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Environmental pathway analysis of a radioactive zirconium sand uploading facility

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Abstract

Graduation date: 2002The Teledyne Wah Chang facility is a manufacturer of the rare metal\ud zirconium. The facility has been in constant production since 1956. In 1973\ud an attempt to utilize different sand ore sources from Nigeria and India in a\ud new carbiding process, prior to chlorination, failed. The resulting\ud byproducts of the carbiding process and approximately 2000 kg of zircon\ud sand ore were lost in what is now called the Former Sand Unloading Area.\ud In 1982, Teledyne Wah Chang facility was listed as a Superfund site. The\ud Former Sand Unloading Area was contaminated with naturally-occurring\ud radioactive material. After being listed, Teledyne Wah Change began the\ud Remedial Investigation / Feasibility Study process in an attempt to cleanup\ud the Former Sand Unloading Area and other contaminated sites.\ud Afterwards, it was discovered that the remediation goals for the Former\ud Sand Unloading Area only addressed exposure pathways to current workers\ud on site. No consideration had been given to possible future occupants under\ud long term exposure scenarios. In this study, three scenarios were modeled\ud to illustrate the most plausible occupancy uses of the Former Sand\ud Unloading Area. The scenarios were: current industrial worker,\ud commercial worker, and a residential occupant. The pathways that were\ud used to model the exposure scenarios were, direct external radiation,\ud inhaled and ingested soil, and plant consumption. The RESRAD computer\ud code was used to estimate the dose rates to current and future occupants\ud working or living on the Former Sand Unloading Facility. The maximum\ud resulting radiation dose received was 16.7 mrem y⁻¹ for the industrial\ud worker scenario. The lowest maximum radiation dose received was 13.6\ud mrem y⁻¹ for the commercial worker scenario. The most conservative\ud assumptions and efforts were used to ensure the maximum dose rate was\ud modeled. The maximum radiation dose rate received at the Former Sand\ud Unloading Area was below the regulatory maximum allowable exposure\ud limit of 25 mrem y⁻¹

Year: 2001
OAI identifier: oai:ir.library.oregonstate.edu:1957/32452
Provided by: ScholarsArchive@OSU
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