Report | June 15, 2018

Evaluation of Nuclear Ballistic Missile Submarine (SSBN) Sustainment DODIG-2018-127




Our objective was to determine whether the Navy can sustain the current Ohio-class Nuclear Ballistic Missile Submarines (SSBNs) until the replacement Columbia-class SSBNs are fielded.


The United States maintains a nuclear triad consisting of manned bombers, land-based intercontinental ballistic missiles, and ballistic missile submarines capable of delivering nuclear weapons. Our review focused on Ohio-class SSBN sustainment.

The Navy decided in 1998 to extend the original 30-year service life of the Ohio-class to 42 years. The first Ohio-class SSBN is scheduled to be retired in 2027; the remaining 13 are scheduled to be retired one per year until 2040.

According to the Navy submarine program office, the first Columbia-class SSBN is expected to enter service in 2031. An additional 11 Columbia-class SSBNs are scheduled to be delivered approximately one per year until the last two join the fleet by 2042.

Each Ohio-class SSBN undergoes three types of maintenance cycles during its service life:

  • Incremental Refit This 35-day maintenance period consists of scheduled repairs, maintenance, and inspections, as well as unscheduled repairs and minor modernization tasks such as sonar, torpedo fire control, and navigation systems.
  • Extended Refit Period. This 7- to 8-month maintenance period replaces and refurbishes the major components of the hull and internal systems.
  • Engineered Refueling Overhaul (ERO). This 27-month overhaul occurs around the 20 –year point for the Ohio-class SSBN and includes extensive inspections, structural repairs, and a nuclear reactor refueling to extend the submarines service life.


The Navy has taken action to sustain the Ohio-class SSBNs at the minimum USSTRATCOM requirements until the replacement Columbia-class SSBNs are fielded.

In order to maintain USSTRATCOM requirements, the Secretary of the Navy designated sustainment of the Ohio-class SSBNs as the Navy's highest priority. Accordingly, the Navy has taken several steps to improve sustainment, which include the following.

  • The Navy has placed SSBNs ahead of aircraft carriers in maintenance priority.

o   This shift has reduced the time required for SSBN EROs. For example, the USS Maine completed the first of two ERO phases with a 43-percent reduction in cycle-time in comparison to the last SSBN that completed an ERO.


  • Shipyards have direct hiring authority to address maintenance manpower shortages.

o   The workforce size at shipyards now matches the workload. For example, in the past 4 years, Puget Sound Naval Shipyard alone hired more than 6,700 employees.


  • The Navy has developed programs to accelerate and improve training of shipyards’ new hires.

o   Shipyards use apprenticeships to develop an experienced workforce. In a recent pilot program, the Navy reduced the journeyman training time to repair a particular valve from 24 months to 10 weeks using a task based learning method.


  • The Navy has improved SSBN maintenance procedures and schedules.

o   Replicas allow personnel to practice difficult tasks prior to performing the task aboard an SSBN.

o   Personnel deploy as needed to conduct inspections and prepare for Incremental Refit maintenance while the submarine is returning to port.

o   Personnel reduced overdue Preventive Maintenance Requirements due to unavailable parts from 37 to 12 instances over a one-year period.