COLUMBIA — A federal audit has found that more than 500 workers at a former nuclear weapons plant in South Carolina were overpaid by nearly $8 million in stimulus money.

The inspector general for the U.S. Department of Energy says in a report released this month that the company that manages the Savannah River Site near Aiken gave employees 60 days of extra severance pay when their jobs were over.

Savannah River Nuclear Solutions manages the site, which once produced plutonium and tritium for atomic bombs. Work there is now focused mostly on research and environmental cleanup.

The site received $1.6 billion in stimulus cash to create and save about 3,000 jobs. Energy Department spokesman Jim Giusti says the company will not have to repay the money.