The core manufacturing facility is being constructed in Raynesway, Derby, and is the third leg of a phased-in modernization program for the existing Rolls-Royce plant.
"We are pleased to begin construction of this important new facility which will use the most advanced manufacturing techniques to enhance our world-leading nuclear manufacturing capability," said Jason Smith, Rolls-Royce president of its submarines business and Chief Operating Officer -Nuclear.
"The investment in this facility demonstrates the high level of trust that the (British) Ministry of Defense has in both our technology and the expertise of our highly skilled workforce."
The ground-breaking ceremony was Wednesday and was performed by Vice Adm. Andrew Mathews.
"Rolls-Royce has played a vital role in supporting the Royal Navy's nuclear submarine propulsion program for over 50 years," he said. "This significant investment to regenerate the facility, to build our nuclear reactor cores, will ensure that the site continues to do so for decades to come."