Editor's note: This version corrections the Block designation of the three submarines.

The Navy's three newest submarines are undergoing inspection after it was discovered that steam pipes associated with the nuclear reactor plant had unauthorized and undocumented weld repairs that require additional testing and repair.

The USS Minnesota (SSN 783) and the USS North Dakota (SSN 784), both homeported in Groton, and the USS John Warner (SSN 785), which was commissioned one week ago in Norfolk, Va., are involved. The North Dakota and the John Warner are Block III Virginia-class attack submarines. The Minnesota is the last boat of Block II.

According to an official statement from Naval Sea Systems Command circulated to news media, "As part of an ongoing investigation into a quality control issue with a supplier, General Dynamics Electric Boat (GDEB) determined that three steam pipe elbows supplied by the vendor in question required additional testing and repair due to unauthorized and undocumented weld repairs having been performed on these elbows."

EB shares Navy contracts to build Virginia-class submarines with Huntington Ingalls Industries in Newport News, Va. The Minnesota and North Dakota are currently in Groton and the John Warner is in Virginia.

Colleen E. O'Rourke, a spokeswoman for NAVSEA, said by email Friday that the issue was identified as part of a Department of Justice Civil Investigative Demand (CID) into a quality control issue with the supplier. 

A CID is a subpoena for documents or, at times, statements. Sometimes a CID is triggered by a tip from a whistleblower, but O'Rourke, citing the ongoing investigation, said she could not comment on what prompted it.

"Anytime you're talking about piping that's part of nuclear propulsion, obviously safety, in my mind, is the biggest priority," U.S. Rep Joe Courtney, D-2nd, said by phone Friday. He noted, however, that "at some point it affects capability as well."

According to DefenseNews, an industry publication that first broke the story last week, the issue revolves around "problems found with elbows in 10-inch pipes that funnel steam from the reactor plant to the propulsion turbines."

Courtney praised the Navy for what he called its "swift response" in addressing the issue, and said that safety is the "cornerstone" of the nuclear Navy.

"There is no immediate safety issue as any impact to the subject components would be the result of long-term use. There is little impact to mission capacity as all affected submarines are in port undergoing inspection and were not scheduled to deploy or are currently under construction," O'Rourke said.

The John Warner's operations are restricted until the investigation is complete, she said.

The Minnesota is currently in Electric Boat's South Yard undergoing its Post-Shakedown Availability, which, O'Rourke said, "has been extended to investigate and adjudicate the issue."

Following delivery to the Navy and before its maiden deployment, a new submarine undergoes a PSA — essentially a last-minute check to correct deficiencies found during the shakedown cruise and an opportunity to address other needed improvements.

The North Dakota is entering a planned maintenance period, according to O'Rourke.

Tim Boulay, director of communications at EB, said the submarine is expected to come to the company's Groton facility later this month for an eight-month-long PSA. He said the PSA was scheduled before the steam pipe issues were revealed.

It's not the first time North Dakota has faced supplier issues. The submarine's commissioning, which took place in October 2014, was delayed because of issues related to vendor components and additional design and certification work required on the submarine's redesigned bow. 

The Navy has completed its technical evaluation and assessment related to those issues, O'Rourke said, but cited the ongoing overall investigation in declining to provide additional information, including the name of the vendor associated with the bow issue that delayed the commissioning last year.

"The vendor will not conduct complex and critical assembly work on future contracts," O'Rourke said. Currently, Huntington Ingalls "is conducting onsite quality and engineering oversight of components the vendor is producing on the existing contract," she said.

Public officials have praised EB for delivering North Dakota to the Navy on time and under budget. When asked whether the issues with the bow and the piping would affect that, O'Rourke said, "North Dakota was delivered to the Navy within budget."

In April 2014, the Navy awarded the biggest shipbuilding contract in its history to EB for 10 Block IV Virginia-class submarines. It is a fixed-price incentive multi-year contract.

"The fixed price contract system in general is intended to shift more of the liability to the builder and supplier, which I think is totally appropriate," Courtney said. While it is too early to judge "who pays, which is always question of the day," he said, "if it turns out that a part came in from a vendor that was cutting corners then clearly taxpayers shouldn't have to feel that burden."

The issues that delayed North Dakota's commissioning are unrelated to the current ones.

"There are no chronic problems that exist" with the North Dakota, O'Rourke said. "The vendor issues are unrelated in any way to the redesigned portions of North Dakota and other Block III submarines."

She noted that submarines "are extremely complex platforms" that feature components and parts from more than 4,000 suppliers and vendors in nearly every state.

North Dakota recently came back from a groundbreaking mission for the Navy during which it successfully launched and recovered an underwater drone.

j.bergman@theday.com

Twitter: @JuliaSBergman

Origin of the Civil Investigative Demand

A Civil Investigative Demand (CID) permits the Department of Justice in the course of a False Claims Act investigation to seek documents and answers to interrogatories, as well as conduct examination of witnesses under oath. A CID can be issued to a target of an investigation and also to third-party witnesses. The CID is issued out of the Department of Justice in Washington, D.C. or out of a U.S. Attorney's Office upon the request of the DOJ attorneys conducting the investigation. CIDs are not issued at the request of agencies.