BAE Systems in Barrow will test two alarms this week.
The firm said the tests will be carried out on Friday, November 14.
The first, at 10.30am, is an internal alarm that may also be heard close to the site.
The second, at 11am, is the Public Nuclear Safety Alert alarm, which will be clearly audible across Barrow and Walney.
The firm said they were scheduled tests only and local authorities and emergency services have already been informed.
There is no cause for anyone outside the site to take any action, it added.
