108 Matching Results

Search Results

Advanced search parameters have been applied.


Description: Efforts made to employ the sigma welding process for plug welding Closures in spun-over fuel cans were unsuccessful. No combination of welding conditions was found which would produce satisfactory, leak-tight, plug welds in aluminum. (auth)
Date: December 1, 1952
Creator: Winsor, F.J.
Partner: UNT Libraries Government Documents Department

Characterization and Modeling of Microstructure Development in Nickel-base Superalloy Welds

Description: Welding is important for economical reuse and reclamation of used and failed nickel-base superalloy blades, respectively [1]. Solidification and solid state decomposition of {gamma} (Face Centered Cubic, FCC) phase into {gamma}{prime} (L1{sub 2}-ordered) phase control the properties of these welds. In previous publications, the microstructure development in electron beam welds of PWA-1480 alloy [2] and laser beam welds of CMSX-4 alloy [3] were presented. These results showed that the weld cracking in these alloys were associated with low melting point eutectic at the dendrite boundaries [1,2]. The eutectic-{gamma}{prime} precipitation was reduced at rapid weld cooling rates and the partitioning between {gamma}-{gamma}{prime} phase was found to be far from equilibrium conditions [3,4]. This observation was related to diffusional growth of {gamma}{prime} precipitate into {gamma} phase. Subsequent to the above work, the precipitation characteristics of {gamma}{prime} phase from {gamma} phase were evaluated during continuous cooling conditions [5]. The results show that the number density of {gamma} precipitates increased with an increase in cooling rate. However, the details of this decomposition and also the fine-scale elemental partitioning characteristics between {gamma}-{gamma}{prime} were not investigated. In this paper, the precipitation characteristics of {gamma}{prime} from {gamma} during continuous cooling conditions were investigated with transmission electron microscopy, and atom probe field ion microscopy. In addition, thermodynamic and kinetic models were used to describe microstructure development in Ni-base superalloy welds.
Date: November 1, 1999
Creator: Babu, S.S.; David, S.A.; Miller, M.K. & Vitek, J.M.
Partner: UNT Libraries Government Documents Department

The Effect of Weld Residual Stress on Life of Used Nuclear Fuel Dry Storage Canisters

Description: With the elimination of Yucca Mountain as the long-term storage facility for spent nuclear fuel in the United States, a number of other storage options are being explored. Currently, used fuel is stored in dry-storage cask systems constructed of steel and concrete. It is likely that used fuel will continue to be stored at existing open-air storage sites for up to 100 years. This raises the possibility that the storage casks will be exposed to a salt-containing environment for the duration of their time in interim storage. Austenitic stainless steels, which are used to construct the canisters, are susceptible to stress corrosion cracking (SCC) in chloride-containing environments if a continuous aqueous film can be maintained on the surface and the material is under stress. Because steel sensitization in the canister welds is typically avoided by avoiding post-weld heat treatments, high residual stresses are present in the welds. While the environment history will play a key role in establishing the chemical conditions for cracking, weld residual stresses will have a strong influence on both crack initiation and propagation. It is often assumed for modeling purposes that weld residual stresses are tensile, high and constant through the weld. However, due to the strong dependence of crack growth rate on stress, this assumption may be overly conservative. In particular, the residual stresses become negative (compressive) at certain points in the weld. The ultimate goal of this research project is to develop a probabilistic model with quantified uncertainties for SCC failure in the dry storage casks. In this paper, the results of a study of the residual stresses, and their postulated effects on SCC behavior, in actual canister welds are presented. Progress on the development of the model is reported.
Date: August 1, 2013
Creator: Ballinger, Ronald G.; Ferry, Sara E.; Black, Bradley P. & Teysseyre, Sebastien P.
Partner: UNT Libraries Government Documents Department


Description: The rapid technological development of the nuclear and space industries has placed a great demand on metal joining processes. One of the most promising processes is electron beam welding. Welding with the electron beam ofiers high integrity in addition to the ability to fabricate unusual configurations. Advanced nuclear fuels require both reliability and unusual designs for satisfactory operation under extreme conditions of temperature and stress. To investigate the problems and techniques involved in fabricating large, advanced nuclear fuel components from Zircaloy-2 material, several cladding pieces were designed and built using the electron beam process. These designs included five basic joint types for assembling the cladding. Destructive and nondestructive examinations were employed including corrosion testing and extensive metallographic examination. Weldment size, fit-up'' of the parts to be joined, fixturing and work carriage mechanisms, as they pertain to electron beam welding, are also discussed. The electron beam process has been demonstrated as a very satisfactory method for fabricating unusual fuel cladding. Fuel cladding components with lengths up to 8 ft have been fabricated for in-reactor irradiation. (auth)
Date: October 1, 1963
Creator: Klein, R.F.
Partner: UNT Libraries Government Documents Department

Microstructure of Titanium Welds

Description: Plates of commercially pure titanium were welded and microscopically analyzed to understand the influence of joining variables on weld microstructure.
Date: February 1, 2003
Creator: Danielson, Paul; Wilson, Rick D. & Alman, David E.
Partner: UNT Libraries Government Documents Department

Ultrasonic Phased Array Technique for Accurate Flaw Sizing in Dissimilar Metal Welds

Description: Described is a manual,portable non-destructive technique to determine the through wall height of cracks present in dissimilar metal welds used in the primary coolling systems of pressure water and boiler light water reactors. Current manual methods found in industry have proven not to exhibit the sizing accuracy required by ASME inspection requirement. The technique described demonstrated an accuracy approximately three times that required to ASME Section XI, Appendix 8 qualification.
Date: March 11, 2005
Creator: Buttram, Jonathan D
Partner: UNT Libraries Government Documents Department


Description: The gas lift pump has not been considered here as a prinme mover for circulating coolant through a primary circuit, in view of the complexity which would arise in designing such a pump to overcome the head losses associated with the secondary large volumetric flow rates. The purpose of this investigation was merely to make a preliminary study of the general character of a heavy liquid metal gas-lift, to compare its operation with that of water, and to obtain some idea of the relationship of efficiency to flow rate. (A.C.)
Date: November 27, 1957
Creator: Draper, B.D. & Roller, H.C.
Partner: UNT Libraries Government Documents Department


Description: Examination of clad uranium reflector slugs wbich falled by rupture and swelling during the first year of operation of Clementine revealed no anisotropic damage to the uranium because of burnup or thermal cycling. The cladding was found to be of high-sulfur-free-machining steel, and it is postulated that thermal stresses caused welding flaws to open enough to permit seepage and corrosive attack upon the uranium cores by the reactor coolant (mercury). (auth)
Date: October 1, 1959
Creator: Paine, S.H.; Murphy, W.F. & Brown, F.L.
Partner: UNT Libraries Government Documents Department