Technology
Safely Managing Waste
In addition to the technologies used for tank retrieval and those proposed for supplemental treatment and disposal, WRPS is exploring ways to gain operational efficiencies while safely and effectively completing the tank operations mission. The technical advances are important to our strategy for making swift and steady progress in our work.
Hose-in-Hose Transfer Lines
Flexible, hose-in-hose transfer lines, developed at Hanford, have helped move waste out of the aging single-shell tanks. The temporary transfer lines are being used in place of existing underground piping systems, most of which were installed in the 1940s and 1950s and no longer meet environmental standards. The new systems also help us avoid the cost of installing expensive infrastructure that would be used only for a short time.
Compatibility Assessment Tool
Development of the Compatibility Assessment Automation Tool (CAAT) is providing WRPS with faster, more reliable data for ensuring compatibility of waste transferred from single-shell tanks to safer double-shell tanks. A job that once took weeks to perform is now accomplished in minutes. Knowledge about the chemical processes that generated the waste is incorporated into the CAAT program and CAAT is connected to the long-established Tank Waste Information Network System which is an electronic repository for data on tank waste inventories. By combining all this data the CAAT program can automatically calculate the tank chemistry and alert engineers to potential problems. Engineers can then respond with appropriate adjustments to minimize adverse chemical reactions.
Remote Inspection of Double-Shell Tanks
A project that took nearly ten years to complete has given the Department of Energy and the Washington State Department of Ecology important assurances about the integrity of Hanford’s 28 double-shell radioactive waste storage tanks. The data, gathered using a remotely controlled ultrasonic examination system, shows the tanks are in good condition. The system uses electronic currents to examine the inner tank walls and look for corrosion, cracking, pitting and defects from construction. Recent data confirm that all the double-shell tanks meet or exceed operating specifications. In some tanks, for example, the steel used in construction was thicker than specifications required. Further, conditions in many tanks that have stored waste for several decades were better than expected.
Corrosion Probe System
Working with the Double-Shell Tank Integrity Project Expert Panel Oversight Committee (EPOC), ARES Corporation, and Parsons Infrastructure and Technology Group, a new Multi-Probe Corrosion Monitoring System was designed, fabricated, and installed in double-shell tank AN-102. The monitoring system will significantly improve the control of waste chemistry in the double-shell tanks, which will reduce the cost for treating tank waste.
The monitoring system consists of six reference electrodes, an electrical resistance probe, and carbon-steel corrosion coupons suspended at various elevations in the tank. The electrodes determine the tank waste chemistry electrochemical potential and the probe measures the corrosion rate of the tank wall. Data from the corrosion of the coupons, made of the same type of steel as the tanks, will augment the electrode and probe data. The monitoring system, along with in-tank video inspections and ultrasonic testing of the inner tank wall from the tank annulus, are part of the Double-Shell Tank Integrity Program. The program has demonstrated that the corrosion rates in the Hanford’s 28 double-shell tanks are less than expected. Continued monitoring will ensure that the double-shell tanks can safely store high-level radioactive waste for decades to come.
Real-Time Monitoring Probes
Two new monitoring probes were deployed in two single-shell tanks to speed waste retrieval and reduce project costs. The probes, which detect concentrations of isotopes and other key constituents in the waste, provide real-time monitoring of waste cleanout during the transfer process. This avoids the time and expense of shutting down retrieval for several weeks while samples are analyzed in the laboratory. Using the probes the continuous chemical composition data are available in real time so operations can proceed steadily and the retrieval process can be managed effectively.
