CLOSURE OF HLW TANKS FORMULATION FOR A COOLING COIL GROUT

The Tank Closure and Technology Development Groups are developing a strategy for closing the High Level Waste (HLW) tanks at the Savannah River Site (SRS). Two Type IV tanks, 17 and 20 in the F-Area Tank Farm, have been successfully filled with grout. Type IV tanks at SRS do not contain cooling coils; on the other hand, the majority of the tanks (Type I, II, III and IIIA) do contain cooling coils. The current concept for closing tanks equipped with cooling coils is to pump grout into the cooling coils to prevent pathways for infiltrating water after tank closure. This task addresses the use of grout to fill intact cooling coils present in most of the remaining HLW tanks on Site. The overall task was divided into two phases. Phase 1 focused on the development of a grout formulation (mix design) suitable for filling the HLW tank cooling coils. Phase 2 will be a large-scale demonstration of the filling of simulated cooling coils under field conditions using the cooling coil grout mix design recommended from Phase 1. This report summarizes the results of Phase 1, the development of the cooling coil grout formulation. A grout formulation is recommended for the full scale testing at Clemson Environmental Technology Laboratory (CETL) that is composed by mass of 90% Masterflow (MF) 816 (a commercially available cable grout) and 10% blast furnace slag, with a water to cementitious material (MF 816 + slag) ratio of 0.33. This formulation produces a grout that meets the fresh and cured grout requirements detailed in the Task Technical Plan (2). The grout showed excellent workability under continuous mixing with minimal change in rheology. An alternative formulation using 90% MF 1341 and 10% blast furnace slag with a water to cementitious material ratio of 0.29 is also acceptable and generates less heat per gram than the MF 816 plus slag mix. However this MF 1341 mix has a higher plastic viscosity than the MF 816 mix due to the presence of sand in the MF 1341 cable grout and a lower water to solids ratio. Nevertheless, the higher viscosity grout may still meet the requirements for the cooling coil grout under certain pumping conditions or alternatively, the mix may be made more fluid by a short period of high shear mixing during production. The mixes have not been optimized for large scale production. It may be possible, for example, to adjust the water to cementitious materials ratio to provide improved performance of these mixes based on the results and conclusions of the large scale testing at CETL. Recommendations from this task include incorporation of a backup mixing/pumping system that is either integrated into the system or is available for immediate use in case of a pump or mixer failure of the primary system. A second recommendation is to conduct a laboratory scale investigation to determine the impact of operational variation on the properties of the grout. This effort would be initiated after feedback is received from the large scale testing at CETL. The purpose of this proposed variability testing is to better understand the limits of the operational variations (such as temperature and mixing time), and to identify possible approaches for remediation to ensure that the grout produced will flow effectively in the coils while still meeting the performance requirements

POTENTIAL IMPACT OF BLENDING RESIDUAL SOLIDS FROM TANKS 18/19 MOUNDS WITH TANK 7 OPERATIONS

High level waste tanks 18F and 19F have residual mounds of waste which may require removal before the tanks can be closed. Conventional slurry pump technology, previously used for waste removal and tank cleaning, has been incapable of removing theses mounds from tanks 18F and 19F. A mechanical cleaning method has been identified that is potentially capable of removing and transferring the mound material to tank 7F for incorporation in a sludge batch for eventual disposal in high level waste glass by the Defense Waste Processing Facility. The Savannah River National Laboratory has been requested to evaluate whether the material transferred from tanks 18F/19F by the mechanical cleaning technology can later be suspended in Tank 7F by conventional slurry pumps after mixing with high level waste sludge. The proposed mechanical cleaning process for removing the waste mounds from tanks 18 and 19 may utilize a high pressure water jet-eductor that creates a vacuum to mobilize solids. The high pressure jet is also used to transport the suspended solids. The jet-eductor system will be mounted on a mechanical crawler for movement around the bottom of tanks 18 and 19. Based on physical chemical property testing of the jet-eductor system processed IE-95 zeolite and size-reduced IE-95 zeolite, the following conclusions were made: (1) The jet-eductor system processed zeolite has a mean and median particle size (volume basis) of 115.4 and 43.3 microns in water. Preferential settling of these large particles is likely. (2) The jet-eductor system processed zeolite rapidly generates settled solid yield stresses in excess of 11,000 Pascals in caustic supernates and will not be easily retrieved from Tank 7 with the existing slurry pump technology. (3) Settled size-reduced IE-95 zeolite (less than 38 microns) in caustic supernate does not generate yield stresses in excess of 600 Pascals in less than 30 days. (4) Preferential settling of size-reduced zeolite is a function of the amount of sludge and the level of dilution for the mixture. (5) Blending the size-reduced zeolite into larger quantities of sludge can reduce the amount of preferential settling. (6) Periodic dilution or resuspension due to sludge washing or other mixing requirements will increase the chances of preferential settling of the zeolite solids. (7) Mixtures of Purex sludge and size-reduced zeolite did not produce yield stresses greater than 200 Pascals for settling times less than thirty days. Most of the sludge-zeolite blends did not exceed 50 Pascals. These mixtures should be removable by current pump technology if sufficient velocities can be obtained. (8) The settling rate of the sludge-zeolite mixtures is a function of the ionic strength (or supernate density) and the zeolite- sludge mixing ratio. (9) Simulant tests indicate that leaching of Si may be an issue for the processed Tank 19 mound material. (10) Floating zeolite fines observed in water for the jet-eductor system and size-reduced zeolite were not observed when the size-reduced zeolite was blended with caustic solutions, indicating that the caustic solutions cause the fines to agglomerate. Based on the test programs described in this report, the potential for successfully removing Tank 18/19 mound material from Tank 7 with the current slurry pump technology requires the reduction of the particle size of the Tank 18/19 mound material

PREPARATION AND CHARACTERIZATION OF POROUS WALLED HOLLOW GLASS MICROSPHERES

Porous-walled hollow glass microspheres (PWHGMs) of a modified alkali borosilicate composition have been successfully fabricated by combining the technology of producing hollow glass microspheres (HGMs) with the knowledge associated with porous glasses. HGMs are first formed by a powder glass--flame process, which are then transformed to PWHGMs by heat treatment and subsequent treatment in acid. Pore diameter and pore volume are most influenced by heat treatment temperature. Pore diameter is increased by a factor of 10 when samples are heat treated prior to acid leaching; 100 {angstrom} in non-heat treated samples to 1000 {angstrom} in samples heat treated at 600 C for 8 hours. As heat treatment time is increased from 8 hours to 24 hours there is a slight shift increase in pore diameter and little or no change in pore volume

IMPACT OF COMPOSITION AND HEAT TREATMENT ON PORE SIZE IN POROUS WALLED HOLLOW GLASS MICROSPHERES

The Savannah River National Laboratory (SRNL) developed a new geometric form: hollow glass microspheres (HGMs), with unique porous walls. The new geometric form combines the existing technology of HGMs with basic glass science knowledge in the realm of glass-in-glass phase separation. Conceptually, the development of a HGM with porous walls (referred to as a PWHGM) provides a unique system in which various media or filling agents can be incorporated into the PWHGM (via transport through the porous walls) and ultimately has the capacity to serve as a functional delivery system in various industrial applications. Applications of these types of systems could range from hydrogen storage, molecular sieves, drug and bioactive delivery systems, to environmental, chemical and biological indicators, relevant to Energy, Environmental Processing and Homeland Security fields. As a specific example, previous studies at SRNL have introduced materials capable of hydrogen storage (as well as other materials) into the interior of the PWHGMs. The goal of this project was to determine if the microstructure (i.e., pore size and pore size distribution) of a PWHGM could be altered or tailored by varying composition and/or heat treatment (time and/or temperature) conditions. The ability to tailor the microstructure through composition or heat treatments could provide the opportunity to design the PWHGM system to accommodate different additives or fill agents. To meet this objective, HGMs of various alkali borosilicate compositions were fabricated using a flame forming apparatus installed at the Aiken County Technical Laboratory (ACTL). HGMs were treated under various heat treatment conditions to induce and/or enhance glass in glass phase separation. Heat treatment temperatures ranged from 580 C to 620 C, while heat treatment times were either 8 or 24 hours. Of the two primary variables assessed in this study, heat treatment temperature was determined to be most effective in changing the porosity of PWHGMs. Pore diameter in a non-heat treated baseline sample is approximately 100 {angstrom} and with heat treatment at 600 C for 8 hours, the diameter is approximately 1000 {angstrom}; an increase of a factor of 10. The results of this study also indicate significant microstructural differences with only a 20 C difference in heat treatment temperature (580 C and 600 C) for constant times. The microstructural changes observed via electron microscopy as a function of heat treatment temperature were confirmed by mercury porosimetry measurements, where considerable increases in pore volume were measured. Under constant heat treatment conditions, composition may impose a secondary effect on the resulting microstructure as micrographs indicate variations in the degree of porosity. Although microstructural differences were observed among the compositions assessed, the magnitude of the impact (i.e., difference in pore size or pore volume) appears to be smaller than that associated with heat treatment temperature. With respect to heat treatment time, the results suggest that the change in the degree of porosity is minimal for samples heat treated between 8 and 24 hours (it should be noted that the assessment of the impact of time on the resulting microstructure was limited to two compositions). The minimal impact of heat treatment time (on the two glasses evaluated) was confirmed by mercury porosimetry measurements indicating that there was a very slight shift in pore diameter and very little increase in pore volume in the baseline sample. Another important parameter, which will need to be considered under manufacturing or operational conditions, is the yield of the HGM and/or PWHGM and the characteristics of the final product (i.e., not only microstructure characteristics, but perhaps strength of the PWHGM for use under certain applications). In this report, yield is defined as the percentage of feed material converted to HGMs or the percentage of HGMs converted to PWHGMs. The yield of HGM formation was found to be a strong function of composition. As the SiO{sub 2} and B{sub 2}O{sub 3} contents are increased or decreased from the baseline composition, the yield is reduced. PWHGM yield doesn't appear to be influenced by composition, but there is a noticeable increase in yield when comparing the non-heat treated samples to those that were heat treated prior to acid leaching. The results of this study suggest that PWHGM microstructures (pore size and pore volume) can be tailored or specifically designed to meet different end-user needs within certain limitations. The primary effect on the resulting microstructure is heat treatment temperature, which can produce a significant shift in pore size or volume even with a very small difference in heat treatment temperature (20 C). The ability to control the microstructure of PWHGMs provides the opportunity to design the PWHGM system to accommodate different additives or fill agents as required

IMPACT OF INCREASED ALUMINATE CONCENTRATIONS ON PROPERTIES OF SALTSTONE MIXES

One of the goals of the Saltstone variability study is to identify the operational and compositional variables that control or influence the important processing and performance properties of Saltstone mixes. The protocols developed in this variability study are ideally suited as a tool to assess the impact of proposed changes to the processing flow sheet for Liquid Waste Operations (LWO). One such proposal that is currently under consideration is to introduce a leaching step in the treatment of the High Level Waste (HLW) sludge to remove aluminum prior to vitrification at the Defense Waste Processing Facility (DWPF). This leachate would significantly increase the soluble aluminate concentrations as well as the free hydroxide ion concentration in the salt feed that will be processed at the Saltstone Processing Facility (SPF). Consequently, an initial study of the impact of increased aluminate concentration on the Saltstone grout properties was performed. The projected compositions and ranges of the aluminate rich salt stream (which includes the blending strategy) are not yet available and consequently, in this initial report, two separate salt stream compositions were investigated. The first stream starts with the previously projected baseline composition of the salt solution that will be fed to SPF from the Salt Waste Processing Facility (SWPF). The second stream is the solution that results from washing of the current Tank 51 sludge and subsequent transfer of the salt solution to Tank 11. The SWPF simulant has higher nitrate and lower free hydroxide than the Tank 11 simulant. In both of these cases, the aluminate was varied up to a maximum of 0.40 to 0.45M aluminate in order to evaluate the impact of increasing aluminate ion concentration on the grout properties. In general, the fresh grout properties of mixes made with SWPF and Tank 11 simulants were relatively insensitive to an increase in aluminate concentration in the salt solutions. However, the overall trends observed as the aluminate concentration increased in the salt solution were decreased Bingham Plastic yield stress and plastic viscosity, greater flowability of the grout, and reduced gel times and bleed volume for SWPF based mixes. On the other hand, the set times increased significantly with increasing aluminate concentration in the salt solutions. For the SWPF mixes, the set time increased from 1 to 4 days and for the Tank 11 mixes, the set time increased from 1 to 2 days. Heat of hydration measurements were consistent with the increased set times with extended induction periods (2 to 4 days) as aluminate concentration increased in the salt solution. This extended induction period of heat evolution observed with increasing aluminate concentrations must be addressed for Saltstone operations to avoid exceeding temperature limits. It is anticipated that the induction period will be temperature dependent and should be measured for future projections and included in the thermal modeling. The overall heat generation was greater in the mixes containing higher concentrations of aluminate. In fact, for the total heat release values calculated using curve fitting for longer times, the amount of heat was increased by 33% for SWPF based solutions and by 46% for Tank 11 based solutions. The larger amount of heat from mixes containing higher aluminate concentration must be accounted for in the modeling effort which determines the pour schedule for Saltstone. The increased induction periods were shown to be associated with hydration reactions of the blast furnace slag. The rate of heat generation with high aluminate solutions and Portland cement were only accelerated whereas high aluminate mixes containing blast furnace slag only showed the characteristic increase in induction time that was observed with mixes prepared using the premix blend of cementitious materials. It was shown that fly ash does not react significantly during the first seven days of curing but then undergoes an accelerated burst for 15 days before beginning to level off. The total amount of heat generated from a fly ash only mix with SWPF solution containing aluminate at 0.33 M is approximately 100 J/g vs. 87 J/g for SWPF with 0.11 M aluminate. Finally, the heat of hydration measurements revealed that the ternary system of cementitious materials (premix) leads to interactions between the hydration reactions of these three components that actually reduce the overall heat generation compared to the summation of the heats of hydration for mixes made only from portland cement, blast furnace slag or fly ash

IMPACT OF ALUMINATE IONS ON THE PROPERTIES OF SALTSTONE GROUT MIXES

It is important to identify and control the operational and compositional variables that impact the important processing and performance properties of Saltstone grout mixes. The grout that is produced at the Saltstone Production Facility (SPF) is referred to as Saltstone and is a waste form that immobilizes low concentrations of radionuclides as well as certain toxic metals. The Saltstone will be disposed of in vaults at Savannah River Site (SRS). An effort referred to as the Saltstone Variability Study has been initiated to achieve this goal. The protocols developed in this variability study are also ideally suited as a tool to assess the impact of proposed changes to the processing flow sheet for Liquid Waste Operations at SRS. One such proposal that is currently under consideration is to introduce a leaching step in the treatment of the High Level Waste (HLW) sludge to remove aluminum prior to vitrification at the Defense Waste Processing Facility (DWPF). This leachate would significantly increase the soluble aluminate concentration in the salt feed that will be processed at the SPF. Consequently, an initial study of the impact of increased aluminate concentration on the Saltstone grout properties was performed. Prior work by Lukens (1) showed that aluminate in the salt solutions increases the amount of heat generation

WASHING AND DEMONSTRATION OF THE DWPF FLOWSHEET IN THE SRNL SHIELDED CELLS USING POST ALUMINUM DISSOLUTION TANK 51 SLUDGE SLURRY

The remaining contents of Tank 51 from Sludge Batch 4 will be blended with Purex sludge from Tank 7 to constitute Sludge Batch 5 (SB5). The Savannah River Site (SRS) Liquid Waste Organization (LWO) has completed caustic addition to Tank 51 to perform low temperature Al dissolution on the H-Modified (HM) sludge material to reduce the total mass of sludge solids and Al being fed to the Defense Waste Processing Facility (DWPF). The Savannah River National Lab (SRNL) has also completed aluminum dissolution tests using a 3-L sample of Tank 51 sludge slurry through funding by DOE EM-21. This report documents assessment of downstream impacts of the aluminum dissolved sludge, which were investigated so technical issues could be identified before the start of SB5 processing. This assessment included washing the aluminum dissolved sludge to a Tank Farm projected sodium concentration and weight percent insoluble solids content and DWPF Chemical Process Cell (CPC) processing using the washed sludge. Based on the limited testing, the impact of aluminum dissolution on sludge settling is not clear. Settling was not predictable for the 3-L sample. Compared to the post aluminum dissolution sample, settling after the first wash was slower, but settling after the second wash was faster. For example, post aluminum dissolution sludge took six days to settle to 60% of the original sludge slurry height, while Wash 1 took nearly eight days, and Wash 2 only took two days. Aluminum dissolution did impact sludge rheology. A comparison between the as-received, post aluminum dissolution and washed samples indicate that the downstream materials were more viscous and the concentration of insoluble solids less than that of the starting material. This increase in viscosity may impact Tank 51 transfers to Tank 40. The impact of aluminum dissolution on DWPF CPC processing cannot be determined because acid addition for the Sludge Receipt and Adjustment Tank (SRAT) cycle was under-calculated and thus under-added. Although the sludge was rheologically thick throughout the SRAT and Slurry Mix Evaporator (SME) cycles, this may have been due to the under addition of acid. Aluminum dissolution did, however, impact analyses of the SRAT receipt material. Two methods for determining total base yielded significantly different results. The high hydroxide content and the relatively high soluble aluminum content of the washed post aluminum dissolution sludge likely contributed to this difference and the ultimate under addition of acid. It should be noted that the simulant used to provide input for the SRAT cycle was an inadequate representation of the waste in terms of acid demand, likely due to the differences in the form of aluminum and hydroxide in the simulant and actual waste. Based on the results of this task, it is recommended that: (1) Sludge settling and rheology during washing of the forthcoming Sludge Batch 5 qualification sample be monitored closely and communicated to the Tank Farm. (2) SRNL receive a sample of Tank 51 after all chemical additions have been made and prior to the final Sludge Batch 5 decant for rheological assessment. Rheology versus wt% insoluble solids will be performed to determine the maximum amount of decant prior to the Tank 51 to Tank 40 transfer. (3) As a result of the problem with measuring total base and subsequently under-calculating acid for the DWPF CPC processing of the post aluminum dissolution sludge; (4) Studies to develop understanding of how the sludge titrates (i.e., why different titration methods yield different results) should be performed. (5) Simulants that better match the properties of post aluminum dissolution sludge should be developed. (6) Work on developing an acid calculation less dependant on the total base measurement should be continued

DEMONSTRATION OF THE DWPF FLOWSHEET IN THE SRNL SHIELDED CELLS USING ARP PRODUCT SIMULANT AND SB4 TANK 40 SLUDGE SLURRY

The radioactive startup of two new SRS processing facilities, the Actinide Removal Process (ARP) and the Modular Caustic-Side-Solvent-Extraction Unit (MCU) will add two new waste streams to the Defense Waste Processing Facility (DWPF). The ARP will remove actinides from the 5.6 M salt solution resulting in a sludge-like product that is roughly half monosodium titanate (MST) insoluble solids and half sludge insoluble solids. The ARP product will be added to the Sludge Receipt and Adjustment Tank (SRAT) at boiling and dewatered prior to pulling a SRAT receipt sample. The cesium rich MCU stream will be added to the SRAT at boiling after both formic and nitric acid have been added and the SRAT contents concentrated to the appropriate endpoint. A concern was raised by an external hydrogen review panel that the actinide loaded MST could act as a catalyst for hydrogen generation (Mar 15, 2007 report, Recommendation 9). Hydrogen generation, and it's potential to form a flammable mixture in the off-gas, under SRAT and Slurry Mix Evaporator (SME) processing conditions has been a concern since the discovery that noble metals catalyze the decomposition of formic acid. Radiolysis of water also generates hydrogen, but the radiolysis rate is orders of magnitude lower than the noble metal catalyzed generation. As a result of the concern raised by the external hydrogen review panel, hydrogen generation was a prime consideration in this experiment. Testing was designed to determine whether the presence of the irradiated ARP simulant containing MST caused uncontrolled or unexpected hydrogen production during experiments simulating the DWPF Chemical Process Cell (CPC) due to activation of titanium. A Shielded Cells experiment, SC-5, was completed using SB4 sludge from Tank 405 combined with an ARP product produced from simulants by SRNL researchers. The blend of sludge and MST was designed to be prototypic of planned DWPF SRAT and SME cycles. As glass quality was not an objective in this experiment, no vitrification of the SME product was completed. The results from this experiment were compared to the results from experiment SC-1, a similar experiment with SB4 sludge without added ARP product. This report documents: (1) The preparation and subsequent composition of the ARP product. (2) The preparation and subsequent compositional characterization of the SRAT Receipt sample. Additional details will be presented concerning the noble metal concentration of the ARP product and the SRAT receipt sample. Also, calculations related to the amount of formic and nitric acid added during SRAT processing will be presented as excess formic acid will lead to additional hydrogen generation. (3) Highlights from processing during the SRAT cycle and SME cycle (CPC processing). Hydrogen generation will be discussed since this was the prime objective for this experiment. (4) A comparison of CPC processing between SC-1 (without ARP simulant) and SC-5. This work was controlled by a Task Technical and Quality Assurance Plan (TTQAP)6, and analyses were guided by an Analytical Sample Support Matrix (ASSM)7. This Research and Development (R&D) was completed to support operation of DWPF

Replication of Lung Cancer Susceptibility Loci at Chromosomes 15q25, 5p15, and 6p21: A Pooled Analysis From the International Lung Cancer Consortium

Background Genome-wide association studies have identified three chromosomal regions at 15q25, 5p15, and 6p21 as being associated with the risk of lung cancer. To confirm these associations in independent studies and investigate heterogeneity of these associations within specific subgroups, we conducted a coordinated genotyping study within the International Lung Cancer Consortium based on independent studies that were not included in previous genome-wide association studies. Methods Genotype data for single-nucleotide polymorphisms at chromosomes 15q25 (rs16969968, rs8034191), 5p15 (rs2736100, rs402710), and 6p21 (rs2256543, rs4324798) from 21 case-control studies for 11 645 lung cancer case patients and 14 954 control subjects, of whom 85% were white and 15% were Asian, were pooled. Associations between the variants and the risk of lung cancer were estimated by logistic regression models. All statistical tests were two-sided. Results Associations between 15q25 and the risk of lung cancer were replicated in white ever-smokers (rs16969968: odds ratio [OR] = 1.26, 95% confidence interval [CI] = 1.21 to 1.32, Ptrend = 2 × 10−26), and this association was stronger for those diagnosed at younger ages. There was no association in never-smokers or in Asians between either of the 15q25 variants and the risk of lung cancer. For the chromosome 5p15 region, we confirmed statistically significant associations in whites for both rs2736100 (OR = 1.15, 95% CI = 1.10 to 1.20, Ptrend = 1 × 10−10) and rs402710 (OR = 1.14, 95% CI = 1.09 to 1.19, Ptrend = 5 × 10−8) and identified similar associations in Asians (rs2736100: OR = 1.23, 95% CI = 1.12 to 1.35, Ptrend = 2 × 10−5; rs402710: OR = 1.15, 95% CI = 1.04 to 1.27, Ptrend = .007). The associations between the 5p15 variants and lung cancer differed by histology; odds ratios for rs2736100 were highest in adenocarcinoma and for rs402710 were highest in adenocarcinoma and squamous cell carcinomas. This pattern was observed in both ethnic groups. Neither of the two variants on chromosome 6p21 was associated with the risk of lung cancer. Conclusions In this international genetic association study of lung cancer, previous associations found in white populations were replicated and new associations were identified in Asian populations. Future genetic studies of lung cancer should include detailed stratification by histolog

Existential Loneliness and end-of-life care: A Systematic Review

Contains fulltext : 88662.pdf (publisher's version ) (Closed access)Patients with a life-threatening illness can be confronted with various types of loneliness, one of which is existential loneliness (EL). Since the experience of EL is extremely disruptive, the issue of EL is relevant for the practice of end-of-life care. Still, the literature on EL has generated little discussion and empirical substantiation and has never been systematically reviewed. In order to systematically review the literature, we (1) identified the existential loneliness literature; (2) established an organising framework for the review; (3) conducted a conceptual analysis of existential loneliness; and (4) discussed its relevance for end-of-life care. We found that the EL concept is profoundly unclear. Distinguishing between three dimensions of EL-as a condition, as an experience, and as a process of inner growth-leads to some conceptual clarification. Analysis of these dimensions on the basis of their respective key notions-everpresent, feeling, defence; death, awareness, difficult communication; and inner growth, giving meaning, authenticity-further clarifies the concept. Although none of the key notions are unambiguous, they may function as a starting point for the development of care strategies on EL at the end of life.1 april 201