Multiple-award contract indefinite-delivery indefinite-quantity (MAC IDIQ) for discrete production, non-discrete production and other production work to support the Navy?s four public shipyards in accomplishing repair, maintenance, and modernization of nuclear-powered attack submarines. The specific requirements will be defined at the delivery order level, and will encompass efforts such as preservation, structural/non-destructive testing, shipboard work, electrical services, component repair, and engineering support. Efforts include performing drydock submarine repair, maintenance and alterations at Norfolk Naval Shipyard (NNSY), Puget Sound Naval Shipyard (PSNS), Pearl Harbor Naval Shipyard (PHNSY), and Portsmouth Naval Shipyard (PNSY), and performing the repair and restoration of select critical components. Offerors are not required to have their own drydock. Work would be performed under delivery orders anticipated to be competed among MAC IDIQ awardees over a five-year base ordering period with three additional option years. The Navy will include rolling admissions provisions enabling the Navy to annually announce an interim competition for the purposes of adding additional contractors to the MAC IDIQ.The Navy has categorized the requirements to be procured under the MAC IDIQ into two tiers: Critical (Lot 1) and Non-Critical (Lot 2), as defined as follows:Critical (Lot 1) requirements consist of efforts that involve critical systems. Due to the nature of critical systems onboard the submarine and the likelihood that delays in completing work associated with these systems will have a significant impact on the overall CNO availability schedule, the Navy will require contractors to possess capability and capacity to meet technical requirements for critical systems to be eligible for Lot 1 scope. To complete this work, awardees are expected to have the knowledge, skills, and experience necessary to complete multiple concurrent complex CNO availabilities on critical systems. Critical systems include but are not necessarily limited to the following (all systems listed imply areas of the system and equipment requiring work certifications that are not subject to Special Emphasis Program Controls (e.g., submarine safety program (SUBSAFE), fly by wire (FBW), deep submergence systems (DSS)): Vertical Launch System (VLS) Ship control system components Torpedo tubes Bow planes Sonar dome Large Vertical Array Shipboard hydraulics systems Normal fuel oil tank and systems Lube oil systems. The Navy intends to issue Critical (Lot 1) efforts under a full and open competition.Non-Critical (Lot 2) requirements consist of efforts that do not involve critical systems but may include systems and equipment requiring work certifications. Lot 2 scope is expected to require fewer specialized contractor capabilities, both in terms of personnel and equipment. The Navy intends to issue Non-Critical (Lot 2) efforts under a Small Business Set-Aside.