A key Savannah River Site (SRS) waste treatment facility returned to operations last month after a three-month scheduled outage to address equipment concerns.
The Saltstone Production Facility (SPF) receives low-radioactive salt solution that has been separated from radioactive sludge. That pre-separation material is stored together in more than 40 liquid waste tanks, which in total hold about 35 million gallons of highly radioactive waste at the Department of Energy facility in South Carolina, 90 percent of which is salt waste.
Following separation of the waste types, the salt waste goes to SPF to be stabilized by being blended with a cement mixture. The final product is pumped into concrete disposal vaults for permanent storage on-site.
The Saltstone Production Facility undergoes routine outages for maintenance, said Dean Campbell, a spokesman for SRS liquid waste contractor Savannah River Remediation (SRR).
The latest outage began in September and ended on Dec. 12. Workers replaced a grout flow element, and also rebuilt a number of valves in the grout line that became hard to operate over time because of grout buildup.
“Maintenance workers clean out the valves and replaces parts as necessary. Also, the grout flow element, which measures the grout flow rate, was not reading correctly so the instrument was replaced with a new one,” Campbell said by email.
Campbell said the SPF did not receive waste during the outage because the facility that processes the salt waste, the Modular Caustic Side Solvent Extraction Unit (MCU), experienced an unplanned outage “for several days during that time to resolve minor equipment-related issues.” Issues included a compressed air system that had to be repaired and condensation buildup in a part of the facility, which was resolved through use of a temporary air conditioning system until repairs could be made.
The MCU has treated upward of 5 million gallons of waste since it became operational in 2008, while DOE awaits the anticipated startup of the Salt Waste Processing Facility (SWPF) in late 2018. The facility is in testing and commissioning after construction was completed in mid-2016. The SWPF is expected to increase SRS liquid waste processing from 1.5 million gallons a year to 6 million.
