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Updated December 13, 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
It is not practical to substitute LEU into existing
availability and service life of the Columbia-class design.
naval fuel systems or to design a VIRGINIA Class
Submarine (VCS) replacement [i.e., the SSN(X)]
These requirements will likely result in an SSN(X) design
around an unproven advanced LEU fuel concept.
that is larger than the original Virginia-class design, which
Developing a newly designed submarine capable of
has a submerged displacement of about 7,800 tons, and
later acceptance of an LEU reactor core would also
possibly larger than the original SSN-21 design, which has
involve insertion of substantial margin (e.g.,
a submerged displacement of 9,138 tons. Due to
increased hull size) that would be difficult to
technological changes over the years for improved quieting
estimate accurately at present and costly to
and other purposes, the designs of U.S. Navy submarines
implement. If future United States policy requires a
with similar payloads have generally been growing in
shift to LEU, at least 15 years of advanced fuel
displacement from one generation to the next.
development and significant investment would be
Potential Procurement Cost
required. This development timeline makes it
A November 2022 Congressional Budget Office (CBO)
impractical to design a lead ship VCS replacement
with an LEU reactor while meeting the Navy’s
report on the Navy’s FY2023 30-year shipbuilding plan
states that in constant FY2022 dollars, the SSN(X)’s
schedule.
average unit procurement cost is estimated at $5.6 billion
FY2023 Funding Request and
by the Navy and $6.2 billion to $7.2 billion by CBO.
CBO’s estimate is
Congressional Action
about 11% to 29% higher than the
Navy’s estimate. The Navy and CBO estimates are about
The Navy’s proposed FY2023 budget requests $237.0
55% (Navy) and 72% to 100% (CBO) higher than the
million in research and development funding for the
current $3.6 billion unit procurement cost of a VPM-
SSN(X) program, including $143.9 million in Project 2368
equipped Virginia-class SSN. The CBO report states that
(SSN[X] Class Submarine Development) within Program
CBO’s estimate assumes that the SSN(X) design would
Element (PE) 0604850N (SSN[X]), which is line 154 in the
have a submerged displacement about 11% greater than that
Navy’s FY2023 research and development account, and
of the SSN-21 design.
$93.1 million in Project 2370 (Next Generation Fast Attack
Nuclear Propulsion Development) within PE 0603570N
Issues for Congress
(Advanced Nuclear Power Systems), which is line 48.
Issues for Congress include the following:
The joint explanatory statement for the FY2023 National
whether the Navy has accurately identified the
Defense Authorization Act (NDAA) (H.R. 7776)
SSN(X)’s required capabilities and accurately analyzed
recommends approving the SSN(X) program’s funding
the impact that various required capabilities can have on
requests in lines 154 and 48 (PDF pages 523 and 517 of
the SSN(X)’s cost;
748). The joint explanatory statement notes that H.R. 7776
the potential impact of the SSN(X) program on funding
does not include either Section 1624 of the House version
that will be available for other Navy program priorities,
of the FY2023 NDAA (H.R. 7900) or Section 1521 of the
particularly if CBO’s estimate of the SSN(X)’s
Senate version of the FY2023 NDAA (S. 4543), both of
procurement cost is more accurate than the Navy’s
which addressed (in different ways) funding for research
estimate;
and development of an advanced naval nuclear fuel system
based on LEU (PDF page 376 of 748).
whether it would be technically feasible for the SSN(X)
to be powered by a reactor plant using low-enriched
The House Appropriations Committee’s report (H.Rept.
uranium (LEU), rather than the highly enriched uranium
117-388 of June 24, 2022, pages 198 and 202) on the
(HEU) used on other Navy nuclear-powered ships, and
FY2023 DOD Appropriations Act (H.R. 8236) recommends
if so, what impact that would have on nuclear arms
approving the SSN(X) program’s funding requests in lines
control and nonproliferation efforts and SSN(X) costs
154 and 48. The Senate Appropriations Committee’s
and capabilities; and
explanatory statement for the FY2023 DOD Appropriations
Act (S. 4663), released on July 28, 2022, recommended
whether each SSN(X) should be built jointly by GD/EB
approving the SSN(X) program’s funding request within
and HII/NNS (the approach used for building Virginia-
line 48 and reducing the SSN(X) program’s funding request
class SSNs and, in modified form, for building
in line 154 by $50.715 million, including recommended
Columbia-class SSBNs), or whether individual SSN(X)s
reductions for “Unjustified studies growth” ($34.715
should instead be completely built within a given
million), “Unjustified studies growth” ($6.0 million), and
shipyard (the separate-yard approach used for building
“Unjustified support growth” ($10.0 million) (page 188).
earlier Navy SSNs and SSBNs).
Regarding the third issue above, a January 2020
Ronald O'Rourke, Specialist in Naval Affairs
Department of Energy (DOE) National Nuclear Security
Administration (NNSA) report to Congress on the potential
IF11826
for using LEU for the SSN(X) that was provided by the
Navy to CRS in unclassified form stated
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Navy Next-Generation Attack Submarine (SSN[X]) Program: Background and Issues for Congress
Disclaimer
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