WPM-E1 - Environmental Montioring Orange B 14:30 - 15:45
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| Chair(s): Tim Jannik, Paul Charp
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WPM-E1.1
14:30 The Creation of a Moose Voxel Model: Part I - Segmentation HR Graham*, University of Ontario Institute of Technology
; EJ Waller, University of Ontario Institute of Technology
Abstract: In order to generate more accurate dose estimates for radiological environmental assessments within the Indigenous Canadian community, it would be advantageous to have voxel models of species that are part of a traditional Indigenous diet. The first species to be modelled as part of this effort is the moose. The moose is an important part of a traditional diet, and is doubly interesting because the diet of the moose varies greatly depending on the time of year. The diet of a moose can be ground foliage, twigs from trees, or mostly aquatic plants depending on the time of year. Due to this variety in their diet, there are many possible intake pathways for radiation. When creating this voxel model, an effort is being made to use software that is open source, so that the technique that is being used can be replicated without great cost. In order to create the voxel model, all the important organs and structures of the CT scan need to be segmented. This was done using a program called 3D Slicer, which can be used for analysis and visualization of medical images. Various tools in the software such as threshold, island, paint, level tracing, grow from seeds, and smoothing were utilized to create these segments.
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WPM-E1.2
14:45 The radiation dose response of Zebra Mussels (Dreissena polymorpha) from the Great Lakes M Tzivaki*, University of Ontario Institute of Technology
; EJ Waller, University of Ontario Institute of Technology
Abstract: The Electron Paramagnetic Resonance (EPR) spectra and dose response of the invasive species of bivalve mollusks zebra mussel (Dreissena polymorpha) was studied with the intention of determining their usefulness as indicators of radioactive material contamination in the environment. The shells were irradiated with a 15 MeV LINAC to doses from 1 to 10 Gy and a Cs-137 gamma irradiator to doses between 0.5 and 3 Gy. Reference measurements and dosimetry were done with alanine powder and OSLDs. Zebra mussels have a strong EPR signal, even when unirradiated, that could be measured and used for determining the dose response. The effects of sample packing density were studied and a normalization methodology is proposed. Both the peak-to-peak signal height and the double integral of the EPR signal show a linearity with the absorbed dose, that is evident even under varying measurement conditions for bulk samples at doses over 2Gy. For lower doses a careful tracking of each sample gives insight into the irradiated dose.
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WPM-E1.3
15:00 Environmental Thermoluminescent Dosimetry Program of Nevada National Security Site na Liu*, Xianan
; W Warren, Ronald
Abstract: This work presents the summary of thirty years of TLD monitoring results from Nevada National Security Site (NNSS, formerly the Nevada Test Site). Over a hundred environmental locations were measured from control, background, and operations sites. The annual exposure rate from the background and non-radiologically impacted operations locations ranged from 59 to 163 milliRoentgens (mR). These results are similar to the offsite exposure rates (100 to 160 mR/y) measured by Community Environmental Monitoring Program (CEMP, Health Physics 101: 606 to 617, 2011), and are considered the background levels for those areas. The TLD exposure rates from radiologically impacted locations were analyzed and compared with the results calculated from in-situ gamma spectroscopy measurements. The effective half-time was estimated from 13 to 25 years based on the decrease of the exposure rate of each TLD location.
This work was done by Mission Support and Test Services LLC, under Contract No. DE-NA0003624 with the U.S. Department of Energy. DOE/NV/03624--0402
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WPM-E1.4
15:15 Effective environmental Half Life of 134Cs and 137Cs in Fukushima Prefecture When Compared to Theoretical Decay Models JM Hayes*, Colorado State University
; TE Johnson, Colorado State University; D Anderson, Fukushima University; K Nanba, Fukushima University
Abstract: On March 11, 2011, a 9.0 magnitude earthquake struck the Tohoku region of Japan. The earthquake caused a 15 meter tsunami that bombarded the east coast of the island nation. Amongst the damage was the Fukushima Daiichi nuclear reactor that lost onsite power and was unable to cool the reactor cores. The reactors melted down and released a plume of radionuclides including cesium-137 (t1/2=30.08 years), cesium-134 (t1/2=2.06 years), and iodine-131 (t1/2=8.04 days) into the environment. Radiocesiums are the long-lived radionuclides of concern that were deposited along the plume and were readily bound by the soil. Physical decay models are typically used to determine the reduction in external radiation dose over time. However, these physical decay models do not take into account physical removals by wind and water erosion, or sedimentation in soil outside expected depths. Thirty five fixed dose rate monitors were used to record dose rates at one month intervals from the time of installation in April of 2012 until December of 2018, utilized to estimate the effective half-life for radiocesium contamination based on external radiation dose rates. The effective half-life of cesium in the environment was calculated at 3.23 years ± .48, and compared to a theoretical half-life of 7.78 years.
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WPM-E1.5
15:30 Public Health Evaluation of Radiologic Contamination in St. Louis – Coldwater Creek JJ Dyken, ATSDR
; E Evans, ATSDR; A Trubiano, ATSDR; PA Charp*, CDC/ATSDR
Abstract: Coldwater Creek borders the St. Louis Airport Site, a former disposal location for uranium purification wastes produced during and after the Manhattan Project. From the 1940s through the early 1990s portions of these wastes entered the creek and were transported downstream toward the Missouri River. Over time, flooding of the creek distributed contaminants to nearby areas, including public parks and private property. The U.S. Army Corps of Engineers and the U.S. Department of Energy Formerly Utilized Sites Remedial Action Program are currently identifying and cleaning up affected properties using a remedial action goal of 0.6 Bq of Th-230 per gram of soil. Within the past decade, a community group in North St. Louis using social media self-identified a perceived increase in appendix and other cancers in members of their 1980s high school class and asked for ATSDR’s assistance. The group stated that, as students, many of them frequented Coldwater Creek for recreational activities. Working with the community, ATSDR identified appropriate time-activity parameters to describe past and recent exposures near the creek. ATSDR used recent data on radiological contamination in residential areas to estimate dose and risk from those exposures. The results indicated that past estimated radiation doses could have increased the lifetime risks of lung cancer, bone cancer, or leukemia.
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