Most of the labs' 18,000 employees are at risk of being furloughed.
New Mexico's two national laboratories are preparing to freeze their nonessential activities in less than two weeks in the event the federal government shutdown is still in place.
The U.S. National Nuclear Security Administration ordered the Los Alamos National Laboratory and the Sandia National Laboratories to be ready to shut down by Oct. 21. A majority of the laboratories' 18,000 employees are at risk of being furloughed, the Albuquerque Journal News reported on Wednesday.
"If a shutdown is needed, programmatic work will not be conducted," Sandia President Paul Hommert said to laboratory employees in a Tuesday memo seen by news organizations. "Those functions that the NNSA directs us to continue will be extremely limited."
The Los Alamos facility issued a statement saying it "has now reached the point where we need to begin standing down certain operations where there is no longer funding available to maintain full operations." It adds: "Protecting special nuclear material, national security information, workers, the public and the environment remains an essential function."
Approximately 300 LANL contractors, some of whom process radioactive waste for shipping, have already been furloughed, according to an anonymous laboratory official.
Should Los Alamos go into shutdown mode after Oct. 21, only 600 of the site's roughly 10,000 employees would still come into work in order to guard atomic substances and perform other essential functions, the official said.
It is not yet known whether the country's third national nuclear laboratory -- Lawrence Livermore Nuclear Laboratory in California -- has been given any orders from NNSA officials to prepare to shut down. A decision on whether to furlough LLNL workers could come as early as Wednesday, according to KGO-TV in San Francisco.
The National Nuclear Security Administration is the semiautonomous Energy Department with oversight of the nation's nuclear weapons complex.
The Y-12 National Security Complex in Tennessee was ordered in recent days to begin an "orderly shutdown." Union officials have reportedly been informed that Oct. 17 will be the final day of work for the majority of Y-12 personnel until the shutdown is lifted, Oakridger.com reported on Wednesday.
Some Republicans in Congress are refusing to support a resolution funding the federal government unless President Obama and his fellow Democrats agree to defund or scale back the Affordable Care Act -- something they have said they will not consider.
The federal shutdown has been in place since Oct. 1.