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Updated July 26, 2022
Navy Next-Generation Attack Submarine (SSN[X]) Program:
Background and Issues for Congress
Introduction
Procurement Schedule
The Navy wants to begin procuring a new class of nuclear-
The Navy wants to shift from procuring Virginia-class
powered attack submarine (SSN), called the Next-
boats to procuring SSN(X)s in the mid-2030s.
Generation Attack Submarine or SSN(X), in the mid-2030s.
The SSN(X) would be the successor to the Virginia-class
Figure 1. Virginia-Class Attack Submarine (SSN)
SSN design, which the Navy has been procuring since
FY1998. The Navy’s proposed FY2023 budget requests
$237.0 million in research and development funding for the
SSN(X) program.
Submarines in the U.S. Navy
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
Source: Cropped version of photograph accompanying Dan Ward,
As mentioned above, the Navy has been procuring
“Opinion: How Budget Pressure Prompted the Success of Virginia-
Virginia-class SSNs (Figure 1) since FY1998. Since
Class Submarine Program,” USNI News, November 3, 2014. The
FY2011, the Navy has been procuring them at a rate of two
caption states that it shows USS Minnesota (SSN-783) under
boats per year. When procured at a rate of two boats per
construction in 2012, and credits the photograph to the U.S. Navy.
year, VPM-equipped Virginia-class SSNs have a current
estimated procurement cost of about $3.6 billion per boat.
Design of the SSN(X)
For additional information on Navy submarine programs,
The Navy states that the SSN(X)
see CRS Report RL32418, Navy Virginia (SSN-774) Class
will be designed to counter the growing threat posed
Attack Submarine Procurement: Background and Issues for
by near peer adversary competition for undersea
Congress, by Ronald O'Rourke, and CRS Report R41129,
supremacy. It will provide greater speed, increased
Navy Columbia (SSBN-826) Class Ballistic Missile
horizontal payload capacity, improved acoustic
Submarine Program: Background and Issues for Congress,
superiority, and higher operational availability.
by Ronald O'Rourke.
SSN(X) will conduct full spectrum undersea
Submarine Construction Industrial Base
warfare and be able to coordinate with a larger
U.S. Navy submarines are built by General Dynamics’
contingent of off-hull vehicles, sensors, and
Electric Boat Division (GD/EB) of Groton, CT, and
friendly forces. It will retain and improve multi-
Quonset Point, RI, and Huntington Ingalls Industries’
mission... capability and sustained combat presence
Newport News Shipbuilding (HII/NNS), of Newport News,
in denied waters.
VA. These are the only two shipyards in the country
(Budget-justification book for FY2023 Research,
capable of building nuclear-powered ships. GD/EB builds
Development, Test, and Evaluation, Navy account,
submarines only, while HII/NNS also builds nuclear-
Vol. 3 [Budget Activity 5], p. 1305.)
powered aircraft carriers. The submarine construction
industrial base also includes hundreds of supplier firms, as
Navy officials have stated that the Navy wants the SSN(X)
well as laboratories and research facilities, in numerous
to be an “apex predator.” More specifically, they have
states. Much of the material procured from supplier firms
stated that the Navy wants the SSN(X) to incorporate the
for building submarines comes from sole-source suppliers.
speed and payload the Navy’s fast and heavily armed
Seawolf (SSN-21) class SSN design, the acoustic quietness
SSN(X) Program
and sensors of the Virginia-class design, and the operational
availability and service life of the Columbia-class design.
Program Designation
In the designation SSN(X), the “X” means that the exact
These requirements will likely result in an SSN(X) design
design of the boat has not yet been determined.
that is larger than the original Virginia-class design, which
has a submerged displacement of about 7,800 tons, and
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Navy Next-Generation Attack Submarine (SSN[X]) Program: Background and Issues for Congress
possibly larger than the original SSN-21 design, which has
around an unproven advanced LEU fuel concept.
a submerged displacement of 9,138 tons. Due to
Developing a newly designed submarine capable of
technological changes over the years for improved quieting
later acceptance of an LEU reactor core would also
and other purposes, the designs of U.S. Navy submarines
involve insertion of substantial margin (e.g.,
with similar payloads have generally been growing in
increased hull size) that would be difficult to
displacement from one generation to the next.
estimate accurately at present and costly to
implement. If future United States policy requires a
Potential Procurement Cost
shift to LEU, at least 15 years of advanced fuel
An April 2021 Congressional Budget Office (CBO) report
development and significant investment would be
states that in constant FY2021 dollars, the SSN(X)’s
required. This development timeline makes it
average unit procurement cost is estimated at $5.8 billion
impractical to design a lead ship VCS replacement
by the Navy and $6.2 billion by CBO—figures that are
with an LEU reactor while meeting the Navy’s
substantially higher than the $3.6 billion unit procurement
schedule.
cost of a VPM-equipped Virginia-class SSN. The report
states that CBO’s estimate assumes that the SSN(X) design
FY2023 Funding Request and
would be similar in size and capabilities to the SSN-21
Congressional Action
design.
The Navy’s proposed FY2023 budget requests $237.0
Issues for Congress
million in research and development funding for the
SSN(X) program, including $143.9 million in Project 2368
Issues for Congress include the following:
(SSN[X] Class Submarine Development) within Program
whether the Navy has accurately identified the
Element (PE) 0604850N (SSN[X]), which is line 154 in the
SSN(X)’s required capabilities and accurately analyzed
Navy’s FY2023 research and development account, and
the impact that various required capabilities can have on
$93.1 million in Project 2370 (Next Generation Fast Attack
the SSN(X)’s cost;
Nuclear Propulsion Development) within PE 0603570N
(Advanced Nuclear Power Systems), which is line 48.
the potential impact of the SSN(X) program on funding
that will be available for other Navy program priorities;
The House Armed Services Committee’s report (H.Rept.
whether it would be technically feasible for the SSN(X)
117-397 of July 1, 2022, pages 473 and 478) on the
to be powered by a reactor plant using low-enriched
FY2023 National Defense Authorization Act (NDAA)
uranium (LEU), rather than the highly enriched uranium
(H.R. 7900), the Senate Armed Services Committee’s
(HEU) used on other Navy nuclear-powered ships, and
report (S.Rept. 117-130 of July 18, 2022, pages 444 and
if so, what impact that would have on nuclear arms
448) on the FY2023 NDAA (S. 4543), and the House
control and nonproliferation efforts and SSN(X) costs
Appropriations Committee’s report (H.Rept. 117-388 of
and capabilities; and
June 24, 2022, pages 198 and 202) on the FY2023 DOD
Appropriations Act (H.R. 8236) all recommend approving
whether each SSN(X) should be built jointly by GD/EB
the Navy’s FY2023 research and development funding
and HII/NNS (the approach used for building Virginia-
requests for the SSN(X) program.
class SSNs and, in modified form, for building
Columbia-class SSBNs), or whether individual SSN(X)s
Section 1521 of S. 4543, as summarized by S.Rept. 117-
should instead be completely built within a given
130 (page 278), would limit the use of FY2023 funds for
shipyard (the separate-yard approach used for building
conducting research and development of an advanced naval
earlier Navy SSNs and SSBNs).
nuclear fuel system based on LEU until certain
Regarding the third issue above, a January 2020
determinations are provided to the congressional defense
Department of Energy (DOE) National Nuclear Security
committees, and require the Administrator for Nuclear
Administration (NNSA) report to Congress on the potential
Security to submit a report on activities conducted for the
for using LEU for the SSN(X) that was provided by the
development of nonproliferation fuels using amounts made
Navy to CRS in unclassified form stated
available for FY2022.
It is not practical to substitute LEU into existing
Ronald O'Rourke, Specialist in Naval Affairs
naval fuel systems or to design a VIRGINIA Class
Submarine (VCS) replacement [i.e., the SSN(X)]
IF11826
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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
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