A submarine escape module for a nuclear battleship?

Could a nuclear submarine serve as the detachable power, command, and escape module of a battleship?

Conceptually it could, but the combined vessel would be extraordinarily expensive rather than a practical historical design.

A viewer proposes putting the nuclear plant and command functions inside a submarine carried as part of a larger surface warship. In normal service, the surrounding hull would provide the crew with more space and conventional shipboard facilities. If the battleship were lost, the submarine could detach in place of ordinary lifeboats and carry the crew away under its own power. The architecture is conceptually interesting, but building two interdependent vessels in one would be extraordinarily expensive. The exchange remains a speculative exercise in modular warship design rather than a description of a historical project.