Here is an overview from Northrop Grumman Corporation's press release about the contract they have just recived to develop the prototype.
Multiple All-Up-Round Canister (MAC) concept ..(is designed) to adapt the missile tubes of Ship Submersible Ballistic Nuclear (SSBN) submarines from launching nuclear ballistic missiles to conventional cruise missiles. The reconfigured submarine will be known as the Ship Submersible Guided Nuclear (SSGN).
The MAC is a subsystem of the AWS that will replace the existing Trident ballistic missile launch tubes and provide for the storage and launch of up to seven Tomahawk missiles from each submarine missile tube. Each SSBN submarine will be able to accommodate as many as 154 precision-guided, conventional land-attack Tomahawk weapons.
It is planned that each of the four SSGNs will be modified to allow two Advanced SEAL Delivery System vehicles (mini subs) to dock, enabling Special Operations Forces deployment to wars worldwide.So less nukes but heaps more conventional firepower oh well.
Thanks to www.irconnect.com