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Title: Using polymerization, glass structure, and quasicrystalline theory to produce high level radioactive borosilicate glass remotely: a 20+ year legacy

Abstract

Vitrification is currently the most widely used technology for the treatment of high level radioactive wastes (HLW) throughout the world. Most of the nations that have generated HLW are immobilizing in borosilicate glass. One of the primary reasons that glass has become the most widely used immobilization media is the relative simplicity of the vitrification process, e.g. melt a highly variable waste with some glass forming additives such as SiO 2 and B 2O 3 in the form of a premelted frit and pour the molten mixture into a stainless steel canister. Seal the canister before moisture can enter the canister (10’ tall by 2’ in diameter) so the canister does not corrode from the inside out. Glass has also become widely used for HLW is that due to the fact that the short range order (SRO) and medium range order (MRO) found in the structure of glass atomistically bonds the radionuclides and hazardous species in the waste. The SRO and MRO have also been found to govern the melt properties such as viscosity and resistivity of the melt and the crystallization potential and solubility of certain species. Furthermore, the molecular structure of the glass also controls the glass durability,more » i.e. the contaminant/radionuclide release, by establishing the distribution of ion exchange sites, hydrolysis sites, and the access of water to those sites. The molecular structure is flexible and hence accounts for the flexibility of glass formulations to HLW waste variability. Nuclear waste glasses melt between 1050-1150°C which minimizes the volatility of radioactive components such as 99Tc, 137Cs, and 129I. Nuclear waste glasses have good long term stability including irradiation resistance. Process control models were developed based on the molecular structure of glass, polymerization theory of glass, and quasicrystalline theory of glass crystallization. These models create a glass which is durable, pourable, and processable with 95% accuracy without knowing from batch to batch what the composition of the waste coming out of the storage tanks will be. These models have operated the Savannah River Site Defense Waste Processing Facility (SRS DWPF), which is the world’s largest HLW Joule heated ceramic melter, since 1996. This unique “feed forward” process control, which qualifies the durability, pourability, and processability of the waste plus glass additive mixture before it enters the melter, has enabled ~8000 tons of HLW glass and 4242 canisters to be produced since 1996 with only one melter replacement.« less

Authors:
 [1]
  1. Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)
Publication Date:
Research Org.:
Savannah River Site (SRS), Aiken, SC (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1407942
Report Number(s):
SRNL-STI-2017-00199
Journal ID: ISSN 1553-5975
Grant/Contract Number:
AC09-08SR22470; AC09-96SR18500; AC09-89SR18035
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of the South Carolina Academy of Science
Additional Journal Information:
Journal Volume: 15; Journal Issue: 1; Journal ID: ISSN 1553-5975
Publisher:
South Carolina Academy of Science
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES

Citation Formats

Jantzen, Carol M. Using polymerization, glass structure, and quasicrystalline theory to produce high level radioactive borosilicate glass remotely: a 20+ year legacy. United States: N. p., 2017. Web.
Jantzen, Carol M. Using polymerization, glass structure, and quasicrystalline theory to produce high level radioactive borosilicate glass remotely: a 20+ year legacy. United States.
Jantzen, Carol M. Mon . "Using polymerization, glass structure, and quasicrystalline theory to produce high level radioactive borosilicate glass remotely: a 20+ year legacy". United States. doi:. https://www.osti.gov/servlets/purl/1407942.
@article{osti_1407942,
title = {Using polymerization, glass structure, and quasicrystalline theory to produce high level radioactive borosilicate glass remotely: a 20+ year legacy},
author = {Jantzen, Carol M.},
abstractNote = {Vitrification is currently the most widely used technology for the treatment of high level radioactive wastes (HLW) throughout the world. Most of the nations that have generated HLW are immobilizing in borosilicate glass. One of the primary reasons that glass has become the most widely used immobilization media is the relative simplicity of the vitrification process, e.g. melt a highly variable waste with some glass forming additives such as SiO2 and B2O3 in the form of a premelted frit and pour the molten mixture into a stainless steel canister. Seal the canister before moisture can enter the canister (10’ tall by 2’ in diameter) so the canister does not corrode from the inside out. Glass has also become widely used for HLW is that due to the fact that the short range order (SRO) and medium range order (MRO) found in the structure of glass atomistically bonds the radionuclides and hazardous species in the waste. The SRO and MRO have also been found to govern the melt properties such as viscosity and resistivity of the melt and the crystallization potential and solubility of certain species. Furthermore, the molecular structure of the glass also controls the glass durability, i.e. the contaminant/radionuclide release, by establishing the distribution of ion exchange sites, hydrolysis sites, and the access of water to those sites. The molecular structure is flexible and hence accounts for the flexibility of glass formulations to HLW waste variability. Nuclear waste glasses melt between 1050-1150°C which minimizes the volatility of radioactive components such as 99Tc, 137Cs, and 129I. Nuclear waste glasses have good long term stability including irradiation resistance. Process control models were developed based on the molecular structure of glass, polymerization theory of glass, and quasicrystalline theory of glass crystallization. These models create a glass which is durable, pourable, and processable with 95% accuracy without knowing from batch to batch what the composition of the waste coming out of the storage tanks will be. These models have operated the Savannah River Site Defense Waste Processing Facility (SRS DWPF), which is the world’s largest HLW Joule heated ceramic melter, since 1996. This unique “feed forward” process control, which qualifies the durability, pourability, and processability of the waste plus glass additive mixture before it enters the melter, has enabled ~8000 tons of HLW glass and 4242 canisters to be produced since 1996 with only one melter replacement.},
doi = {},
journal = {Journal of the South Carolina Academy of Science},
number = 1,
volume = 15,
place = {United States},
year = {Mon Mar 27 00:00:00 EDT 2017},
month = {Mon Mar 27 00:00:00 EDT 2017}
}

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  • In this paper, the structure and properties of the different solid forms currently being developed for high-level radioactive waste disposal are compared. Good capacity to accept all the elements in the waste and flexibility of composition range to accommodate variations in the waste, are primarily discussed. 13 refs.
  • A new vitrification process has been invented. The Glass Material Oxidation and Dissolution System (GMODS) allows direct conversion of radioactive and hazardous chemical wastes to borosilicate glass. GMODS directly converts metals, ceramics and amorphous solids to glass, oxidizes organics with the residue converted to glass, and converts halides (such as chlorides) to borosilicate glass and a secondary sodium halide stream. The glass is designed to meet EPA criteria for chemically non-hazardous waste forms. Laboratory work has demonstrated the conversion of stainless steel, aluminum, cerium (a plutonium surrogate), uranium, Zircaloy, multiple oxides and other materials to glass. Equipment options have beenmore » identified for processing rates between 1 and 100,000 t/y. Significant work, including a pilot plant, is required to develop GMODS for applications at an industrial scale.« less
  • The authors discuss the volatility of /sup 137/Cs and /sup 106/Ru from borosilicate glass containing actual high-level waste measured in an almost closed stainless-steel canister. The temperature dependence of the volatility of /sup 137/Cs was close to that obtained in a previous study using /sup 134/Cs. The volatility of /sup 106/Ru was about one-fifth that of /sup 137/Cs at 600{sup 0} and 800{sup 0}C. The air contamination by /sup 137/Cs and /sup 106/Ru in the canister at 400{sup 0}C was estimated at 1.8 x 10/sup 2/ and 2 x 10 Bq/cm/sup 3/, respectively, when it was assumed that the glassmore » contained a realistic amount of /sup 137/Cs and /sup 106/Ru expected in commercial waste glass. These results are useful for predicting safety in a storage facility under operation.« less
  • The local environment of Cm{sup 3+} in a borosilicate glass has been probed by a combination of laser spectroscopy, structural modeling, and extended x-ray absorption fine structure (EXAFS) spectroscopy. The Stark splitting for the Cm f-f state transitions is significantly larger than the inhomogeneous line broadening that results from the disordered environment. As a result, the Cm optical spectrum can be fit using an effective operator Hamiltonian to obtain a set of crystal-field parameters. The fitting procedure, which requires the use of a descent-in-symmetry approach, provides a set of parameters for a best fit within tetragonal symmetry. These parameters aremore » then linked to the local environment of Cm through exchange-charge modeling (ECM) of crystal field interactions. Cm in our borosilicate glass is best modeled with six oxygen ions with approximately tetragonal symmetry, and at an average distance of 2.31 (3) Aa. The results of crystal-field modeling are supported by EXAFS results. (c) 2000 American Institute of Physics.« less