Honeywell officials say a radioactive leak at the Metropolis facility last week may not have been handled properly.
In a report to the Nuclear Regulatory Commission, the company determined emergency response protocol should have brought the facility to what’s called an alert status.
This could have led to a faster response.
The United Steelworkers Union says the facility had no active sensors where the leak occurred.
Company officials say testing showed that no Uranium Hexafluoride left the property and surrounding homes faced no danger.
Malfunctioning equipment has been blamed for the leak.