Only a small part, near 400 people, of the employees at the nuclear safety authority (NNSA) will continue the safety work. The necessary work that cannot be interrupted is "protection of property and human safety", states the US Department of Energy in a statement.
The US has 5,177 nuclear warheads, of which 1,770 are deployed.
The shutdown, which on Monday entered its fourth week, affects the US federal activities as Congress has not managed to agree on a budget.
Corrected: In an earlier version of the text, a misleading profession was stated in the headline.