REMOTE HANDLED TRANSURANIC (RH-TRU) SLUDGE CONSOLIDATION ACTIVITIES AT THE OAK RIDGE NATIONAL LABORATORY

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1 WM 1 Conference, February 25-March 1, 21, Tucson, AZ REMOTE HANDLED TRANSURANIC (RH-TRU) SLUDGE CONSOLIDATION ACTIVITIES AT THE OAK RIDGE NATIONAL LABORATORY B. D. Oakley K. P. Guay G. L. Riner K. M. Billingsley Duratek Federal Bechtel Jacobs U.S. Department of Advanced Integrated Services Company Energy Management Services, Inc. ABSTRACT The Oak Ridge National Laboratory Liquid Low-Level Waste (LLLW) System collects aqueous radioactive waste solutions in large underground storage tanks from various programmatic sources for onsite neutralization, concentration, and storage. Due to the nature of the concentrated, highly alkaline LLLW, remote-handled transuranic (RH-TRU) sludge accumulated in the system as precipitants settled out of the LLLW. To support treatment of the RH-TRU sludge by the Foster Wheeler Environmental Corporation (Foster Wheeler), the U.S. Department of Energy privatization subcontractor, all ORNL RH- TRU sludge is being transferred into the Melton Valley Storage Tanks (MVSTs) as part of an integrated tank waste consolidation plan. The MVSTs are eight large 189 m 3 (5,-gallon) capacity tanks that provide the majority of storage for ORNL s untreated RH-TRU sludge. Operation of the MVSTs will be turned over to Foster Wheeler during fiscal year (FY) 21 in preparation of RH-TRU sludge and associated LLLW retrieval and treatment operations that will be conducted at the planned ORNL TRU Waste Treatment Facility. Several high profile tank waste removal projects have been successfully completed at ORNL as part of the sludge consolidation activities. Over 466 m 3 (123, gallons) of RH-TRU sludge have been transferred to the MVSTs from various inactive and active LLLW storage tanks since the sludge consolidation activities began of in FY Approximately 84 m 3 (222, gallons) of RH-TRU sludge will be transferred to the MVSTs upon the completion of the sludge consolidation activities at the end of FY 21. This paper provides a synopsis of the waste removal projects, and an overview of the integrated sludge waste consolidation activities. INTRODUCTION The Liquid Low-Level Waste (LLLW) System at Oak Ridge National Laboratory (ORNL) is a system of underground storage tanks of varying shapes, sizes, and volumes. The LLLW System also includes evaporator facilities that are used to collect, neutralize, concentrate, and store liquid radioactive waste solutions from various research and development, radiochemical processing, and radioisotope production facility sources at ORNL. LLLW was/is discharged from the source buildings into waste collection/storage tanks. This waste is periodically transferred to the ORNL Bethel Valley Evaporator facility for volume reduction, which began operating in Two steam coil evaporator systems at the facility are used to annually concentrate approximately 1,514 m 3 (4, gallons) of newly generated programmatic LLLW at a rate of 2.3 m 3 per hour (6 gallons per hour). The facility achieves a typical volume reduction ratio of approximately 3:1 with decontamination factors ranging from 1x1 4 to 1x1 5. The facility s evaporator overheads are transferred to the Process Waste Treatment Complex to remove radiochemical constituents prior to being discharged to a National Pollution Discharge Elimination System (NPDES) permitted outfall. The evaporator facility s LLLW concentrate is transferred to one of the active waste storage tanks at ORNL.

2 WM 1 Conference, February 25-March 1, 21, Tucson, AZ The active waste storage tank system consists of: five 189 m 3 (5,-gallon) stainless steel tanks in Bethel Valley, known as the Bethel Valley Evaporator Service Tanks (BVESTs) (tank numbers W-23, W-24, W-25, C-1 and C-2), eight 189 m 3 (5,-gallon) stainless steel tanks located in Melton Valley, known as the Melton Valley Storage Tanks (MVSTs) (tank numbers W-24 through W-31), and six 378 m 3 (1,-gallon) tanks located in Melton Valley, known as the Melton Valley Storage Tanks Capacity Increase Project (MVST-CIP) (tank numbers W-32 through W-37). Over the years of LLLW storage at ORNL (1943 to the present), remote handled transuranic (RH-TRU) mixed waste sludge has accumulated in the inactive and active tanks that are part of ORNL s LLLW system due to the nature of the highly alkaline concentrated LLLW stored in these tanks. The U.S. Department of Energy (DOE) has implemented an integrated tank waste consolidation plan at ORNL to allow for the treatment, packaging, and off-site disposal of this RH-TRU sludge and associated LLLW. INTEGRATED SLUDGE CONSOLIDATION ACTIVITIES AT ORNL In 1996 and 1997 ORNL began to aggressively plan for the consolidation of RH-TRU mixed waste sludge and associated LLLW from ORNL s inactive waste storage tanks into the MVSTs (Figure 1). The consolidation of this waste was required in order close ORNL s inactive waste storage tanks, and to prepare these wastes for treatment at the planned ORNL TRU Waste Treatment Facility. The DOE implemented an integrated tank waste consolidation plan at ORNL in The plan was implemented in order to meet a Tennessee Department of Environment and Conservation (TDEC) Commissioner s Order milestone that requires the first shipment of treated RH-TRU sludge to be shipped offsite to the Waste Isolation Pilot Plant by January 23. The DOE Oak Ridge Operations ORNL Tanks Program and TRU Waste Program coordinated the sludge consolidation activitie s for the ORNL tanks. Fig. 1. Conceptual drawing of DOE s Integrated Tank Waste Management Plan that calls for RH-TRU sludge and associated LLLW to be transferred to the MVSTs so that it can be retrieved for waste treatment and shipment offsite.

3 WM 1 Conference, February 25-March 1, 21, Tucson, AZ In order to maximize the amount of waste transferred within a specific time period, the main waste consolidation activities were performed as four separate projects, which were integrated into the master waste consolidation plan. The four projects included: the Bethel Valley Evaporator Service Tanks (BVESTs) Waste Removal Project; the BVESTs C-Tanks Waste Removal Project; the Old Hydrofracture Facility (OHF) Waste Removal Project; and the Gunite and Associated Tanks (GAAT) Waste Removal Project. Fig. 2. The Melton Valley Storage Tanks are active tanks in the ORNL LLLW System that are the consolidation tanks for ORNL s RH-TRU waste sludge and associated LLLW. Also included in the plan, but with a lesser impact, was the waste retrieval and closure of several smaller inactive tanks at ORNL that are regulated under the Federal Facility Agreement between the DOE, the TDEC, and the U.S. Environmental Protection Agency (EPA). Since the beginning of the RH-TRU sludge consolidation activities in FY 1997, over 466 m 3 (123, gallons) of RH-TRU mixed waste sludge have been transferred to the MVSTs (figure 2) from various LLLW storage tanks as shown in Table I. The DOE plans for the RH-TRU sludge consolidation activities to be completed by the end of fiscal year (FY) 21.

4 WM 1 Conference, February 25-March 1, 21, Tucson, AZ Table I. Sludge transfers (m 3 ) to the ORNL Melton Valley Storage Tanks (MVSTs) performed as part of the integrated tank waste consolidation plan. Originating MVSTS Consolidation Tank Number Total Tank Number W-24 W-25 W-26 W-27 W-28 W-29 W-3 W-31 (m 3 ) Bethel Valley Evaporator Service Tanks C C W W W Old Hydrofracture FACILITY TANKS T T T T T Gunite and Associated Tanks (based on suspended Solids Only) W Total(m 3 ) From FY 1998 through FY 2, the Wastewater Triad Project performed LLLW processing operations. The Wastewater Triad Project provided additional volume reduction of the LLLW concentrate stored in the MVSTs. These operations helped to free up storage tank capacity in the MVSTs to support sludge consolidation activities. The waste processing activities also reduced the radioactivity of the processed supernate. The Wastewater Triad Project was located at the MVSTs facility and consisted of three modular skid-mounted waste processing systems that are self-contained and individually shielded. The three systems included the Solids/Liquid Separation skid, the Cesium Removal skid, and the Out-of-Tank Evaporator skid. Fourteen waste processing campaigns were completed since the start of operations in December 1997 processing approximately 1,136 m 3 (3, gallons) of LLLW and creating over 378 m 3 (1, gallons) of additional free space. Since 1997, over 2,65 m 3 (7, gallons) of non-programmatic LLLW were generated during the ORNL sludge consolidation activities. The Bethel Valley Evaporator facility treated the wastes. The LLLW generated from the sludge consolidation activities had a significantly higher radionuclide content, as compared to newly generated LLLW during ORNL research and develop, radiochemical processing, and isotope production activities, and will require remote handling. Based on the facility s waste decontamination performance abilit ies, the Bethel Valley Evaporator was limited to effective volume reduction ratios of this waste that ranged from 5:1 to 1:1. The facility is capable of a achieving 3:1 volume reduction ratio for ORNL s regular programmatic LLLW. Approximately 1, 136 m 3 (3, gallons) of the total volume of non-programmatic LLLW remains to be volume reduced. This LLLW is the remaining liquid used to sluice and transfer sludge during the GAAT waste removal project. This waste is currently stored in the larger 643 m 3 (17,-gallon) tanks located in the South Tank Farm at ORNL. The waste will be treated at the Bethel Valley Evaporator through FY 22 to achieve a volume reduction ratio that ranges between 5:1 and 1:1. The concentrated LLLW will be transferred to the MVSTs. Figure 3 shows the actual and projected concentrated LLLW volume in the active tank system resulting from both routine LLLW System operations and sludge consolidation activities.

5 WM 1 Conference, February 25-March 1, 21, Tucson, AZ 4, 3,5 (MVSTs-CIP became operational) 3, 2,5 2, 1,5 Actual Forecast 1, 5 Total Active System Operational Safety Requirements Capacity July, 1997 September, 1997 November, 1997 January, 1998 March, 1998 May, 1998 July, 1998 September, 1998 November, 1998 January, 1999 March, 1999 May, 1999 July, 1999 September, 1999 November, 1999 January, 2 March, 2 May, 2 July, 2 September, 2 November, 2 January, 21 March, 21 May, 21 July, 21 September, 21 Fig. 3. Total concentrated LLLW volume consolidated in the active tank system at ORNL.

6 WM 1 Conference, February 25-March 1, 21, Tucson, AZ In August 2, the U.S. Department of Energy (DOE) awarded a privatization contract to the Foster Wheeler Environmental Corporation (Foster Wheeler) for the design, construction, operation, and decontamination and decommissioning (D&D) of the ORNL TRU Waste Treatment Facility. The operation of the MVSTs will be turned over to Foster Wheeler during FY 21 to prepare for the RH-TRU sludge and associated LLLW retrieval and treatments operations. At the end of sludge consolidation activities in September 21, an estimated volume of approximately 841m 3 (22, gallons) of sludge will be consolidated in the MVSTs. The current and projected sludge volumes in the active waste storage tanks are shown in Table II. Table II. Current and projected of RH-TRU and associated LLLW volumes stored in the major waste storage tanks at ORNL. Current (1/1/1) Projected (9/3/1) Sludge (m 3 ) LLLW Volum e (m 3 ) Total (m 3 ) Sludge (m 3 ) LLLW (m 3 ) Total (m 3 ) Tank Number Bethel Valley Evaporator Storage Tanks (BVESTS) C C W W W BVESTS Total (m 3 ) Melton Valley Storage Tanks (MVSTS) W W W W W W W W MVSTS Total (m 3 ) Melton Valley Storage Tanks Capacity Increase Project (MVST-CIP) MVSTS -CIP Total 1,478. (m 3 ) , , ,427.3 Gunite and Associated Tanks (GAAT) W W W W W W GAAT Total (m 3 ) Grand Total , , , , , ,486.9

7 WM 1 Conference, February 25-March 1, 21, Tucson, AZ THE BETHEL VALLEY EVAPORATOR SERVICE TANKS WASTE REMOVAL PROJECT (1) The BVESTs Waste Removal Project included waste mixing and sludge transfers from three of the BVESTs (W-21, W-22, and W-23). These active tanks have historically served as feed tanks to the Bethel Valley Evaporator facility, and storage tanks for the LLLW concentrate. The tanks are all welded cylindrical vessels fabricated of ½ inch stainless steel. Approximately 3.5 m (12 ft) in diameter by 18.5 m (61 ft) long, the three tanks and are horizontally mounted in below grade reinforced concrete vaults. The vault floors and walls are lined with 16-gauge stainless steel to a height slightly over 2 m (7 feet) to provide double containment of the waste. The tanks have limited access by means of a single.5 m (19-inch) riser located approximately 5 m (17 feet) from the north end of each tank. A modular Fluidic Pulse Jet Mixing System, designed, fabricated, and operated by AEA Technology, was used to mobilize the RH-TRU sludges contained in tanks W-21, W-22, and W-23. The modular mixing system was connected to the six existing mixing nozzles in the individual tanks via connections in the tank s valve pit. The nozzles are 7.6 cm (3-inches) diameter pipes that enter the tanks from the top and extend to about 8-inches above the tank bottom. The bottoms of the nozzles have a 9-degree elbow. The six nozzles were installed in opposing pairs along the length of the tank. Waste removal was conducted in the individual tanks in a series of waste mixing campaigns. After waste mixing with the Pulse Jet Mixing System, the resulting slurry was transferred to the MVSTs through approximately 2164 m (7,1 ft) (equivalent length) of existing double-contained pipeline using the existing progressive cavity pumps. Table III summarizes the sludge transfers for tanks W-21, W-22, and W-23. The sludge removal operations from Tank W-23 were not performed to the same extent as the other two tanks due to its planned use as an interim waste storage tank in subsequent sludge transfers from other ORNL tanks. Fig. 3. The Pulse Jet Mixing System was installed at the BVESTs pump and valve pit to perform waste mixing operations in tanks W-21, AND W-23

8 WM 1 Conference, February 25-March 1, 21, Tucson, AZ Table III. Summary of the waste transfers conducted during the BVEST Waste Removal Project. of Date Starting Transfer Sludge Suspended Solids Density [m 3 ] [m 3 ] [m 3 ] [wt. %] [g/ml] Tank W-21 Initial Sludge = /17/ /26/ /6/ /1/ /14/ /27/ /27/ /28/ /13/ Totals % 98.6% W-22 Initial Sludge = /21/ /26/ /3/ /2/ /9/ Totals % 97.1% W-23 Initial Sludge = /27/ /1/ /4/ Totals % BVESTs C-TANKS WASTE REMOVAL PROJECT (2) 96.% The BVESTs C-Tanks Waste Removal Project was responsible for the sludge transfers from tanks C-1 and C-2. These two active tanks have historically served as LLLW concentrate storage tanks. The tanks are similar to tanks W-21, W-22, and W-23 in their construction and size. Each tank has two 2-inch diameter risers that provide tank access. The risers are located on opposite ends of the tanks, approximately 1.5 m (5 feet) from each end. The tanks are horizontally mounted in below grade reinforced concrete vaults, and the vault floors and walls are lined with 16-gauge stainless steel to provide double containment of the waste. The tanks were originally designed to store high-level waste, but were never used for that purpose. Similar to the BVESTs Waste Removal Project, the waste mixing in the two C-tanks was performed using a modified modular Fluidic Pulse Jet Mixing System, designed and fabricated by AEA Technology. Since these tanks did not contain existing interior nozzles, waste mixing was accomplished by inserting a charge vessel into both of the tank access risers on each tank. The

9 WM 1 Conference, February 25-March 1, 21, Tucson, AZ charge vessels were designed so that they could be rotated about a vertical axis during waste mixing operations. The discharge nozzle at the bottom of each charge vessel had two opposing jets; so the contents of the charge vessel were discharged simultaneously in opposite directions. After adequately mixing the tank waste with the modified mixing system, the resulting slurry was transferred to tank W-23 (the interim waste consolidation tank located north of the C-tanks) using the existing progressive cavity pumps. The original Pulse Jet Mixing System installed in tank W- 23 operated during the interim waste storage to keep the waste slurry in suspension until it could be transferred to the MVSTs as previously described. After completing the sludge transfers from tank C-2, the charge vessels were moved to tank C-1. Table IV summarizes the sludge transfers from tanks C-1 and C-2. Table IV. Summary of the waste transfer conducted during the BVESTs C-Tanks Waste Removal Project. of Date Starting Transfer Sludge Suspended Solids Density [m 3 ] [m 3 ] [m 3 ] [wt. %] [g/ml] Tank V-1 Initial Sludge = 12.3 m 3 2/25/ /1/ /5/ n/a n/a 3/8/ n/a n/a Totals % of Sludge 95.5% Tank C-2 Initial Sludge = 31. m 3 2/8/ /11/ /16/ /22/ Totals % of Sludge 98.9% THE OLD HYDROFRACTURE FACILITY (OHF) TANKS WASTE REMOVAL PROJECT The OHF Tanks Waste Removal Project was responsible for the waste removal from the five OHF tanks (T-1, T-2, T-3, T-4, and T-9). The OHF facility was constructed in Melton Valley in 1963, near the existing MVSTs, and it operated from 1964 through The facility was used to dispose of LLLW by mixing it with grout, and then injecting the grout mixture into shale formations over 1, feet below the ground s surface. T he OHF tanks were used to store LLLW during the OHF operations. The mobilization and transfer of RH-TRU sludge and associated LLLW from the OHF tanks was conducted in July 1998 as a technology demonstration project in coordination with the DOE Tank Focus Area. The project demonstrated the remotely operated Borehole Miner Extendable Nozzle, manufactured by Waterjet Technologies, to sluice the RH-TRU sludge from these tanks. The Borehole Miner was deployed into the tanks through tank access risers added to allow the access of the sluicing and pumping equipment into the cylindrical, horizontally positioned, underground storage tanks. Waste removal operators were able to remotely rotate/position the extendable

10 WM 1 Conference, February 25-March 1, 21, Tucson, AZ sluicing nozzle to avoid internal tank obstructions. The single high-pressure jet nozzle used recycled supernatant and about 31 m 3 of water to breakup the sludge and mix the tank contents. The resulting waste slurry was transferred out of the tanks to the MVSTs via existing double-contained underground piping. Table V summarizes the sludge transfers from the OHF tanks. Table V. Summary of the waste transfer data for the OHF Tanks Waste Removal Project. Waste Slurry Transfer of Sludge Percentage Transfer Number [m 3 ] [m 3 ] [%] Total Initial Sludge = 37.1 m % % % % Total % THE GUNITE AND ASSOCIATED TANKS (GAAT) WASTE REMOVAL PROJECT The GAAT Waste Removal Project was responsible for the waste removal operations from eight large underground storage tanks (W-3, W-4, W-5, W-6, W-7, W-8, W-9, and W-1). These inactive tanks were the largest of 12 gunite tanks constructed at ORNL using standard gunite practices between 1943 and The eight domed tanks ranged in capacity from 161 m 3 (42,5 gallons) to 643 m 3 (17, gallons), and were 7.6 to 15.2 m 3 (25 to 5 ft) in diameter with 3.7 m 3 (12 ft) high walls. The gunite tanks were used to store LLLW from radiochemical processing activities conducted at ORNL. The tanks were removed from service in the early 197 s and a standard practice sluicing campaign in the 198 s removed a majority of the sludge waste contained in the tanks. Tank inspections and tank waste characterization indicated that approximately 341 m 3 (9, gallons) of RH-TRU sludge heels remained in these tanks. Removal of the remaining sludge was required in order to meet the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) target risk reduction goals. Waste removal in the gunite tanks was accomplished thought the utilization of robotic and remotely operated equipment (Figure 4). The project integrated the equip ment into a system that effectively mobilized and transferred the sludge out of the tanks and into tank W-9, which served as an interim waste consolidation tank for the project. Major equipment components included: the robotic Modified Light Duty Utility Arm; the Houdini I and Houdini II remotely operated vehicles; the Waste Dislodging and Conveyance System, which included a confined sluicing endeffector, a gunite scarifying end-effector, the waste transfer hose management arm, and jet pump; and the sludge conditioning system that aided waste transfer to the active tank system.

11 WM 1 Conference, February 25-March 1, 21, Tucson, AZ The waste removal system utilized high pressure water jets contained in the confined sluicing end-effector to break up and mobilize the sludge, and an axial flow jet pump to transfer the sludge into tank W-9. Two Flygt mixers were installed in tank W-5 to mobilize the sludge in this tank for waste transfer due to the deteriorating conditions found in this tank. A combination of three PulseAir mixers and a Flygt mixer were used in tank W-9 to keep the transferred waste from settling in this interim waste consolidation tank. A 125 horsepower submersible pump transferred the resulting waste slurry out of tank W-9 through approximately 2164 m 3 (7,1 ft) (equivalent length) of existing double-contained pipeline to the MVSTs. During the final waste removal operations in tank W-9 in late FY 2, the robotic and remotely operated waste removal equipment was deployed in this tank to effectively mobilize the remaining sludge. The waste slurry was transferred to tank W-23 (one of the Bethel Valley Evaporator Service Tanks), and the Pulse Jet Mixing System was operated in tank W-23 to keep the waste slurry mixed and in suspension until it could be transferred to the MVSTs as previously described. Table VI summarizes the sludge transfers that were performed during the GAAT Waste Removal Project. Figure 4. Robotic and remotely operated waste removal equipment installed on the equipment platform over tank W-9 in the ORNL South Tank Farm during the final stages of waste removal and transfers during the GAAT Waste Removal Project.

12 WM 1 Conference, February 25-March 1, 21, Tucson, AZ Table VI. Summary of the waste transfers conducted during the GAAT Waste Removal Project. Waste Slurry Transfer Date Date Waste Slurry Transfer of Sludge Transferre d Percenta ge Transferr ed of Sludge Transferr ed [m 3 ] [m 3 ] [%] [m 3 ] [m 3 ] [%] Total Initial Sludge in the GAAT = 34.7 m 3 Year 1999 Transfers Year 2 Transfers 5/25/ % 1/13/ % 6/11/ % 1/2/ % 6/22/ % 2/11/ % 7/22/ % 2/18/ % 7/27/ % 3/14/ % 8/17/ % 3/23/ % 9/9/ % 3/3/ % 9/28/ % 7/13/ % 1/26/ % 7/18/ % 9 11/17/ % 7/22/ % 12/7/ % 7/27/ % Subtotal 1, /2/ % s Total Waste Slurry Total Sludge Total Percentage of Sludge 8/16/ % 2,385.4 m 3 8/21/ % 33.5 m 3 8/3/ % 97% 9/7/ % Subtota 1, ls Percenta ge Transferr ed

13 WM 1 Conference, February 25-March 1, 21, Tucson, AZ CONCLUSIONS The ORNL RH-TRU sludge consolidation activities have been ongoing since 1997 as part of an integrated tank waste retrieval plan implemented by the DOE. The majority of RH-TRU sludge transfers to the MVSTs were completed by the end of FY 2. Some small RH-TRU and associated LLLW transfers will be performed through FY 22. To support treatment of the RH- TRU sludge by Foster Wheeler, the DOE privatization subcontractor, over 84 m 3 of RH-TRU sludge will ultimately be consolidated in the MVSTs. Operation of the MVSTs will be turned over to Foster Wheeler during FY 21 to prepare for the tank waste treatment activities. RH- TRU sludge treatment should begin in early FY 23 so that the first shipment of treated RH- TRU sludge can be shipped to the Waste Isolation Pilot Plant in New Mexico by the end of January 23. REFERENCES T. E. Kent, T. E. Helton, S. A. Taylor, and J. W. Moore, Deployment of a Fluidic Pulse Jet Mixing System for Horizontal Waste Storage Tanks at Oak Ridge National Laboratory, Oak Ridge Tennessee, BJC/OR-82, August 1998 T. L. Dahl, A. C. Lay, S. A. Taylor, and J. W. Moore, Transuranic Sludge Removal from the C- 1, C-2, and W-23 Waste Storage Tanks at Oak Ridge National Laboratory, Oak Ridge, Tennessee, BJC/OR-279, May 1999.