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Title: COMSOL Multiphysics Model for HLW Canister Filling

The U.S. Department of Energy (DOE) is building a Tank Waste Treatment and Immobilization Plant (WTP) at the Hanford Site in Washington to remediate 55 million gallons of radioactive waste that is being temporarily stored in 177 underground tanks. Efforts are being made to increase the loading of Hanford tank wastes in glass while meeting melter lifetime expectancies and process, regulatory, and product quality requirements. Wastes containing high concentrations of Al2O3 and Na2O can contribute to nepheline (generally NaAlSiO4) crystallization, which can sharply reduce the chemical durability of high level waste (HLW) glass. Nepheline crystallization can occur during slow cooling of the glass within the stainless steel canister. The purpose of this work was to develop a model that can be used to predict temperatures of the glass in a WTP HLW canister during filling and cooling. The intent of the model is to support scoping work in the laboratory. It is not intended to provide precise predictions of temperature profiles, but rather to provide a simplified representation of glass cooling profiles within a full scale, WTP HLW canister under various glass pouring rates. These data will be used to support laboratory studies for an improved understanding of the mechanismsmore » of nepheline crystallization. The model was created using COMSOL Multiphysics, a commercially available software. The model results were compared to available experimental data, TRR-PLT-080, and were found to yield sufficient results for the scoping nature of the study. The simulated temperatures were within 60 ºC for the centerline, 0.0762m (3 inch) from centerline, and 0.2286m (9 inch) from centerline thermocouples once the thermocouples were covered with glass. The temperature difference between the experimental and simulated values reduced to 40 ºC, 4 hours after the thermocouple was covered, and down to 20 ºC, 6 hours after the thermocouple was covered. This level of precision is considered acceptable for the scoping nature of the model and the subsequent laboratory glass studies Using the model, two additional glass pouring cycles were conducted. Representative thermocouple data were plotted to show the variations between the two cycles. This provides preliminary data that will be used in laboratory experiments to determine the potential for controlling nepheline crystallization in glass by varying the glass pouring conditions.« less
Authors:
 [1]
  1. Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)
Publication Date:
OSTI Identifier:
1250756
Report Number(s):
SRNL--STI-2015-00207
TRN: US1601332
DOE Contract Number:
AC09-08SR22470
Resource Type:
Technical Report
Research Org:
Savannah River Site (SRS), Aiken, SC (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; 36 MATERIALS SCIENCE; HANFORD RESERVATION; HIGH-LEVEL RADIOACTIVE WASTES; TANKS; SERVICE LIFE; THERMOCOUPLES; STAINLESS STEELS; GLASS; CRYSTALLIZATION; WASTE PROCESSING; COOLING; COMPARATIVE EVALUATIONS; CONCENTRATION RATIO; COMPUTERIZED SIMULATION; UNDERGROUND; ABUNDANCE; ACCURACY; FORECASTING; VARIATIONS; SODIUM SILICATES; ALUMINIUM SILICATES; ALUMINIUM OXIDES; SODIUM OXIDES; REMEDIAL ACTION; TEMPERATURE DISTRIBUTION Waste Glass; Thermal Modeling; Hanford