Abstract
The calorimeter in the transfer area in building 7920 is used to measure the amount of Pu-238 inside of an ORISC/FSO assembly before loading into the CV and shipping container. The equipment is used in three specific configurations: zero measurement (nothing in the sample cup), FSO measurement (actual measurement of Pu-238), and reference calibration measurement (using the reference FSO as a known heat source). System checks were performed in July of 2023 in preparation for scheduled material loadout. During these checks, it was discovered that the reference FSO had experience an electrical short in the heater cable and was no longer functional. The calorimeter was in the reference calibration measurement configuration at this time. Facility management was notified when the damage was discovered. The data from the Yokogawa recorder was pulled and analyzed for a span of time between September of 2022 and July of 2023. An unusual spike was found in the sample cup temperature data that started on October 19th and ended on October 20th. The sample cup reached a temperature of 191.1 degrees Celsius (°C). The maximum allowable temperature for the calorimeter thermopile to reach is 220°C based on the manufacturer statement in Appendix B. The calorimeter thermopile and the sample cup thermocouple are physically close to each other; therefore, the data suggests that the calorimeter itself never saw a temperature in excess of 191.1°C. There was physical damage to the cable, tape, and insulation that suggests that the temperature reached a higher value in some locations within the sample cup than the data shows. Due to this discrepancy, testing of the calorimeter was required to confirm that the calorimeter is functioning the same as it was before the electrical short. The intent of this report is to access the functionality of the calorimeter and determine if it is acceptable to use for Pu-238 loadout material measurement. Testing showed that it is functionally equivalent to the initial calibration that was performed in the summer of 2021 and cleared to be used for its intended purposes.
