Resource Type

States

ANL Technical Support Program for DOE Environmental Restoration and Waste Management Annual Report October 1993 - September 1994 (open access)

ANL Technical Support Program for DOE Environmental Restoration and Waste Management Annual Report October 1993 - September 1994

A program was established for DOE Environmental Restoration and Waste Management (EM) to evaluate factors that are anticipated to affect waste glass reaction during repository disposal, especially in an unsaturated environment typical of what may be expected for the proposed Yucca Mountain repository site.
Date: June 1995
Creator: Bates, John K.
System: The UNT Digital Library
D0 Silicon Upgrade: Cryogenic Lines at Refrigerator : Thermal Contraction Analysis of Four Cryogenic Utility Lines for the D0 Upgrade (open access)

D0 Silicon Upgrade: Cryogenic Lines at Refrigerator : Thermal Contraction Analysis of Four Cryogenic Utility Lines for the D0 Upgrade

The cryogenic lines GHE and LN2 contain two lines each, one for supply and the other for return. The tubing was stress analyzed per ASME code for pressure piping, standard ANSI/ASME B31.3. A commercial pipe stress analysis and design system by ALGOR{reg_sign} was used for the analysis along with the calculated maximum stress, 25,050 psi. They were all analyzed for combined pressure, thermal movement, and dead weight and all the stresses were below this allowable stress limit. There are sections of the transfer lines that will be increased from a 1-1/2-inch vacuum jacket to a 2-inch vacuum jacket. This increase accounts for the maximum displacement, 0.466-inch in troubled areas as seen in subsequent drawings. The greatest displacement allowed for a 1-1/2-inch vacuum jacket is 0.421-inch for a 1/2-inch pipe on the nominal centerline. The greatest displacement allowed for a 2-inch vacuum jacket is 0.658-inch. We will have a clearance of 0.192-inch when using the 2-inch vacuum jacket.
Date: June 23, 1995
Creator: Kuwazaki, Andrew
System: The UNT Digital Library
D0 Silicon Upgrade: Thermal Contraction Analysis of the Solenoid and VLPC Cryogenic Transfer Lines for the D0 Upgrade (open access)

D0 Silicon Upgrade: Thermal Contraction Analysis of the Solenoid and VLPC Cryogenic Transfer Lines for the D0 Upgrade

The stresses developed in the solenoid and VLPC transfer lines have been investigated with the PipePlus v4.5 software package from Algor. 4 cases were considered for each transfer line and the following results were obtained. Pipe deflections have also been kept to a minimum by carefully considering the location of spider guides. Their placement should be as close as possible to the locations shown in Figures 4-7. With regard to chosen pipe sizes, the 2.5-inch OD Cu radiation shield in the solenoid transfer line should be replaced with a 3.5-inch OD tube. The vacuum jackets should also be replaced with 5-inch or larger pipe. These changes should safely accommodate the maximum displacements caused by thermal loading. This engineering note investigates the ability of the solenoid and VLPC cryogenic transfer lines to accommodate thermal stresses. The solenoid and VLPC transfer lines are similar in their construction in that they consist of an outer vacuum jacket, liquid nitrogen supply and return lines, a copper thermal radiation shield, and liquid helium supply and return lines. See Figure 1 for details on their specific construction. Line drawings for the solenoid and VLPC transfer lines are shown in Figures 2 and 3, respectively. The transfer …
Date: June 6, 1995
Creator: Leicht, Todd M.
System: The UNT Digital Library
D0 Silicon Upgrade: Transfer Line Branch Considerations for Solenoid & VLPC (open access)

D0 Silicon Upgrade: Transfer Line Branch Considerations for Solenoid & VLPC

The transfer line for the solenoid currently has a dead branch on it. Issues regarding the solenoid transfer line also apply to the VLPC transfer line. Issues that need to be addressed are: (1) What is the heat load on the branch? (2) Would it be a good idea to run the LN2 radiation shield on the branch? (3) What are the thermal acoustic oscillation parameters of a dead headed branch? A simple remedy, although not analyzed was to install a jumper with a flow restriction at the end of the helium piping to allow a small flow to pass from supply to return. Thus eliminating a stagnant gas volume in which pressure pulses would develop. (4) Do we need to have a vapor trap to keep liquid from sloshing back and forth from the cold end to the warm end? (5) Comment: The tee that passes the 2-phase return into the nested LHe supply/return pipe should be pointed up so that the volume of transfer line acts sort of like a phase separator full of liquid. It is very difficult to predict the behavior of the dead ended branch. Therefore the conservative thing to do is to keep the …
Date: June 16, 1995
Creator: Rucinski, Russ
System: The UNT Digital Library
Department of Energy Review of Laboratory Programs for Women Points-of-Contact Committee: Comparative Report, June 1995 (open access)

Department of Energy Review of Laboratory Programs for Women Points-of-Contact Committee: Comparative Report, June 1995

A survey of the DOE facilities was undertaken by the Points-of-Contact for the DOE Review of Laboratory Programs for Women in order to gather data to be used as a baseline against which to measure future progress. We plan to look at current programs already in place and evaluate them with a view to deciding which programs are most effective, and selecting model programs suitable for implementation at other facilities. The survey focused on four areas: 1) statistical data, 2) laboratory policy, 3) formal and informal programs which affect the quality of life in the work environment, and career development and advancement, and 4) educational programs. Although this report focuses on women, the problems discussed affect all DOE facility employees.
Date: June 1, 1995
Creator: McLane, V. & Layne, A.
System: The UNT Digital Library
CO{sub 2} exchange, environmental productivity indices, and productivity of Agaves and Cacti under current and elevated atmospheric CO{sub 2} concentrations. Terminal report (open access)

CO{sub 2} exchange, environmental productivity indices, and productivity of Agaves and Cacti under current and elevated atmospheric CO{sub 2} concentrations. Terminal report

The research described in the proposal investigated net CO{sub 2} uptake and biomass accumulation for an extremely productive CAM plant, the prickly pear cactus Opuntia ficus-indica, under conditions of elevated CO{sub 2} concentrations for relatively long periods. The influences of soil water status, air temperature, and the photosynthetic photon flux (PPF) on net CO{sub 2} uptake over 24-h periods were evaluated to enable predictions to be made based on an Environmental Productivity Index (EPI). Specifically, EPI predicts the fraction of maximal daily net CO{sub 2} uptake based on prevailing environmental conditions. It is the product of indices for temperature, soil water, and intercepted PPF, each of which range from 0.00 when that index factor completely inhibits net CO{sub 2} uptake to 1.00 when no limitation occurs. For instance, the Water Index is 1.00 under wet conditions and decreases to 0.00 during prolonged drought. Although the major emphasis of the research was on net CO{sub 2} uptake and the resulting biomass production for O. ficus-indica, effects of elevated CO{sub 2} concentrations on root: shoot ratios and on the activities of the two carboxylating enzymes were also investigated. Moreover, experiments were also done on other CAM plants, including Agave deserti, Agave salmiana, …
Date: June 1, 1995
Creator: unknown
System: The UNT Digital Library
An atlas of thermal data for biomass and other fuels (open access)

An atlas of thermal data for biomass and other fuels

Biomass is recognized as a major source of renewable energy. In order to convert biomass energy to more useful forms, it is necessary to have accurate scientific data on the thermal properties of biomass. This Atlas has been written to supply a uniform source of that information. In the last few decades Thermal analysis (TA) tools such as thermogravimetry, differential thermal analysis, thermo mechanical analysis, etc. have become more important. The data obtained from these techniques can provide useful information in terms of reaction mechanism, kinetic parameters, thermal stability, phase transformation, heat of reaction, etc. for gas-solid and gas-liquid systems. Unfortunately, there are no ASTM standards set for the collection of these types of data using TA techniques and therefore, different investigators use different conditions which suit their requirements for measuring this thermal data. As a result, the information obtained from different laboratories is not comparable. This Atlas provides the ability to compare new laboratory results with a wide variety of related data available in the literature and helps ensure consistency in using these data.
Date: June 1, 1995
Creator: Gaur, S. & Reed, T. B.
System: The UNT Digital Library
Creep in Topopah Spring Member welded tuff. Yucca Mountain Site Characterization Project (open access)

Creep in Topopah Spring Member welded tuff. Yucca Mountain Site Characterization Project

A laboratory investigation has been carried out to determine the effects of elevated temperature and stress on the creep deformation of welded tuffs recovered from Busted Butte in the vicinity of Yucca Mountain, Nevada. Water saturated specimens of tuff from thermal/mechanical unit TSw2 were tested in creep at a confining pressure of 5.0 MPa, a pore pressure of 4.5 MPa, and temperatures of 25 and 250 C. At each stress level the load was held constant for a minimum of 2.5 {times} 10{sup 5} seconds and for as long as 1.8 {times} 10{sup 6} seconds. One specimen was tested at a single stress of 80 MPa and a temperature of 250 C. The sample failed after a short time. Subsequent experiments were initiated with an initial differential stress of 50 or 60 MPa; the stress was then increased in 10 MPa increments until failure. The data showed that creep deformation occurred in the form of time-dependent axial and radial strains, particularly beyond 90% of the unconfined, quasi-static fracture strength. There was little dilatancy associated with the deformation of the welded tuff at stresses below 90% of the fracture strength. Insufficient data have been collected in this preliminary study to determine …
Date: June 1, 1995
Creator: Martin, R. J., III; Boyd, P. J.; Noel, J. S. & Price, R. H.
System: The UNT Digital Library
Human Reliability Analysis for In-Tank Precipitation Alignment and Startup of Emergency Purge Ventilation Equipment. Revision 4 (open access)

Human Reliability Analysis for In-Tank Precipitation Alignment and Startup of Emergency Purge Ventilation Equipment. Revision 4

This report documents the methodology used for calculating the human error probability for establishing air based ventilation using emergency purge ventilation equipment on In-Tank Precipitation (ITP) processing tanks 48 and 49 after a failure of the nitrogen purge system following a seismic event. The analyses were performed according to THERP (Technique for Human Error Rate Prediction) as describes in NUREG/CR-1278-F.
Date: June 1, 1995
Creator: Shapiro, B. J. & Britt, T. E.
System: The UNT Digital Library
Report of ground water monitoring for expansion of the golf course, Salt Lake City, Utah, vitro processing site (open access)

Report of ground water monitoring for expansion of the golf course, Salt Lake City, Utah, vitro processing site

To determine the potential impacts of the proposed golf course expansion on the south side of the Vitro site, ground water data from the UMTRA Vitro processing site were evaluated in response to the U.S. Department of Energy (DOE) Uranium Mill Tailings Remedial Action (UMTRA) Project Office request. Golf in the Round, Inc., has proposed an expansion of the present driving range to include a 9-hole golf course on the UMTRA Vitro processing site, which is owned by the Central Valley Water Reclamation Facility (CVWRF). An expanded golf course would increase irrigation and increase the amount of water that could infiltrate the soil, recharging the unconfined aquifer. Increased water levels in the aquifer could alter the ground water flow regime; contaminants in the shallow ground water could then migrate off the site or discharge to surface water in the area. Dewatering of the unconfined aquifer on CVWRF property could also impact site contaminant migration; a significant amount of ground water extraction at CVWRF could reduce the amount of contaminant migration off the site. Since 1978, data have been collected at the site to determine the distribution of tailings materials (removed from the site from 1985 to 1987) and to characterize …
Date: June 1, 1995
Creator: unknown
System: The UNT Digital Library
Plutonium Consumption Program, CANDU Reactor Project: Feasibility of BNFP Site as MOX Fuel Supply Facility. Final report (open access)

Plutonium Consumption Program, CANDU Reactor Project: Feasibility of BNFP Site as MOX Fuel Supply Facility. Final report

An evaluation was made of the technical feasibility, cost, and schedule for converting the existing unused Barnwell Nuclear Fuel Facility (BNFP) into a Mixed Oxide (MOX) CANDU fuel fabrication plant for disposition of excess weapons plutonium. This MOX fuel would be transported to Ontario where it would generate electricity in the Bruce CANDU reactors. Because CANDU MOX fuel operates at lower thermal load than natural uranium fuel, the MOX program can be licensed by AECB within 4.5 years, and actual Pu disposition in the Bruce reactors can begin in 2001. Ontario Hydro will have to be involved in the entire program. Cost is compared between BNFP and FMEF at Hanford for converting to a CANDU MOX facility.
Date: June 30, 1995
Creator: unknown
System: The UNT Digital Library
Contaminant plumes containment and remediation focus area. Technology summary (open access)

Contaminant plumes containment and remediation focus area. Technology summary

EM has established a new approach to managing environmental technology research and development in critical areas of interest to DOE. The Contaminant Plumes Containment and Remediation (Plumes) Focus Area is one of five areas targeted to implement the new approach, actively involving representatives from basic research, technology implementation, and regulatory communities in setting objectives and evaluating results. This document presents an overview of current EM activities within the Plumes Focus Area to describe to the appropriate organizations the current thrust of the program and developing input for its future direction. The Plumes Focus Area is developing remediation technologies that address environmental problems associated with certain priority contaminants found at DOE sites, including radionuclides, heavy metals, and dense non-aqueous phase liquids (DNAPLs). Technologies for cleaning up contaminants of concern to both DOE and other federal agencies, such as volatile organic compounds (VOCs), polychlorinated biphenyls (PCBs), and other organics and inorganic compounds, will be developed by leveraging resources in cooperation with industry and interagency programs.
Date: June 1, 1995
Creator: unknown
System: The UNT Digital Library
Site environmental report for calendar year 1994, Yucca Mountain Site, Nye County, Nevada. (open access)

Site environmental report for calendar year 1994, Yucca Mountain Site, Nye County, Nevada.

The Yucca Mountain Site Characterization office has established an environmental program to ensure that facilities are operated in order to protect, maintain, and restore environmental quality, minimize potential threats to the environment and the public, and comply with environmental policies and US DOE orders. The status of the environmental program has been summarized in this annual report to characterize performance, confirm compliance with environmental requirements, and highlight significant programs and efforts during CY 1994. Monitoring, archaeology, groundwater, ecosystems, tortoise conservation, waste minimization, etc., are covered.
Date: June 1, 1995
Creator: unknown
System: The UNT Digital Library
Board on Earth Sciences and Resources and its activities (open access)

Board on Earth Sciences and Resources and its activities

The Board on Earth Sciences and Resources (BESR) coordinates, the National Research Council`s advice to the federal government on solid-earth science issues. The board identifies opportunities for advancing basic research and understanding, reports on applications of earth sciences in such areas as disaster mitigation and resource utilization, and analyzes the scientific underpinnings and credibility of earth science information for resource, environmental and other applications and policy decision. Committees operating under the guidance of the Board conducts studies addressing specific issues within the earth sciences. The current committees are as follows: Committee on Geophysical and Environmental Data; Mapping Sciences Committee; Committee on Seismology; Committee on Geodesy; Rediscovering Geography Committee; Committee on Research Programs of the US Bureau of Mines. The following recent reports are briefly described: research programs of the US Bureau of Mines, first assessment 1994; Mount Rainier, active cascade volcano; the national geomagnetic initiative; reservoir class field demonstration program; solid-earth sciences and society; data foundation for the national spatial infrastructure; promoting the national spatial data infrastructure through partnerships; toward a coordinated spatial data infrastructure for the nation; and charting a course into the digital era; guidance to the NOAA`s nautical charting mission.
Date: June 1, 1995
Creator: unknown
System: The UNT Digital Library
Development of dry control technology for emissions of mercury in flue gas (open access)

Development of dry control technology for emissions of mercury in flue gas

In flue gases from coal-combustion systems, mercury in either the elemental state or its chloride form (HgCl{sub 2}) can be predominant among all the possible mercury species present; this predominance largely depends on the chlorine-to-mercury ratio in the coal feeds. Conventional flue-gas cleanup technologies are moderately effective in controlling HgCl{sub 2} but are very poor at controlling elemental mercury. Experiments were conducted on the removal of elemental mercury vapor by means of a number of different types of sorbents, using a fixed-bed adsorption system. Of the four commercial activated carbons evaluated, the sulfur-treated carbon sample gives the best removal performance, with good mercury-sorption capacities. Promising removal results also have been obtained with low-cost minerals after chemical treatments. These inorganic sorbents could potentially be developed into a cost-effective alternative to activated carbons for mercury removal.
Date: June 1, 1995
Creator: Huang, Hann S.; Wu, Jiann M. & Livengood, C.D.
System: The UNT Digital Library
Electron energy spectra of H{sup {minus}} autodetaching states resulting from collisions of H{sup {minus}} with He at 1 keV (open access)

Electron energy spectra of H{sup {minus}} autodetaching states resulting from collisions of H{sup {minus}} with He at 1 keV

Electron energy spectra for H{sup {minus}} autodetaching states resulting from collisions H{sup {minus}} with He at 1 keV are rigorously calculated by including couplings between doubly excited states and continuum states and their interference with direct detachment processes. An energy sampling procedure, based on the Gauss quadratures, is used to discretize continuum states. The present theoretical result, for the first time, clarifies mechanisms of excitation to doubly excited states, quantitatively reproduces the experimental spectra first observed by Risley and Geballe in 1974, separates the contributions from each of three autodetaching states, and identifies the cause of the interference between autodetaching and direct-detaching excitation channels.
Date: June 1, 1995
Creator: Kimura, M.; Sato, H.; Hino, K. & Matsuzawa, M.
System: The UNT Digital Library
Multifrequency crosshole EM imaging for reservoir characterization. FY 1994 annual report (open access)

Multifrequency crosshole EM imaging for reservoir characterization. FY 1994 annual report

Electrical conductivity of sedimentary rocks is controlled by the porosity, hydraulic permeability, temperature, saturation, and the pore fluid conductivity. These rock parameters play important roles in the development and production of hydrocarbon (petroleum and natural gas) resources. For these reasons, resistivity well logs have long been used by geologists and reservoir engineers in petroleum industries to map variations in pore fluid, to distinguish between rock types, and to determine completion intervals in wells. Reservoir simulation and process monitoring rely heavily on the physical characteristics of the reservoir model. Over a period of three years (1991-1993) there was an initial phase of crosshole EM technique development via an informal partnership between LLNL and LBL. Researchers developed field instrumentation to apply to oil field for monitoring EOR thermal processes. Specifically, a prototype single-frequency instrumentation was developed and with this system we have conducted field surveys in four separate locations. Theory and software were developed to interpret these data by providing subsurface images of the electrical conductivity. In spite of our initial success in developing practical EM techniques, we still had severe instrumentation limitations and shortcomings in interpretation for other than simple structures. The field equipment was designed to work only at a …
Date: June 1, 1995
Creator: Lee, K. H.
System: The UNT Digital Library
A specialized boundary element algorithm developed to calculate the state of stress in the Anza Gap, San Jacinto Fault Zone, Southern, CA (open access)

A specialized boundary element algorithm developed to calculate the state of stress in the Anza Gap, San Jacinto Fault Zone, Southern, CA

The widely-used algorithm of Crouch and Starfield is unstable when used to solve our mixed boundary equation problem of interest. Altering the boundary conditions and correspondingly rearranging the system of equations to utilize double-sided boundary elements overcomes this drawback. The new algorithm described here is more physically realistic as in that it allows for rotation of the fault segments in the strain field resulting from satisfying the fault static shear strength condition. Preliminary test results indicate that a fault trifurcation gap model may describe the non-strike slip components to some of the seismicity.
Date: June 1, 1995
Creator: Aster, R.; Flores, R. & Fehler, M.
System: The UNT Digital Library
P2 performance measurement tools workbook: Draft (open access)

P2 performance measurement tools workbook: Draft

The underlying purpose of the Department of Energy`s (DOE) Waste Minimization and Pollution Prevention (WMin/P2) Program is compliance with the waste management regulations set forth by the DOE, the federal government, and individual state and local agencies 1. In addition to these regulatory mandates, the increases in waste management costs and public interest in environmental issues have created other drivers to develop and demonstrate an effective WMin/P2 Program. The Waste Minimization Division (EM-334) must have adequate methods to calculate and roll up pollution prevention (P2) progress to meet the WMin/P2 requirements; these requirements support DOE and national objectives and direct funding. This document outlines a system to evaluate DOE`s P2 progress towards the waste reduction requirements. The emphasis of these pollution prevention measurements is to evaluate whether P2 activities are effective, (i.e., has the required amount of waste been reduced as a result of the P2 activities) and to evaluate the cost management of P2 projects. The performance evaluation system presented in this document encompass these aspects: (1) site requirements that apply to all DOE waste generating organizations, (2) a baseline that is not affected by short-term waste generation, and (3) key indicators that can be rolled up across DOE …
Date: June 1, 1995
Creator: unknown
System: The UNT Digital Library
Infrared absorption spectroscopy and chemical kinetics of free radicals. Final performance report, August 1, 1985--July 31, 1994 (open access)

Infrared absorption spectroscopy and chemical kinetics of free radicals. Final performance report, August 1, 1985--July 31, 1994

This research was directed at the detection, monitoring, and study (by infrared absorption spectroscopy) of the chemical kinetic behavior of small free radical species thought to be important intermediates in combustion. The work typically progressed from the detection and analysis of the infrared spectrum of combustion radical to the utilization of the infrared spectrum thus obtained in the investigation of chemical kinetics of the radical species. The methodology employed was infrared kinetic spectroscopy. In this technique the radical is produced by UV flash photolysis using an excimer laser and then its transient infrared absorption is observed using a single frequency cw laser as the source of the infrared probe light. When the probe laser frequency is near the center of an absorption line of the radical produced by the flash, the transient infrared absorption rises rapidly and then decays as the radical reacts with the precursor or with substances introduced for the purpose of studying the reaction kinetics or with itself. The decay times observed in these studies varied from less than one microsecond to more than one millisecond. By choosing appropriate time windows after the flash and the average infrared detector signal in a window as data channels, the …
Date: June 1, 1995
Creator: Curl, R. F. & Glass, G. P.
System: The UNT Digital Library
Tribology and coatings (open access)

Tribology and coatings

The future use of fuel-efficient, low-emission, advanced transportation systems (for example, those using low-heat-rejection diesel engines or advanced gas turbines) presents new challenges to tribologists and materials scientists. High service temperatures, corrosive environments, and extreme contact pressures are among the concerns that make necessary new tribological designs, novel materials, and effective lubrication concepts. Argonne is working on methods to reduce friction, wear and corrosion, such as soft metal coatings on ceramics, layered compounds, diamond coatings, and hard surfaces.
Date: June 1995
Creator: unknown
System: The UNT Digital Library
Formulation and numerical analysis of nonisothermal multiphase flow in porous media (open access)

Formulation and numerical analysis of nonisothermal multiphase flow in porous media

A mathematical formulation is presented for describing the transport of air, water and energy through porous media. The development follows a continuum mechanics approach. The theory assumes the existence of various average macroscopic variables which describe the state of the system. Balance equations for mass and energy are formulated in terms of these macroscopic variables. The system is supplemented with constitutive equations relating fluxes to the state variables, and with transport property specifications. Specification of various mixing rules and thermodynamic relations completes the system of equations. A numerical simulation scheme, employing the method of lines, is described for one-dimensional flow. The numerical method is demonstrated on sample problems involving nonisothermal flow of air and water. The implementation is verified by comparison with existing numerical solutions.
Date: June 1, 1995
Creator: Martinez, M.J.
System: The UNT Digital Library
Renewal: Continential lithosphere evolution as a function of tectonic environment (open access)

Renewal: Continential lithosphere evolution as a function of tectonic environment

The Cenozoic tectonic environment and stress regime of the southwestern United States have changed dramatically from compression during shallow-angle subduction during the Laramide orogeny in the early Cenozoic to the current mode of Basin and Range extension. Questions remain unresolved concerning the causes of this transition, including the timing of the initiation of extension (estimates range from 36 to 25 Ma), and is the Basin and Range simply an mega-example of back-arc extension, or is extension related to the subduction of an oceanic spreading center about 30 Ma? We have examined the patterns of magmagenesis and geochemical composition through Cenozoic time in southern New Mexico. We have defined four magma sources that have contributed to Cenozoic magmas. Immediately following the Laramide, magmas contain substantial contributions from the lower crust. Mid-Tertiary extension is related to the eruption of rhyolitic ash-flow tuffs and basalts. The basalts were generated by melting of the lithospheric mantle; intercalated rhyolites have a strong upper crustal signature. Eruption of basalts and andesites with sources in the lithospheric mantle and lower crust continued for several million years after rhyolitic volcanism ceased. The region was nearly void of volcanic activity for 16 million years despite continued extension, but at …
Date: June 1, 1995
Creator: McMillan, N.J. & Baldridge, W.S.
System: The UNT Digital Library
The corrosion behavior of DWPF glasses (open access)

The corrosion behavior of DWPF glasses

The authors analyzed the corroded surfaces of reference glasses developed for the Defense Waste Processing Facility (DWPF) to characterize their corrosion behavior. The corrosion mechanism of nuclear waste glasses must be known in order to provide source terms describing radionuclide release for performance assessment calculations. Different DWPF reference glasses were corroded under conditions that highlighted various aspects of the corrosion process and led to different extents of corrosion. The glasses corroded by similar mechanisms, and a phenomenological description of their corrosion behavior is presented here. The initial leaching of soluble glass components results in the formation of an amorphous gel layer on the glass surface. The gel layer is a transient phase that transforms into a layer of clay crystallites, which equilibrates with the solution as corrosion continues. The clay layer does not act as a barrier to either water penetration or glass dissolution, which continues beneath it, and may eventually separate from the glass. Solubility limits for glass components may be established by the eventual precipitation of secondary phases; thus, corrosion of the glass becomes controlled by the chemical equilibrium between the solution and the assemblage of secondary phases. In effect, the solution is an intermediate phase through which …
Date: June 1, 1995
Creator: Ebert, W.L. & Bates, J.K.
System: The UNT Digital Library