ASTRI’s Advanced Materials program involved the AMDTR group conducting exposure tests where alloys such as SS316 and IN625 were submerged in liquid sodium. In order to carry out these experiments, the AMDTR group had to design and construct a custom made apparatus that was able to prevent the liquid sodium from vaporizing under testing conditions and maintain an inert gas environment. This apparatus was specially made in house and has been documented in greater detail in one of our publications. This liquid sodium system allows for exposure testing under a static configuration (as opposed to a sodium flow loop) and can be tested either isothermally or under a cyclic temperature regime.
The static liquid sodium test system is comprised of primary chambers that contain alloy samples in the form of small rectangular coupons submerged in a small quantity of liquid sodium. The primary chambers are sealed shut in a glove box so that they contain only high purity argon gas as the cover atmosphere over the liquid sodium and the test coupons.
Isometric view of primary chamber that houses a ceramic liner. Cross sectional view showing at the bottom of the ceramic liner sits the metal coupon submerged in molten sodium
The primary chambers are then situated on a platform (holder stage) within the secondary chamber (3 primary chambers can be tested at a time), which has connected inlet and oulet pipes that pump argon throughout the secondary chamber during the experiment. This ensures that if the primary chambers lose their internal argon atmosphere, the argon flow in the secondary chamber will still maintain an inert atmosphere overall. The secondary chamber is designed to prevent any escape of potential sodium vapour leaks from the primary chamber. To ensure any evolved gases are isolated, the gas line is also passed through a bubbler and vented out in a fumehood.
Isometric view of primary chamber and holder stage, which both fit into the secondary chamber
The entire assembly then fits into a furnace that heats the apparatus and its associated components to the required temperature. This system can be tested for any required duration, whether it is a short term or long term exposure test. With a temperature controller connected to the furnace, the test system is able to be heated according to any required temperature profile.
Isometric view of secondary chamber fitted into one of our Tetlow tempering furnaces
Cross-sectional view of simulated component temperatures of test apparatus, with thermal zones identified
Upon completion of the test, the entire system is cooled to room temperature and the test coupon and solidified sodium can be extracted from the primary chamber in one of our gloveboxes maintained with a high purity argon environment. The test coupon is then sent to our Central Analytical Research Facility (CARF) for subsequent analysis.
Find out more about the analysis equipment available from CARF.