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Title: EVALUATION OF AN UPWARD TREND IN BACKGROUND COUNT RATES FROM A STACK PARTICULATE CONTINUOUS AIR MONITOR

Abstract

The Pacific Northwest National Laboratory (PNNL) operates the Radiochemical Processing Laboratory (RPL), which is a multi-purpose, non-reactor nuclear research facility. Regulations require both continuous sampling and monitoring of radioactive particulates and tritium gas in the exhaust from the main stack. Releases of other radioactive gases, including planned releases of radon, are tracked separately in a database and reported. During the 2015 calibration of the RPL stack continuous air monitor (CAM), measured alpha and beta background count rates were much higher than expected, especially when compared to count rates from previous calibrations. The source of the higher background count rates was examined by trending of historical CAM measurements and a comparison to the sampler data. The analysis revealed that the sample results showed no increase in emissions, whereas the CAM showed a steady increase in count rates. Ultimately, the CAM filter was analyzed and found to contain higher-than-normal background levels of 220Rn progeny. Assessments were performed to determine the cause of the increased background values, including reviews of building research activities, radioactive material usage and storage, adequacy of procedures, and the potential for internal CAM contamination. Project reviews determined that a research activity involving 228Th was left in a semi-stored state,more » resulting in 220Rn being released from a hot cell into the exhaust system. The 228Th source material was subsequently repackaged and contained resulting in a decrease of CAM background count rates. An estimate of the 220Rn release was made and the contribution to the annual offsite dose from the facility was calculated. The released activity and reported dose results were well below the permit limits for the facility.« less

Authors:
 [1]; ORCiD logo [1];  [1];  [1];  [1];  [1]; ORCiD logo [1];  [1];  [1]
  1. BATTELLE (PACIFIC NW LAB)
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1542066
Report Number(s):
PNNL-SA-131367
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Health Physics
Additional Journal Information:
Journal Volume: 115; Journal Issue: 4
Country of Publication:
United States
Language:
English
Subject:
radon, 220Rn, environmental assessment, air monitoring, effuents

Citation Formats

Rishel, Jeremy P., Barnett, John M., Mozhayev, Andrey V., Dutcher, Elliott B., Colby, Scott A., Carter, Gregory L., Patello, Gertrude K., Steen, Franciska H., and Hanson, Eric M. EVALUATION OF AN UPWARD TREND IN BACKGROUND COUNT RATES FROM A STACK PARTICULATE CONTINUOUS AIR MONITOR. United States: N. p., 2018. Web. doi:10.1097/HP.0000000000000901.
Rishel, Jeremy P., Barnett, John M., Mozhayev, Andrey V., Dutcher, Elliott B., Colby, Scott A., Carter, Gregory L., Patello, Gertrude K., Steen, Franciska H., & Hanson, Eric M. EVALUATION OF AN UPWARD TREND IN BACKGROUND COUNT RATES FROM A STACK PARTICULATE CONTINUOUS AIR MONITOR. United States. doi:10.1097/HP.0000000000000901.
Rishel, Jeremy P., Barnett, John M., Mozhayev, Andrey V., Dutcher, Elliott B., Colby, Scott A., Carter, Gregory L., Patello, Gertrude K., Steen, Franciska H., and Hanson, Eric M. Mon . "EVALUATION OF AN UPWARD TREND IN BACKGROUND COUNT RATES FROM A STACK PARTICULATE CONTINUOUS AIR MONITOR". United States. doi:10.1097/HP.0000000000000901.
@article{osti_1542066,
title = {EVALUATION OF AN UPWARD TREND IN BACKGROUND COUNT RATES FROM A STACK PARTICULATE CONTINUOUS AIR MONITOR},
author = {Rishel, Jeremy P. and Barnett, John M. and Mozhayev, Andrey V. and Dutcher, Elliott B. and Colby, Scott A. and Carter, Gregory L. and Patello, Gertrude K. and Steen, Franciska H. and Hanson, Eric M.},
abstractNote = {The Pacific Northwest National Laboratory (PNNL) operates the Radiochemical Processing Laboratory (RPL), which is a multi-purpose, non-reactor nuclear research facility. Regulations require both continuous sampling and monitoring of radioactive particulates and tritium gas in the exhaust from the main stack. Releases of other radioactive gases, including planned releases of radon, are tracked separately in a database and reported. During the 2015 calibration of the RPL stack continuous air monitor (CAM), measured alpha and beta background count rates were much higher than expected, especially when compared to count rates from previous calibrations. The source of the higher background count rates was examined by trending of historical CAM measurements and a comparison to the sampler data. The analysis revealed that the sample results showed no increase in emissions, whereas the CAM showed a steady increase in count rates. Ultimately, the CAM filter was analyzed and found to contain higher-than-normal background levels of 220Rn progeny. Assessments were performed to determine the cause of the increased background values, including reviews of building research activities, radioactive material usage and storage, adequacy of procedures, and the potential for internal CAM contamination. Project reviews determined that a research activity involving 228Th was left in a semi-stored state, resulting in 220Rn being released from a hot cell into the exhaust system. The 228Th source material was subsequently repackaged and contained resulting in a decrease of CAM background count rates. An estimate of the 220Rn release was made and the contribution to the annual offsite dose from the facility was calculated. The released activity and reported dose results were well below the permit limits for the facility.},
doi = {10.1097/HP.0000000000000901},
journal = {Health Physics},
number = 4,
volume = 115,
place = {United States},
year = {2018},
month = {10}
}