Improving Turn Around Times Of Calorimeter Measurements In The LLNL MC&A Labs Through Reduction Of Thermal Impedance

The LLNL MC&A program has experienced a nearly two-fold increase in measurement demand since September of 2007. This influx is due to the NNSA decision that LLNL de-inventory its Safeguards Category I/II nuclear material no later than September 30, 2012. Adding new measurement equipment was considered, but the requisite procurement, installation, and certification processes would not have been completed in time to have a sufficient impact. Further, such an effort would have diverted the time and attention of specialized personnel away from the de-inventory effort itself. Instead, measurement throughput was increased largely through overtime and meticulous workflow planning. Strategic adaptations to existing techniques and equipment provided the remaining gains in throughput that enabled all of the de-inventory milestones to be met or exceeded. For calorimeter measurements we sought ways to reduce run-times by speeding the time to thermal equilibrium. We accomplished this by minimizing the thermal resistance of our packing material and striving to improve conduction. The result was an overall increase of 25% in the number of calorimeter runs. This was significant since most items measured during the de-inventory period required calorimetery. We continue to strive for maximum speed with investigations into configurations that facilitate the end-point prediction method through improved heat transfer. We describe our experiences to optimize heat-flow and dub it our quest for, “Positive Internal Heat Goodness.”