SOLVENT DISPERSION AND FLOW METER CALCULATION RESULTS

Savannah River National Laboratory (SRNL) found that the dispersion numbers for the six combinations of CSSX:Next Generation Solvent (NGS) “blend” and pure NGS versus salt solution, caustic wash, and strip aqueous solutions are all good. The dispersion numbers are indications of processability with centrifugal contactors. A comparison of solvent physical and thermal properties shows that the Intek™ solvent flow meter in the plant has a reading biased high versus calibrated flow when NGS is used, versus the standard CSSX solvent. The flow meter, calibrated for CSSX solvent, is predicted to read 2.8 gpm of NGS in a case where the true flow of NGS is 2.16 gpm

ANALYSIS OF THE LEACHING EFFICIENCY OF INHIBITED WATER AND TANK 23H SIMULANT IN REMOVING RESIDUES ON TANK 48H WALLS

Solid residues on two sets of thermowell pipe samples from the D2 riser in SRS Tank 48H were characterized. The residue thickness was determined using the ASTM standard D 3483-05 and was found to be three order of magnitudes below the 1mm thickness estimated from an earlier video of the tank cooling coil inspection. The actual estimated thickness ranged from 4 to 20.4 microns. The mass per unit area ranged from 1 to 5.3 milligrams per square inch. The residues appear to consist primarily of potassium tetraphenylborate (39.8 wt% KTPB) and dried salt solution (33.5 wt% total of nitrates, nitrites and oxalate salts), although {approx}30% of the solid mass was not accounted for in the mass balance. No evidence of residue buildup was found inside the pipe, as expected. The residue leaching characteristics were measured by placing one pipe in inhibited water and one pipe in DWPF Recycle simulant. After soaking for less than 4 weeks, the inhibited water was 95.4% effective at removing the residue and the DWPF Recycle simulant was 93.5% effective. The surface appearance of the pipes after leaching tests appeared close to the clean shiny appearance of a new pipe. Total gamma counts of leachates averaged 48.1 dpm/ml, or an equivalent of 2.35E-11 Ci/gm Cs-137 (dry solids basis), which is much lower than the 1.4 E-03 Ci/gm expected for Tank 48 dry slurry solids

Determination of the Impact of Glycolate on ARP and MCU Operations

Savannah River Remediation (SRR) is evaluating an alternate flowsheet for the Defense Waste Processing Facility (DWPF) using glycolic acid as a reductant. An important aspect of the development of the glycolic acid flowsheet is determining if glycolate has any detrimental downstream impacts. Testing was performed to determine if there is any impact to the strontium and actinide sorption by monosodium titanate (MST) and modified monosodium titanate (mMST) or if there is an impact to the cesium removal, phase separation, or coalescer performance at the Modular Caustic-Side Solvent Extraction Processing Unit (MCU). Sorption testing was performed using both MST and modified MST (mMST) in the presence of 5000 and 10,000 ppm (mass basis) glycolate. 10,000 ppm is the estimated bounding concentration expected in the DWPF recycle stream based on DWPF melter flammable gas model results. The presence of glycolate was found to slow the removal of Sr and Pu by MST, while increasing the removal rate of Np. Results indicate that the impact is a kinetic effect, and the overall capacity of the material is not affected. There was no measurable effect on U removal at either glycolate concentration. The slower removal rates for Sr and Pu at 5000 and 10,000 ppm glycolate could result in lower DF values for these sorbates in ARP based on the current (12 hours) and proposed (8 hours) contact times. For the highest glycolate concentration used in this study, the percentage of Sr removed at 6 hours of contact decreased by 1% and the percentage of Pu removed decreased by nearly 7%. The impact may prove insignificant if the concentration of glycolate that is returned to the tank farm is well below the concentrations tested in this study. The presence of glycolate also decreased the removal rates for all three sorbates (Sr, Pu, and Np) by mMST. Similar to MST, the results for mMST indicate that the impact is a kinetic effect, and the overall capacity of the material is not affected. The presence of glycolate did not change the lack of affinity of mMST for U. Pre-contacting the MST or mMST with glycolate did not have a significant effect on the performance of the materials when compared to tests having the same concentration of glycolate present in the simulant. These findings suggest that the glycolate is likely influencing removal by sorbate complexation and not by depositing onto or forming a film on the surface of the MST solids. Since the DF values are salt batch dependent, it is not possible to a priori quantify the impacts of glycolate on future processing campaigns. However, we recommend that the impacts of glycolate be evaluated during each salt batch qualification when a final processing concentration is defined, and recommendations can then be made on how to mitigate negative impacts, if needed. Impacts to the performance of the MST or mMST could be mitigated by increasing contact time or increasing sorbent concentrations. Testing was performed to determine if there is an impact to the cesium removal at Modular Caustic-Side Solvent Extraction Processing Unit (MCU). An Extraction-Scrub-Strip (ESS) test routine was used to simulate cesium removal at the MCU. For this, SRNL performed three ESS tests, using the same basic aqueous waste simulant and solvent. For one test, SRNL added 5000 ppm (mass basis) of glycolate and added 10,000 ppm of glycolate to a second test. A control test contained no glycolate. The results of all three tests were virtually identical for all the extraction, scrub and strip tests

RESULTS OF COPPER CATALYZED PEROXIDE OXIDATION (CCPO) OF TANK 48H SIMULANTS

Savannah River National Laboratory (SRNL) performed a series of laboratory-scale experiments that examined copper-catalyzed hydrogen peroxide (H{sub 2}O{sub 2}) aided destruction of organic components, most notably tetraphenylborate (TPB), in Tank 48H simulant slurries. The experiments were designed with an expectation of conducting the process within existing vessels of Building 241-96H with minimal modifications to the existing equipment. Results of the experiments indicate that TPB destruction levels exceeding 99.9% are achievable, dependent on the reaction conditions. A lower reaction pH provides faster reaction rates (pH 7 > pH 9 > pH 11); however, pH 9 reactions provide the least quantity of organic residual compounds within the limits of species analyzed. Higher temperatures lead to faster reaction rates and smaller quantities of organic residual compounds. A processing temperature of 50 �C as part of an overall set of conditions appears to provide a viable TPB destruction time on the order of 4 days. Higher concentrations of the copper catalyst provide faster reaction rates, but the highest copper concentration (500 mg/L) also resulted in the second highest quantity of organic residual compounds. The data in this report suggests 100-250 mg/L as a minimum. Faster rates of H{sub 2}O{sub 2} addition lead to faster reaction rates and lower quantities of organic residual compounds. An addition rate of 0.4 mL/hour, scaled to the full vessel, is suggested for the process. SRNL recommends that for pH adjustment, an acid addition rate 42 mL/hour, scaled to the full vessel, is used. This is the same addition rate used in the testing. Even though the TPB and phenylborates can be destroyed in a relative short time period, the residual organics will take longer to degrade to <10 mg/L. Low level leaching on titanium occurred, however, the typical concentrations of released titanium are very low (~40 mg/L or less). A small amount of leaching under these conditions is not surprising and is consistent with a previous study. Acidification with phosphoric and formic acids, in lieu of nitric acid, provides benefits in reducing the amount of benzene emitted over the lifetime of a reaction. Analyses of the post-reaction residual material indicate that slurry initially adjusted down to a pH 7 produced a greater degree of energetic material than material initially adjusted to a pH of 9. No more than 140 {micro}g/m{sup 3} of mercury was indicated in reactor head spaces at any time. An estimation of less than 1% of the initial mercury was vaporized in each experiment. A limited number of replicate tests were performed to determine experimental reproducibility. These tests indicate a reasonable degree of reproducibility. The conclusion of the simulant testing has provided a set of reaction conditions that can destroy the TPB and phenylborates quickly. While longer times will be required to degrade the residual organics, the reactions appear to perform in a consistent manner. A real waste test or tests are recommended and further investigation into the use of phosphoric or formic acid is warranted

MEASUREMENT OF ENTRAINED ORGANIC DROPLET SIZES AND TOTAL CONCENTRATION FOR AQUEOUS STREAMS FROM THE CAUSTIC-SIDE SOLVENT EXTRACTION PROCESS

The Modular Caustic-Side Solvent Extraction Unit (MCU) and the Salt Waste Processing Facility will remove radioactive cesium from Savannah River Site supernate wastes using an organic solvent system. Both designs include decanters and coalescers to reduce carryover of organic solvent droplets. Savannah River National Laboratory personnel conducted experimental demonstrations using a series of four 2-cm centrifugal contactors. They also examined organic carryover during operation of a CINC (Costner Industries Nevada Corporation) V-5 contactor under prototypical conditions covering the range of expected MCU operation. This report details the findings from those studies and the implications on design for the MCU

Entrainment of Solvent in Aqueous Stream from CINC V-5 Contactor

Personnel completed a rapid study of organic entrainment during operation of a CINC V-5 contactor under prototypical conditions covering the range of expected MCU operation. The study only considered the entrainment of organic into the strip acid effluent destined for the Defense Waste Processing Facility. Based on this work, the following observations are noted: (1) Concentrations of total organic from the contactor discharge, based upon modifier measurements, in the acid typically averaged 330 ppm{sub m}, for a range to 190-610 ppm{sub m}. (2) Entrained droplet sizes remained below 18 microns for samples collected at the decanter outlet and below 11 microns for samples taken from the contactor discharge. (3) Scouting tests showed that a vendor coalescer material promotes coalescence of smaller size droplets from the decanter effluent. (4) Personnel observed a previously unreported organic impurity in the solvent used for this study. Additional efforts are needed to ascertain the source of the impurity and its implication on the overall process. (5) Process throughputs and planned operating conditions result in very stable hydraulics, suggesting that the MCU stripping stages will have spare operating capacity. (6) The V-5 contactors show operated with relatively cool surfaces under the planned operating conditions. (7) If operating conditions result in an imbalance of the relative mixing and separation conditions within the contactor, a very stable emulsion may result. In this instance, the emulsion remained stable for weeks. The imbalance in this study resulted from use of improperly sized weir plates. (8) Personnel demonstrated an effective means of recovering emulsified solvent following a non-optimal equipment configuration. The protocols developed may offer benefit for MCU and SWPF operations. (9) This study developed and demonstrated the effectiveness of several analytical methods for support of the Caustic-Side Solvent Extraction process including infrared spectroscopy and droplet size measurement by a MicroTrac{trademark} S3000. Interfacial tension measurements also showed sensitivity to purity of the solvent suggesting that this technique may prove valuable for future process diagnostics. The study highlighted limitations of the current gas chromatography configuration for determination of modifier content of samples. Additional development of analytical methods for determining composition--and particularly modifier content--of organic and mixed aqueous-organic samples is warranted. Infrared spectroscopy shows particular promise. Additional full-scale studies are warranted to investigate the entrainment of organic in the aqueous effluent from the extraction operation. Since waste composition may differ appreciably for the process, this stream may exhibit much wider variance in hydraulic behavior, organic entrainment, and may pose a greater risk for poor hydraulics. Conducting contactor studies at SRNL allowed numerous personnel to view operations and facilitated the training of staff members. Members of the Design Authority, Engineering, and Training groups benefited from tours. Consideration should be given to procuring and installing a full-scale contactor at SRNL for future support and for assistance during commissioning of the MCU. Additional study of surface and interfacial tension is recommended. This tool may also offer economical and rapid process diagnostics for future operations

Applications des méthodes granulométriques à l''interprétation d'une série détritique actuelle. Etude de la sédimentation entre Granville et Chausey

National audienc

SOLVENT DISPERSION AND FLOW METER CALCULATION RESULTS

Savannah River National Laboratory (SRNL) found that the dispersion numbers for the six combinations of CSSX:Next Generation Solvent (NGS) “blend” and pure NGS versus salt solution, caustic wash, and strip aqueous solutions are all good. The dispersion numbers are indications of processability with centrifugal contactors. A comparison of solvent physical and thermal properties shows that the Intek™ solvent flow meter in the plant has a reading biased high versus calibrated flow when NGS is used, versus the standard CSSX solvent. The flow meter, calibrated for CSSX solvent, is predicted to read 2.8 gpm of NGS in a case where the true flow of NGS is 2.16 gpm