Savannah River Site officials reported Tuesday the site’s Saltstone Disposal Unit 6 (SDU 6) failed a leak test this month and now will not be finished until March – about five months later than expected, but still about a year before DOE is expected to need it, in February 2018.
The unit’s concrete cell has been constructed, but the water tightness test did not meet requirements, SRS reported at Tuesday’s SRS Citizens Advisory Board (CAB) meeting in Savannah, Ga.
“An alternative repair method and path forward to install an interior liner has been proposed and is being pursued by the contractor,” SRS officials said in written notes. The next leak test is slated for fall.
SDU 6 is the first 30-million gallon, salt-waste disposal unit constructed at the site. Once complete, it will be a permanent disposal unit for saltstone, a low radioactive salt waste found in the SRS storage tanks.
In the test, SDU 6 was filled with water to check for potential leakage. The SDU 6 tank is based on a commercial design for storing water and other liquids.
Salt waste constitutes about 90 percent of the total waste found in the SRS storage tanks. The waste is now treated using an interim facility, but DOE expects to finish construction of a permanent Salt Waste Processing Facility (SWPF) in June.
Once operable, SWPF will separate the highly radioactive cesium and actinides from the salt solution found in the SRS waste storage tanks. After completing the separation process, the cesium and actinide waste will be sent to the nearby Defense Waste Processing Facility (DWPF), which converts waste to a glassy form, a process known as vitrification. The remaining decontaminated salt solution will be mixed with grout at the nearby Saltstone facility for disposal onsite.
Meanwhile, Savannah River Remediation, DOE’s liquid-waste contractor at SRS, reported updates at Tuesday’s meeting on its production goals. The contractor has treated 439,000 gallons of saltstone this fiscal year. The fiscal goal for saltstone is 1.5 million gallons.
In an email, an SRR spokesperson said it may miss some fiscal 2016 production goals due to a leak in the 3H evaporator, a facility that reduces the amount of waste stored in the tanks so more waste can be placed there. The spokesperson said SRR is currently evaluating the issue with DOE.
In addition to salt waste news, the contractor updated the CAB on the DWPF waste treatment. SRR reported that DWPF has produced 84 of the 150 canisters of vitrified waste it is expected to produce for fiscal 2016. The facility has reached the halfway mark of its projected lifetime and recently celebrated 20 years of use and 4,000 canisters of waste.
