link to page 1 
Updated August 30, 2022
Navy Next-Generation Attack Submarine (SSN[X]) Program:
Background and Issues for Congress
Introduction
SSN(X) Program
The Navy wants to begin procuring a new class of nuclear-
powered attack submarine (SSN), called the Next-
Program Designation
Generation Attack Submarine or SSN(X), in the mid-2030s.
In the designation SSN(X), the “X” means that the exact
The SSN(X) would be the successor to the Virginia-class
design of the boat has not yet been determined.
SSN design, which the Navy has been procuring since
FY1998. The Navy’s proposed FY2023 budget requests
Procurement Schedule
$237.0 million in research and development funding for the
The Navy wants to shift from procuring Virginia-class
SSN(X) program.
boats to procuring SSN(X)s in the mid-2030s.
Submarines in the U.S. Navy
Figure 1. Virginia-Class Attack Submarine (SSN)
The U.S. Navy operates nuclear-powered ballistic missile
submarines (SSBNs), nuclear-powered cruise missile and
special operations forces (SOF) submarines (SSGNs), and
nuclear-powered attack submarines (SSNs). The SSNs are
general-purpose submarines that can perform a variety of
peacetime and wartime missions.
Virginia-Class Program
As mentioned above, the Navy has been procuring
Virginia-class SSNs (Figure 1) since FY1998. Since
FY2011, the Navy has been procuring them at a rate of two
boats per year. When procured at a rate of two boats per
year, Virginia-class SSNs equipped with the Virginia
Payload Module (VPM) have a current estimated
Source: Cropped version of photograph accompanying Dan Ward,
procurement cost of about $3.6 billion per boat. (Most
“Opinion: How Budget Pressure Prompted the Success of Virginia-
Virginia-class boats procured in FY2019 and subsequent
Class Submarine Program,” USNI News, November 3, 2014. The
years are to be built with the VPM, an additional mid-body
caption states that it shows USS Minnesota (SSN-783) under
section equipped with four large-diameter, vertical launch
construction in 2012, and credits the photograph to the U.S. Navy.
tubes.) For additional information on Navy submarine
programs, see CRS Report RL32418, Navy Virginia (SSN-
Design of the SSN(X)
774) Class Attack Submarine Procurement: Background
The Navy states that the SSN(X)
and Issues for Congress, by Ronald O'Rourke, and CRS
will be designed to counter the growing threat posed
Report R41129, Navy Columbia (SSBN-826) Class Ballistic
by near peer adversary competition for undersea
Missile Submarine Program: Background and Issues for
supremacy. It will provide greater speed, increased
Congress, by Ronald O'Rourke.
horizontal payload capacity, improved acoustic
Submarine Construction Industrial Base
superiority, and higher operational availability.
U.S. Navy submarines are built by General Dynamics’
SSN(X) will conduct full spectrum undersea
Electric Boat Division (GD/EB) of Groton, CT, and
warfare and be able to coordinate with a larger
Quonset Point, RI, and Huntington Ingalls Industries’
contingent of off-hull vehicles, sensors, and
Newport News Shipbuilding (HII/NNS), of Newport News,
friendly forces. It will retain and improve multi-
VA. These are the only two shipyards in the country
mission... capability and sustained combat presence
capable of building nuclear-powered ships. GD/EB builds
in denied waters.
submarines only, while HII/NNS also builds nuclear-
(Budget-justification book for FY2023 Research,
powered aircraft carriers. The submarine construction
Development, Test, and Evaluation, Navy account,
industrial base also includes hundreds of supplier firms, as
Vol. 3 [Budget Activity 5], p. 1305.)
well as laboratories and research facilities, in numerous
states. Much of the material procured from supplier firms
Navy officials have stated that the Navy wants the SSN(X)
for building submarines comes from sole-source suppliers.
to be an “apex predator.” More specifically, they have
stated that the Navy wants the SSN(X) to incorporate the
speed and payload the Navy’s fast and heavily armed
Seawolf (SSN-21) class SSN design, the acoustic quietness
https://crsreports.congress.gov
Navy Next-Generation Attack Submarine (SSN[X]) Program: Background and Issues for Congress
and sensors of the Virginia-class design, and the operational
later acceptance of an LEU reactor core would also
availability and service life of the Columbia-class design.
involve insertion of substantial margin (e.g.,
increased hull size) that would be difficult to
These requirements will likely result in an SSN(X) design
estimate accurately at present and costly to
that is larger than the original Virginia-class design, which
implement. If future United States policy requires a
has a submerged displacement of about 7,800 tons, and
shift to LEU, at least 15 years of advanced fuel
possibly larger than the original SSN-21 design, which has
development and significant investment would be
a submerged displacement of 9,138 tons. Due to
required. This development timeline makes it
technological changes over the years for improved quieting
impractical to design a lead ship VCS replacement
and other purposes, the designs of U.S. Navy submarines
with an LEU reactor while meeting the Navy’s
with similar payloads have generally been growing in
schedule.
displacement from one generation to the next.
FY2023 Funding Request and
Potential Procurement Cost
Congressional Action
An April 2021 Congressional Budget Office (CBO) report
The Navy’s proposed FY2023 budget requests $237.0
states that in constant FY2021 dollars, the SSN(X)’s
million in research and development funding for the
average unit procurement cost is estimated at $5.8 billion
SSN(X) program, including $143.9 million in Project 2368
by the Navy and $6.2 billion by CBO—figures that are
(SSN[X] Class Submarine Development) within Program
substantially higher than the $3.6 billion unit procurement
Element (PE) 0604850N (SSN[X]), which is line 154 in the
cost of a VPM-equipped Virginia-class SSN. The report
Navy’s FY202
states that CBO’s estimate assumes that the SSN(X) design
3 research and development account, and
$93.1 million in Project 2370 (Next Generation Fast Attack
would be similar in size and capabilities to the SSN-21
Nuclear Propulsion Development) within PE 0603570N
design.
(Advanced Nuclear Power Systems), which is line 48.
Issues for Congress
The House Armed Services Committee’s report (H.Rept.
Issues for Congress include the following:
117-397 of July 1, 2022, pages 473 and 478) on the
whether the Navy has accurately identified the
FY2023 National Defense Authorization Act (NDAA)
SSN(X)’s required capabilities and accurately analyzed
(H.R. 7900), the Senate Armed Services Committee’s
the impact that various required capabilities can have on
report (S.Rept. 117-130 of July 18, 2022, pages 444 and
the SSN(X)’s cost;
448) on the FY2023 NDAA (S. 4543), and the House
Appropriations Committee’s report (H.Rept. 117-388 of
the potential impact of the SSN(X) program on funding
June 24, 2022, pages 198 and 202) on the FY2023 DOD
that will be available for other Navy program priorities;
Appropriations Act (H.R. 8236) all recommend approving
whether it would be technically feasible for the SSN(X)
the SSN(X) program’s funding requests in lines 154 and 48.
to be powered by a reactor plant using low-enriched
uranium (LEU), rather than the highly enriched uranium
The Senate Appropriations Committee’s explanatory
(HEU) used on other Navy nuclear-powered ships, and
statement for the FY2023 DOD Appropriations Act (S.
if so, what impact that would have on nuclear arms
4663), released on July 28, 2022, recommended approving
control and nonproliferation efforts and SSN(X) costs
the SSN(X) program’s funding request within line 48 and
and capabilities; and
reducing the SSN(X) program’s funding request in line 154
by $50.715 million, including recommended reductions for
whether each SSN(X) should be built jointly by GD/EB
“Unjustified studies growth” ($34.715 million),
and HII/NNS (the approach used for building Virginia-
“Unjustified studies growth” ($6.0 million), and
class SSNs and, in modified form, for building
“Unjustified support growth” ($10.0 million). (Page 188)
Columbia-class SSBNs), or whether individual SSN(X)s
should instead be completely built within a given
Section 1521 of S. 4543, as summarized by S.Rept. 117-
shipyard (the separate-yard approach used for building
130 (page 278), would limit the use of FY2023 funds for
earlier Navy SSNs and SSBNs).
conducting research and development of an advanced naval
Regarding the third issue above, a January 2020
nuclear fuel system based on LEU until certain
Department of Energy (DOE) National Nuclear Security
determinations are provided to the congressional defense
Administration (NNSA) report to Congress on the potential
committees, and require the Administrator for Nuclear
for using LEU for the SSN(X) that was provided by the
Security to submit a report on activities conducted for the
Navy to CRS in unclassified form stated
development of nonproliferation fuels using amounts made
available for FY2022.
It is not practical to substitute LEU into existing
naval fuel systems or to design a VIRGINIA Class
Ronald O'Rourke, Specialist in Naval Affairs
Submarine (VCS) replacement [i.e., the SSN(X)]
around an unproven advanced LEU fuel concept.
IF11826
Developing a newly designed submarine capable of
https://crsreports.congress.gov
Navy Next-Generation Attack Submarine (SSN[X]) Program: Background and Issues for Congress
Disclaimer
This document was prepared by the Congressional Research Service (CRS). CRS serves as nonpartisan shared staff to
congressional committees and Members of Congress. It operates solely at the behest of and under the direction of Congress.
Information in a CRS Report should not be relied upon for purposes other than public understanding of information that has
been provided by CRS to Members of Congress in connection with CRS’s institutional role. CRS Reports, as a work of the
United States Government, are not subject to copyright protection in the United States. Any CRS Report may be
reproduced and distributed in its entirety without permission from CRS. However, as a CRS Report may include
copyrighted images or material from a third party, you may need to obtain the permission of the copyright holder if you
wish to copy or otherwise use copyrighted material.
https://crsreports.congress.gov | IF11826 · VERSION 18 · UPDATED