David M. Hamby

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  • D M Hamby
  • Environmental monitoring and assessment
  • 1994
Mathematical models are utilized to approximate various highly complex engineering, physical, environmental, social, and economic phenomena. Model parameters exerting the most influence on model results are identified through a 'sensitivity analysis'. A comprehensive review is presented of more than a dozen sensitivity analysis methods. This review is(More)
Modeling the movement and consequence of radioactive pollutants is critical for environmental protection and control of nuclear facilities. Sensitivity analysis is an integral part of model development and involves analytical examination of input parameters to aid in model validation and provide guidance for future research. Sensitivities of 21 input(More)
A radiation dose distribution has been calculated for an individual exposed to tritium oxide (tritiated water vapor) in the atmosphere. A specific activity model was used that is similar to that detailed in the Nuclear Regulatory Commission's Regulatory Guide 1.109. The values of 19 parameters are sampled consistent with assigned probability distributions(More)
Specific activity models are frequently used to estimate the concentration of tritium oxide in vegetation. In such models, a single value represents the ratio (R) of the specific activity of tritium oxide in vegetation to the specific activity of atmospheric tritium oxide. Federal agencies such as the Nuclear Regulatory Commission and the Environmental(More)
Inhalation exposures of 131I may occur in the physical form of a gas as well as a particulate. The physical characteristics pertaining to these different types of releases influence the intake and subsequent dose to an exposed individual. The thyroid dose received is influenced by the route through which 131I enters the body and its subsequent clearance,(More)
Previous research has shown that people err when making decisions aided by probability information. Surprisingly, there has been little exploration into the accuracy of decisions made based on many commonly used probabilistic display methods. Two experiments examined the ability of a comprehensive set of such methods to effectively communicate critical(More)
Environmental releases of tritium oxide at a number of Department of Energy nuclear weapons facilities contribute to a significant portion of environmental dose. Several conversion factors are utilized in the estimation of human impact from these releases, e.g., dispersion coefficients, consumption rates, uptake factors, transport factors, dose conversion(More)
The production of weapons-grade nuclear materials and their by-products has resulted in a number of releases from United States Department of Energy facilities. 131I, a fission by-product, is one of the most common radionuclides generated and released to the environment. It is known that there are differences in various physiological parameters over all age(More)
Measured tritium oxide concentrations in air at various offsite locations are compared with concentrations predicted by three computer codes that are utilized at the Savannah River Site to estimate doses to maximally exposed offsite individuals. Annual average concentrations calculated by the computer models were compared with measured average(More)
The ICRP 66 lung model may be used to determine dose estimates for members of the public via the inhalation pathway. A significant source of uncertainty in internal dosimetric modelling is due to particulate deposition in regions of the respiratory tract. Uncertainties in estimates of particulate deposition are present because model input parameters have(More)