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Title: ACCOUNTING FOR A VITRIFIED PLUTONIUM WASTE FORM IN THE YUCCA MOUNTAIN REPOSITORY TOTAL SYSTEM PERFORMANCE ASSESSMENT (TSPA)

Abstract

A vitrification technology utilizing a lanthanide borosilicate (LaBS) glass appears to be a viable option for dispositioning excess weapons-useable plutonium that is not suitable for processing into mixed oxide (MOX) fuel. A significant effort to develop a glass formulation and vitrification process to immobilize plutonium was completed in the mid-1990s to support the Plutonium Immobilization Program (PIP). Further refinement of the vitrification process was accomplished as part of the Am/Cm solution vitrification project. The LaBS glass formulation was found to be capable of immobilizing in excess of 10 wt% Pu and to be very tolerant of the impurities accompanying the plutonium material streams. Thus, this waste form would be suitable for dispositioning plutonium owned by the Department of Energy-Office of Environmental Management (DOE-EM) that may not be well characterized and may contain high levels of impurities. The can-in-canister technology demonstrated in the PIP could be utilized to dispose of the vitrified plutonium in the federal radioactive waste repository. The can-in-canister technology involves placing small cans of the immobilized Pu form into a high level waste (HLW) glass canister fitted with a rack to hold the cans and then filling the canister with HLW glass. Testing was completed to demonstrate thatmore » this technology could be successfully employed with little or no impact to current Defense Waste Processing Facility (DWPF) operation and that the resulting canisters were essentially equivalent to the present HLW glass canisters to be dispositioned in the federal repository. The performance of wastes in the repository and, moreover, the performance of the entire repository system is being evaluated by the Department of Energy-Office of Civilian Radioactive Waste Management (DOE-RW) using a Total System Performance Assessment (TSPA) methodology. Technical bases documents (e.g., Analysis/Modeling Reports (AMR)) that address specific issues regarding waste form performance are being used to develop process models as input to the TSPA analyses. In this report, models developed in five AMRs for waste forms currently slated for disposition in the repository are evaluated for their applicability to waste forms with plutonium immobilized in LaBS glass using the can-in-canister technology. Those AMRs address: high-level waste glass degradation; radionuclide inventory; in-package chemistry; dissolved concentration limits of radioactive elements; and colloid-associated radionuclide concentrations. Based on evaluation of how the models treated HLW glass and similarities in the corrosion behaviors of borosilicate HLW glasses and LaBS glass, the models in the AMRs were deemed to be directly applicable to the disposition of excess weapons-useable plutonium. The evaluations are summarized.« less

Authors:
Publication Date:
Research Org.:
SRS
Sponsoring Org.:
USDOE
OSTI Identifier:
901094
Report Number(s):
WSRC-TR-2003-00530
TRN: US0702571
DOE Contract Number:
DE-AC09-96SR18500
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; BOROSILICATE GLASS; CONTAINERS; CORROSION; GLASS; IMPURITIES; OXIDES; PERFORMANCE; PLUTONIUM; RADIOACTIVE WASTE MANAGEMENT; RADIOACTIVE WASTES; RADIOISOTOPES; RARE EARTHS; VITRIFICATION; WASTE FORMS; WASTE PROCESSING; YUCCA MOUNTAIN

Citation Formats

Marra, J. ACCOUNTING FOR A VITRIFIED PLUTONIUM WASTE FORM IN THE YUCCA MOUNTAIN REPOSITORY TOTAL SYSTEM PERFORMANCE ASSESSMENT (TSPA). United States: N. p., 2007. Web. doi:10.2172/901094.
Marra, J. ACCOUNTING FOR A VITRIFIED PLUTONIUM WASTE FORM IN THE YUCCA MOUNTAIN REPOSITORY TOTAL SYSTEM PERFORMANCE ASSESSMENT (TSPA). United States. doi:10.2172/901094.
Marra, J. Mon . "ACCOUNTING FOR A VITRIFIED PLUTONIUM WASTE FORM IN THE YUCCA MOUNTAIN REPOSITORY TOTAL SYSTEM PERFORMANCE ASSESSMENT (TSPA)". United States. doi:10.2172/901094. https://www.osti.gov/servlets/purl/901094.
@article{osti_901094,
title = {ACCOUNTING FOR A VITRIFIED PLUTONIUM WASTE FORM IN THE YUCCA MOUNTAIN REPOSITORY TOTAL SYSTEM PERFORMANCE ASSESSMENT (TSPA)},
author = {Marra, J},
abstractNote = {A vitrification technology utilizing a lanthanide borosilicate (LaBS) glass appears to be a viable option for dispositioning excess weapons-useable plutonium that is not suitable for processing into mixed oxide (MOX) fuel. A significant effort to develop a glass formulation and vitrification process to immobilize plutonium was completed in the mid-1990s to support the Plutonium Immobilization Program (PIP). Further refinement of the vitrification process was accomplished as part of the Am/Cm solution vitrification project. The LaBS glass formulation was found to be capable of immobilizing in excess of 10 wt% Pu and to be very tolerant of the impurities accompanying the plutonium material streams. Thus, this waste form would be suitable for dispositioning plutonium owned by the Department of Energy-Office of Environmental Management (DOE-EM) that may not be well characterized and may contain high levels of impurities. The can-in-canister technology demonstrated in the PIP could be utilized to dispose of the vitrified plutonium in the federal radioactive waste repository. The can-in-canister technology involves placing small cans of the immobilized Pu form into a high level waste (HLW) glass canister fitted with a rack to hold the cans and then filling the canister with HLW glass. Testing was completed to demonstrate that this technology could be successfully employed with little or no impact to current Defense Waste Processing Facility (DWPF) operation and that the resulting canisters were essentially equivalent to the present HLW glass canisters to be dispositioned in the federal repository. The performance of wastes in the repository and, moreover, the performance of the entire repository system is being evaluated by the Department of Energy-Office of Civilian Radioactive Waste Management (DOE-RW) using a Total System Performance Assessment (TSPA) methodology. Technical bases documents (e.g., Analysis/Modeling Reports (AMR)) that address specific issues regarding waste form performance are being used to develop process models as input to the TSPA analyses. In this report, models developed in five AMRs for waste forms currently slated for disposition in the repository are evaluated for their applicability to waste forms with plutonium immobilized in LaBS glass using the can-in-canister technology. Those AMRs address: high-level waste glass degradation; radionuclide inventory; in-package chemistry; dissolved concentration limits of radioactive elements; and colloid-associated radionuclide concentrations. Based on evaluation of how the models treated HLW glass and similarities in the corrosion behaviors of borosilicate HLW glasses and LaBS glass, the models in the AMRs were deemed to be directly applicable to the disposition of excess weapons-useable plutonium. The evaluations are summarized.},
doi = {10.2172/901094},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Feb 12 00:00:00 EST 2007},
month = {Mon Feb 12 00:00:00 EST 2007}
}

Technical Report:

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  • This report describes an assessment of the long-term performance of a repository system that contains deeply buried highly radioactive waste; the system is assumed to be located at the potential site at Yucca Mountain, Nevada. The study includes an identification of features, events, and processes that might affect the potential repository, a construction of scenarios based on this identification, a selection of models describing these scenarios (including abstraction of appropriate models from detailed models), a selection of probability distributions for the parameters in the models, a stochastic calculation of radionuclide releases for the scenarios, and a derivation of complementary cumulativemore » distribution functions (CCDFs) for the releases. Releases and CCDFs are calculated for four categories of scenarios: aqueous flow (modeling primarily the existing conditions at the site, with allowances for climate change), gaseous flow, basaltic igneous activity, and human intrusion. The study shows that models of complex processes can be abstracted into more simplified representations that preserve the understanding of the processes and produce results consistent with those of more complex models.« less
  • Sandia National Laboratories (SNL) (1) and Pacific Northwest Laboratory (PNL) (2) completed the first iteration of total-system performance assessment (TSPA-91) for Yucca Mountain during 1991 and 1992. TSPA-93, the successor to TSPA-91, was conducted by SNL and the Civilian Radioactive Waste Management System Management and Operating (M&O) contractor. The TSPA-93 calculations were formulated based on recommendations generated in TSPA-91. The process models used to describe contaminant mobilization and transport were expanded and the associated parameter sets were improved. Significant improvements include more sophisticated treatments of climate change and percolation flux; saturated zone flow and transport; near-field processes, such as containermore » degradation and radionuclide mobilization; and hydrogeologic and geochemical parameter sets. New features in TSPA-93 include hydrothermal processes associated with elevated thermal loads, alternative waste container packages, and geostatistical representations of the lithologic units. Results of the analyses are shown both as releases and as individual doses, to evaluate the effect of possible changes in standards governing a high-level radioactive waste repository. 10,000-year cumulative releases are similar to those in TSPA-91, and are dominated by gaseous release of {sup 14}C. Longer term cumulative releases increase surprisingly little, with gaseous release and aqueous release more nearly equal. However, substantial individual doses are projected at very long times, as a consequence of certain features of the arid environment. Recommendations for future work to support site characterization, design, regulation assessment, and TSPAs are given, based on the results of the two studies.« less
  • Sandia National Laboratories has completed the second iteration of the periodic total-system performance assessments (TSPA-93) for the Yucca Mountain Site Characterization Project (YMP). Scenarios describing expected conditions (aqueous and gaseous transport of contaminants) and low-probability events (human-intrusion drilling and volcanic intrusion) are modeled. The hydrologic processes modeled include estimates of the perturbations to ambient conditions caused by heating of the repository resulting from radioactive decay of the waste. TSPA-93 incorporates significant new detailed process modeling, including two- and three-dimensional modeling of thermal effects, groundwater flow in the saturated-zone aquifers, and gas flow in the unsaturated zone. Probabilistic analyses are performedmore » for aqueous and gaseous flow and transport, human intrusion, and basaltic magmatic activity. Results of the calculations lead to a number of recommendations concerning studies related to site characterization. Primary among these are the recommendations to obtain better information on percolation flux at Yucca Mountain, on the presence or absence of flowing fractures, and on physical and chemical processes influencing gaseous flow. Near-field thermal and chemical processes, and waste-container degradation are also areas where additional investigations may reduce important uncertainties. Recommendations for repository and waste-package design studies are: (1) to evaluate the performance implications of large-size containers, and (2) to investigate in more detail the implications of high repository thermal power output on the adjacent host rock and on the spent fuel.« less