Creep of the copper canister in the Swedish program

2006 ◽  
Vol 932 ◽  
Author(s):  
William H Bowyer

ABSTRACTThe Swedish programme for disposal of high level nuclear waste includes the development of a container which comprises a cast iron load bearing canister contained in a 50 mm thick copper corrosionshield.The temperature of the outside of the canister is likely be up to 100°C, and repository processes may lead to long term loads of up to 50MPa. Creep of the copper is therefore an issue. SKB (The Swedish Nuclear Fuel and Waste Management Co.) have been conducted tests on three materials, OF copper containing 10ppm sulphur (OF1), OF copper containing 6ppm sulphur (OF2) and OF copper containing 6ppm sulphur and 50ppm phosphorus (OFP). In order to improve confidence in extrapolation of test results to practical temperatures and stresses, it is desirable to support the extrapolation procedures with a physical model.Life predictions made using the Frost and Ashby model [5] together with a simplification of the Cocksand Ashby model [6] provide good agreement with published experimental data for OF2 and OFPmaterials. Extrapolation of this data using the model leads to life predictions of 12,000 years for the OF2material and 120,000 years for OFP material. The prediction for OFP depends on an assumption that an observed strengthening mechanism conferred by phosphorus at high stresses and temperatures, is equally as effective under repository conditions.OF1 material fails after a relatively short life and by a different mechanism to OF2 and OFP. The changein mechanism may be explained, using the model [6], for cases where segregating species reduce surface energy of grain boundary voids. It is suggested that in this case the segregating species is sulphur.

1990 ◽  
Vol 212 ◽  
Author(s):  
D. E. Grandstaff ◽  
V. J. Grassi ◽  
A. C. Lee ◽  
G. C. Ulmer

ABSTRACTSystematic differences in pH, cation/proton ion activity ratios, and redox have been observed between solutions produced in rock-water hydrothermal experiments with tuff, granite, and basalt. Stable pH values in tuff-water experiments may be as much as 1.5 pH units more acidic than basalt-water experiments at the same temperature and ionic strength. Redox (log fO2) values in 300°C tuff experiments are 4–7 orders of magnitude more oxidizing than basalt experiments and ca. 4 log units more oxidizing than the magnetite-hematite buffer. Such fluid differences could significantly affect the performance of a high-level nuclear waste repository and should be considered in repository design and siting.


2019 ◽  
Vol 9 (12) ◽  
pp. 2437 ◽  
Author(s):  
Sebastian Wegel ◽  
Victoria Czempinski ◽  
Pao-Yu Oei ◽  
Ben Wealer

The nuclear industry in the United States of America has accumulated about 70,000 metric tons of high-level nuclear waste over the past decades; at present, this waste is temporarily stored close to the nuclear power plants. The industry and the Department of Energy are now facing two related challenges: (i) will a permanent geological repository, e.g., Yucca Mountain, become available in the future, and if yes, when?; (ii) should the high-level waste be transported to interim storage facilities in the meantime, which may be safer and more cost economic? This paper presents a mathematical transportation model that evaluates the economic challenges and costs associated with different scenarios regarding the opening of a long-term geological repository. The model results suggest that any further delay in opening a long-term storage increases cost and consolidated interim storage facilities should be built now. We show that Yucca Mountain’s capacity is insufficient and additional storage is necessary. A sensitivity analysis for the reprocessing of high-level waste finds this uneconomic in all cases. This paper thus emphasizes the urgency of dealing with the high-level nuclear waste and informs the debate between the nuclear industry and policymakers on the basis of objective data and quantitative analysis.


1993 ◽  
Vol 333 ◽  
Author(s):  
R. A. Van Konynenburg

ABSTRACTThe 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, the scientific approach 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.


2008 ◽  
Vol 59 (2) ◽  
pp. 140-144
Author(s):  
Laurentiu Popa ◽  
Maria Radulescu ◽  
Alice Dinu ◽  
Lucian Velciu ◽  
Ioan Viorel Branzoi

Geological disposal is identified by nearly all experts in the field of waste management as the only safe and sustainable option presently available, but the progress towards its implementation is slow. The nuclear waste must be safely storaged for hundreds of thousand years. Titanium alloys are some of the most promising candidates as container materials for the long-term disposal of high level nuclear waste (HLW) in rock salt formations. In the case of titanium waste containers, between the containers walls and the surrounding buffer material used to pack the disposal borehole some crevices can appear in the welded zone container/ shielding lid, under a biofilm etc. For this purpose we studied the effect of chloride concentration on crevice corrosion of some welded titanium alloys (Grade 2 and Grade 12, respectively) in chloride solutions at 90oC by electrochemical methods (Ecorr vs time, potentiodynamic tests).


1990 ◽  
Vol 212 ◽  
Author(s):  
R. Daniel McCright

ABSTRACTCandidate container materials for high-level nuclear waste packages to be emplaced at the proposed Yucca Mountain repository site are being considered for their long-term resistance to corrosion, oxidation, embrittlement and other kinds of degradation. Selection criteria have been established, and a method has been developed for recommending a material for advanced container design activities. An extensive compilation of the degradation phenomena for six candidate materials is complete, and further studies have begun on the degradation modes affecting additional candidate materials. Phenomenological models for predicting container degradation rates are being advanced for environmental conditions applicable to Yucca Mountain. An experimental program is underway to evaluate the susceptibility of container materials to localized corrosion, stress corrosion cracking, and enhancement of corrosion and oxidation attack by gamma radiation. Initial evaluations of container fabrication and welding processes have identified some processes that appear to alleviate some long-term corrosion susceptibility concerns.


1991 ◽  
Vol 257 ◽  
Author(s):  
R.L. Schulz ◽  
D.E. Clark ◽  
A.R. Lodding ◽  
G.G. Wicks

ABSTRACTField leaching studies were carried out in granite at the Stripa site in Sweden and also in salt in the Materials Interface Interaction Test at the Waste Isolation Pilot Plant (MIIT/WIPP) in New Mexico. The goal of these studies is to assess the durability of various glass compositions engineered to isolate high-level nuclear waste from the biosphere. An additional goal of the MIIT study is to determine how the glasses interact with a wide array of proposed materials that may be a part of the multi-barrier waste package. These substances include metals, geological host specimens,, as well as engineered backfill and overpack materials.Two year data on the SRLY (165/TDS) glass compositions has been extracted from both studies (Stripa and WIPP/MIIT) and five year data has recently become available from the MIIT study. Results from SEM/EDS, SIMS and FTIRRS analyses on glass/glass interfaces are presented in this paper.


2006 ◽  
Vol 985 ◽  
Author(s):  
Jared M. Smith ◽  
Z. Qin ◽  
J. C. Wren ◽  
D. W. Shoesmith

AbstractScandinavian/Canadian high-level nuclear waste repository conditions are expected to evolve from initially warm and oxic to eventually cool and anoxic. During the warm oxic period, corrosion products will accumulate on the container surface. These deposits could impede the reaction of Cu with aqueous sulphide, the only reaction that could lead to the significant accumulation of additional corrosion damage under the long-term anoxic conditions. The kinetics of reaction of Cu with aqueous sulphide solutions have been studied using electrochemical and surface analytical techniques. Corrosion potential measurements were used to follow the evolution of the surface as oxides/hydroxides were converted to sulphides in the sulphide concentration range 10-5 to 10-3 mol/L. Changes in composition were followed by in-situ Raman spectroscopy. Of critical importance is whether or not a period of preoxidation of a Cu container surface can prevent subsequent reaction of the surface with remotely produced sulphide


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