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A laser-based solution to industrial decontamination problems

Description: The ability of lasers to deposit significant amounts of energy on surfaces located at large distances from the laser can be exploited to solve very difficult industrial problems. The Ames Laboratory has been working in partnership with Lockheed Martin Idaho Technologies (LMIT) to apply laser technologies to the decontamination of radioactively contaminated surfaces located in hostile environments. Many such applications exist within former USDOE and nuclear industry facilities. As opposed to laser coating removal systems, which are designed to ``strip`` relatively soft coatings from a substrate without damage to the substrate, the system being developed by Ames - LMIT is designed to remove contaminants that are embedded within the metal surface itself. The system generates irradiance levels sufficient to remove microns of metal from a surface and an off-gas system that prevents the redeposition of materials removed from the surface. Process control is assisted by monitoring the laser-generated plasma produced during laser surface ablation. Results achieved using this apparatus for various metal types will be presented along with a discussion of other potential industrial applications.
Date: December 31, 1995
Creator: Edelson, M.C.; Pang, Ho-ming & Ferguson, R.L.
Partner: UNT Libraries Government Documents Department

Ductility minimum and its reversal with aging in cobalt-base superalloys

Description: Good mechanical properties in the face of long-term aging at high temperatures are required of superalloys for nuclear and solar power-conversion applications. Of special concern are losses in ductility and toughness resulting from microstructural instability. The report compares the tensile ductility responses in two cobalt-base superalloys for the solution annealed and aged conditions and endeavors to rationalize results with contemporary concepts. The cobalt-base superalloys Haynes alloy No. 25 and Haynes alloy No. 188 show a pronounced ductility minimum at 760/sup 0/C for the solution annealed condition. However, after prolonged (11,000 h) aging at 816/sup 0/C, copious precipitates form and completely reverse this behavior. These precipitates drastically reduce tensile ductility up to the temperature at which the ductility begins to dip for the solution annealed condition; then the brittle behavior from aging gives way to greatly enhanced ductility. This behavior in Haynes alloy No. 25 was examined in detail. Tensile properties in the solution annealed and 816/sup 0/C-aged conditions are correlated with mode of fracture and the amounts, identity, and morphology of the precipitates. The latter were assessed by optical and scanning electron metallography, microhardness, electron microprobe, and x-ray diffraction. The minimum and its reversal are explained by thermally activated processes that began with the onset of recovery.
Date: January 1, 1979
Creator: Hammond, J. P.
Partner: UNT Libraries Government Documents Department

Containment of $sup 90$SrF$sub 2$ at 800 to 1100$sup 0$C preliminary results

Description: A program is currently underway at PNL to develop the data needed to license $sup 90$SrF$sub 2$ for heat source applications. A major portion of the program involves determining the compatibility of $sup 90$SrF$sub 2$ with containment materials at elevated temperatures. The compatibility studies are divided into two phases: an initial series of short-term scouting tests lasting up to 4400 h in which a number of containment materials were evaluated, and a subsequent series of long-term tests in which the three best containment materials identified in the short-term tests will be tested for up to 30,000 h with WESF-produced $sup 90$SrF$sub 2$. The results of the first phase tests are summarized. The short-term tests were carried-out at temperatures of 800, 1000, and 1100$sup 0$C for 1500 and 4400 h using both radioactive and nonradioactive strontium fluoride. Nine potential containment materials were evaluated in the tests: two refractory metals (tungsten and TZM); two cobalt base alloys (Haynes Alloy 25 and Haynes Alloy 188); and five nickel base alloys (Hastelloy C-276, Hastelloy X, Hastelloy N, Inconel 600 and Inconel 625). Test results show that both of the refractory metals are very resistant to fluoride attack, and tungsten and TZM specimens exposed to $sup 90$SrF$sub 2$ exhibited little or no attack. Haynes Alloy 25 was the best of the Ni- and Co-base alloys, but attack up to a depth of 0.004 in. was observed in some Haynes Alloy 25 specimens exposed to $sup 90$SrF$sub 2$. Based on the results of the short-term compatibility tests and several other factors, TZM, Haynes Alloy 25 and Hastelloy C-276, the present WESF capsule material, were selected for long-term testing with $sup 90$SrF$sub 2$. (auth)
Date: November 1, 1975
Creator: Fullam, H.T.
Partner: UNT Libraries Government Documents Department

Ductility minimum and its reversal with prolonged aging in cobalt- and nickel-base superalloys

Description: The cobalt-base superalloys Haynes alloy No. 25 and Haynes alloy No. 188 and the nickel-base superalloy Inconel 625 show a pronounced ductility minimum at temperatures of 760 and 704/sup 0/C, respectively, in the solution-annealed condition. However, after prolonged (11,000 h) aging at 816/sup 0/C (1500/sup 0/F), copious precipitates form to completely reverse the behavior. These precipitates reduce tensile ductility drastically up to temperatures where the ductility dip is observed for the solution-annealed condition; then the brittle behavior from aging gives way to greatly enhanced ductility. This behavior in Haynes alloy No. 25 is examined in detail. Its tensile properties in the solution-annealed and 816/sup 0/C-aged conditions are correlated with mode of fracture and the amounts, identity, and morphology of the precipitates. The latter were assessed by optical and scanning electron metallography, microhardness, electron microprobe, and x-ray diffraction. The minimum and its reversal are explained by thermally activated processes, which began with the onset of recovery.
Date: January 1, 1978
Creator: Hammond, J. P.
Partner: UNT Libraries Government Documents Department

Effect of long-term aging at 815/sup 0/C on the tensile properties and microstructural stability of four cobalt- and nickel-base superalloys

Description: Two heats of Haynes alloy 25 and one heat each of Haynes alloy 188, Hastelloy N, and Inconel 625 were tensile tested after aging for 11,000 h at 816/sup 0/C. Yield strength, ultimate tensile strength, and elongation were determined 24, 316, 760, and 982/sup 0/C and compared with typical properties for these materials in the solution annealed condition. Toughness values were determined for these materials from their engineering stress-strain curves. The long-term aging treatment degraded ductility and toughness at room temperature but, contrary to behavior expected for overaging, enhanced them over those for the solution annealed condition in tests at 760/sup 0/C. The tensile properties of the aged superalloys were correlated with mode of fracture and the amounts, identity, and morphology of the precipitates. Aging substantially depleted the hardener tungsten from the matrix in the cobalt-base alloys.
Date: August 1, 1976
Creator: Hammond, J. P.
Partner: UNT Libraries Government Documents Department

TRU waste cyclone drum incinerator and treatment system: January--March 1978

Description: The cyclone incinerator was operated throughout the past quarter, generating additional data on system characteristics, equipment life expectancies, and by-product generation. Several changes in the incinerator system are in various stages of completion. The lid assembly, secondary chamber, and expansion unit for the new exhaust equipment are nearly ready for installation. A new heat exchanger has been installed in the scrubber system. An ash handling system has been designed for possible future addition to the system. Continuing studies will determine the best delivery mechanism for continuously feeding the cyclone incinerator. Preliminary investigations are being conducted to select an independent system to treat incinerator scrubber solution for recycling and to remove salts and sludge for disposal. Metal samples of two possible materials for incinerator construction were examined for corrosion degradation suffered at the incinerator exhaust outlet. Controlled experiments were conducted on the pressed ash-cement pellet matrix to define compressive strength, mechanical stability, density, and effect of curing environment (wet cure and dry cure). Leachability studies were initiated on pressed sludge/cement matrix in distilled water at ambient temperature. Compressive strengths of sludge/cement pressed matrix samples were investigated. Physical and chemical attributes of incinerated ash were evaluated in relationship to the ash/cement matrix.
Date: May 5, 1978
Creator: Klingler, L.M.; Batchelder, D.M. & Lewis, E.L.
Partner: UNT Libraries Government Documents Department