SCALE-UP OF CAUSTIC-SIDE SOLVENT EXTRACTION PROCESS FOR REMOVAL OF CESIUM AT SAVANNAH RIVER SITE. PDF Download
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Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
In 2004, the Department of Energy (DOE) directed Westinghouse Savannah River Company (WSRC) to develop a Caustic-Side Solvent Extraction (CSSX) process at the Savannah River Site (SRS) capable of removing cesium from 1 million gallons a year of dissolved salt solution. This facility would provide interim processing for cesium containing salt solution until the Salt Waste Processing Facility (SWPF) comes on-line. The DOE design inputs1 were to utilize contactors similar in design to those to be used in the SWPF, assume class C waste with less than 0.5 Ci/gal Cs-137, achieve a Decontamination Factor (DF) greater than 12, include the ability to clean the contactors in place, and assume an operating life of three years. WSRC embarked on a design, test, and build program to achieve these criteria as described in the following text. All DOE design criteria have been met or exceeded by WSRC.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
In 2004, the Department of Energy (DOE) directed Westinghouse Savannah River Company (WSRC) to develop a Caustic-Side Solvent Extraction (CSSX) process at the Savannah River Site (SRS) capable of removing cesium from 1 million gallons a year of dissolved salt solution. This facility would provide interim processing for cesium containing salt solution until the Salt Waste Processing Facility (SWPF) comes on-line. The DOE design inputs1 were to utilize contactors similar in design to those to be used in the SWPF, assume class C waste with less than 0.5 Ci/gal Cs-137, achieve a Decontamination Factor (DF) greater than 12, include the ability to clean the contactors in place, and assume an operating life of three years. WSRC embarked on a design, test, and build program to achieve these criteria as described in the following text. All DOE design criteria have been met or exceeded by WSRC.
Author: JR. J. F. Birdwell Publisher: ISBN: Category : Languages : en Pages :
Book Description
This report presents the results of a conceptual design of a solvent extraction process for the selective removal of {sup 137}Cs from high-level radioactive waste currently stored in underground tanks at the U.S. Department of Energy's Savannah River Site (SRS). This study establishes the need for and feasibility of deploying a simplified version of the Caustic-Side Solvent Extraction (CSSX) process; cost/benefit ratios ranging from 33 to 55 strongly support the considered deployment. Based on projected compositions, 18 million gallons of dissolved salt cake waste has been identified as having {sup 137}Cs concentrations that are substantially lower than the worst-case design basis for the CSSX system that is to be deployed as part of the Salt Waste Processing Facility (SWPF) but that does not meet the waste acceptance criteria for immobilization as grout in the Saltstone Manufacturing and Disposal Facility at SRS. Absent deployment of an alternative cesium removal process, this material will require treatment in the SWPF CSSX system, even though the cesium decontamination factor required is far less than that provided by that system. A conceptual design of a CSSX processing system designed for rapid deployment and having reduced cesium decontamination factor capability has been performed. The proposed accelerated-deployment CSSX system (CSSX-A) has been designed to have a processing rate of 3 million gallons per year, assuming 90% availability. At a more conservative availability of 75% (reflecting the novelty of the process), the annual processing capacity is 2.5 million gallons. The primary component of the process is a 20-stage cascade of centrifugal solvent extraction contactors. The decontamination and concentration factors are 40 and 15, respectively. The solvent, scrub, strip, and wash solutions are to have the same compositions as those planned for the SWPF CSSX system. As in the SWPF CSSX system, the solvent and scrub flow rates are equal. The system is designed to facilitate remote operation and direct maintenance. Two general deployment concepts were considered: (1) deployment in an existing but unused SRS facility and (2) deployment in transportable containers. Deployment in three transportable containers was selected as the preferred option, based on concerns regarding facility availability (due to competition from other processing alternatives) and decontamination and renovation costs. A risk assessment identified environmental, safety, and health issues that exist. These concerns have been addressed in the conceptual design by inclusion of mitigating system features. Due to the highly developed state of CSSX technology, only a few technical issues remain unresolved; however, none of these issues have the potential to make the technology unviable. Recommended development tasks that need to be performed to address technical uncertainties are discussed in this report. Deployment of the proposed CSSX-A system provides significant qualitative and quantitative benefits. The qualitative benefits include (1) verification of full-scale contactor performance under CSSX conditions that will support SWPF CSSX design and deployment; (2) development of design, fabrication, and installation experience bases that will be at least partially applicable to the SWPF CSSX system; and (3) availability of the CSSX-A system as a means of providing contactor-based solvent extraction system operating experience to SWPF CSSX operating personnel. Estimates of fixed capital investment, development costs, and annual operating cost for SRS deployment of the CSSX-A system (in mid-2003 dollars) are $9,165,199, $2,734,801, and $2,108,820, respectively. When the economics of the CSSX-A system are compared with those of the baseline SWPF CSSX system, benefit-to-cost ratios ranging from 20 to 47 are obtained. The benefits in the cost/benefit comparison arise from expedited tank closure and reduced engineering, construction, and operating costs for the SWPF CSSX system. No significant impediments to deployment were determined in the reported analysis, and where technical uncertainties were identified, development tasks to mitigate them are indicated. It is recommended that deployment of the CSSX-A system be pursued in a timely manner in order to derive the greatest possible cost and accelerated treatment benefits.
Author: Publisher: ISBN: Category : Languages : en Pages : 5
Book Description
Researchers at the Savannah River Technology Center (SRTC) successfully demonstrated the Caustic-Side Solvent Extraction (CSSX) process flow sheet using a 33-stage, 2-cm centrifugal contactor apparatus in two 24-hour tests using actual high level waste. Previously, we demonstrated the solvent extraction process with actual SRS HLW supernatant solution using a non-optimized solvent formulation. Following that test, the solvent system was optimized to enhance extractant solubility in the diluent by increasing the modifier concentration. We now report results of two tests with the new and optimized solvent.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
The Modular Caustic-Side Solvent Extraction Unit (MCU) is the first, production-scale Caustic-Side Solvent Extraction process for cesium separation to be constructed. The process utilizes an engineered solvent to remove cesium from waste alkaline salt solution resulting from nuclear processes. While the application of this solvent extraction process is unique, the process uses commercially available centrifugal contactors for the primary unit operation as well as other common methods of physical separation of immiscible liquids. The fission product, cesium-137, is the primary focus of the process due to the hazards associated with its decay. The cesium is extracted from the waste, concentrated, and stripped out of the solvent resulting in a low-level waste salt solution and a concentrated cesium nitrate stream. The concentrated cesium stream can be vitrified into borosilicate glass with almost no increase in glass volume, and the salt solution can be dispositioned as a low-level grout. The unit is deployed as an interim process to disposition waste prior to start-up of the Salt Waste Processing Facility. The Salt Waste Processing Facility utilizes the same cesium removal technology, but will treat more contaminated waste. The MCU is not only fulfilling a critical need, it is the first demonstration of the process at production-scale.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
Savannah River Site (SRS) personnel have completed construction and assembly of the Modular Caustic Side Solvent Extraction Unit (MCU) facility. Following assembly, they conducted testing to evaluate the ability of the process to remove non-radioactive cesium and to separate the aqueous and organic phases. They conducted tests at salt solution flow rates of 3.5, 6.0, and 8.5 gpm. During testing, the MCU Facility collected samples and submitted them to Savannah River National Laboratory (SRNL) personnel for analysis of cesium, Isopar{reg_sign} L, and Modifier [1-(2,2,3,3-tetrafluoropropoxy)-3-(4-sec-butylphenoxy)-2-propanol]. SRNL personnel analyzed the aqueous samples for cesium by Inductively-Coupled Plasma Mass Spectroscopy (ICP-MS) and the solvent samples for cesium using a Parr Bomb Digestion followed by ICP-MS. They analyzed aqueous samples for Isopar{reg_sign} L and Modifier by gas chromatography (GC).
Author: Publisher: ISBN: Category : Languages : en Pages : 85
Book Description
An alkaline-side solvent extraction process for cesium removal from Savannah River Site (SRS) tank waste was evaluated experimentally using a laboratory-scale centrifugal contactor. Single-stage and multistage tests were conducted with this contactor to determine hydraulic performance, stage efficiency, and general operability of the process flowsheet. The results and conclusions of these tests are reported along with those from various supporting tests. Also discussed is the ability to scale-up from laboratory- to plant-scale operation when centrifugal contractors are used to carry out the solvent extraction process. While some problems were encountered, a promising solution for each problem has been identified. Overall, this alkaline-side cesium extraction process appears to be an excellent candidate for removing cesium from SRS tank waste.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
Researchers successfully demonstrated the chemistry and process equipment of the Caustic-Side Solvent Extraction (CSSX) flowsheet using MaxCalix for the decontamination of high level waste (HLW). The demonstration was completed using a 12-stage, 2-cm centrifugal contactor apparatus at the Savannah River National Laboratory (SRNL). This represents the first CSSX process demonstration of the MaxCalix solvent system with Savannah River Site (SRS) HLW. Two tests lasting 24 and 27 hours processed non-radioactive simulated Tank 49H waste and actual Tank 49H HLW, respectively. A solvent extraction system for removal of cesium from alkaline solutions was developed utilizing a novel solvent invented at the Oak Ridge National Laboratory (ORNL). This solvent consists of a calix[4]arene-crown-6 extractant dissolved in an inert hydrocarbon matrix. A modifier is added to the solvent to enhance the extraction power of the calixarene and to prevent the formation of a third phase. An additional additive is used to improve stripping performance and to mitigate the effects of any surfactants present in the feed stream. The process that deploys this solvent system is known as Caustic Side Solvent Extraction (CSSX). The solvent system has been deployed at the Savannah River Site (SRS) in the Modular CSSX Unit (MCU) since 2008.
Author: Publisher: ISBN: Category : Languages : en Pages : 22
Book Description
A caustic-side solvent extraction (CSSX) process to remove cesium from Savannah River Site (SRS) high-level waste was tested for 71 hours in a 33-stage minicontactor (2-cm centrifugal contactor). This multi-day demonstration used an average SRS simulant for the waste feed. The two key process goals were achieved: (1) the cesium was removed from the waste with decontamination factors greater than 40,000, and (2) the recovered cesium was concentrated by a factor of 15 in dilute nitric acid. These goals were maintained for 71 h as 1.4 L of solvent was recycled 42 times at 14 mL/min while processing 180 L of SRS simulant at 43 mL/min. The average decontamination factor was 159,000 for cesium and the average concentration factor was 14.9. The process had to be shut down twice for minor problems, which were fixed and testing resumed. The results confirmed that the CSSX process could be used to help decontaminate the millions of gallons of SRS waste now stored in underground tanks.
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