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Updated August 10, 2021
Navy Next-Generation Attack Submarine (SSN[X]) Program:
Background and Issues for Congress
Introduction and Issue for Congress
In addition to GD/EB and HII/NNS, the submarine
The Navy wants to begin procuring a new class of nuclear-
construction industrial base includes hundreds of supplier
powered attack submarine (SSN), called the Next-
firms, as well as laboratories and research facilities, in
Generation Attack Submarine or SSN(X), in FY2031. The
numerous states. Much of the material procured from
SSN(X) would be the successor to the Virginia-class SSN
supplier firms for the construction of submarines comes
design, which the Navy has been procuring since FY1998.
from sole-source suppliers. For nuclear-propulsion
The Navy’s proposed FY2022 budget requests $98.0
component suppliers, an additional source of work is the
million in research and development funding for the
Navy’s nuclear-powered aircraft carrier construction
SSN(X) program. An issue for Congress is whether to
program.
approve, reject, or modify the Navy’s funding requests and
acquisition strategy for the SSN(X) program.
Figure 1. Virginia-Class Attack Submarine (SSN)
Submarines in the U.S. Navy
The U.S. Navy operates three types of submarines—
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
Since FY2011, Virginia-class SSNs (Figure 1) have been
procured at a rate of two boats per year, and a total of 34
have been procured through FY2021. Most Virginia-class
Source: Cropped version of photograph accompanying Dan Ward,
boats procured in FY2019 and subsequent years are to be
“Opinion: How Budget Pressure Prompted the Success of Virginia-
built with the Virginia Payload Module (VPM), an
Class Submarine Program,” USNI News, November 3, 2014. The
additional, 84-foot-long, mid-body section equipped with
caption states that it shows USS Minnesota (SSN-783) under
four large-diameter, vertical launch tubes for storing and
construction in 2012, and credits the photograph to the U.S. Navy.
launching Tomahawk cruise missiles or other payloads.
SSN(X) Program
When procured at a rate of two boats per year, VPM-
equipped Virginia-class SSNs have an estimated
Program Designation
procurement cost of about $3.4 billion per boat.
In the designation SSN(X), the “X” means that the exact
design of the boat has not yet been determined.
For additional information on Navy submarines, the
Virginia-class SSN program, and the Columbia-class SSBN
Procurement Schedule
program, see CRS Report RL32418, Navy Virginia (SSN-
Under the Navy’s FY2020 30-year (FY2020-FY2049)
774) Class Attack Submarine Procurement: Background
shipbuilding plan, the first SSN(X) would be procured in
and Issues for Congress, by Ronald O'Rourke, and CRS
FY2031, along with a single Virginia-class boat. In FY2032
Report R41129, Navy Columbia (SSBN-826) Class Ballistic
and FY2033, the final four Virginia-class boats would be
Missile Submarine Program: Background and Issues for
procured, at a rate of two per year. Procurement of follow-
Congress, by Ronald O'Rourke.
on SSN(X)s, at a rate of two per year, would then begin in
Submarine Construction Industrial Base
FY2034. The 30-year plan’s sustained procurement rate of
two SSNs per year would achieve a force of 66 SSNs —the
U.S. Navy submarines are built by General Dynamics’
Navy’s current SSN force-level goal—in FY2048.
Electric Boat Division (GD/EB) of Groton, CT, and
Quonset Point, RI, and Huntington Ingalls Industries’
A long-range Navy shipbuilding document released by the
Newport News Shipbuilding (HII/NNS), of Newport News,
Trump Administration on December 9, 2020, proposed a
VA. These are the only two shipyards in the country
new SSN force-level goal of 72 to 78 boats. To meet this
capable of building nuclear-powered ships. GD/EB builds
goal by the latter 2040s, it projected an SSN procurement
submarines only, while HII/NNS also builds nuclear-
rate of three boats per year during the period FY2035-
powered aircraft carriers and is capable of building other
FY2041, and two and two-thirds boats per year (in annual
types of surface ships.
quantities of 2-3-3) during the period FY2042-FY2050. A
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Navy Next-Generation Attack Submarine (SSN[X]) Program: Background and Issues for Congress
long-range Navy shipbuilding document released by the
uranium (LEU), rather than the highly enriched uranium
Biden Administration on June 17, 2021, proposed a new
(HEU) used on other Navy nuclear-powered ships, and
SSN force-level goal of 66 to 72 boats and envisaged
if so, what impact using LEU in the SSN(X) would have
increasing the SSN procurement rate years from now to
on nuclear arms control and nonproliferation efforts and
something more than two boats per year.
SSN(X) costs and capabilities; and
Design of the SSN(X)
whether each SSN(X) should be built jointly by GD/EB
The Navy states that the SSN(X)
and HII/NNS (the approach used for building Virginia-
class SSNs and, in modified form, is to be used for
will be designed to counter the emerging threat
building Columbia-class SSBNs), or whether individual
posed by near peer adversary competition for
SSN(X)s should instead be completely built within a
undersea supremacy. Unlike the VIRGINIA Class
given shipyard (the separate-yard approach used for
Submarine, which was designed for multimission
building earlier Navy SSNs and SSBNs).
dominance in the littoral, SSN(X) will be designed
Regarding the third issue above, a January 2020
for greater transit speed under increased stealth
Department of Energy (DOE) National Nuclear Security
conditions in all ocean environments, and carry a
Administration (NNSA) report to Congress on the potential
larger inventory of weapons and diverse payloads.
for using LEU for the SSN(X) that was provided by the
It will also be designed to retain multi-mission
Navy to CRS in unclassified form stated:
capability and sustained combat presence in denied
waters, with a renewed priority in the anti-
It is not practical to substitute LEU into existing
submarine warfare (ASW) mission against
naval fuel systems or to design a VIRGINIA Class
sophisticated threats in greater numbers. SSN(X)
Submarine (VCS) replacement [i.e., the SSN(X)]
will be required to defend against threat UUVs
around an unproven advanced LEU fuel concept.
[unmanned underwater vehicles], and coordinate
Developing a newly designed submarine capable of
with a larger contingent of off-hull vehicles,
later acceptance of an LEU reactor core would also
sensors, and friendly forces.
involve insertion of substantial margin (e.g.,
increased hull size) that would be difficult to
(Budget-justification book for FY2022 Research,
estimate accurately at present and costly to
Development, Test, and Evaluation, Navy account,
implement. If future United States policy requires a
Vol. 3 [Budget Activity 5], p. 1301.)
shift to LEU, at least 15 years of advanced fuel
development and significant investment would be
A Navy official stated in July 2021 that the Navy wants the
SSN(X) to incorporate the speed and payload the Navy’s
required. This development timeline makes it
fast and heavily armed Seawolf (SSN-21) class SSN design,
impractical to design a lead ship VCS replacement
with an LEU reactor while meeting the Navy’s
the acoustics (i.e., quietness) and sensors of the Virginia-
class design, and the operational availability and service life
schedule.
of the Columbia-class design. (Justin Katz, “SSN(X) Will
Be ‘Ultimate Apex Predator,’” Breaking Defense, July 21,
FY2022 Funding Request and
2021.)
Congressional Action
The Navy’s proposed FY2022 budget requests $98.0
Potential Procurement Cost
million in research and development funding for the
An April 2021 Congressional Budget Office (CBO) report
SSN(X) program, including $29.8 million in Project 2368
states that in constant FY2021 dollars, the SSN(X)’s
(SSN[X] Class Submarine Development) within Program
average unit procurement cost is estimated at $5.8 billion
Element (PE) 0604850N (SSN[X]), which is line 154 in the
by the Navy and $6.2 billion by CBO—figures that are
Navy’s FY2022 research and development account, and
substantially higher than the $3.4 billion unit procurement
$68.1 million in Project 2370 (Next Generation Fast Attack
cost of a VPM-equipped Virginia-class SSN.
Nuclear Propulsion Development) within PE 0603570N
(Advanced Nuclear Power Systems), which is line 48.
Issues for Congress
Issues for Congress include the following:
The House Appropriations Committee, in its report
(H.Rept. 117-88 of July 15, 2021) on the FY2022 DOD
whether the Navy has accurately identified the
Appropriations Act (H.R. 4432), recommended reducing
SSN(X)’s required capabilities and accurately analyzed
the Navy’s line 154 funding request by $4.98 million for
and incorporated the impact that various required
“excess to need” (page 270), and recommended reducing
capabilities can have on the SSN(X)’s cost;
the Navy’s line 48 funding request by $18.082 million for a
the potential impact of the SSN(X) program—given the
“Classified adjustment” that may or may not be related to
design’s currently estimated unit procurement cost and
the SSN(X) program (page 266).
potential future Navy funding levels—on funding that
will be available for other Navy program priorities;
Ronald O'Rourke, Specialist in Naval Affairs
whether it would be technically feasible for the SSN(X)
IF11826
to be powered by a reactor plant using low-enriched
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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
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
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