Huron Industries’ Neolube® No 1260. This can be used in critical service applications up to 635°C, exhibits excellent lubricity even as the temperature rises, and is ideal for containment and/or secondary side in nuclear applications. Aside from its thermal stability, it is also strongly resistant to radiation, which is another vital consideration for nuclear applications.
Huron Industries is a woman-owned and woman-led industrial sealant and lubricant supplier for the nuclear industry. Our Neolube® No. 1260 is specially formulated for high-temperature applications and designed with the nuclear industry in mind. For more information on our range of lubricants for nuclear, aeronautic and military applications, contact us.