EVALUATION OF ALTERNATIVE FILTER MEDIA FOR THE ROTARY MICROFILTER, PHASE 2

Testing was conducted at the Savannah River National Laboratory (SRNL) to investigate filter membrane performance in an effort to increase rotary microfilter (RMF) throughput. Membranes were tested in the SpinTek Filtration, Inc. Static Test Cell (STC), which permitted quick and easy testing of several different membranes. Testing consisted of 100 hours tests with two different slurry feeds, based on recommendations from the phase 1 testing. One feed contained Monosodium Titanate (MST) solids in a simulated salt solution. The other feed contained simulated sludge batch 6 (SB6) solids in a simulated salt solution. Five membranes were tested, one each from filter manufactures Pall and Porvair and three from the Oak Ridge National Laboratory (ORNL). The membrane from Pall is the current membrane used on the latest generation RMF. The Porvair membrane performed well in previous STC tests as well as one of the ORNL membranes. The other two membranes from ORNL were recently developed and not available for the previous STC test. The results indicate that the Porvair filter performed best with the MST slurry and the ORNL SVB6-1B filter performed best with the SB6 slurry. Difficulty was encountered with the ORNL filters due to their dimensional thickness, which was greater than the recommended filter thickness for the STC. The STC equipment was modified to complete the testing of the ORNL filters

EVALUATION OF ALTERNATIVE FILTER MEDIA FOR THE ROTARY MICROFILTER, PHASE 2

Testing was conducted at the Savannah River National Laboratory (SRNL) to investigate filter membrane performance in an effort to increase rotary microfilter (RMF) throughput. Membranes were tested in the SpinTek Filtration, Inc. Static Test Cell (STC), which permitted quick and easy testing of several different membranes. Testing consisted of 100 hours tests with two different slurry feeds, based on recommendations from the phase 1 testing. One feed contained Monosodium Titanate (MST) solids in a simulated salt solution. The other feed contained simulated sludge batch 6 (SB6) solids in a simulated salt solution. Five membranes were tested, one each from filter manufactures Pall and Porvair and three from the Oak Ridge National Laboratory (ORNL). The membrane from Pall is the current membrane used on the latest generation RMF. The Porvair membrane performed well in previous STC tests as well as one of the ORNL membranes. The other two membranes from ORNL were recently developed and not available for the previous STC test. The results indicate that the Porvair filter performed best with the MST slurry and the ORNL SVB6-1B filter performed best with the SB6 slurry. Difficulty was encountered with the ORNL filters due to their dimensional thickness, which was greater than the recommended filter thickness for the STC. The STC equipment was modified to complete the testing of the ORNL filters

BLENDING STUDY FOR SRR SALT DISPOSITION INTEGRATION: TANK 50H SCALE-MODELING AND COMPUTER-MODELING FOR BLENDING PUMP DESIGN, PHASE 2

The Salt Disposition Integration (SDI) portfolio of projects provides the infrastructure within existing Liquid Waste facilities to support the startup and long term operation of the Salt Waste Processing Facility (SWPF). Within SDI, the Blend and Feed Project will equip existing waste tanks in the Tank Farms to serve as Blend Tanks where 300,000-800,000 gallons of salt solution will be blended in 1.3 million gallon tanks and qualified for use as feedstock for SWPF. Blending requires the miscible salt solutions from potentially multiple source tanks per batch to be well mixed without disturbing settled sludge solids that may be present in a Blend Tank. Disturbing solids may be problematic both from a feed quality perspective as well as from a process safety perspective where hydrogen release from the sludge is a potential flammability concern. To develop the necessary technical basis for the design and operation of blending equipment, Savannah River National Laboratory (SRNL) completed scaled blending and transfer pump tests and computational fluid dynamics (CFD) modeling. A 94 inch diameter pilot-scale blending tank, including tank internals such as the blending pump, transfer pump, removable cooling coils, and center column, were used in this research. The test tank represents a 1/10.85 scaled version of an 85 foot diameter, Type IIIA, nuclear waste tank that may be typical of Blend Tanks used in SDI. Specifically, Tank 50 was selected as the tank to be modeled per the SRR, Project Engineering Manager. SRNL blending tests investigated various fixed position, non-rotating, dual nozzle pump designs, including a blending pump model provided by the blend pump vendor, Curtiss Wright (CW). Primary research goals were to assess blending times and to evaluate incipient sludge disturbance for waste tanks. Incipient sludge disturbance was defined by SRR and SRNL as minor blending of settled sludge from the tank bottom into suspension due to blending pump operation, where the sludge level was shown to remain constant. To experimentally model the sludge layer, a very thin, pourable, sludge simulant was conservatively used for all testing. To experimentally model the liquid, supernate layer above the sludge in waste tanks, two salt solution simulants were used, which provided a bounding range of supernate properties. One solution was water (H{sub 2}O + NaOH), and the other was an inhibited, more viscous salt solution. The research performed and data obtained significantly advances the understanding of fluid mechanics, mixing theory and CFD modeling for nuclear waste tanks by benchmarking CFD results to actual experimental data. This research significantly bridges the gap between previous CFD models and actual field experiences in real waste tanks. A finding of the 2009, DOE, Slurry Retrieval, Pipeline Transport and Plugging, and Mixing Workshop was that CFD models were inadequate to assess blending processes in nuclear waste tanks. One recommendation from that Workshop was that a validation, or bench marking program be performed for CFD modeling versus experiment. This research provided experimental data to validate and correct CFD models as they apply to mixing and blending in nuclear waste tanks. Extensive SDI research was a significant step toward bench marking and applying CFD modeling. This research showed that CFD models not only agreed with experiment, but demonstrated that the large variance in actual experimental data accounts for misunderstood discrepancies between CFD models and experiments. Having documented this finding, SRNL was able to provide correction factors to be used with CFD models to statistically bound full scale CFD results. Through the use of pilot scale tests performed for both types of pumps and available engineering literature, SRNL demonstrated how to effectively apply CFD results to salt batch mixing in full scale waste tanks. In other words, CFD models were in error prior to development of experimental correction factors determined during this research, which provided a technique to use CFD models for salt batch mixing and transfer pump operations. This major scientific advance in mixing technology resulted in multi-million dollar cost savings to SRR. New techniques were developed for both experiment and analysis to complete this research. Supporting this success, research findings are summarized in the Conclusions section of this report, and technical recommendations for design and operation are included in this section of the report

TESTING OF THE DUAL ROTARY FILTER SYSTEM

The Savannah River National Laboratory (SRNL) installed and tested two hydraulically connected SpinTek rotary microfilter (RMF) units to determine the behavior of a multiple filter system. Both units were successfully controlled by a control scheme written in DELTA-V architecture by Savannah River Remediation (SRR) Process Control Engineering personnel. The control system was tuned to provide satisfactory response to changing conditions during the operation of the multi-filter system. Stability was maintained through the startup and shutdown of one of the filter units while the second was still in operation. The installation configuration originally proposed by the Small Colum Ion Exchange (SCIX) project of independent filter and motor mountings may be susceptible to vibration. Significant stiffening of the filter and motor mounts was required to minimize the vibration. Alignment of the motor to the filter was a challenge in this test configuration. The deployment configuration must be easy to manipulate and allow for fine adjustment. An analysis of the vibration signature of the test system identified critical speeds. Whether it corresponds to the resonance frequency of a rotor radial vibration mode that was excited by rotor unbalance is uncertain based upon the measurements. A relative motion series should be completed on the filter with the final shaft configuration to determine if the resonances exist in the final filter design. The instrumentation selected for deployment, including the concentrate discharge control valve and flow meters, performed well. Automation of the valve control integrated well with the control scheme and when used in concert with the other control variables, allowed automated control of the dual RMF system. The one area of concern with the instrumentation was the condition resulting when the filtrate flow meter operated with less than three gpm. This low flow was at the lower range of performance for the flow meter. This should not be an issue in deployment where the desired flow rate will be within the normal operating range of the meter. Testing demonstrated that the use of a flexible line for the filtrate discharge is highly desired at the outlet of the rotary union to transition to the system piping. Isolating the vibration from the rotary union will significantly improve the lifetime of the seals. Methods to monitor and isolate individual filters should be considered during deployment. The ability to diagnose issues and isolate individual filters would allow isolation prior to failure. Thus, filters may be cleaned or repaired instead of requiring complete replacement if the condition were to continue unnoticed. Isolating the filtrate line of each filter during startup will minimize the premature buildup of solids on the filter disks. Several tests have shown that the method of filter startup can improve performance lifetime of the filters. The installation must factor in an air inlet for the draining of a filter that does not involve a reverse flow through the filter disks. The reverse flow may cause deformation of the disks or may damage other components of the filters themselves

TESTING OF THE DUAL ROTARY FILTER SYSTEM

The Savannah River National Laboratory (SRNL) installed and tested two hydraulically connected SpinTek rotary microfilter (RMF) units to determine the behavior of a multiple filter system. Both units were successfully controlled by a control scheme written in DELTA-V architecture by Savannah River Remediation (SRR) Process Control Engineering personnel. The control system was tuned to provide satisfactory response to changing conditions during the operation of the multi-filter system. Stability was maintained through the startup and shutdown of one of the filter units while the second was still in operation. The installation configuration originally proposed by the Small Colum Ion Exchange (SCIX) project of independent filter and motor mountings may be susceptible to vibration. Significant stiffening of the filter and motor mounts was required to minimize the vibration. Alignment of the motor to the filter was a challenge in this test configuration. The deployment configuration must be easy to manipulate and allow for fine adjustment. An analysis of the vibration signature of the test system identified critical speeds. Whether it corresponds to the resonance frequency of a rotor radial vibration mode that was excited by rotor unbalance is uncertain based upon the measurements. A relative motion series should be completed on the filter with the final shaft configuration to determine if the resonances exist in the final filter design. The instrumentation selected for deployment, including the concentrate discharge control valve and flow meters, performed well. Automation of the valve control integrated well with the control scheme and when used in concert with the other control variables, allowed automated control of the dual RMF system. The one area of concern with the instrumentation was the condition resulting when the filtrate flow meter operated with less than three gpm. This low flow was at the lower range of performance for the flow meter. This should not be an issue in deployment where the desired flow rate will be within the normal operating range of the meter. Testing demonstrated that the use of a flexible line for the filtrate discharge is highly desired at the outlet of the rotary union to transition to the system piping. Isolating the vibration from the rotary union will significantly improve the lifetime of the seals. Methods to monitor and isolate individual filters should be considered during deployment. The ability to diagnose issues and isolate individual filters would allow isolation prior to failure. Thus, filters may be cleaned or repaired instead of requiring complete replacement if the condition were to continue unnoticed. Isolating the filtrate line of each filter during startup will minimize the premature buildup of solids on the filter disks. Several tests have shown that the method of filter startup can improve performance lifetime of the filters. The installation must factor in an air inlet for the draining of a filter that does not involve a reverse flow through the filter disks. The reverse flow may cause deformation of the disks or may damage other components of the filters themselves

TESTING OF THE SECOND GENERATION SPINTEK ROTARY FILTER -11357

The SpinTek rotary microfilter has been developed under the Department of Energy (DOE) Office of Environmental Management (EM) for the purpose of deployment in radioactive service in the DOE complex. The unit that was fabricated and tested is the second generation of the filter that incorporates recommended improvements from previous testing. The completion of this test satisfied a key milestone for the EM technology development program and technology readiness for deployment by Savannah River Remediation in the Small Column Ion Exchange and Sludge Washing processes at the Savannah River Site (SRS). The Savannah River National Laboratory (SRNL) contracted SpinTek Filtration to fabricate a full scale 25 disk rotary filter and perform a 1000 hour endurance test with a simulated SRS sludge. Over 1500 hours of operation have been completed with the filter. SpinTek Filtration fabricated a prototypic 25 disk rotary filter including updates to manufacturing tolerances, an updated design to the rotary joint, improved cooling to the bottom journal, decreases in disk and filter shaft hydraulic resistances. The filter disks were fabricated with 0.5 {micro} pore size, sintered-metal filter media manufactured by Pall Corporation (M050). After fabrication was complete, the filter passed acceptance tests demonstrating rejection of solids and clean water flux with a 50% improvement over the previous filters. Once the acceptance test was complete, a 1000 hour endurance test was initiated simulating a sludge washing process. The test used a simulated SRS Sludge Batch 6 recipe. The insoluble solids started at 5 wt% and were raised to 10 and 15 wt% insoluble solids to simulate the concentration of a large volume tank. The filter system was automated and set up for 24 hour unattended operation. To facilitate this, process control logic was written to operate the filter. During the development it was demonstrated that the method of starting and stopping the filter can affect the build up of filter cake on the disks and therefore the performance of the filter. The filter performed well with the simulant. Very little drop in production was noticed between the 5 and 10 wt% insoluble solids feed. Increasing to 15 wt% had a more pronounced impact due to the rheology of the feed. Acid cleaning was used to clean the filter disks in-situ and restore filtration rate to almost 90% of the initial clean disk rate. Eighty liters of 0.2 M nitric acid in conjunction with water rinses were used to clean the filter in less than 2 hours. Filter testing was completed after 1000 hours of operation were performed on the final filter assembly configuration. The total run time for the testing was over 1500 hours. At the end of the test, the sludge washing was performed successfully from approximately 5.6 M to less than 1 M sodium

PARAMETRIC EFFECTS OF ANTI-FOAM COMPOSITION, SIMULANT PROPERTIES AND NOBLE METALS ON THE GAS HOLDUP AND RELEASE OF A NON-NEWTONIAN WASTE SLURRY SIMULANT

Gas holdup tests were performed in bench-scale and small-scale mechanically-agitated mixing systems at the Savannah River National Laboratory (SRNL) for a simulant of waste from the Hanford Tank 241-AZ-101. These featured additions of DOW Corning Q2-3183A anti-foam agent. Results indicated that this anti-foam agent (AFA) increased gas holdup in the waste simulant by about a factor of four and, counter-intuitively, that the holdup increased as the non-newtonian simulant shear strength decreased (apparent viscosity decreased). Such results raised the potential of increased flammable gas retention in Hanford Waste Treatment and Immobilization Plant (WTP) vessels mixed by air sparging and pulse-jet mixers (PJMs) during a Design Basis Event (DBE). Additional testing was performed to determine the effects of simulant properties, composition of alternate AFAs, and presence of trace noble metals. Key results are that: (1) Increased gas holdup resulting from addition of Q2-3183A is due to a decrease in surface tension that supports small bubbles which have low rise velocities. (2) Dow Corning 1520-US AFA shows it to be a viable replacement to Dow Corning Q2-3183A AFA. This alternative AFA, however, requires significantly higher dosage for the same anti-foam function. (3) Addition of noble metals to the AZ-101 waste simulant does not produce a catalytic gas retention effect with the AFA