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Title: Performance of a Steel/Oxide Composite Waste Form for Combined Waste Steams from Advanced Electrochemical Processes

Abstract

The results of electrochemical corrosion tests and modeling activities performed collaboratively by researchers at the University of Illinois at Chicago and Argonne National Laboratory as part of workpackage NU-13-IL-UIC-0203-02 are summarized herein. The overall objective of the project was to develop and demonstrate testing and modeling approaches that could be used to evaluate the use of composite alloy/ceramic materials as high-level durable waste forms. Several prototypical composite waste form materials were made from stainless steels representing fuel cladding, reagent metals representing metallic fuel waste streams, and reagent oxides representing oxide fuel waste streams to study the microstructures and corrosion behaviors of the oxide and alloy phases. Microelectrodes fabricated from small specimens of the composite materials were used in a series of electrochemical tests to assess the corrosion behaviors of the constituent phases and phase boundaries in an aggressive acid brine solution at various imposed surface potentials. The microstructures were characterized in detail before and after the electrochemical tests to relate the electrochemical responses to changes in both the electrode surface and the solution composition. The results of microscopic, electrochemical, and solution analyses were used to develop equivalent circuit and physical models representing the measured corrosion behaviors of the different materialsmore » pertinent to long-term corrosion behavior. This report provides details regarding (1) the production of the composite materials, (2) the protocol for the electrochemical measurements and interpretations of the responses of multi-phase alloy and oxide composites, (3) relating corrosion behaviors to microstructures of multi-phase alloys based on 316L stainless steel and HT9 (410 stainless steel was used as a substitute) with added Mo, Ni, and/or Mn, and (4) modeling the corrosion behaviors and rates of several alloy/oxide composite materials made with added lanthanide and uranium oxides. These analyses show the corrosion behaviors of the alloy/ceramic composite materials are very similar to the corrosion behaviors of multi-phase alloy waste forms, and that the presence of oxide inclusions does not impact the corrosion behaviors of the alloy phases. Mixing with metallic waste streams is beneficial to lanthanide and uranium oxides in that they react with Zr in the fuel waste to form highly durable zirconates. The measured corrosion behaviors suggest properly formulated composite materials would be suitable waste forms for combined metallic and oxide waste streams generated during electrometallurgical reprocessing of spent nuclear fuel. Electrochemical methods are suitable for evaluating the durability and modeling long-term behavior of composite waste forms: the degradation model developed for metallic waste forms can be applied to the alloy phases formed in the composite and an affinity-based mineral dissolution model can be applied to the ceramic phases.« less

Authors:
 [1];  [1];  [1];  [1]
  1. Univ. of Illinois, Chicago, IL (United States)
Publication Date:
Research Org.:
Univ. of Illinois, Chicago, IL (United States)
Sponsoring Org.:
USDOE Office of Nuclear Energy (NE). Nuclear Energy University Programs (NEUP)
OSTI Identifier:
1364135
Report Number(s):
DOE/NEUP-13-5059
13-5059; TRN: US1702248
DOE Contract Number:
NE0000705
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; STAINLESS STEEL-316L; WASTE FORMS; ELECTROCHEMICAL CORROSION; URANIUM OXIDES; SPENT FUELS; CLADDING

Citation Formats

Indacochea, J. E., Gattu, V. K., Chen, X., and Rahman, T.. Performance of a Steel/Oxide Composite Waste Form for Combined Waste Steams from Advanced Electrochemical Processes. United States: N. p., 2017. Web. doi:10.2172/1364135.
Indacochea, J. E., Gattu, V. K., Chen, X., & Rahman, T.. Performance of a Steel/Oxide Composite Waste Form for Combined Waste Steams from Advanced Electrochemical Processes. United States. doi:10.2172/1364135.
Indacochea, J. E., Gattu, V. K., Chen, X., and Rahman, T.. 2017. "Performance of a Steel/Oxide Composite Waste Form for Combined Waste Steams from Advanced Electrochemical Processes". United States. doi:10.2172/1364135. https://www.osti.gov/servlets/purl/1364135.
@article{osti_1364135,
title = {Performance of a Steel/Oxide Composite Waste Form for Combined Waste Steams from Advanced Electrochemical Processes},
author = {Indacochea, J. E. and Gattu, V. K. and Chen, X. and Rahman, T.},
abstractNote = {The results of electrochemical corrosion tests and modeling activities performed collaboratively by researchers at the University of Illinois at Chicago and Argonne National Laboratory as part of workpackage NU-13-IL-UIC-0203-02 are summarized herein. The overall objective of the project was to develop and demonstrate testing and modeling approaches that could be used to evaluate the use of composite alloy/ceramic materials as high-level durable waste forms. Several prototypical composite waste form materials were made from stainless steels representing fuel cladding, reagent metals representing metallic fuel waste streams, and reagent oxides representing oxide fuel waste streams to study the microstructures and corrosion behaviors of the oxide and alloy phases. Microelectrodes fabricated from small specimens of the composite materials were used in a series of electrochemical tests to assess the corrosion behaviors of the constituent phases and phase boundaries in an aggressive acid brine solution at various imposed surface potentials. The microstructures were characterized in detail before and after the electrochemical tests to relate the electrochemical responses to changes in both the electrode surface and the solution composition. The results of microscopic, electrochemical, and solution analyses were used to develop equivalent circuit and physical models representing the measured corrosion behaviors of the different materials pertinent to long-term corrosion behavior. This report provides details regarding (1) the production of the composite materials, (2) the protocol for the electrochemical measurements and interpretations of the responses of multi-phase alloy and oxide composites, (3) relating corrosion behaviors to microstructures of multi-phase alloys based on 316L stainless steel and HT9 (410 stainless steel was used as a substitute) with added Mo, Ni, and/or Mn, and (4) modeling the corrosion behaviors and rates of several alloy/oxide composite materials made with added lanthanide and uranium oxides. These analyses show the corrosion behaviors of the alloy/ceramic composite materials are very similar to the corrosion behaviors of multi-phase alloy waste forms, and that the presence of oxide inclusions does not impact the corrosion behaviors of the alloy phases. Mixing with metallic waste streams is beneficial to lanthanide and uranium oxides in that they react with Zr in the fuel waste to form highly durable zirconates. The measured corrosion behaviors suggest properly formulated composite materials would be suitable waste forms for combined metallic and oxide waste streams generated during electrometallurgical reprocessing of spent nuclear fuel. Electrochemical methods are suitable for evaluating the durability and modeling long-term behavior of composite waste forms: the degradation model developed for metallic waste forms can be applied to the alloy phases formed in the composite and an affinity-based mineral dissolution model can be applied to the ceramic phases.},
doi = {10.2172/1364135},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2017,
month = 6
}

Technical Report:

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  • The particle mass loadings exiting the furnace and entering the ESP were within the expected range predicted by the EPRI data base for the ash content of the coal burned. In general, only minor variations in mass loadings were observed between the test phases. At full load, the dry standard mass loadings were within 1 standard deviation of the mean of all tests. For all test phases, the average difference from the baseline mass loading was 6%. This is very little change, and is as likely to be related to coal characteristics or noise in the measurement as to low-NO{submore » x} modifications. ESP performance modeling was performed on the assumption that the only differences between the test phases were the gas volume changes caused by the measured differences in long-term oxygen levels. Otherwise, all test phases were assumed to have the same operating conditions as the baseline condition. Projections were made for a series of hypothetical ESPs with SCA values ranging from 150 to 500 ft{sup 2}/1000 acfm. Hot-side modeling results showed that LNCFS 2 operation is expected to increase the ESP particle penetration over the baseline values by from 8% for a small ESP to 27% for a large ESP. For LNCFS 3 operation, the increase is from 5 to 19% for small and large ESPs. For LNCFS 1 operation, the ESP particle penetration is reduced from the baseline levels by from 4% for a small ESP to 13% for a large ESP. Because of basic differences in their natures, the projected performance of the cold-side ESPs was significantly better than the hot-side units for all cases. Because of the lower overall emissions, the changes produced by the volume flow increases resulted in higher relative changes. The model predicted penetration increases of 9% to 35% for LNCFS 2 and 7% to 25% for LNCFS 3. The reduced oxygen during LNCFS 1 reduced penetration by 6% to 17%.« less
  • Experience with the operation of an experimental engineering-development pot-calcination facility, including two types of evaporators with associated control systems and a calciner pot up to 8 in. in diameter and 90 in. high, formed the basis for the recommendation of equipment and operating procedures for the hot-pilot-plant phase of the waste-calcination program. The operating data and results from about 20 runs are shown in tables and graphs, and significant operating variables are discussed. A continuous waste evaporator with a 25-liter operating volume, a batch evaporator with a capacity of 500 liters, and waste calciner pot with a 60-liter operating capacitymore » were operated to obtain the necessary data to facilitate the design of the pot-calcination pilot plant. The three types of feed used were Purex, TBP-25, and Darex. The average feed rates varied from a low of 7.0 liters/h to a maximum of 30.6. The total feed volume calcined varied from 325 to 641 liters. The reduction in volume for the Purex waste was about 10 to 1, and for TBP-25 and Darex the reduction was about 8 to 1. The volume ratio of water added to strip the nitric acid from the evaporator to feed volume varied from 2.0:1.0 to 4.1:1.0. The resulting calcined solids had bulk densities of about 0.6 g/cc for TBP-25 waste, about 1.2 g/cc for Darex, and about 1.25 g/cc for Purex. The pot-calcination process is a simple direct approach for preparing high-activity liquid wastes for ultimate disposal, as it requires a small number of processing steps. It is versatile enough to handle a variety of fuel processing wastes, for example, Purex, TBP-25, and Darex, and it produces a small volume of off-gas to be processed for recycle or disposal to the environment.« less
  • Experience with the operation of an experimental engineering-development pot-calcination facility, including two types of evaporators with associated control systems and a calciner pot up to 8 in. in diameter and 90 in. high, formed the basis for the recommendation of equipment and operating procedures for the hot-pilot-plant phase of the waste-calcination program. The operating data and results from about 20 runs are shown in tables and graphs, and significant operating variables are discussed. A continuous waste evaporator with a 25-liter operating volume, a batch evaporator with a capacity of 500 liters, and waste caiciner pot with a 60-liter operating capacitymore » were operated to obtain the necessary data to facilitate the design of the pot-calcination pilot plant. The three types of feed used were Purex, TBP-25, and Darex. The average feed rates varied from a low of 7.0 liters/hr to a maximum of 30.6. The total feed volume calcined varied from 325 to 641 liters. The reduction in volume for the Purex waste was about 10 to 1, and for TBP-25 and Darex the reduction was about 8 to 1. The volume ratio of water added to strip the nitric acid from the evaporator to feed volume varied from 2.0: 1.0 to 4.1: 1.0. The resulting calcined solids had bulk densities of about 0.6 g/cc for TBP-25 waste, about 1.2 g/cc for Darex, and about 1.25 g/cc for Purex. The pot-calcination process is a simple direct approach for preparing high-activity liquid wastes for ultimate disposal, as it requires a small number of processing steps. It is versatile enough to handle a variety of fuel processing wastes, for example, Purex, TBP-25, and Darex, and it produces a small volume of off-gas to be processed for recycle or disposal to the environment. (auth)« less
  • This report summarizes treatment and waste form options being evaluated for waste streams resulting from the electrochemical/pyrometallurgical (pyro ) processing of used oxide nuclear fuel. The technologies that are described are South Korean (Republic of Korea – ROK) and United States of America (US) ‘centric’ in the approach to treating pyroprocessing wastes and are based on the decade long collaborations between US and ROK researchers. Some of the general and advanced technologies described in this report will be demonstrated during the Integrated Recycle Test (IRT) to be conducted as a part of the Joint Fuel Cycle Study (JFCS) collaboration betweenmore » US Department of Energy (DOE) and ROK national laboratories. The JFCS means to specifically address and evaluated the technological, economic, and safe guard issues associated with the treatment of used nuclear fuel by pyroprocessing. The IRT will involve the processing of commercial, used oxide fuel to recover uranium and transuranics. The recovered transuranics will then be fabricated into metallic fuel and irradiated to transmutate, or burn the transuranic elements to shorter lived radionuclides. In addition, the various process streams will be evaluated and tested for fission product removal, electrolytic salt recycle, minimization of actinide loss to waste streams and waste form fabrication and characterization. This report specifically addresses the production and testing of those waste forms to demonstrate their compatibility with treatment options and suitability for disposal.« less
  • The electrochemical industry is one of the most highly energy intensive industries today. However, there have been no significant advances in the electrodes that these industries use. The dimensionally stable anode (DSA), which ELTECH introduced under a license agreement, has been the industry standard for the past twenty-five years. But, DSAs are nearing the end of their technological prevalence. The principal problems with DSAs include high capital and operating costs, and the proprietary nature of the technology. In addition, DSAs experience problems that include: contamination of the process solution by anode materials, failure when the electrocatalytic coating peels from underattack,more » generally low anode performance due to inherent limitations in operating current density, and short anode lifetime because of corrosion. The proposed innovation combines the low electrical resistance of copper with the corrosion resistance of electrically conductive diamond to achieve energy efficient, long-lifetime electrodes for electrochemistry. The proposed work will ultimately develop a composite electrode that consists of a copper substrate, a conductive diamond coating, and a catalytic precious metal coating. The scope of the current work includes preparation, testing, and evaluation of diamond-coated titanium electrodes.« less