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Title: Accelerated Weathering of High-Level and Plutonium-bearing Lanthanide Borosilicate Waste Glasses under Hydraulically Unsaturated Conditions

Abstract

A can-in-canister waste package design has been proposed for disposal of excess weapons plutonium at the proposed mined geologic repository at Yucca Mountain, NV. by the U. S. Department of Energy Office of Fissile Material Disposition. This configuration consists of a high-level waste (HLW) canister fitted with a rack that holds mini-canisters containing a Pu-bearing lanthanide borosilicate (LaBS) waste glass and/or ceramic (~15% of the total canister volume). The larger canister is then filled with HLW glass, SRL-202, (~85% of the total canister volume). A 6-year pressurized unsaturated flow (PUF) test was conducted to investigate waste form/waste form interactions that may occur when water penetrates the canisters and contacts the waste forms. Volumetric water content was observed to increase steadily during PUF testing from accumulation of water mass as waters of hydration associated with alteration phases formed on the glass surface. Periodic excursions in effluent pH, electrical conductivity, and solution chemistry were monitored and correlated with the formation of a clay phase(s) during the test. Thermodynamic modeling of select effluent solution samples suggests the dominant secondary reaction product for the SRL-202 glass is a smectite di-octahedral clay phase(s), possibly nontronite [Na0.33Fe2(AlSi)4O10(OH)2•n(H2O)] or beidellite [Na0.33Al2.33Si3.67O10(OH)2]. This phase was identified in SEMmore » images as discrete spherical particles found growing out of a gel-layer on reacted SRL-202 glass. Plutonium analyses of filtered and unfiltered solutions indicate that >80% of the Pu exiting the PUF system is as filterable particulates. In this advection-dominated system, Pu is migrating principally as colloids after being released from the LaBS glass. Analysis of reacted LaBS glass using SEM-EDS illustrates that Pu has segregated into a discrete disk-like phase, possibly PuO2. Alteration products that contain the neutron absorber Gd have not been positively identified. Separation of the Pu and its neutron absorbers during glass dissolution and transport is a potential criticality concern in the proposed repository. However, the translation and interpretation of these long-term PUF test results to actual disposed waste packages requires further analysis.« less

Authors:
; ;  [1]; ; ;
  1. PNNL
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
913322
Report Number(s):
PNNL-SA-44281
Journal ID: ISSN 0883-2927; APPGEY; 14592; 830403000; TRN: US0800713
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Applied Geochemistry, 22(9):1841-1859
Additional Journal Information:
Journal Volume: 22; Journal Issue: 9; Journal ID: ISSN 0883-2927
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; 11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; BOROSILICATE GLASS; CERAMICS; COLLOIDS; CONTAINERS; DISSOLUTION; ELECTRIC CONDUCTIVITY; FISSILE MATERIALS; NEUTRON ABSORBERS; PARTICULATES; PLUTONIUM; RARE EARTHS; SECONDARY REACTIONS; SMECTITE; THERMODYNAMICS; WASTE FORMS; WASTES; WEATHERING; YUCCA MOUNTAIN; Plutonium Immobilization; Lathanide Borosilicate (LaBS) Glass; High-Level Waste Glass; Pressurized Unsaturated Flow (PUF) System; Glass Dissolution; Glass Corrosion; can-in-canister configuration; Environmental Molecular Sciences Laboratory

Citation Formats

Pierce, Eric M, McGrail, B Peter, Martin, Paul, Marra, James C, Arey, Bruce W, and Geiszler, Keith N. Accelerated Weathering of High-Level and Plutonium-bearing Lanthanide Borosilicate Waste Glasses under Hydraulically Unsaturated Conditions. United States: N. p., 2007. Web. doi:10.1016/j.apgeochem.2007.03.056.
Pierce, Eric M, McGrail, B Peter, Martin, Paul, Marra, James C, Arey, Bruce W, & Geiszler, Keith N. Accelerated Weathering of High-Level and Plutonium-bearing Lanthanide Borosilicate Waste Glasses under Hydraulically Unsaturated Conditions. United States. https://doi.org/10.1016/j.apgeochem.2007.03.056
Pierce, Eric M, McGrail, B Peter, Martin, Paul, Marra, James C, Arey, Bruce W, and Geiszler, Keith N. Sat . "Accelerated Weathering of High-Level and Plutonium-bearing Lanthanide Borosilicate Waste Glasses under Hydraulically Unsaturated Conditions". United States. https://doi.org/10.1016/j.apgeochem.2007.03.056.
@article{osti_913322,
title = {Accelerated Weathering of High-Level and Plutonium-bearing Lanthanide Borosilicate Waste Glasses under Hydraulically Unsaturated Conditions},
author = {Pierce, Eric M and McGrail, B Peter and Martin, Paul and Marra, James C and Arey, Bruce W and Geiszler, Keith N},
abstractNote = {A can-in-canister waste package design has been proposed for disposal of excess weapons plutonium at the proposed mined geologic repository at Yucca Mountain, NV. by the U. S. Department of Energy Office of Fissile Material Disposition. This configuration consists of a high-level waste (HLW) canister fitted with a rack that holds mini-canisters containing a Pu-bearing lanthanide borosilicate (LaBS) waste glass and/or ceramic (~15% of the total canister volume). The larger canister is then filled with HLW glass, SRL-202, (~85% of the total canister volume). A 6-year pressurized unsaturated flow (PUF) test was conducted to investigate waste form/waste form interactions that may occur when water penetrates the canisters and contacts the waste forms. Volumetric water content was observed to increase steadily during PUF testing from accumulation of water mass as waters of hydration associated with alteration phases formed on the glass surface. Periodic excursions in effluent pH, electrical conductivity, and solution chemistry were monitored and correlated with the formation of a clay phase(s) during the test. Thermodynamic modeling of select effluent solution samples suggests the dominant secondary reaction product for the SRL-202 glass is a smectite di-octahedral clay phase(s), possibly nontronite [Na0.33Fe2(AlSi)4O10(OH)2•n(H2O)] or beidellite [Na0.33Al2.33Si3.67O10(OH)2]. This phase was identified in SEM images as discrete spherical particles found growing out of a gel-layer on reacted SRL-202 glass. Plutonium analyses of filtered and unfiltered solutions indicate that >80% of the Pu exiting the PUF system is as filterable particulates. In this advection-dominated system, Pu is migrating principally as colloids after being released from the LaBS glass. Analysis of reacted LaBS glass using SEM-EDS illustrates that Pu has segregated into a discrete disk-like phase, possibly PuO2. Alteration products that contain the neutron absorber Gd have not been positively identified. Separation of the Pu and its neutron absorbers during glass dissolution and transport is a potential criticality concern in the proposed repository. However, the translation and interpretation of these long-term PUF test results to actual disposed waste packages requires further analysis.},
doi = {10.1016/j.apgeochem.2007.03.056},
url = {https://www.osti.gov/biblio/913322}, journal = {Applied Geochemistry, 22(9):1841-1859},
issn = {0883-2927},
number = 9,
volume = 22,
place = {United States},
year = {2007},
month = {9}
}