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Updated December 21, 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
for using LEU for the SSN(X) that was provided by the
availability and service life of the Columbia-class design.
Navy to CRS in unclassified form stated
It is not practical to substitute LEU into existing
These requirements will likely result in an SSN(X) design
that is larger than the original Virginia-class design, which
naval fuel systems or to design a VIRGINIA Class
has a submerged displacement of about 7,800 tons, and
Submarine (VCS) replacement [i.e., the SSN(X)]
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
A November 2022 Congressional Budget Office (CBO)
development and significant investment would be
report on the Navy’s FY2023 30-year shipbuilding plan
required. This development timeline makes it
states that in constant FY2022 dollars, the SSN(X)’s
impractical to design a lead ship VCS replacement
average unit procurement cost is estimated at $5.6 billion
with an LEU reactor while meeting the Navy’s
by the Navy and $6.2 billion to $7.2 billion by CBO.
schedule.
CBO’s estimate is about 11% to 29% higher than the
Navy’s estimate. The Navy and CBO estimates are about
FY2023 Funding Request and
55% (Navy) and 72% to 100% (CBO) higher than the
Congressional Action
current $3.6 billion unit procurement cost of a VPM-
The Navy’s proposed FY2023 budget requests $237.0
equipped Virginia-class SSN. The CBO report states that
million in research and development funding for the
CBO’s estimate assumes that the SSN(X) design would
SSN(X) program, including $143.9 million in Project 2368
have a submerged displacement about 11% greater than that
(SSN[X] Class Submarine Development) within Program
of the SSN-21 design.
Element (PE) 0604850N (SSN[X]), which is line 154 in the
Issues for Congress
Navy’s FY2023 research and development account, and
$93.1 million in Project 2370 (Next Generation Fast Attack
Issues for Congress include the following:
Nuclear Propulsion Development) within PE 0603570N
whether the Navy has accurately identified the
(Advanced Nuclear Power Systems), which is line 48.
SSN(X)’s required capabilities and accurately analyzed
the impact that various required capabilities can have on
The joint explanatory statement for the FY2023 National
the SSN(X)’s cost;
Defense Authorization Act (NDAA) (H.R. 7776)
recommends approving the SSN(X) program’s funding
the potential impact of the SSN(X) program on funding
requests in lines 154 and 48 (PDF pages 523 and 517 of
that will be available for other Navy program priorities,
748). The joint explanatory statement notes that H.R. 7776
particularly if CBO’s estimate of the SSN(X)’s
does not include either Section 1624 of the House version
procurement cost is more accurate than the Navy’s
of the FY2023 NDAA (H.R. 7900) or Section 1521 of the
estimate;
Senate version of the FY2023 NDAA (S. 4543), both of
whether it would be technically feasible for the SSN(X)
which addressed (in different ways) funding for research
to be powered by a reactor plant using low-enriched
and development of an advanced naval nuclear fuel system
uranium (LEU), rather than the highly enriched uranium
based on LEU (PDF page 376 of 748).
(HEU) used on other Navy nuclear-powered ships, and
if so, what impact that would have on nuclear arms
The explanatory statement for the FY2023 DOD
control and nonproliferation efforts and SSN(X) costs
Appropriations Act (Division C of H.R. 2617) as released
and capabilities; and
by the Senate Appropriations Committee on December 19,
2022, approved the SSN(X) program’s funding request in
whether each SSN(X) should be built jointly by GD/EB
line 48 (PDF page 214 of 329) and reduced the SSN(X)
and HII/NNS (the approach used for building Virginia-
program’s funding request in line 154 by $10.0 million for
class SSNs and, in modified form, for building
“Unjustified management growth” ($4.0 million) and
Columbia-class SSBNs), or whether individual SSN(X)s
“Unjustified support growth” ($6.0 million) (PDF page 219
should instead be completely built within a given
of 329).
shipyard (the separate-yard approach used for building
earlier Navy SSNs and SSBNs).
Ronald O'Rourke, Specialist in Naval Affairs
Regarding the third issue above, a January 2020
IF11826
Department of Energy (DOE) National Nuclear Security
Administration (NNSA) report to Congress on the potential
https://crsreports.congress.gov
Navy Next-Generation Attack Submarine (SSN[X]) Program: Background and Issues for Congress
Disclaimer
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