Strain and temperature measurements from the SNS* mercury target vessel during high intensity beam pulses

To better understand the mechanical impact of the proton beam on the lifetime on Spallation Neutron Source (SNS*) mercury-filled, stainless steel targets, these targets are now instrumented with optical and metal strain sensors, temperature sensors, and accelerometers. The strain and temperature sensors are placed inside the target vessel, between the water shroud and mercury vessel, while the accelerators are placed outside on the target mount and on the mercury return line. We now have data from four targets. The first instrumented target used regular multimode optical sensors, while later targets have used radhard multimode sensors. We are also developing super-radhard single-mode optical strain sensors to get data further into the production cycle. In this paper, we describe the data-acquisition system, compare the measured strain to the simulated strain for the different targets, estimate the survivable radiation level for each type of sensor, and discuss the implications of the results on the lifetime of the target.