Leaching of Fully Radioactive High-level Waste Glass
Leaching of Fully Radioactive High-level Waste Glass

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Published: 1978

Total Pages:

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As part of continuing Department of Energy (DOE)-sponsored studies in waste management, the Pacific Northwest Laboratory (PNL) has been conducting the High-Level Waste Immobilization Program. The purpose of this program is to develop and demonstrate technology for incorporating nuclear wastes into final waste forms. The preparation and leach testing of fully radioactive, zinc borosilicate glass, which was prepared from power reactor waste, are described. Leach testing using the International Atomic Energy Association (IAEA) procedure was performed in deionized water for a period of 1.75 years. Leach rates were determined for activation products, fission products, and actinides. These rates ranged from 4 x 10−5 g of glass/cm2-day, based on cesium, to 4 x 10−9 g of glass/cm2-day, based on cerium. Following is the ranking of the release rates of the elements, from highest to lowest: Cs> Sr> Co> Sb> Mn> Pu> Eu> Rh> Cm> Ce. A similar leach test, using the same glass composition but with nonradioactive elements, has recently been completed. The leach rates of Cs and Sr for the nonradioactive glass were found to be in close agreement with those in this study. Slopes calculated from curves of cumulative fractions leached show that radioisotope release begins with a diffusion-type mechanism and changes gradually to a silicate lattice alteration mechanism. Changes in sampling frequency altered the apparent release mechanism when leachant changes were longer than one month. The leach rates were quite constant for samples taken from the top to the bottom of the glass melt, indicating a homogeneous product. Safety assessment studies and modeling programs use leach rates to predict the amount of radioactive material released should the waste be contacted by aqueous solutions. Further tests, focusing on geologic storage conditions and using fully radioactive wastes, are planned.

Leaching Fully Radioactive SRP Nuclear Waste Glass in Tuff Groundwater in Stainless Steel Vessels
Leaching Fully Radioactive SRP Nuclear Waste Glass in Tuff Groundwater in Stainless Steel Vessels

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Published: 1986

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SRP glass containing actual radioactive waste was leached in static tests at 90°C in a tuffaceous groundwater (J-13 water at pH (approximately)7.4) at a SA/V ratio of 100m−1 in 316 stainless steel vessels. Tests were performed for time periods up to 134 days. Normalized mass losses were calculated for 137Cs, 9°Sr, and 238Pu. The 137Cs in the leachate appeared to reach a steady value of (approximately)3 g/m2, corresponding to a steady-state concentration of only 1.0 ppB for total cesium. The mass losses based on 9°Sr and 238Pu appearing in solution were low (

Handbook of Advanced Radioactive Waste Conditioning Technologies
Handbook of Advanced Radioactive Waste Conditioning Technologies

Author: Michael I. Ojovan

Publisher: Elsevier

Published: 2011-01-24

Total Pages: 505

ISBN-13: 085709095X

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Radioactive wastes are generated from a wide range of sources, including the power industry, and medical and scientific research institutions, presenting a range of challenges in dealing with a diverse set of radionuclides of varying concentrations. Conditioning technologies are essential for the encapsulation and immobilisation of these radioactive wastes, forming the initial engineered barrier required for their transportation, storage and disposal. The need to ensure the long term performance of radioactive waste forms is a key driver of the development of advanced conditioning technologies.The Handbook of advanced radioactive waste conditioning technologies provides a comprehensive and systematic reference on the various options available and under development for the treatment and immobilisation of radioactive wastes. The book opens with an introductory chapter on radioactive waste characterisation and selection of conditioning technologies. Part one reviews the main radioactive waste treatment processes and conditioning technologies, including volume reduction techniques such as compaction, incineration and plasma treatment, as well as encapsulation methods such as cementation, calcination and vitrification. This coverage is extended in part two, with in-depth reviews of the development of advanced materials for radioactive waste conditioning, including geopolymers, glass and ceramic matrices for nuclear waste immobilisation, and waste packages and containers for disposal. Finally, part three reviews the long-term performance assessment and knowledge management techniques applicable to both spent nuclear fuels and solid radioactive waste forms.With its distinguished international team of contributors, the Handbook of advanced radioactive waste conditioning technologies is a standard reference for all radioactive waste management professionals, radiochemists, academics and researchers involved in the development of the nuclear fuel cycle. - Provides a comprehensive and systematic reference on the various options available and under development for the treatment and immobilisation of radioactive wastes - Explores radioactive waste characterisation and selection of conditioning technologies including the development of advanced materials for radioactive waste conditioning - Assesses the main radioactive waste treatment processes and conditioning technologies, including volume reduction techniques such as compaction

High Level Waste Properties
High Level Waste Properties

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Publisher:

Published: 1979

Total Pages:

ISBN-13:

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Devitrification and leaching analyses of four waste glasses were made to compare non-radioactive compositions to compositions made using fully radioactive waste calcine. Microstructural analyses of the phase behavior of glasses were performed by means of optical microscopy, x-ray diffraction, x-ray fluorescence, scanning electron microscopy, and electron microprobe analysis. The author's summary of the major findings are: Melt insoluables and crystallization products were found to the same extent in both radioactive and non-radioactive glasses of similar composition. High radiation field appeared to have no effect on the crystallization behavior. The results of long-term IAEA static leach tests indicated no significant difference between the average leach rates of the fully radioactive and non-radioactive glass formulations. Glass composition was more important in determining leach rates than was the extent of devitrification. In both short time tests at 75°C or longer leach tests at 25°C elemental analyses suggested that congruent dissolution did not occur.

Performing a Chemical Durability Test on Radioactive High-level Nuclear Waste Glass
Performing a Chemical Durability Test on Radioactive High-level Nuclear Waste Glass

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Publisher:

Published: 1990

Total Pages: 31

ISBN-13:

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Savannah River Site (SRS), currently is storing (approximately)30 million gallons of highly radioactive nuclear wastes. The Defense Waste Processing Facility (DWPF) nearing completion at SRS will incorporate the radionuclides in these wastes into solid borosilicate glass for final disposal in a geologic repository. Because of the variability of the wastes in the tanks, borosilicate glasses of different compositions will be produced by the DWPF during the 20--25 years required to solidify all the wastes at SRS. A chemical durability test, the Product Consistency Test (PCT), has been developed at SRS to measure the consistency of the durability of these glasses. This paper describes the remote and hands-on procedures for performing the PCT on these radioactive glasses. Results will be presented that indicate the good precision of the PCT and indicate some of the chemistry involved in leaching radioactive elements from the glass. 9 refs., 1 fig., 4 tabs.