Post Service Examination of Turbomolecular Pumps After Stress Testing with kg-Scale Tritium Throughput

Turbomolecular pumps (TMP) will be used with large amounts of tritium in future fusion machines like ITER, DEMO and in the KATRIN Experiment. In the work presented, a stress test of a Leybold® MAG W2800 with a tritium throughput of 1.1 kg over 384 days of operation was performed at TLK. After this, the pump was dismantled and the tritium uptake in several parts was determined. Especially the non-metallic parts of the pump absorb large amounts of tritium and are most likely responsible for the observed pollution of the process gas. The total tritium uptake of the TMP was estimated with 0.1-1.1 TBq. No radiation-induced damages were found on the inner parts of the pump. The TMP showed no signs of functional limitations during the 384 days of operation.