Spinel Settling in HLW Melters

2001 ◽  
Author(s):  
Josef Matyáš ◽  
Jaroslav Kloužek ◽  
Lubomír Němec ◽  
Miroslav Trochta
Keyword(s):  
Liquidus Temperature ◽  
Linear Growth ◽  
Critical Level ◽  
High Level Waste ◽  
Input Concentration ◽  
Average Temperature ◽  
Input Size ◽  
Waste Loading ◽  
High Level ◽  
The Impact

Abstract The efficiency of high-level waste (HLW) melters is limited by spinel settling and accumulation on the melter bottom if the waste loading is increased above a certain limit at which spinel crystallizes from the melt. Spinel accumulation interferes with melter operation and shortens melter lifetime. The mathematical modeling of spinel settling in a HLW melter was applied to define the critical level of spinel deposition during the lifetime of the melter and the corresponding increase in waste loading. In this study, spinel settled on the bottom, slant melter walls, and in the output pipe with a linear growth of spinel-sludge thickness after its concentration stabilized inside the melter. The calculations provided a higher concentration of spinel crystals in the melter regions where the temperature was lower then the liquidus temperature, i.e., T<TL. The effects of the following parameters on sludge-layer thickness were examined: 1) the impact of input concentration of spinel crystals of the same size, 2) the impact of different input size of spinel crystals of the same concentration entering from cold cap (melting batch on the melt surface), and 3) the influence of the average temperature (Tavg) inside of the melting space. The calculations showed that higher a concentration and bigger crystals caused thicker sludge layers in the melter, either because of a higher settling density of crystals or because of their higher settling rate. The nucleation of spinel crystals plays a more important role with decreasing of average temperature inside of the melter, and the thicker layer was formed at lower average temperatures.

Liquidus Temperature of Spinel Precipitating High-Level Waste Glasses

1996 ◽  
Vol 465 ◽  
Author(s):  
M. Mika ◽  
M. J. Schweiger ◽  
J. D. Vienna ◽  
P. Hrma
Keyword(s):  
Mixture Models ◽  
Crystalline Phase ◽  
Liquidus Temperature ◽  
Glass Composition ◽  
High Level Waste ◽  
Hanford Site ◽  
High Iron ◽  
Negative Effect ◽  
High Level ◽  
Glass Viscosity

ABSTRACTThe liquidus temperature (TL) often limits the loading of high-level waste in glass through the constraint that TL must be at least 100°C below the temperature at which the glass viscosity is 5 Pa-s. In this study, values of TL for spinel primary crystalline phase were measured as a function of glass composition. The test glasses were based on high-iron Hanford Site tank wastes. All studied glasses precipitated spinel (Ni,Fe,Mn)(Cr,Fe)2O4 as the primary crystalline phase. TL was increased by additions of Cr2O3, NiO, Al2O3, Fe2O3, MgO, and MnO; while Li2O, Na2O, B2O3, and SiO2 had a negative effect. Empirical mixture models were fitted to data.

scholarly journals High Waste Loading Glass Formulations for Hanford High-Aluminum High-Level Waste Streams

2011 ◽  
Author(s):  
Albert A. Kruger
Keyword(s):  
Previous Experience ◽  
High Level Waste ◽  
Waste Streams ◽  
Testing Program ◽  
Glass Formulation ◽  
Waste Loading ◽  
Production Requirement ◽  
High Level ◽  
Glass Compositions ◽  
High Aluminum

The current estimates and glass formulation efforts have been conservative in terms of achievable waste loadings. These formulations have been specified to ensure that the glasses are homogenous, contain essentially no crystalline phases, are processable in joule-heated, ceramic-lined melters and meet WTP Contract terms. The WTP’s overall mission will require the immobilization of tank waste compositions that are dominated by mixtures of aluminum (Al), chromium (Cr), bismuth (Bi), iron (Fe), phosphorous (P), zirconium (Zr), and sulfur (S) compounds as waste-limiting components. Glass compositions for these waste mixtures have been developed based upon previous experience and current glass property models. Recently, DOE has initiated a testing program to develop and characterize HLW glasses with higher waste loadings. Results of this work have demonstrated the feasibility of increases in waste loading from about 25 wt% to 33–50 wt% (based on oxide loading) in the glass depending on the waste stream. It is expected that these higher waste loading glasses will reduce the HLW canister production requirement by about 25% or more.

scholarly journals Development of a ceramic waste form for high-level waste disposal

1999 ◽  
Vol 556 ◽  
Author(s):  
D. W. Esh ◽  
K. M. Goff ◽  
K. T. Hirsche ◽  
T. J. Battisti ◽  
M. F. Simpson ◽  
...  
Keyword(s):  
Spent Nuclear Fuel ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Fission Products ◽  
Waste Form ◽  
High Level Waste ◽  
Durability Test ◽  
Ceramic Waste ◽  
High Level ◽  
The Impact

AbstractA ceramic waste form is being developed by Argonne National Laboratory* (ANL) as part of the demonstration of the electrometallurgical treatment of spent nuclear fuel [1]. The halide, alkaline earth, alkali, transuranic, and rare earth fission products are stabilized in zeolite which is combined with glass and processed in a hot isostatic press (HIP) to form a ceramic composite. The mineral sodalite is formed in the HIP from the zeolite precursor. The process, from starting materials to final product, is relatively simple. An overview of the processing operations is given. The metrics that have been developed to measure the success or completion of processing operations are developed and discussed. The impact of variability in processing metrics on the durability of the final product is presented. The process is demonstrated to be robust for the type and range of operation metrics considered and the performance metric (PCT durability test) against which the operation metrics are evaluated.

scholarly journals Glass Formulation Development in Support of Melter Testing to Demonstrate Enhanced High Level Waste Throughput

2008 ◽  
Vol 1107 ◽  
Author(s):  
James C. Marra ◽  
Kevin M. Fox ◽  
David K. Peeler ◽  
Thomas B. Edwards ◽  
Amanda L. Youchak ◽  
...  
Keyword(s):  
Product Quality ◽  
Department Of Energy ◽  
High Alumina ◽  
High Level Waste ◽  
Alumina Concentration ◽  
Formulation Development ◽  
Technology Innovations ◽  
Glass Formulation ◽  
Waste Loading ◽  
High Level

AbstractThe U.S. Department of Energy (DOE) is currently processing high-level waste (HLW) through a Joule-heated melter (JHM) at the Savannah River Site (SRS) and plans to vitrify HLW and Low activity waste (LAW) at the Hanford Site. Over the past few years at the Defense Waste Processing Facility (DWPF), work has concentrated on increasing waste throughput. These efforts are continuing with an emphasis on high alumina concentration feeds. High alumina feeds have presented specific challenges for the JHM technology regarding the ability to increase waste loading yet still maintain product quality and adequate throughput. Alternatively, vitrification technology innovations are also being investigated as a means to increase waste throughput. The Cold Crucible Induction Melter (CCIM) technology affords the opportunity for higher vitrification process temperatures as compared to the current reference JHM technology. Higher process temperatures may allow for higher waste loading and higher melt rate.Glass formulation testing to support melter demonstration testing was recently completed. This testing was specifically aimed at high alumina concentration wastes. Glass composition/property models developed for DWPF were utilized as a guide for formulation development. Both CCIM and JHM testing will be conducted so glass formulation testing was targeted at both technologies with a goal to significantly increase waste loading and maintain melt rate without compromising product quality.

Impact of Advanced Fuel Cycles on Geological Disposal

2009 ◽  
Vol 1193 ◽  
Author(s):  
Jan Marivoet ◽  
Eef Weetjens
Keyword(s):  
Radioactive Waste ◽  
Cooling Time ◽  
High Level Waste ◽  
Waste Streams ◽  
Geological Disposal ◽  
Fuel Cycles ◽  
Thermal Output ◽  
Advanced Fuel ◽  
High Level ◽  
The Impact

AbstractIn recent years the increasing oil prices and the need for carbon-free energy to limit global warming have resulted in a revival of interests in nuclear energy. Advanced nuclear fuel cycles are being studied worldwide. They aim at making more efficient use of the available resources, reducing the risk of proliferation of nuclear weapons, and facilitating the management of the resulting radioactive waste. Recently, the Red-Impact project has investigated the impact of a number of representative advanced fuel cycles on radioactive waste management, and more specific on geological disposal. The thermal output of the high-level waste arising from advanced fuel cycles in which all the actinides are recycled is reduced with a factor 3 for a 50 years cooling time and with a factor 5 for a 100 years cooling time in comparison with the spent fuel arising from the once-through fuel cycle. This reduction of the thermal output allows for a significant reduction of the length of the disposal galleries and of the size of the repository. Separation of Cs and Sr drastically reduces further the thermal output of the high-level waste, but it requires a long-term management of those heat generating separated waste streams, which contain the very long-lived 135Cs. Recycling all the actinides strongly reduces the radiotoxicity in the waste, resulting in significantly lower doses to an intruder in the case of a human intrusion into the repository. However, the reduction of radiotoxicity has little impact on the main safety indicator of a geological repository, i.e. the effective dose in the case of the expected evolution scenario; for disposal in clay formations, this dose is essentially due to mobile fission and activation products. The deployment of advanced fuel cycles will necessitate the development of low activation materials for the new nuclear facilities and fuels and of specific waste matrices to condition the high-level and medium-level waste streams that will arise from the advanced reprocessing plants.

scholarly journals Optimization of the Solidification Method of High-Level Waste for Increasing the Thermal Stability of the Magnesium Potassium Phosphate Compound

Energies ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3789
Author(s):  
Svetlana A. Kulikova ◽  
Sergey S. Danilov ◽  
Kseniya Yu. Belova ◽  
Anastasiya A. Rodionova ◽  
Sergey E. Vinokurov
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Compressive Strength ◽  
Potassium Phosphate ◽  
Treatment Temperature ◽  
High Level Waste ◽  
Leaching Rate ◽  
High Level ◽  
The Impact ◽  
Thermal Stability Of

The key task in the solidification of high-level waste (HLW) into a magnesium potassium phosphate (MPP) compound is the immobilization of mobile cesium isotopes, the activity of which provides the main contribution to the total HLW activity. In addition, the obtained compound containing heat-generating radionuclides can be significantly heated, which increases the necessity of its thermal stability. The current work is aimed at assessing the impact of various methodological approaches to HLW solidification on the thermal stability of the MPP compound, which is evaluated by the mechanical strength of the compound and its resistance to cesium leaching. High-salt surrogate HLW solution (S-HLW) used in the investigation was prepared for solidification by adding sorbents of various types binding at least 93% of 137Cs: ferrocyanide K-Ni (FKN), natural zeolite (NZ), synthetic zeolite Na-mordenite (MOR), and silicotungstic acid (STA). Prepared S-HLW was solidified into the MPP compound. Wollastonite (W) and NZ as fillers were added to the compound composition in the case of using FKN and STA, respectively. It was found that heat treatment up to 450 °C of the compound containing FKN and W (MPP-FKN-W) almost did not affect its compressive strength (about 12–19 МPa), and it led to a decrease of high compressive strength (40–50 MPa) of the compounds containing NZ, MOR, and STA (MPP-NZ, MPP-MOR, and MPP-STA-NZ, respectively) by an average of 2–3 times. It was shown that the differential leaching rate of 137Cs on the 28th day from MPP-FKN-W after heating to 250 °C was 5.3 × 10−6 g/(cm2∙day), however, at a higher temperature, it increased by 20 and more times. The differential leaching rate of 137Cs from MPP-NZ, MPP-MOR, and MPP-STA-NZ had values of (2.9–11) × 10−5 g/(cm2∙day), while the dependence on the heat treatment temperature of the compound was negligible.

Liquidus Temperature Model for Hanford High-Level Waste Glasses with High Concentrations of Zirconia

1996 ◽  
Vol 465 ◽  
Author(s):  
J. V. Crum ◽  
M. J. Schweiger ◽  
P. Hrma ◽  
J. D. Vienna
Keyword(s):  
Crystalline Phase ◽  
Liquidus Temperature ◽  
Heat Treating ◽  
Primary Phase ◽  
High Level Waste ◽  
Mass Fractions ◽  
High Concentrations ◽  
Phase Glass ◽  
High Level ◽  
Temperature Furnace

ABSTRACTA study was conducted on glasses based on a simulated transuranic waste with high concentrations of ZrO2and Bi2O3 to determine the compositional dependence of primary crystalline phases and liquidus temperature (TL). Starting from a baseline composition, glasses were formulated by changing mass fractions of Al2O3, B2O3, Bi2O3, CeO2, Li2O, Na2O, P2O5, SiO2, and ZrO2, one at a time, while keeping the remaining components in the same relative proportions as in the baseline glass. Liquidus temperature was measured by heat treating glass samples for 24 h in a uniform temperature furnace. The primary crystalline phase in the baseline glass and the majority of the glasses was zircon (ZrSiO4). A change in the concentration of certain components (Al2O3, ZrO2, Li2O, B2O3 and SiO2) changed the primary phase to baddeleyite (ZrO2), while cerium oxide (CeO2) precipitated from glasses with more than 3 wt% CeO2. Zircon TL was strongly increased by Al2O3, Zrb2 and CeO2, and slightly by P2O5 and SiO2; decreased strongly by Li2O and Na2O and moderately by B2O3. A first-order model was constructed for TL as a function of composition for zircon primary crystalline phase glass.

scholarly journals Temperature and tortuosity effect on gas migration in a high-level waste disposal tunnel

2015 ◽  
Vol 79 (6) ◽  
pp. 1317-1325 ◽  
Author(s):  
D. Justinavicius ◽  
P. Poskas
Keyword(s):  
Initial Temperature ◽  
Computer Code ◽  
Hydrogen Gas ◽  
High Level Waste ◽  
Gas Migration ◽  
Geological Repository ◽  
High Level ◽  
Clay Formation ◽  
Corrosion Of Steel ◽  
The Impact

AbstractCorrosion of steel canisters, disposed of in a repository for high-level waste (HLW), leads to generation of hydrogen gas for a long period after the repository's closure. The accumulation of hydrogen gas may lead to significant desaturation and unacceptable build-up of pressure in the backfilled disposal tunnels if the gas cannot escape through the low-permeability host rock. Consequently, the investigation of gas migration is of high relevance in the assessment of the repository's performance.In this paper, the results of numerical investigations on gas migration performed using the computer code TOUGH2 (USA) are presented. The objective was to investigate migration of gas generated in a single disposal tunnel of a conceptual geological repository in a clay formation, which was suggested for benchmark studies in the European Commission project FORGE (Fate Of Repository GasEs). The analysis was focused on evaluation of the impact of an initial temperature in the repository and of different tortuosity models on gas migration. It was revealed that gas migration results were dependent on tortuosity model, while temperature variation in the repository had minor impact.

Effect of Molybdenum and Ruthenium on the Crystallization Tendency of a New Nuclear Glass Containing High Rare-earth Concentration

2010 ◽  
Vol 1265 ◽  
Author(s):  
Daniel Caurant ◽  
Nolwenn Chouard ◽  
Odile Majerus ◽  
Jean-Luc Dussossoy ◽  
Aurelien Ledieu ◽  
...  
Keyword(s):  
Room Temperature ◽  
Nucleating Agent ◽  
High Level Waste ◽  
Optical Absorption Spectroscopy ◽  
Thermal Treatments ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Level ◽  
The Impact ◽  
Crystallization Tendency

AbstractThe impact of Nd2O3, MoO3 and RuO2 addition on the competition between the crystallization of apatite Ca2Nd8(SiO4)6O2 and powellite CaMoO4 phases which both may appear in High Level Waste nuclear glass (under certain specific conditions of cooling and glass composition) has been studied on a simplified composition belonging to the system SiO2-Na2O-CaO-Al2O3-B2O3. X-ray diffraction (at room temperature and high temperature) and scanning electron microscopy measurements have been performed on five glasses under two different thermal treatments. We show that RuO2 acts as a nucleating agent for apatite. Moreover, neodymium and molybdenum cations seem to be very close in the glassy network as Nd2O3 addition stops the phase separation of molybdates and inhibits the crystallization of CaMoO4. On the contrary, MoO3 seems to favor the crystallization of apatite. For several samples, the evolution of the distribution of Nd3+ cations after crystallization was followed by optical absorption spectroscopy.

The Effect of Increased Waste Loading on the Durability of High Level Waste Glass

2010 ◽  
Vol 1265 ◽  
Author(s):  
Chris Brookes ◽  
Mike Harrison ◽  
Andrew Riley ◽  
Carl James Steele
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Level Waste ◽  
Sample Type ◽  
Test Rig ◽  
Consistency Test ◽  
Mass Losses ◽  
Waste Loading ◽  
High Level ◽  
Scanning Electron

AbstractThis paper describes the results from static leach tests using the ASTM International standard Materials Characterisation Centre (MCC-1) and Product Consistency Test (PCT) protocols for inactive High Level Waste (HLW) glasses fabricated at full scale on the Sellafield Vitrification Test Rig. The samples comprised monoliths and powders of a 75:25 Oxide:Magnox Blend glass with 31 wt% waste incorporation and a Magnox-only glass with 35 wt% waste incorporation. The tests were carried out in de-ionized water at 90 °C for durations up to 42 days and normalized mass losses calculated.The results of MCC-1 and PCT tests on both 31 wt% Blend and 35 wt% Magnox glasses, showing measurable differences to the corresponding standard 25 wt% waste incorporation glasses, are presented. A series of Scanning Electron Microscopy (SEM) investigations were also undertaken. The variation in composition and thickness of the alteration layer with sample type and duration is reported.

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