Graduate Thesis Or Dissertation

 

The quantitative evaluation of radiological workplace indicators Public Deposited

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https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/5t34sn14x

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  • Two research studies at the U.S. Department of Energy's Hanford Site and Rocky Flats Environmental Technology Site (RFETS) explore the quantitative relationship between surface contamination, airborne radioactivity, worker intakes, and subsequent dose. In the first study, resuspension factors are developed and evaluated at the U.S. Department of Energy's (U.S. DOE) Hanford facility currently undergoing decommissioning, decontamination, and demolition. Resuspension factors are developed from historical breathing zone and general area grab air sample data coupled temporally and spatially with loose surface contamination data. A Monte Carlo approach termed the proportional contribution method (PCM) is used to innovatively calculate the uncertainty of a resuspension factor by randomly assigning a proportional contribution of each surface contamination survey smear data point to airborne radioactivity. For the purpose of work planning, site procedures require that radiation protection personnel use a l x 10⁻⁵ m ⁻¹ resuspension factor. Monte Carlo simulations result in geometric mean general area grab and breathing zone air sample resuspension factors of 2.6 × 10⁻⁵m ⁻¹ (× or ÷) 12 and 4.7 x 10⁻⁶ (× or ÷) 17, respectively. Results of this study suggest the 1 × 10⁻⁵ m ⁻¹ resuspension factor routinely used at the study facility is a reasonable estimate. The second study investigates the accuracy of the nasal swab test in predicting acute intakes at RFETS. Ratios of intakes confirmed by bioassay (Bq) to nasal swab results (Bq) are developed for 323 acute intake investigations. A novel biostatistics approach is used to assess the accuracy and predictive value of the nasal swab diagnostic test in predicting acute intakes. The maximum upper bound ratio of intakes confirmed by bioassay > DL to nasal swab results > DL is 1,295. A linear regression revealed the nasal smear intakes are weakly correlated (R = 0.25 and R²= 0.063) to confirmed intakes. The sensitivity of the nasal swab test is low at 0.166, with a false negative result of 0.834. The specificity of the nasal swab test is 0.774, with a false positive result of 0.226. The predictive value positive of the nasal swab test is 0.600. The low sensitivity and predictive values, in the context of the study population, suggest the nasal swab diagnostic test does not add any useful information in predicting intakes.
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