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Updated November 28, 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
Submarine (VCS) replacement [i.e., the SSN(X)]
availability and service life of the Columbia-class design.
around an unproven advanced LEU fuel concept.
Developing a newly designed submarine capable of
These requirements will likely result in an SSN(X) design
later acceptance of an LEU reactor core would also
that is larger than the original Virginia-class design, which
involve insertion of substantial margin (e.g.,
has a submerged displacement of about 7,800 tons, and
increased hull size) that would be difficult to
possibly larger than the original SSN-21 design, which has
estimate accurately at present and costly to
a submerged displacement of 9,138 tons. Due to
implement. If future United States policy requires a
technological changes over the years for improved quieting
shift to LEU, at least 15 years of advanced fuel
and other purposes, the designs of U.S. Navy submarines
development and significant investment would be
with similar payloads have generally been growing in
required. This development timeline makes it
displacement from one generation to the next.
impractical to design a lead ship VCS replacement
Potential Procurement Cost
with an LEU reactor while meeting the Navy’s
A November 2022 Congressional Budget Office (CBO)
schedule.
report on the Navy’s FY2023 30-year shipbuilding plan
FY2023 Funding Request and
states that in constant FY2022 dollars, the SSN(X)’s
Congressional Action
average unit procurement cost is estimated at $5.6 billion
The Navy’s proposed FY202
by the Navy and $6.2 billion to $7.2 billion by CBO.
3 budget requests $237.0
CBO’s estimate is about 11% to 29% higher than the
million in research and development funding for the
Navy’s estimate. The Navy and CBO estimates are about
SSN(X) program, including $143.9 million in Project 2368
55% (Navy) and 72% to 100% (CBO) higher than the
(SSN[X] Class Submarine Development) within Program
current $3.6 billion unit procurement cost of a VPM-
Element (PE) 0604850N (SSN[X]), which is line 154 in the
Navy’s FY202
equipped Virginia-class SSN. The CBO report states that
3 research and development account, and
CBO’s estimate assumes that the SSN(X) design would
$93.1 million in Project 2370 (Next Generation Fast Attack
have a submerged displacement about 11% greater than that
Nuclear Propulsion Development) within PE 0603570N
of the SSN-21 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
FY2023 National Defense Authorization Act (NDAA)
whether the Navy has accurately identified the
(H.R. 7900), the Senate Armed Services Committee’s
SSN(X)’s required capabilities and accurately analyzed
report (S.Rept. 117-130 of July 18, 2022, pages 444 and
the impact that various required capabilities can have on
448) on the FY2023 NDAA (S. 4543), and the House
the SSN(X)’s cost;
Appropriations Committee’s report (H.Rept. 117-388 of
June 24, 2022, pages 198 and 202) on the FY2023 DOD
the potential impact of the SSN(X) program on funding
Appropriations Act (H.R. 8236) all recommend approving
that will be available for other Navy program priorities,
particularly if CBO’s estimate of the SSN(X)’s
the SSN(X) program’s funding requests in lines 154 and 48.
procurement cost is more accurate than the Navy’s
The Senate Appropriations Committee’s explanatory
estimate;
statement for the FY2023 DOD Appropriations Act (S.
whether it would be technically feasible for the SSN(X)
4663), released on July 28, 2022, recommended approving
to be powered by a reactor plant using low-enriched
the SSN(X) program’s funding request within line 48 and
uranium (LEU), rather than the highly enriched uranium
reducing the SSN(X) program’s funding request in line 154
(HEU) used on other Navy nuclear-powered ships, and
by $50.715 million, including recommended reductions for
if so, what impact that would have on nuclear arms
“Unjustified studies growth” ($34.715 million),
control and nonproliferation efforts and SSN(X) costs
“Unjustified studies growth” ($6.0 million), and
and capabilities; and
“Unjustified support growth” ($10.0 million). (Page 188)
whether each SSN(X) should be built jointly by GD/EB
Section 1521 of S. 4543, as summarized by S.Rept. 117-
and HII/NNS (the approach used for building Virginia-
130 (page 278), would limit the use of FY2023 funds for
class SSNs and, in modified form, for building
conducting research and development of an advanced naval
Columbia-class SSBNs), or whether individual SSN(X)s
nuclear fuel system based on LEU until certain
should instead be completely built within a given
determinations are provided to the congressional defense
shipyard (the separate-yard approach used for building
committees, and require the Administrator for Nuclear
earlier Navy SSNs and SSBNs).
Security to submit a report on activities conducted for the
Regarding the third issue above, a January 2020
development of nonproliferation fuels using amounts made
Department of Energy (DOE) National Nuclear Security
available for FY2022.
Administration (NNSA) report to Congress on the potential
for using LEU for the SSN(X) that was provided by the
Ronald O'Rourke, Specialist in Naval Affairs
Navy to CRS in unclassified form stated
IF11826
It is not practical to substitute LEU into existing
naval fuel systems or to design a VIRGINIA Class
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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
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