Provide hands-on shift-work process engineering support for pilot-plant testing of a solids filtration and ion exchange extraction system for the removal of cesium from a radioactive waste stream at the Department of Energy Hanford Site.
Process Engineering Associates, LLC (PROCESS) was contracted by a northwestern US based engineering company to provide support and assistance with a 1/9th scale non-radioactive surrogate/simulant pilot plant to test viability of a chemical process in support of Hanford tank waste remediation efforts. Equipment was being installed, connected by piping, and readied for testing according to pre-existing P&IDs when PROCESS was contracted. This 1/9th engineering scale non-radioactive simulant pilot plant was part of the Low Activity Waste Pre-treatment System (LAWPS) project to remove entrained solids from a liquid effluent stream of radioactive waste using cross-flow filtration. The cross-flow filters (CFF) allowed a nominal 1% of the liquid passing over the surface of the filter to pass through it. The retained solids were concentrated in the feed solution and were not collected and removed which would have resulted in an additional waste stream. Non-radioactive cesium, used as a surrogate for radioactive cesium, was removed from the filtered, caustic (high pH), high sodium effluent using a proprietary ion exchange resin. The extremely selective ion exchange resin was very susceptible to dissolved oxygen. The ion exchange resin was a rich burgundy color in the sodium form, and a bright salmon color in the hydrogen form, but it turned black, lost activity and was non-recoverable once it reacted with dissolved oxygen.
The work scope that PROCESS contracted to perform for MCE included:
- Writing operating procedures for start-up, normal operations, and shutdown of the process
- Contacting chemical suppliers and obtaining cost and schedule estimates
- Contacting waste disposal companies and obtaining cost estimates
- Training operators and operating crews
- Performing chemical make-up operations of feed chemicals
- Performing on-shift 24/7 supervision/lead responsibilities.
- Monitoring filtration for indications of fouling and cleaning as needed using: back pulse, drain & fill, and/or chemical cleaning in normal flow configuration.
Ion Exchange Operations
- Loading of cesium onto ion exchange resin
- Regenerating ion exchange resin: displacing process fluids with caustic solution, rinsing of resin with DI water, eluting cesium from ion exchange resin using acidic solution, rinsing of resin with DI water, and regenerating ion exchange resin with caustic solution
- Providing customer consultation on chemical, environmental, safety and health issues.
Five (5) months of preparation (writing procedures, obtaining chemicals, contracting disposal services, and training) were followed by five (5) months of operating the pilot plant, sometimes at a rapid pace (24/7 for up to 10 days straight with only two crews). As a direct result of the involvements suggested by PROCESS, the project was completed weeks ahead of schedule, under budget, safely, and with the highest attention to quality.
Radioactive Waste Treatment
- On-site operations support
- Pilot-plant operations support.