The Department of Energy aims later this month to resume liquid waste processing at the Savannah River Site, two months after the initial March projection. Meeting that schedule would cap off a 15- month pause of waste processing at the DOE facility near Aiken, S.C.
The two-month delay was caused by a malfunctioning diesel generator at the site’s Defense Waste Processing Facility (DWPF), which converts sludge waste into a less radioactive form for temporary storage on-site. The two DWPF generators ensure power in the event of an electricity outage or interruption.
“During a scheduled diesel surveillance, the diesel did not energize a safety load as expected under a specific facility configuration. There was a delay to resolve this issue,” a DOE spokesperson said by email.
The DWPF began chemical operations on May 8, which includes pretreatment of sludge to prepare for the waste conversion process.
The Savannah River Site today holds about 35 million gallons of highly radioactive liquid waste in 43 underground tanks, the byproduct of Cold War nuclear weapons production. Waste treatment began in 1996 when DWPF first started converting the waste into less harmful, glassy form.
Liquid waste processing at Savannah River has been on hold since February 2017, when DOE determined it needed to replace the Defense Waste Processing Facility’s Melter 2: a 65-ton refractory-lined vessel that mixes the waste with borosilicate frit to form a molten glass that can be poured into stainless-steel canisters for safe storage.
Melter 3 arrived at DWPF last August and in January poured a canister of waste that had already been treated last year before operations were paused. The replacement cost $3 million.
Since then, workers have been following protocol to ensure a safe restart. That has included following procedure in the documented safety analysis, which helps ensure compliance in operations.
The DOE spokesperson said Monday the 15-month pause will have a minimum impact on the site’s waste processing schedule because the SRS Liquid Waste Plan is padded to include pauses in work. The liquid waste mission is expected to last until 2039 and carries a life-cycle cost of $33 billion to $57 billion.
The Energy Department has already closed out eight storage tanks, representing roughly 7 million gallons of waste. Two were closed in the 1990s, and liquid waste contractor Savannah River Remediation has operationally closed another six since winning its $4.1 billion contract in 2008.
The waste is 10 percent sludge and 90 percent salt waste. The sludge is sent to DWPF for processing, and the salt waste is treated using a pilot process that makes it suitable for permanent disposal on-site. Salt waste will eventually be treated using the SRS Salt Waste Processing Facility (SWPF), which is expected to increase processing from 1.5 million gallons per year to 6 million.
