Vapor adsorption testing of ambient molecular sieve bed in coolant purification system

Abstract

A helium cooling system (HCS) circulates helium coolant to remove heat from a tritium breeding blanket in a fusion reactor. A small amount of tritium can permeate into the HCS from the blanket, and it should be removed as per safety requirements in the system. A coolant purification system (CPS) is connected to the HCS, and one percent of the helium flow is bypassed into the CPS from the HCS for purification of the coolant. An ambient molecular sieve bed (AMSB) will play a role in capturing the tritiated water, Q2O. In order to develop and confirm the AMSB design and its function, a test facility is constructed especially for the experimental validation of the adsorption characteristics under a very low concentration of vapor. An experiment will be conducted under a helium flow. However, before the main helium test, air tests are performed at room temperature and 0.33 MPa. The facility can be divided into two parts, one part containing a device generating a small amount of moisture and the other containing the test section including the AMSB. The vapor generator can continuously supply vapor of 1 to hundreds of ppm to the dry gas. Various AMSBs can be installed in the test section. The adsorption performance and saturation characteristics according to the diameter, length, and flow rate are compared. The experiment was conducted on two columns of different lengths. Specifically, when the performance validation test with the 64 mm AMSB was conducted over a period of more than 10 days, it showed very stable adsorption performance. The length of the AMSB estimated in the experiment was several times shorter than that obtained through a correlation equation. If these results are reflected in the design, the design can be more compact or the operation cycle can be increased. These experiments can contribute to the development of AMSB designs.