The National Nuclear Security Administration (NNSA) was tracking 13 new cases of COVID-19 across the civilian nuclear weapons enterprise last week ahead of the Independence Day holiday.

The weekly count of active cases rose to 46 from 33 as of Thursday, a spokesperson for the semiautonomous Department of Energy nuclear weapons agency said. That makes for a total of 109 confirmed positive COVID-19 cases, none fatal, among NNSA employees since the first confirmed U.S. case in January.

Citing privacy and operational security, the NNSA does not specify the locations of COVID-19 cases.

The agency has not publicly quantified the disease’s enterprise-wide effect on productivity, including the number of workers quarantining at home after displaying symptoms and the number of workers quarantining because of exposure to possibly symptomatic colleagues. Quarantine numbers are typically higher than confirmed cases.

As with the rest of the country, NNSA facilities have for weeks been ramping back up toward something like normal operations, even amid continuing increases in the number of confirmed cases of the respiratory disease around the nation.

Energy Department headquarters buildings in the Washington, D.C., region, where about 1,000 NNSA employees work, entered Phase 2 of its reopening plan last week, meaning personnel who are especially at risk to the disease may elect to return to their offices. Phase 1, in which essential employees returned to offices to do work that cannot easily be done from home, began June 8. Of the 7,000 or so DoE employees in the D.C. region, a few hundred were expected back in Phase 1, and around 1,400 were due to return in Phase 2. The process ends with Phase 3, in which offices return to something like normal operations.

With the rate of new cases rising nationwide, several states with NNSA nuclear-weapon operations have reported increases in confirmed infections during the early summer months, according to data from The Washington Post and other sources. These include: California, home of the Lawrence Livermore National Laboratory; Texas, host state for the Pantex weapons assembly and disassembly plant; Nevada, with the Nevada National Security Site; and South Carolina, with the Savannah River Site, where the NNSA harvests tritium for nuclear weapons and is working toward production of plutonium nuclear-warhead cores by 2030.