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Stage III dislocation pinning in silver resulting from gamma irradiation

Description: A brief summary of the history of research in the fields of radiation damage, point defects, and dislocation effects is presented. Theory and previous experiments are discussed. Apparatus capable of continuously measuring changes in the elastic modulus and internal friction during gamma irradiation over the temperature range from <4 deg K to well above room temperature is described. A novel hollow-cylinder sample geometry permits use of a source strength of only 1 Ci. Survey experiments over a wide temperature range and isothermal irradiations above room temperature are discussed. Results are explained in terms of the KoehlerGranato- Luecke vibrating-string dislocation model and the Thompson- Buck- Huntington- Barnes defect-dislocation interaction model. Consistent results are obtained under the assumptions of wide dislocation splitting and the presence of two dislocation components. Long-range migration appears to-occur first in Stuge I in silver. The activation energy for the observed Stage III annealing is about 0.48 eV. The responsible defect is most likely the single interstitial atom. Pipe diffusion is necessary to explain the results. The trapping efficiency of dislocations could not be determined because of the presence of more than one dislocation component. (27 figures, 9 tables, 157 references) (DLC)
Date: November 14, 1973
Creator: Van Konynenburg, R.A.
Partner: UNT Libraries Government Documents Department

Radiation chemical effects in experiments to study the reaction of glass in an environment of gamma-irradiated air, groundwater, and tuff

Description: The results of experiments performed by John K. Bates et al. on the reaction of nuclear waste glass with a gamma-irradiated 90{sup 0}C aqueous solution were analyzed using theory developed from past research in radiation chemistry. The aqueous solution they used is similar to what would be expected in a water-saturated environment in a nuclear waste repository in tuff. The purpose of our study was to develop an understanding of the radiation-chemical processes that occurred in the Bates et al. experiments so the results could be applied to the design and performance analysis of a proposed repository in unsaturated tuff in Nevada. For the Bates et al. experiments at the highest dose (269 Mrad), which originally contained about 16 ml of "equilibrated" water taken from Nevada Test Site Well J-13 and 5.4 ml of air, we predicted that water decomposition to H{sub 2} and O{sub 2} would produce a pressure increase of at least 1.0 MPa at 20{sup 0}C. We also predicted that nitrogen fixation from the air would occur, producing an increase of 1.6 x 10{sup -4} M in total fixed nitrogen concentration in solution. In addition, an equimolar production of H{sup +} would occur, which would be buffered by the HCO{sub 3}{sup -} in the water. The fixed nitrogen in solution was predicted to be present as NO{sub 2}{sup -} and NO{sub 3}{sup -} with the ratio influenced by the presence of materials catalytic to the decomposition of H{sub 2}O{sub 2}. We found reasonable agreement between our predictions and the observations of Bates et al., where comparisons were possible. We apply the results to the proposed Nevada repository to the degree possible, given the different expected conditions.
Date: May 2, 1986
Creator: Van Konynenburg, R.A.
Partner: UNT Libraries Government Documents Department

Radiation doses in granite around emplacement holes in the Spent Fuel Test - Climax. Final report

Description: Final comparisons are made between measured and calculated radiation doses around the holes in which the spent fuel was emplaced in the Spent Fuel Test - Climax. Neutron doses were found to be negligible compared with gamma doses. Good agreement was found between the doses predicted by Monte Carlo calculations and those measured by short-exposure thermoluminescence dosimetry. Poor agreement was found between the calculational results and doses measured by exposure of LiF optical-absorption-type dosimeters for long periods, probably because of an inability to accurately correct for fade resulting from elevated temperature exposure over several months. The maximum dose to the rock occurred at the walls of the emplacement holes, and amounted to 1.6 MGy (1.6 x 10{sup 8} rad) in granite for the emplacement period of nearly 3 years. It is recommended that dose evaluations for future high-level nuclear waste storage facilities also be performed by combining calculations and dosimetry. Passive dosimetry techniques, if used, should involve short exposures, so that laboratory calibrations can be performed with duplicate time, temperature, dose rate, and dose parameters. An attractive alternative would be to use active ionization chambers, inserted only periodically. These could be calibrated under appropriate temperature and pressure conditions, and could be read directly. 23 references, 7 figures, 8 tables.
Date: July 26, 1984
Creator: Van Konynenburg, R.A.
Partner: UNT Libraries Government Documents Department

Comparison of measured and calculated radiation doses in granite around emplacement holes in the spent-fuel test: Climax, Nevada Test Site

Description: Lawrence Livermore National Laboratory (LLNL) has emplaced eleven spent nuclear-reactor fuel assemblies in the Climax granite at the Nevada Test Site as part of the DOE Nevada Nuclear-Waste Storage Investigations. One of our objectives is to study radiation effects on the rock. The neutron and gamma-ray doses to the rock have been determined by MORSE-L Monte Carlo calculations and measurements using optical absorption and thermoluminescence dosimeters and metal foils. We compare the results to date. Generally, good agreement is found in the spatial and time dependence of the doses, but some of the absolute dose results appear to differ by more than the expected uncertainties. Although the agreement is judged to be adequate for radiation effects studies, suggestions for improving the precision of the calculations and measurements are made.
Date: October 11, 1982
Creator: van Konynenburg, R. A.
Partner: UNT Libraries Government Documents Department

Stage III dislocation pinning in silver resulting from gamma irradiation

Description: The objectives of this work were fourfold: (1) to test the validity of the vibrating string dislocation model in silver, (2) to determine in which annealing stage long-range migration first occurs, (3) to measure the migration energy and identify the defect responsible for observed annealing, and (4) to investigate the possibility of dislocation pipe diffusion. Apparatus is described which is capable of continuously measuring changes in the elastic modulus and internal friction during gamma irradiation over the temperature range from less than 4$sup 0$K to well above room temperature. A novel hollow-cylinder sample geometry permits use of a source strength of only 1 Ci. Survey experiments over a wide temperature range and isothermal irradiations above room temperature are discussed. The results are explained in terms of the Koehler- Granato-Lucke vibrating string dislocation model and the Thompson-Buck-Huntington- Barnes defect-dislocation interaction model. (auth)
Date: September 19, 1975
Creator: Van Konynenburg, R.A. & Guinan, M.W.
Partner: UNT Libraries Government Documents Department

Corrosion performance of metals and alloys in a tuff geochemical environment

Description: Reference and alternate alloy systems have been chosen for use in fabricating waste packages for a potential high-level nuclear waste repository in tuff. The main corrosion concerns have been identified. Testing performed to date indicates that austenitic stainless steels woul perform well as package materials under the expected conditions as well as the less likely extreme conditions so far postulated. Carbon steel appears to be adequate as a material for borehole liners. Copper-based alloys and Zircaloys are also undergoing corrosion testing, the former as alternate package materials, and the latter because of their presence as spent fuel cladding. 17 references, 2 tables.
Date: March 20, 1985
Creator: Van Konynenburg, R.A. & McCright, R.D.
Partner: UNT Libraries Government Documents Department

Effect of ionizing radiation on moist air systems

Description: The radiation chemistry of nitrogen/oxygen/water systems is reviewed. General radiolytic effects in dry nitrogen/oxygen systems are relatively well characterized. Irradiation results in the formation of steady state concentrations of ozone, nitrous oxide and nitrogen dioxide. In closed systems, the concentration observed depends on the total dose, temperature and initial gas composition. Only three studies have been published that focus on the radiation chemistry of nitrogen/oxygen/water homogeneous gas systems. Mixed phase work that is relevant to the gaseous system is also summarized. The presence of water vapor results in the formation of nitric acid and significantly changes the chemistry observed in dry air systems. Mechanistic evidence from the studies reviewed are summarized and discussed in relation to characterizing the gas phase during the containment period of a repository in tuff.
Date: December 1987
Creator: Reed, D. T. & Van Konynenburg, R. A.
Partner: UNT Libraries Government Documents Department

Electrical insulator requirements for mirror fusion reactors

Description: The requirements for mirror fusion electrical insulators are discussed. Insulators will be required at the neutral beam injectors, injector power supplies, direct converters, and superconducting magnets. Insulators placed at the neutral beam injectors will receive the greatest radiation exposure, 10/sup 14/ to 10/sup 16/ neutrons/m/sup 2/.s and 0.3 to 3 Gy/s (10/sup 5/ to 10/sup 6/ R/h) of gamma rays, with shielding. Direct converter insulators may receive the highest temperature (up to 1300/sup 0/K), but low voltage holding requirements. Insulators made from organic materials (e.g., plastics) for the magnet coils may be satisfactory. Immediate conductivity increases of all insulators result from gamma irradiation. With an upper limit to gamma flux exposures of 300 Gy/s in a minimally shielded region, the conductivity could reach 10/sup -6/ S/m. Damage from neutron irradiation may not be serious during several years' exposure. Surface changes in ceramics at the neutral beam injector may be serious. The interior of the injector will contain atomic hydrogen, and sputtering may transfer material away from or onto the ceramic insulators. Unknown and potentially damaging interactions between irradiation, electric fields, temperature gradients, cycling of temperature, surface and joint reactions, sputtering, polarization, and electrotransport in the dielectrics are of concern. Materials research to deal with these problems is needed.
Date: October 30, 1977
Creator: Condit, R.H. & Van Konynenburg, R.A.
Partner: UNT Libraries Government Documents Department

Radiation effects in SYNROC-D

Description: This paper describes SYNROC-D and the irradiation it will be subjected to over the first million years of storage. This will include about 8 x 10/sup 24/ alpha decays per m/sup 3/ and a total ionization dose of about 1 x 10/sup 11/ rads. Methods of simulating the radiation effects are discussed. Previous work by others is reviewed and compared on a dpa basis. /sup 238/Pu doping experiments to simulate internal alpha decay are described, and the progress is discussed. It is concluded that dose rate effects on swelling and metamictization of perovskite and zirconolite are small over a wide range of dose rate, and that swelling and metamictization in these minerals does not anneal significantly over geological time periods.
Date: September 30, 1981
Creator: Van Konynenburg, R.A. & Guinan, M.W.
Partner: UNT Libraries Government Documents Department

Relative radiation sensitivity of insulators, stabilizers, and superconductors

Description: The objective of this work was to compare the radiation sensitivity of the various parts of superconducting magnet systems. Using the radiation spectra calculated by Engholm for the Engineering Test Facility (ETF) toroidal field magnet inboard leg and available data on radiation effects, commonly used magnet components were ranked in order of radiation sensitivity. It was found that epoxy-based insulators and copper and aluminum stabilizers were the most sensitive parts of the magnets, more sensitive than the superconductors. Use of polyimide-based insulators would make the insulators less vulnerable than the stabilizers and superconductors. An experiment is planned to study the effects of various degrees of cold work on the radiation-induced magnetoresistance of copper, since this will be an important factor for fusion magnet stabilizers.
Date: January 15, 1982
Creator: Van Konynenburg, R.A. & Guinan, M.W.
Partner: UNT Libraries Government Documents Department

Relative radiation sensitivity of insulators, stabilizers, and superconductors

Description: The operating conditions of the magnets including temperature and radiation fields are discussed. Comments were made on the nuclear heating. Components of the magnet system, including the materials used, the important properties, the atomic structure, the damage mechanism, and the effects of room temperature warmup are described. Some failure criteria for the various components are suggested. Available data concerning radiation effects on each component are discussed. Their radiation sensitivities are compared using the conditions calculated for the ETF toroidal field magnet inboard leg, and ranked in order of sensitivity. Comments were made on the implications of this ranking for the directions of future applied materials research.
Date: December 1, 1980
Creator: Van Konynenburg, R.A. & Guinan, M.W.
Partner: UNT Libraries Government Documents Department

Radiation effects on superconductors and magnet stabilizer materials

Description: Previously-irradiated Nb/sub 3/Sn wires have been given additional irradiation at room temperature in order to reach the anticipated serious decline in critical current and to evaluate the fluence where it occurs. In addition, an experiment is in preparation which will measure the magnetoresistance of copper and aluminum in fields up to 12 tesla after 14-MeV neutron irradiation. The same experiment will test the effects of repeated irradiation and room temperature annealing on NbTi critical current.
Date: January 1, 1980
Creator: Van Konynenburg, R.A. & Guinan, M.W.
Partner: UNT Libraries Government Documents Department

Fusion-neutron effects on magnetoresistivity of copper stabilizer materials

Description: The objective of this work is to quantify the changes which occur in the magnetoresistivity of coppers (having various purities and pretreatments, and at magnetic fields up to 12 T during the course of sequential fusion neutron irradiations at about 4/sup 0/K and anneals to room temperature. In conjunction with work in progress by Coltman and Klabunde of ORNL, the results should lead to engineering design data for the stabilizers of superconducting magnets in fusion reactors. These magnets are expected to be irradiated during reactor operation and warmed to room temperature periodically during maintenance.
Date: February 24, 1983
Creator: Guinan, M.W. & Van Konynenburg, R.A.
Partner: UNT Libraries Government Documents Department

Helium generation in copper by 14.8-MeV neutrons

Description: High purity copper foils were irradiated with 14.8-MeV neutrons from the rotating target neutron source facility at LLL. The average energy of the neutrons was 14.75 +- 0.1 MeV, and the average fluence was 7.0 x 10$sup 16$ n/ cm$sup 2$. After irradiation each foil was heated to the melting point and the released helium was measured by a mass spectrometer of special design. Isochronal heating was carried out on several samples to establish the type and temperature of maximum release. Calculated cross sections from the literature for the (eta,$alpha$) and (eta,eta'$alpha$) nuclear reactions were used, and the predicted amount of helium was consistently about 0.5 of that actually measured. Because there is very little data on helium generation in metals irradiated with high energy neutrons, these results are important and will be related to potential CTR materials. (auth)
Date: September 22, 1975
Creator: Holt, J.B.; Hosmer, D.W. & Van Konynenburg, R.A.
Partner: UNT Libraries Government Documents Department

Progress report on the results of testing advanced conceptual design metal barrier materials under relevant environmental conditions for a tuff repository

Description: This report discusses the performance of candidate metallic materials envisioned for fabricating waste package containers for long-term disposal at a possible geological repository at Yucca Mountain, Nevada. Candidate materials include austenitic iron-base to nickel-base alloy (AISI 304L, AISI 316L, and Alloy 825), high-purity copper (CDA 102), and copper-base alloys (CDA 613 and CDA 715). Possible degradation modes affecting these container materials are identified in the context of anticipated environmental conditions at the repository site. Low-temperature oxidation is the dominant degradation mode over most of the time period of concern (minimum of 300 yr to a maximum of 1000 yr after repository closure), but various forms of aqueous corrosion will occur when water infiltrates into the near-package environment. The results of three years of experimental work in different repository-relevant environments are presented. Much of the work was performed in water taken from Well J-13, located near the repository, and some of the experiments included gamma irradiation of the water or vapor environment. The influence of metallurgical effects on the corrosion and oxidation resistance of the material is reviewed; these effects result from container fabrication, welding, and long-term aging at moderately elevated temperatures in the repository. The report indicates the need for mechanisms to understand the physical/chemical reactions that determine the nature and rate of the different degradation modes, and the subsequent need for models based on these mechanisms for projecting the long-term performance of the container from comparatively short-term laboratory data. 91 refs., 17 figs., 16 tabs.
Date: December 1, 1987
Creator: McCright, R.D.; Halsey, W.G. & Van Konynenburg, R.A.
Partner: UNT Libraries Government Documents Department

Corrosion test plan to guide canister material selection and design for a tuff repository

Description: Corrosion rates and the mode of corrosion attack form a most important basis for selection of canister materials and design of a nuclear waste package. Type 304L stainless steel was selected as the reference material for canister fabrication because of its generally excellent corrosion resistance in water, steam and air. However, 304L may be susceptible to localized and stress-assisted forms of corrosion under certain conditions. Alternative alloys are also investigated; these alloys were chosen because of their improved resistance to these forms of corrosion. The fabrication and welding processes, as well as the glass pouring operation for defense and commercial high-level wastes, may influence the susceptibility of the canister to localized and stress forms of corrosion. 12 references, 2 figures, 4 tables.
Date: November 1, 1983
Creator: McCright, R.D.; van Konynenburg, R.A. & Ballou, L.B.
Partner: UNT Libraries Government Documents Department

Metallurgical analysis of a 304L stainless steel canister from the Spent Fuel Test - Climax

Description: Results of a metallurgical examination of a type 304L stainless steel canister that had been used to store spent nuclear fuel in an underground granite formation for about three years are reported. No observable corrosion or cracking were found. The results are applied to waste packages in a potential high level nuclear waste repository in tuff. 10 refs., 9 figs., 2 tabs.
Date: April 23, 1985
Creator: Weiss, H.; Van Konynenburg, R.A. & McCright, R.D.
Partner: UNT Libraries Government Documents Department

Science and licensing: Let`s get off the collision course

Description: Our best possibility for gaining an understanding of the likely future behavior of a high level nuclear waste disposal system is use of the scientific method. However, science has inherent limitations when it comes to making long-term predictions with confidence. This paper examines these limiting factors as well as the criteria for admissibility of scientific evidence in the legal arena, and concludes that the prospects are doubtful for successful licensing of a potential repository under the regulations that were binding until recently. Suggestions are made for remedying this situation.
Date: October 1, 1993
Creator: Van Konynenburg, R.A.
Partner: UNT Libraries Government Documents Department

Electrochemical corrosion studies on copper-base waste package container materials in unirradiated 0.1 N NaNO{sub 3} at 95{degrees}C

Description: Three candidate materials were investigated in this study in terms of their electrochemical corrosion behavior in unirradiated 0.1 N NaNO{sub 3} solutions at 95{degrees}C. Anodic polarization experiments were conducted to determine the passive current densities, pitting potentials, and other parameters, together with Cyclic Current Reversal Voltammetry tests to evaluate the stability and protectiveness of the passive oxides formed. X-ray diffraction and Auger Electron Spectroscopy were used for identification of the corrosion products as well as Scanning Electron Microscopy for the surface morphology studies. 2 refs., 22 figs., 2 tabs.
Date: May 1, 1988
Creator: Akkaya, M.; Verink, E.D. Jr. & Van Konynenburg, R.A.
Partner: UNT Libraries Government Documents Department

Gaseous release of carbon-14: Why the high level waste regulations should be changed

Description: The high-level nuclear waste regulations pertaining to gaseous release of carbon-14 from a repository should be changed to allow greater release, for several reasons. Some of them are as follows. First, the total amount of carbon-14 that would be placed in a repository is small compared to that produced naturally in the atmosphere by cosmic rays. Second, the dose that would result to an individual from total release of repository carbon-14 would be very small compared to that from natural radiation sources and would be well below the ``Below Regulatory Concern`` criterion. Third, the limits on gaseous carbon-14 release from a repository have been set unreasonably low compared to the limits set for carbon-14 release from other fuel cycle facilities. Fourth, the additional cost for waste packages to attempt to meet the regulations for carbon-14 release would likely be of the order of a billion dollars or more, too high to be justified by the small reduction in dose that might result. 32 refs.
Date: April 1, 1991
Creator: Van Konynenburg, R.A.
Partner: UNT Libraries Government Documents Department

Limitations on scientific prediction and how they could affect repository licensing

Description: The best possibility for gaining an understanding of the likely future behavior of a high level nuclear waste disposal system is to use the scientific method. However, the scientific approach has inherent limitations when it comes to making long-term predictions with confidence. This paper examines some of these limiting factors as well as the criteria for admissibility of scientific evidence in the legal arena, and concludes that the prospects are doubtful for successful licensing of a potential repository under the regulations that are now being reconsidered. Suggestions am made for remedying this situation.
Date: January 1, 1994
Creator: Van Konynenburg, R.A.
Partner: UNT Libraries Government Documents Department

Effects of low-temperature fusion neutron irradiation on critical properties of a monofilament niobium-tin superconductor

Description: The objective of this work was to irradiate a Nb/sub 3/Sn superconductor with 14.8 MeV neutrons at 4 K and measure critical current in transverse fields of up to 12 T, irradiating up to a fluence sufficient to decrease the critical current to below its initial value. Critical temperatures were also to be measured. The samples were to be kept near 4 K between the irradiation and the measurement of critical properties. This work is directed toward establishing an engineering design fluence limit for Nb/sub 3/Sn when used in fusion reactor superconducting magnets.
Date: March 22, 1984
Creator: Guinan, M.W.; Van Konynenburg, R.A. & Mitchell, J.B.
Partner: UNT Libraries Government Documents Department