2018 | AFC ACCOMPLISHMENTS 109 Figure 2. A picture of team members and the assembled test train prior to insertion into the ATR. and shake-down testing was performed at theWestinghouse flowing autoclave facility outside of Pittsburgh to assess the reliability of the instrumentation. Based on the extraordinary efforts of the all involved, the Sensor QualificationTest was inserted into theATR in September of 2017. Figure 2 shows the team alongside the completed test train, just prior to insertion. Unfortunately, a few days after the test began, tungsten was detected in the loop coolant which indicated that at least one of the instrumented pins was breached.Although there is no conclu- sive evidence as to the cause of the breach, the most likely explanation is judged to be failure of a thermocouple sheath. In the first insertion of the ATF-2 experiment in June of 2018, no instrumentation was provide based in part because of the suspected thermo- couple failures in the Sensor Qualifica- tionTest, but also because of schedule pressures and because difficulties in the development of a particularATF concept reduced the need for instrumentation. In spite of these challenges, however, the Sensor QualificationTest has made and will continue to make a lasting impact in our ability to develop and test advanced light water reactor fuel systems. In the near-term, the test demonstrated that the instrumentation technologies were not sufficiently mature to be used in fueled test experiments so that it likely prevented fuel pin leaks in theATF-2 test. Moreover, the infrastructure that was put into place in theATR as part of this test will undoubtedly be used in future experiments when the reliability of the instrumentation has been more clearly demonstrated.