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Stack Monitoring at the BATAN Teknologie (BaTek) Facility and Implications for Tracking Medical Isotope Plumes Justin McIntyre 1 , Stephanie Doll 1 , Paul Eslinger 1 , Harry Miley 1 , Amanda Prinke 1 , Vincent Woods 1 , Ulrich Stoehlker 2 , Susilo Widodo 3 ,Yudi Imardjoko 3 , Johannes Robert Dumais 3 , Pujadi Marsoem 3 , Gatot Suhariyono 3 , 1 Pacific Northwest National Laboratory (PNNL), 2 Comprehensive Nuclear-Test-Ban Treaty-International Data Center (CTBTO-IDC), 3 BATAN Introduction With increased interest in the radioxenon emissions from radiopharmaceutical production, it has become important to study the best methods to incorporate the data into the International Data Center (IDC) analysis of radioxenon stations. A first step is to actually obtain spectroscopy from stack emissions and to apply atmospheric modeling and isotopic ratios to best screen out mundane medical isotope signatures from daily radioxenon data sets. As part of this effort, a small stack monitoring system was developed, assembled, and deployed during 2012 by a joint CTBTO-IDC/BATAN/PNNL team at the BaTek medical isotope production facility in Jakarta, Indonesia. Equipment The existing stack monitor is pictured below and is a typical commercial monitoring unit with detection capability for particulate via small filters, iodine and bromine trapping via charcoal traps, and noble gas detection via beta detection. New Stack Monitor The new stack monitor was placed in line with the current system to comply with the monitoring requirements for the BaTek facility. The nuclear detector was purchased by the European Union III Project, proposed by the Provisional Technical Secretariat of the CTBTO. The nuclear detector consisted of a 5x5cm LaBr 3 crystal with matching photomultiplier and data acquisition system. Readout was via a stand-alone laptop and data files were saved every 10 minutes automatically. PNNL assembled a whole-air sampling system that presented a known volume of air to the detector from the stack. See diagram: Spectral Data The choice of a mid-range energy resolution gamma detector made it possible to measure several important gamma rays from radioxenon and short-lived radiokrypton isotopes. In addition, the detector has an internal gamma-ray source, 138 La, which provides several gamma rays for energy calibration. The spectra below shows the response of the detector to both normal background (no stack emissions) and during stack emissions. 138 La Data Analysis Automatic Data Viewing and Analysis software was developed for the rapid processing of very large sets of data. Data sets are animated and presented to the user in an accelerating manner, allowing the rapid observation of analyzed samples over a large time scale. Off normal and transient events can be more easily observed and flagged for further analysis. Multiple spectra can be integrated over time and specific regions of interest investigated. From the automated data analysis trend charts were generated that showed the trending of radioxenon emissions that were due to processing within the facility (see chart below). While there were several interesting emissions that included short-lived radiokrypton isotopes, the objective was to quantify the radioxenon emissions only. These emissions could then be used in forward atmospheric transport models (ATMs) to calculate the impact on the regional network and the nearby Transportable Xenon Laboratory (TXL). The week-long trend data chart above shows the transient nature of the 135 Xe (250-keV) and 133 Xe (81-keV). Included is a gamma from 137 Cs which is a stable background gamma line and a gamma line from 131 I which is trapped on a nearby charcoal filter. It is clear from the chart that the processing gives both long and very rapid releases during the course of the work week. Local TXL Hits The CTBTO deployed a SAUNA-based TXL to Jakarta during March of 2012. The unit was placed at the BATAN facility and was located about 25km from the BaTek isotope facility. A strong hit of 133 Xe, 133m Xe, and 135 Xe was detected by the system on April 05, 2012, and was supported by ATM backtracking. The chart below shows the beta-gated gamma spectra. The ATM modeling (seen in the diagram below) clearly shows that the plume from the BaTek site (dark circle), was encompassed by the ATM back track calculation done at the TXL site (star). This data was taken several months before the deployment of the stack monitor and so it is not possible to compare the concentration of the plume with what was released at the stack. Integrated 12-hour concentration near the surface in a plume based on hypothetical release of 1×10 13 Bq of 133 Xe released uniformly over 24 hours on April 4, 2012. Unfortunately, there have been no measured releases from the stack that have been detected by the TXL to date due to weather patterns and equipment failure. 0 10 1 10 2 10 3 10 4 10 0 50 100 150 200 250 300 Gamma Graph (0 ): C o i n ci d en ce Gamma C ount s Gamma Energy Conclusions The stack monitor developed by a joint CTBTOIDC/ BATAN/ PNNL effort has provided several months of highquality spectral data. These data sets have provided invaluable informaJon that will be used to develop future stack monitoring equipment and more importantly reduce the impact that stack emissions from medical isotope producJon has on the IMS radioxenon network. Next Steps Ongoing work will include ATM calculaJons for regional radioxenon staJons: Australia (AUX04, AUX09) and New Zealand (NZX46), as well as the new posiJon of the TXL unit in eastern Indonesia. In addiJon work conJnues on the development of methods to incorporate the stack data sets into ongoing event categorizaJon. Contact: Justin McIntyre (509) 375-5596 [email protected] 133 Xe 135 Xe PNNL-SA-95836 T1-P52
