Preliminary investigations of a testing method to examine additively manufactured materials under the influence of advanced reactor coolants

Metals with low melting points are used as thermal fluids in thermodynamic applications, like cooling circuits of advanced nuclear power plants or high temperature heat pipes. For alkali metals such as sodium and potassium, there is a risk of spontaneous, highly exothermic reactions with oxygen or formation of an explosive hydrogen atmosphere when in contact with water. In the event of a leak or a complete rupture of e.g., a heat pipe, liquid alkali metals will be released into the environment. These highly exothermic or potentially explosive reactions pose a hazard potential, which is currently difficult to assess. An experimental setup was developed, in which potassium is heated up and then released suddenly into air in a controlled manner. As a basis for further experimental work, reactions of potassium released at high temperatures into air are qualitatively evaluated at different temperatures and potassium quantities. The experiments allow to draw conclusions on the hazard potential and to ensure safety of staff and surroundings during mechanical testing of specimens filled with liquid potassium. The experimental methodology is transferable to other highly heated reactive coolants.