The Savannah River Site in South Carolina as of Wednesday had confirmed 70 cases of COVID-19 among its workforce, the most known within the facilities of the Department of Energy nuclear complex.

The Energy Department this week recorded the first COVID-19-related death among the site’s 11,000-person workers. Officials said Monday that an employee of operations contractor Savannah River Nuclear Solutions became ill last week and died shortly afterward. It is believed to be the second death experienced at DOE during the pandemic, following the death in April of an agency employee at headquarters in Washington, D.C.

Forty-five workers at Savannah River have recovered from the viral disease and been cleared to return to work as of Tuesday morning, according to the SRS website.

Meanwhile, another employee at the Hanford Site in Washington state tested positive for the coronavirus, according to the DOE website for the facility. The individual was last at the Hanford worksite on July 1. That brings Hanford’s total number of cases during the pandemic to 22, based on an informal count.

Both federal properties, which are overseen by DOE’s Office of Environmental Management, reduced on-site personnel in March to curb the spread of the disease. While they have started bringing personnel back, neither is yet close to normal operations.

A small fraction of Savannah River Site personnel are on-site now, including those supporting missions for DOE’s semiautonomous National Nuclear Security Administration (NNSA).

The tight quarters in which some SRS personnel work, compared to the more spread-out Hanford, could be one reason for the high number at the South Carolina site, an industry source has speculated.

Both Hanford and SRS are in Phase 1 of DOE restart, which involves recalling small groups of people who can best perform certain low-risk work on-site. The Hanford website indicates there is a marginal increase being made this week in the on-site headcount at the Waste Treatment Plant being built by Bechtel. No specific numbers were provided.

As of Friday, there were 24 active COVID cases in the Office of Environmental Management complex, a source said.