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Effects of tuff waste package components on release from 76-68 simulated waste glass: Final report

Description: An experimental matrix has been conducted that will allow evaluation of the effects of waste package constituents on the waste form release behavior in a tuff repository environment. Tuff rock and groundwater were used along with 304L, 316, and 1020M ferrous metals to evaluate release from uranium-doped MCC 76-68 simulated waste glass. One of the major findings was that in the absence of 1020M mild steel, tuff rock powder dominates the system. However, when 1020M mild steel is present, it appears to dominate the system. The rock-dominated system results in suppressed glass-water reaction and leaching while the 1020M-dominated system results in enhanced leaching - but the metal effectively scavenges uranium from solution. The 300-series stainless steels play no significant role in affecting glass leaching characteristics. 6 refs., 28 figs., 5 tabs.
Date: April 1, 1984
Creator: McVay, G.L. & Robinson, G.R.
Partner: UNT Libraries Government Documents Department

Review of DOE waste package program. Subtask 1.1. National waste package program, April-September 1983. Volume 5

Description: The current effort is part of an ongoing task to review the national high-level waste package effort. It includes evaluations of reference waste form, container, and packing material components with respect to determining how they may contribute to the containment and controlled release of radionuclides after waste packages have been emplaced in salt, basalt, and tuff repositories. In the current Biannual Report a section on carbon steel container corrosion has been included to complement prior work on TiCode-12 and Type 304 stainless steel. The use of crushed tuff as a packing material is discussed and waste package component interaction test data are included. Licensing data requirements to estimate the degree of compliance with NRC performance objectives are specified. 41 figures, 24 tables.
Date: August 1, 1984
Creator: Soo, P. (ed.)
Partner: UNT Libraries Government Documents Department

Electrochemical determination of the corrosion behavior of candidate alloys proposed for containment of high level nuclear waste in tuff

Description: Long-term geological disposal of nuclear waste requires corrosion-resistant canister materials for encapsulation. Several austenitic stainless steels are under consideration for such purposes for the disposal of high-level waste at the candidate repository site located at Yucca Mountain, Nevada. With regard to corrosion considerations, a worst case scenario at this prospective repository location would result from the intrusion of vadose water. This preliminary study focuses on the electrochemical and corrosion behavior of the candidate canister materials under worst-case repository environments. Electrochemical parameters related to localized attack (e.g., pitting potentials) and the electrochemical corrosion rates have been examined. 15 references, 15 figures, 4 tables.
Date: June 18, 1984
Creator: Glass, R.S.; Overturf, G.E.; Garrison, R.E. & McCright, R.D.
Partner: UNT Libraries Government Documents Department

Behavior of stressed and unstressed 304L specimens in tuff repository environmental conditions

Description: This paper presents preliminary results of an investigation of the behavior of candidate barrier material for high-level nuclear waste storage, Type 304L stainless steel, in tuff repository environmental conditions. Tuff is a densely welded, devitrified, igneous rock common to the proposed repository site at Yucca Mountain, Nevada. The results discussed include: irradiation corrosion tests, U-bend irradiation corrosion tests, slow strain rate tests, and bent beam stress corrosion tests. Results indicate that Type 304L stainless steel shows excellent resistance to general, localized, and stress corrosion under the environmental and microstructural conditions tested so far. The environmental test conditions are 50 to 100{sup 0}C J-13 well water (non-saline, near neutral pH, and oxic in nature) and saturated steam at 100{sup 0}C. Microstructural conditions include solution annealed and long furnace heat treatments to provoke a sensitized structure. However, this particular type of stainless steel may be susceptible to long-term, low-temperature sensitization because of the combination of expected time at elevated temperature and residual stress in the container after emplacement in the repository. Other grades of austenitic stainless steels are reported to be more resistant to low-temperature sensitization. Future work will therefore include more extensive testing of these grades. 15 references, 5 figures, 7 tables.
Date: November 1, 1984
Creator: Juhas, M.C.; McCright, R.D. & Garrison, R.E.
Partner: UNT Libraries Government Documents Department

Laboratory experiments designed to provide limits on the radionuclide source term for the NNWSI Project

Description: The Nevada Nuclear Waste Storage Investigations Project is investigating the suitability of the tuffaceous rocks at Yucca Mountain Nevada for potential use as a high-level nuclear waste repository. The horizon under investigation lies above the water table, and therefore offers a setting that differs substantially from other potential repository sites. The unsaturated zone environment allows a simple, but effective, waste package design. The source term for radionuclide release from the waste package will be based on laboratory experiments that determine the corrosion rates and mechanisms for the metal container and the dissolution rate of the waste form under expected long term conditions. This paper describes the present status of laboratory results and outlines the approach to be used in combining the data to develop a realistic source term for release of radionuclides from the waste package. 16 refs., 3 figs., 1 tab.
Date: November 1, 1984
Creator: Oversby, V.M. & McCright, R.D.
Partner: UNT Libraries Government Documents Department

Leaching Savannah River Plant nuclear waste glass in a saturated tuff environment

Description: Samples of SRP glass containing either simulated or actual radioactive waste were leached at 90{sup 0}C under conditions simulating a saturated tuff repository environment. The leach vessels were fabricated of tuff and actual tuff groundwater was used. Thus, the glass was leached only in the presence of those materials (including the Type 304L stainless steel canister material) that would be in the actual repository. Tests were performed for time periods up t 6 months at a SA/V ratio of 100 m{sup -1}. Results with glass containing simulated waste indicated that stainless steel canister material around the glass did not significantly affect the leaching. Based on Li and B (elements not in significant concentrations in the tuff or tuff groundwater), glass containing simulated waste leached identically to glass containing actual radioactive waste. The tuff buffered the pH so that only a slight increase was observed as a result of leaching. Results with glass containing actual radioactive waste indicated that tuff reduced the concentrations of Cs-137, Sr-90, and Pu-238 in the free groundwater in the simulated repository by 10 to 100X. Also, radiolysis of the groundwater by the glass (approximately 1000 rad/h) did not significantly affect the pH in the presence of tuff. Measured normalized mass losses in the presence of tuff for the glass based on Cs-137, Sr-90, and Pu-238 in the free groundwater were extremely low, nominally 0.02, 0.02, and 0.005 g/m{sup 2}, respectively, indicating that the glass-tuff system retained radionuclides well. 9 references, 2 figures, 3 tables.
Date: November 1984
Creator: Bibler, N. E.; Wicks, G. G. & Oversby, V. M.
Partner: UNT Libraries Government Documents Department

Determination of corrosion rates for steel alloys in process solvent. Final technical report

Description: The objectives of this program were to determine the corrosion rate, under static and dynamic conditions, of AISI 1010, 5 Cr-0.5 Mo, Type 304L and Type 316L steels in an SRC-I, V-178, coal-derived liquid at temperatures ranging from 550/sup 0/F (288/sup 0/C) to 700/sup 0/F (371/sup 0/C) and to analyze the after-test liquids for metal content, and physical and chemical properties to determine stability under these test conditions. In addition, the program included a study to determine the storage stability of the V-178 coal-derived liquid at 110/sup 0/F (43.3/sup 0/C) in air. 6 references, 32 figures, 35 tables.
Date: January 1, 1984
Creator: Latos, E. J.
Partner: UNT Libraries Government Documents Department

Decontamination of DWPF canisters by glass frit blasting

Description: High-level radioactive waste at the Savannah River Plant will be incorporated in borosilicate glass for permanent disposal. The waste glass will be encapsulated in a 304L stainless steel canister. During the filling operation the outside of the canister will become contaminated. This contamination must be reduced to an accepable level before the canister leaves the Defense Waste Processing Facility (DWPF). Tests with contaminated coupons have demonstrated that this decontamination can be accomplished by blasting the surface with glass frit. The contaminated glass frit byproduct of this operation is used as a feedstock for the waste glass process, so no secondary waste is created. Three blasting techniques, using glass frit as the blasting medium, were evaluated. Air-injected slurry blasting was the most promising and was chosen for further development. The optimum parametric values for this process were determined in tests using coupon weight loss as the output parameter. 1 reference, 13 figures, 3 tables.
Date: January 1, 1984
Creator: Ward, C R & Rankin, W N
Partner: UNT Libraries Government Documents Department