Independent determination of the accuracy of the OSTR stack gas monitor and its operational application
- Battelle-Pacific Northwest Laboratories, Richland, WA (United States)
- Oregon State University Radiation Center (United States)
This study was undertaken to determine the accuracy of the stack gas monitor, using techniques which were independent of the monitoring system itself. Samples of argon-41 to be used as the standards in this study were carefully produced in the thermal column of the OSTR and counted on a Ge(Li) detector which was connected to a multichannel analyzer (MCA). As the argon-41 standard in the gas sample flask decayed, the concentration of the argon-41 was compared to the output of the Ge(Li)/MCA system. This established a calibration curve for the counting system, whereby a sample with an unknown concentration of argon-41 could be counted and the subsequent count rate from the sample converted to a concentration expressed in mCi per milliliter. Gas samples were extracted from various points in the reactor exhaust system and the concentrations of argon-41 were determined by counting on the Ge(Li)/MCA system. Each sample concentration was then compared to the argon-41 concentration indicated by the stack gas monitor. The initial results indicated that, although possibly intermittent, the argon-41 concentrations displayed by the stack gas monitor were often approximately 50% of those predicted by analysis of individual samples from the exhaust system. Several possible sources for the discrepancy were checked, including the method of SGM calibration, uneven mixing of exhaust air and argon-41 in the reactor building exhaust stream, and dilution of the gas concentration in the SGM system by air leakage into the system. After considerable effort, the latter cause was found to be the culprit, due to an aging gasket around the stack monitor's moving particulate-filter-paper housing.
- Research Organization:
- General Atomic Co., San Diego, CA (United States); Argonne National Laboratory-West, Idaho Falls, ID (United States)
- OSTI ID:
- 21149359
- Report Number(s):
- INIS-US--09N0101; TOC--14
- Country of Publication:
- United States
- Language:
- English
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