Naval Sea Systems Command Spokesman Rory O'Connor told Defense News that the Virginia-class attack subs (like the one pictured above) USS Minnesota, North Dakota, and John Warner had faulty elbow welds on the 10-inch pipes that channel steam from the sub's reactor to its propulsion turbines.
"General Dynamics Electric Boat along with Huntington Ingalls Industries-Newport News Shipbuilding are performing additional inspections to bound the issue," O'Connor told Defense News. "The Navy is committed to ensuring the safety of its crews and ships. High quality standards for submarine components are an important part of the overall effort to ensure safety."
An additional source within the Navy told DN that the investigation is more focused on the "long-term wear-and-tear," and that it "is not a safety concern in terms of what's involved right now. Basically it's being prudent in looking into it."
It's unclear how long the operations of the three subs will be restricted.