The Savannah River Site expects in 2019 to use a mixture of new and old methods to increase removal of mercury from its liquid waste system.
In late 2017, officials at the Department of Energy facility in South Carolina discovered they could raise pH levels in the waste evaporator tank, a part of the site’s Defense Waste Processing Facility (DWPF). This draws more mercury from DWPF and the site’s entire liquid waste system, demonstrated by routine testing that shows mercury levels have largely stayed the same even as the material is naturally produced during waste treatment operations.
In addition to increased pH levels, Savannah River in 2019 will bring another approach online that will pump more mercury out of the system.
In addition to that, Savannah River also plans to increase removal by installing equipment that will enable direct pumping of mercury out of the DWPF. “Installation of mercury removal equipment into DWPF is being coordinated with adjacent equipment replacements in 2019,” the site spokesperson said via email.
The equipment is needed because the mercury often builds up in the system rather than flowing to the spots where it can be removed. However, “No regulatory limits have been exceeded, and there have been no compromises to the safety of workers, public, or the environment. The overall mercury removal progress has not been significantly impacted,” the site spokesperson said.
The Savannah River Site liquid waste system includes more than 40 storage tanks that house roughly 35 million gallons of radioactive, Cold War-era material. It encompasses waste processing operations including the Defense Waste Processing Facility, which converts some of that waste into a less harmful form suitable for interim storage on-site.
At any given time, about 60 metric tons of mercury inhabit the site’s tank farms and facilities, a DOE site spokesperson said in a recent email. The material dates to its use as a dissolvent of reactor fuel during decades of nuclear material processing operations at Savannah River’s H Canyon. When mercury is removed from the liquid waste system, it is recycled back to H Canyon for reuse.
There is no designated funding for the mercury removal project. Rather, it comes out of the liquid waste budget line, which in recent years has been upward of $600 million.
Mercury is a nonradioactive contaminant, but is a chemical of concern based on the impacts it could have on fish in waters adjacent to SRS near Aiken, S.C. For example, consuming fish with higher levels of mercury could negatively impact the nervous system for young children. Also, mercury is a potential worker hazard if it comes in contact with the skin, but protective clothing and access to medical screening are adequate methods to prevent exposure.
Savannah River officials say mercury will always be present in the liquid waste system, and it is unclear how much mercury is removed at any given time. The goal is to safely manage the material through methods such as the pH level increase.
