Confined Swelling Pressure Tests for Spherical Resorcinol-Formaldehyde Resin
Joseph Walker, Paul Taylor, and Trent Walker
Oak Ridge National Laboratory
An ion exchange process using spherical resorcinol-formaldehyde (sRF) resin from Microbeads AS (Skedsmokorset, Norway) is the baseline process for removing cesium from the approximately 53 million gallons of highly radioactive nuclear waste currently stored in underground tanks at the Department of Energy (DOE) Hanford site. Since the selected sRF resin is known to swell during processing as it is converted from a hydrogen form to a sodium form, there is a concern about the pressure the resin could exert if it were to become trapped in process piping.
A test system (see Fig. 1) was fabricated and operated at Oak Ridge National Laboratory to measure the swelling pressure of various batches of sRF resin. The test vessel consists of a 6 inch long section of 2 inch, schedule 80, 304L stainless steel pipe welded to 2 inch, class 600 pipe flanges at the top and bottom. With the flanges, the total depth of the resin bed within the test vessel is 6.5 inches. The inlet and outlet filter assemblies, which are modified Swagelok ½-in. stainless inline filters, are welded to the sides of the vessel. Pressure elements/transmitters are bolted to the top and bottom flanges of the test vessel to monitor the pressures during testing. The top pressure assembly is a 0–750 psi, WIKA general industrial transmitter (WIKA Instrument, LP, Lawrenceville, GA) with a flush diaphragm seal, and the bottom pressure assembly is a 0–1500 psi assembly of the same design.
Fig. 1. Photograph of the test system before instruments were connected to the data acquisition system.
Six batches of the sRF resin were tested:
Blue drum (batch # 5J-370/686)
Black drum (batch # BSC-3380-3-0200)
Finncont-1 (batch # BSC-3380-2P-0201)
Finncont-2 (batch # 6C-370/745)
Finncont-3 (batch # 0L-370-1312)
Microbeads (batch # 1f-370-1392)
For each test, the test vessel was filled to the top flange (see Fig. 2) with preconditioned, hydrogen-form sRF resin in water, and then the top flange/pressure transducer was connected, air was vented from the lines, and dilute sodium hydroxide was pumped through the resin to convert it to the hydroxide form. The pressures at the top and bottom of the test vessel were measured as the resin swelled inside the test vessel. When the pressures had stabilized, the flow of sodium hydroxide was stopped so that the static pressures inside the test vessel could be measured. A small amount of deionized water was then pumped through the test vessel to displace the sodium hydroxide, and the top flange was removed, allowing the resin to expand (see Fig. 3).
Fig. 2. H-form sRF resin loaded in test vessel Fig. 3. sRF resin expansion after top flange was removed
One run each was made with the first five resin batches listed above, and five runs were made with the sixth batch. After each test, samples of resin were collected from different locations within the column, titrated to determine the extent of conversion to the sodium form, and examined microscopically to look for bead breakage and changes in the bead sizes and shapes.