Literature Review and Assessment of Plant and Animal Transfer Factors Used in Performance Assessment Modeling (open access)

Literature Review and Assessment of Plant and Animal Transfer Factors Used in Performance Assessment Modeling

A literature review and assessment was conducted by Pacific Northwest National Laboratory (PNNL) to update information on plant and animal radionuclide transfer factors used in performance-assessment modeling. A group of 15 radionuclides was included in this review and assessment. The review is composed of four main sections, not including the Introduction. Section 2.0 provides a review of the critically important issue of physicochemical speciation and geochemistry of the radionuclides in natural soil-water systems as it relates to the bioavailability of the radionuclides. Section 3.0 provides an updated review of the parameters of importance in the uptake of radionuclides by plants, including root uptake via the soil-groundwater system and foliar uptake due to overhead irrigation. Section 3.0 also provides a compilation of concentration ratios (CRs) for soil-to-plant uptake for the 15 selected radionuclides. Section 4.0 provides an updated review on radionuclide uptake data for animal products related to absorption, homeostatic control, approach to equilibration, chemical and physical form, diet, and age. Compiled transfer coefficients are provided for cow’s milk, sheep’s milk, goat’s milk, beef, goat meat, pork, poultry, and eggs. Section 5.0 discusses the use of transfer coefficients in soil, plant, and animal modeling using regulatory models for evaluating radioactive waste …
Date: July 20, 2003
Creator: Robertson, David E.; Cataldo, Dominic A.; Napier, Bruce A.; Krupka, Kenneth M. & Sasser, Lyle B.
System: The UNT Digital Library
Insulators and Materials for Closed-Spaced Thermoelectric Modules (open access)

Insulators and Materials for Closed-Spaced Thermoelectric Modules

The primary goal of this Phase I program has been accomplished: to demonstrate a ceramic, injection-molded eggcrate which will form the support structure for a close-spaced thermoelectric module which can operate at significantly higher temperatures than presently possible with such modules. It has been shown that yttria-stabilized zirconia is compatible at high temperatures with typical thermoelectric materials (TAGS, SnTE and PbTe) and that it can serve as a barrier between them to preclude cross-contamination and doping of the constituents of one leg type by those from the other. Using a 2 x 2 ceramic eggcrate, thermally sprayed molybdenum electrodes have been deposited on a test module which effectively seal each pocket, further reducing the possibility of migration of elements. Based on these results the next tasks are to refine the design of the injection tool and the injection parameters to produce consistent results and to allow increase in the size of the module to that on which commercial, high-temperature thermoelectric modules can be based. In addition, development of the fabrication techniques for segmented thermoelectric legs for use with these ceramic eggcrates at high temperatures must be continued.
Date: July 20, 2003
Creator: Snowden, Donald P.
System: The UNT Digital Library