Download or read book Corrosion Behavior of Technetium Waste Forms Exposed to Various Aqueous Environments written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Technetium is a long-lived beta emitter produced in high yields from uranium as a waste product in spent nuclear fuel and has a high degree of environmental mobility as pertechnetate. It has been proposed that Tc be immobilized into various metallic waste forms to prevent Tc mobility while producing a material that can withstand corrosion exposed to various aqueous medias to prevent the leachability of Tc to the environment over long periods of time. This study investigates the corrosion behavior of Tc and Tc alloyed with 316 stainless steel and Zr exposed to a variety of aqueous media. To date, there is little investigative work related to Tc corrosion behavior and less related to potential Tc containing waste forms. Results indicate that immobilizing Tc into stainless steel-zirconium alloys can be a promising technique to store Tc for long periods of time while reducing the need to separately store used nuclear fuel cladding. Initial results indicate that metallic Tc and its alloys actively corrode in all media. We present preliminary corrosion rates of 100% Tc, 10% Tc - 90% SS{sub 85%}Zr{sub 15%}, and 2% Tc - 98% SS{sub 85%}Zr{sub 15%} in varying concentrations of nitric acid and pH 10 NaOH using the resistance polarization method while observing the trend that higher concentrations of Tc alloyed to the sample tested lowers the corrosion rate of the proposed waste package.

Download or read book Corrosion Passivity Behavior of Technetium Waste Forms written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Passive Corrosion Behavior of Alloy 22 in Multi Ionic Aqueous Environments written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In current waste packaging design, Alloy 22 (Ni-22Cr-13Mo-3W-3Fe) has been chosen as the candidate materials to fabricate a 2 cm outer layer of the high-level nuclear waste containers, as part of proposed geological repository at Yucca Mountain, Nevada. During the repository period, the container materials will be subject to the corrosion due to its exposure to the multi-ionic aqueous environments. Although Alloy 22 has demonstrated excellent corrosion resistance, but accumulation of small yearly corrosion rate for 10,000 or more years can be significant enough. The goal of this research is to seek alternative techniques to obtain a reasonably confident corrosion rate determination, since the conventional weight loss technique requires many years to achieve a detectable weight loss in Alloy 22 samples. This paper will discuss the latest experiment results in using potentiostatic technique to determine passive dissolution rates.

Download or read book Electrochemical Corrosion Studies for Modeling Metallic Waste Form Release Rates written by and published by . This book was released on 2016 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: The isotope 99Tc is an important fission product generated from nuclear power production. Because of its long half-life (t1/2 = 2.13.105 years) and beta-radiotoxicity ([beta]-= 292 keV), it is a major concern in the long-term management of spent nuclear fuel.1 In the spent nuclear fuel, Tc is present as an alloy with Mo, Ru, Rh, and Pd called the epsilon-phase, the relative amount of which increases with fuel burn-up.2 In some separation schemes for spent nuclear fuel, Tc would be separated from the spent fuel and disposed of in a durable waste form.3 Technetium waste forms under consideration include metallic alloys, oxide ceramics and borosilicate glass.4, 5 In the development of a metallic waste form, after separation from the spent fuel, Tc would be converted to the metal, incorporated into an alloy and the resulting waste form stored in a repository.6 Metallic alloys under consideration include Tc-Zr alloys, Tc-stainless-steel alloys and Tc- Inconel alloys (Inconel is an alloy of Ni, Cr and iron which is resistant to corrosion). To predict the long term behavior of the metallic Tc waste form, understanding the corrosion properties of Tc metal and Tc alloys in various chemical environments is needed but efforts to model the behavior of Tc metallic alloys are limited. 7 One parameter that should also be considered in predicting the long-term behavior of the Tc waste form, is the ingrowth of stable Ru that occurs from the radioactive decay of 99Tc (99Tc "99Ru + [beta]- ). After a geological period of time, significant amount of Ru will be present in the Tc and may affect its corrosion properties. Studying the effect of Ru on the corrosion behavior of Tc is also of importance.

Download or read book Treatment Tank Corrosion Studies for the Enhanced Chemical Cleaning Process written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Radioactive waste is stored in high level waste tanks on the Savannah River Site (SRS). Savannah River Remediation (SRR) is aggressively seeking to close the non-compliant Type I and II waste tanks. The removal of sludge (i.e., metal oxide) heels from the tank is the final stage in the waste removal process. The Enhanced Chemical Cleaning (ECC) process is being developed and investigated by SRR to aid in Savannah River Site (SRS) High-Level Waste (HLW) as an option for sludge heel removal. Corrosion rate data for carbon steel exposed to the ECC treatment tank environment was obtained to evaluate the degree of corrosion that occurs. These tests were also designed to determine the effect of various environmental variables such as temperature, agitation and sludge slurry type on the corrosion behavior of carbon steel. Coupon tests were performed to estimate the corrosion rate during the ECC process, as well as determine any susceptibility to localized corrosion. Electrochemical studies were performed to develop a better understanding of the corrosion mechanism. The tests were performed in 1 wt.% and 2.5 wt.% oxalic acid with HM and PUREX sludge simulants. The following results and conclusions were made based on this testing: (1) In 1 wt.% oxalic acid with a sludge simulant, carbon steel corroded at a rate of less than 25 mpy within the temperature and agitation levels of the test. No susceptibility to localized corrosion was observed. (2) In 2.5 wt.% oxalic acid with a sludge simulant, the carbon steel corrosion rates ranged between 15 and 88 mpy. The most severe corrosion was observed at 75 C in the HM/2.5 wt.% oxalic acid simulant. Pitting and general corrosion increased with the agitation level at this condition. No pitting and lower general corrosion rates were observed with the PUREX/2.5 wt.% oxalic acid simulant. The electrochemical and coupon tests both indicated that carbon steel is more susceptible to localized corrosion in the HM/oxalic acid environment than in the PUREX/oxalic acid environment. (3) The corrosion rates for PUREX/8 wt.% oxalic acid were greater than or equal to those observed for the PUREX/2.5 wt.% oxalic acid. No localized corrosion was observed in the tests with the 8 wt.% oxalic acid. Testing with HM/8 wt.% oxalic acid simulant was not performed. Thus, a comparison with the results with 2.5 wt.% oxalic acid, where the corrosion rate was 88 mpy and localized corrosion was observed at 75 C, cannot be made. (4) The corrosion rates in 1 and 2.5 wt.% oxalic acid solutions were temperature dependent: (a) At 50 C, the corrosion rates ranged between 90 to 140 mpy over the 30 day test period. The corrosion rates were higher under stagnant conditions. (b) At 75 C, the initial corrosion rates were as high as 300 mpy during the first day of exposure. The corrosion rates increased with agitation. However, once the passive ferrous oxalate film formed, the corrosion rate decreased dramatically to less than 20 mpy over the 30 day test period. This rate was independent of agitation. (5) Electrochemical testing indicated that for oxalic acid/sludge simulant mixtures the cathodic reaction has transport controlled reaction kinetics. The literature suggests that the dissolution of the sludge produces a di-oxalatoferrate ion that is reduced at the cathodic sites. The cathodic reaction does not appear to involve hydrogen evolution. On the other hand, electrochemical tests demonstrated that the cathodic reaction for corrosion of carbon steel in pure oxalic acid involves hydrogen evolution. (6) Agitation of the oxalic acid/sludge simulant mixtures typically resulted in a higher corrosion rates for both acid concentrations. The transport of the ferrous ion away from the metal surface results in a less protective ferrous oxalate film. (7) A mercury containing species along with aluminum, silicon and iron oxides was observed on the interior of the pits formed in the HM/2.5 wt.% oxalic acid simulant at 75 C. The pitting rates in the agitated and non-agitated solution were 2 mils/day and 1 mil/day, respectively. A mechanism by which the mercury interacts with the aluminum and silicon oxides in this simulant to accelerate corrosion was proposed.

Download or read book Stress Corrosion Cracking Behavior of Alloy 22 in Multi Ionic Aqueous Environments written by and published by . This book was released on 2002 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: The US Department of Energy is characterizing a potential repository site for nuclear waste in Yucca Mountain (NV). In its current design, the nuclear waste containers consist of a double metallic layer. The external layer would be made of NO6022 or Alloy 22 (Ni-22Cr-13Mo-3W-3Fe). Since over their lifetime, the containers may be exposed to multi-ionic aqueous environments, a potential degradation mode of the outer layer could be environmentally assisted cracking (EAC) or stress corrosion cracking (SCC). In general, Alloy 22 is extremely resistant to SCC, especially in concentrated chloride solutions. Current results obtained through slow strain rate testing (SSRT) shows that Alloy 22 may suffer SCC in simulated concentrated water (SCW) at applied potentials approximately 400 mV more anodic than the corrosion potential (E{sub rr}).

Download or read book Waste Forms Technology and Performance written by National Research Council and published by National Academies Press. This book was released on 2011-09-05 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Department of Energy's Office of Environmental Management (DOE-EM) is responsible for cleaning up radioactive waste and environmental contamination resulting from five decades of nuclear weapons production and testing. A major focus of this program involves the retrieval, processing, and immobilization of waste into stable, solid waste forms for disposal. Waste Forms Technology and Performance, a report requested by DOE-EM, examines requirements for waste form technology and performance in the cleanup program. The report provides information to DOE-EM to support improvements in methods for processing waste and selecting and fabricating waste forms. Waste Forms Technology and Performance places particular emphasis on processing technologies for high-level radioactive waste, DOE's most expensive and arguably most difficult cleanup challenge. The report's key messages are presented in ten findings and one recommendation.

Download or read book Corrosion Behavior of Nuclear Waste Storage Canister Materials written by John Grant and published by . This book was released on 2012 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt: The nature of interaction of mild steel nuclear waste storage containers with technetium ions is not fully known. Technetium is formed during nuclear processing and some of this technetium has leaked at the Hanford nuclear waste storage site in Washington State. It is often found as highly oxidized pertechnetate (TeO 4- ) anions at these storage sites which also happen to be highly alkaline and contain a significant amount of nitrate. Theoretically, pertechnetate anions can act as electron acceptors and interact with the mild steel containers and accelerate the oxidation (corrosion) of steel. It is of interest to identify if pertechnetate anions pose a corrosion hazard to the mild steel nuclear waste storage tanks, under the conditions of the storage sites, as that can accelerate the degradation of the tanks and lead to further contamination. In this thesis, the interaction of two relevant container materials, namely, steel alloys A285 and A537 with a technetium surrogate, rhenium was studied. Perrhenate was used as an analog for pertechnetate. As all isotopes of technetium are radioactive, rhenium was chosen as the experimental surrogate due to its chemical similarity to technetium. Electrochemical behavior was evaluated using potentiodynamic polarization tests, and the surface morphology was studied using optical microscopy and scanning electron microscopy. Potentiodynamic polarization tests were conducted in 1.0M NaNO 3 + 0.1M NaOH and 1.0M NaNO3 + 0.1M NaOH + 0.02M NaReO4 . Tests were performed at three different temperatures, namely, (i) room temperature, (ii) 50°C and (iii) 80°C to study the effect of higher temperatures found in the storage sites. Corrosion current, corrosion potential, anodic and cathodic Tafel slopes, polarization resistance and corrosion rates were obtained from electrochemical testing and evaluated. Increasing temperatures was found to lead to increasing corrosion rates for all samples. The data also revealed increased corrosion from sodium perrhenate on the mild steel A285 samples. The perrhenate anion (ReO 4- ) formed a redox couple with iron in the mild steel and accelerated metal dissolution that increased with temperature. Pitting and uniform corrosion was observed in the A285 and A537 mild steel samples. The A537 mild steel, however, displayed lower corrosion rates in the presence of perrhenate compared in the absence of perrhenate. A hypothesis has been proposed to explain the differences between the two alloys.

Download or read book Electrochemical Corrosion Testing of Metal Waste Forms written by and published by . This book was released on 1999 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electrochemical corrosion tests have been conducted on simulated stainless steel-zirconium (SS-Zr) metal waste form (MWF) samples. The uniform aqueous corrosion behavior of the samples in various test solutions was measured by the polarization resistance technique. The data show that the MWF corrosion rates are very low in groundwaters representative of the proposed Yucca Mountain repository. Galvanic corrosion measurements were also conducted on MWF samples that were coupled to an alloy that has been proposed for the inner lining of the high-level nuclear waste container. The experiments show that the steady-state galvanic corrosion currents are small. Galvanic corrosion will, hence, not be an important mechanism of radionuclide release from the MWF alloys.

Download or read book Strategy and Methodology for Radioactive Waste Characterization written by International Atomic Energy Agency and published by IAEA. This book was released on 2007 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past decade significant progress has been achieved in the development of waste characterization and control procedures and equipment as a direct response to ever-increasing requirements for quality and reliability of information on waste characteristics. Failure in control procedures at any step can have important, adverse consequences and may result in producing waste packages which are not compliant with the waste acceptance criteria for disposal, thereby adversely impacting the repository. The information and guidance included in this publication corresponds to recent achievements and reflects the optimum approaches, thereby reducing the potential for error and enhancing the quality of the end product. -- Publisher's description.

Download or read book An Introduction to Nuclear Waste Immobilisation written by Michael I Ojovan and published by Elsevier. This book was released on 2013-12-06 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Drawing on the authors' extensive experience in the processing and disposal of waste, An Introduction to Nuclear Waste Immobilisation, Second Edition examines the gamut of nuclear waste issues from the natural level of radionuclides in the environment to geological disposal of waste-forms and their long-term behavior. It covers all-important aspects of processing and immobilization, including nuclear decay, regulations, new technologies and methods. Significant focus is given to the analysis of the various matrices used, especially cement and glass, with further discussion of other matrices such as bitumen. The final chapter concentrates on the performance assessment of immobilizing materials and safety of disposal, providing a full range of the resources needed to understand and correctly immobilize nuclear waste.

Download or read book Radioactive Waste Management written by and published by . This book was released on 1981 with total page 556 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Chemical Precipitation Processes for the Treatment of Aqueous Radioactive Waste written by and published by . This book was released on 1992 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this report is to provide a review of chemical precipitation processes for the treatment of low and intermediate level aqueous waste. It supersedes Technical Reports Series No. 89, Chemical Treatment of Radioactive Wastes, published in 1968. It provides data on the performance of existing plants and on improved processes that are in an advanced state of development.

Download or read book Comprehensive Nuclear Materials written by Todd R Allen and published by Elsevier. This book was released on 2011-05-12 with total page 3552 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comprehensive Nuclear Materials, Five Volume Set discusses the major classes of materials suitable for usage in nuclear fission, fusion reactors and high power accelerators, and for diverse functions in fuels, cladding, moderator and control materials, structural, functional, and waste materials. The work addresses the full panorama of contemporary international research in nuclear materials, from Actinides to Zirconium alloys, from the worlds' leading scientists and engineers. Critically reviews the major classes and functions of materials, supporting the selection, assessment, validation and engineering of materials in extreme nuclear environment Fully integrated with F-elements.net, a proprietary database containing useful cross-referenced property data on the lanthanides and actinides Details contemporary developments in numerical simulation, modelling, experimentation, and computational analysis, for effective implementation in labs and plants

Download or read book Energy Research Abstracts written by and published by . This book was released on 1986 with total page 600 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Government Reports Announcements Index written by and published by . This book was released on 1996 with total page 600 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book INIS Atomindeks written by and published by . This book was released on 1987 with total page 1414 pages. Available in PDF, EPUB and Kindle. Book excerpt: