The Lawrence Livermore National Laboratory, the Department of Energy nuclear-weapon site closest to a major metropolitan area, is preparing for another month of stay-at-home orders in surrounding Alameda County, Calif., which has a high number of COVID-19 cases and deaths.

Livemore is still performing only essential national security work and still requires most of its roughly 6,300 employees to stay home. 

With Alameda and other San Francisco Bay Area counties extending shelter-in-place orders through May, Livermore is getting more strict about employee behavior amind the continuing pandemic. The lab brought about 800 people back on site in April, after abruptly locking down in late March, and is requiring everyone on-site to wear face masks.

Like its older affiliate laboratory, the Los Alamos National Laboratory in New Mexico, Livermore’s Health Services Department has also formalized a policy for preventing transmission of COVID-19 throughout the nuclear-weapon workforce. Among the new rules, anybody diagnosed with COVID-19 in the last 30 days must report the diagnosis to the Health Services Department, according to a statement the lab released Friday.

At some other nuclear weapon sites, workers are asked, rather than told, to report COVID-19 diagnoses and test results.

National Nuclear Security Administration (NNSA) headquarters in Washington had tracked 65 confirmed cases of COVID-19 among its sites, labs, production facilities, and the Nevada National Security Site, as of Friday. At that time, 33 of those people had recovered, 32 were still ill, and none had died.

Livermore had four active cases of Friday. The lab has not tracked and new confirmed cases among its workforce for about two weeks. Typically, even one confirmed case will set off a chain-reaction of two-week quarantines as site management figures out who the infected had contact with in the period before showing symptoms of the viral respiratory disease.