The Hanford nuclear reservation in Washington state was initially created during World War II for the production of plutonium to be used in atomic bombs. A perceived need for a large increase in the number of nuclear weapons spurred expansions in production facilities at Hanford through the 1960's, and production was continued through the mid 1980's. The production process included irradiation of uranium fuel in reactors followed by chemical separation of the plutonium from the other fuel constituents, and finally transformation of plutonium nitrate to plutonium metal. The various steps in the process produced large amounts of radioactive as well as chemical hazardous waste. Some of this waste was released to the environment either through deliberate disposal methods or by leaks in transfer and storage systems. As a result, the soil at many areas of Hanford is contaminated to a point at which it would be unsafe for human contact for more than a short period of time. The current focus of efforts at Hanford is cleanup of the environment as well as decommissioning of the facilities. As part of the cleanup process, future land use must be determined which will then affect the scale of the remediation effort. The proposed land use will determine the residual contamination which will be left after all remediation is complete and access is allowed to the site. This document details the process for determining the residual contamination levels associated with various land use options. Some possible land use options are explained in the form of exposure scenarios. These scenarios give data in the form of exposure factors which describe the possible exposure level of an individual to contaminated media. Once the exposure factors are determined, they can be used in the equations outlined in the Hanford Site Risk Assessment Methodology to calculate preliminary remediation goals. These goals are presented as contaminant concentrations in environmental media which are the maximum allowable in order to meet regulatory limits. The limits are expressed either as a risk for carcinogens, or as a hazard quotient for non-carcinogens. / Graduation date: 1997

Graduation date: 1997

Thesis (Ph. D.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2002. / Includes bibliographical references.

published_or_final_version / Physics / Master / Master of Philosophy

published_or_final_version / Radioisotope / Master / Master of Philosophy

published_or_final_version / Mechanical Engineering / Master / Master of Philosophy

No description available.

Thesis (M. Phil.)--University of Hong Kong, 1991.

Thesis (M.S. in engineering)--Washington State University, August 2005. / Includes bibliographical references.

>Magister Scientiae - MSc / Radon is a naturally occurring radioactive element in the 238U decay series that is found in high concentrations in certain geological formations such as Caves. Exposure to high concentrations of radon has been positively linked to the incidence of lung cancer. This study used Electret ion chambers and the RAD7 continuous radon monitor to measure radon concentrations in the Cango Caves in the Western Cape Province, South Africa. Measurements were taken during summer i.e. February 2004 and March 2005. The results for the radon activity concentrations range from the minimum of about 800 Bq.m-3 to a maximum of 2600 Bq.m-3. The two techniques give very similar results, though the Electret ion chamber results appear to be consistently higher by a few percent where measurements were taken at the same locations. A mathematical model has been developed to investigate the radon concentrations in the Cave. Diffusion and ventilation have been considered as mechanisms for explaining the distribution of radon concentrations. The ventilation rate in the Cave has been estimated under certain assumptions, and it is found to be about 7 ×10−6 s−1 for the Van Zyl hall which is the first large chamber in the Cave. The radon concentration increases as one goes deeper into the Cave, but then becomes fairly constant for the deeper parts. The annual effective dose that the guides are exposed to in the Cave as a result of the radon concentrations, depends strongly on the time that they spend in the Cave and in which, halls they spend most of their time in the Cave. The initial results indicate an annual effective dose of 4-10 mSv, but this needs to be further investigated. / South Africa