No regulatory will accept a PCB fuse as it is not reliable and will not break fire safe.
Thanks, and in the face of it, you are of course correct.
However, we do not need them to work "over time"..but just for the immediate test that we are about to do......we will attach them to the FET....in 10 mins the FET will get up to steady state temperature.....and the soldered/twisted thermocouple wires will last ok for 10 mins...then,, during the following 2 hours of the soak test, any sudden changes in the FET temperature would of course, indicate that the thermocouple had come to grief.......so we would at least know if it happened.