The Y-12 National Security Complex in Oak Ridge has completed a major milestone in efforts to refurbish components for a strategic nuclear weapons system that is vital to the US nuclear deterrent. A new bomb called the B61-12 was certified at the plant on Dec. 6, 2018. The nuclear device can be carried on several types of military aircraft and has an extended life of 20 years. It will be shipped to the Pantex Plant in Texas for final assembly. It is the first of eight such bombs which have a production end-date of March 2020.