Two interconnected facilities at the Department of Energy’s Savannah River Site in South Carolina have stopped receiving nuclear materials due to growing infrastructure problems that could have significant consequences in the event of an earthquake.
A newly released report from the Defense Nuclear Facilities Safety Board noted the suspension of nuclear materials receipts at H Canyon, a nuclear materials separation operation, and HB Line, the facility on top of the canyon that helps feed material through the complex. The decision was made after Savannah River Nuclear Solutions (SRNS), the site’s management and operations contractor, noted degradation in concrete walls inside the canyon.
SRNS halted shipments on June 28, according to Glenn Sklar, DNFSB general manager. Following the suspension, the contractor completed an evaluation of the safety of the situation (ESS) document to address the potential release of radiological material at the facility following an earthquake “The ESS permits limited nuclear processing activities in H-Canyon,” Sklar said via email.
The Savannah River Nuclear Laboratory (SRNL) has been conducting tests on the extent of the degradation following the halt and will continue testing to learn more about the viability of the concrete. conducting tests following the halt and will continue testing to learn more about the viability of the concrete. Those analyses should wrap up by the end of the year, allowing material receipts to resume, said SRS spokesperson Monte Volk. “In the meantime, processing of existing inventory in H Canyon continues, so there is not expected to be any overall impact on H Canyon missions,” Volk said, adding that there is no projected cost for the current suspension.
Sklar said the laboratory might conclude that the concrete is degraded to the point it that affects the capacity of the H Canyon air exhaust tunnel. If that is the case, the tunnel might not provide a safe pathway for transporting radiologically contaminated canyon air to the sand filter after a design basis earthquake. “Radiological material released in H-Canyon during an earthquake could then be released unfiltered through cracks and expansion joints in the building’s structure due to a loss of negative pressure in the facility,” he said.
Volk said calculations involving concrete degradation identified before this year determined the exhaust duct could tolerate even the most powerful earthquake likely to occur in the area around the Savannah River Site – which happen roughly once in 2,500 years. “The initial analysis of the new potential degradation is that the exhaust duct would remain operable in all cases except the maximum earthquake,” he stated. “A new structural analysis technique is expected to conclude that the duct would continue to be operable following a maximum earthquake, even with the potential degradation identified in the 2017 inspection.”
H Canyon serves multiple functions, including conversion of domestic and foreign materials, such as highly enriched uranium (HEU), into less harmful forms. Some of these materials are stored on site after being processed and others are shipped elsewhere for disposal or reuse — for example, sending the material to the Tennessee Valley Authority to be used as a nuclear power source. The site’s inability to accept materials at H Canyon could impede progress with the DOE’s foreign and domestic missions.
In a separate June report, Savannah River Nuclear Solutions highlighted the future of the site’s nuclear materials program through fiscal 2031. The plan “documents the activities required to disposition the legacy and/or surplus enriched uranium and plutonium and other nuclear materials already stored or anticipated to be received.” According to the plan, for example, SRS is expected to receive nuclear materials through fiscal 2031 that will be processed through H Canyon. The plan does not include any cost projections for that work.
The document also does not mention the concrete degradation at H Canyon. However, it does cite the decision to cease plutonium receipts at the facility. The SRNS plan says the dissolver – which breaks down the material – recently being used at H Canyon will be replaced and that the facility will resume processing with two dissolvers in fiscal 2018.
“Due to equipment and operational issues, the facility has not yielded the planned rates of production therefore the planned future production is under review,” SRNS wrote in the report.
The plutonium that has already been sent to HB Line will undergo the usual process: it will be processed and sent to the site’s K Area for temporary storage.
Last September, SRS began downblending 6 metric tons of nuclear weapon-usable plutonium at H Canyon. The material will be shipped to the Waste Isolation Pilot Plant (WIPP) near Carlsbad, N.M.
