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Updated October 19, 2021
Navy Next-Generation Attack Submarine (SSN[X]) Program:
Background and Issues for Congress
Introduction
source of work is the Navy’s nuclear-powered aircraft
The Navy wants to begin procuring a new class of nuclear-
carrier construction program.
powered attack submarine (SSN), called the Next-
Generation Attack Submarine or SSN(X), in FY2031. The
Figure 1. Virginia-Class Attack Submarine (SSN)
SSN(X) would be the successor to the Virginia-class SSN
design, which the Navy has been procuring since FY1998.
The Navy’s proposed FY2022 budget requests $98.0
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.
Source: Cropped version of photograph accompanying Dan Ward,
Virginia-Class Program
“Opinion: How Budget Pressure Prompted the Success of Virginia-
Virginia-class SSNs (Figure 1) have been procured sicne
Class Submarine Program,” USNI News, November 3, 2014. The
FY2011 at a rate of two boats per year. Most Virginia-class
caption states that it shows USS Minnesota (SSN-783) under
boats procured in FY2019 and subsequent years are to be
construction in 2012, and credits the photograph to the U.S. Navy.
built with the Virginia Payload Module (VPM), an
SSN(X) Program
additional, 84-foot-long, mid-body section equipped with
four large-diameter, vertical launch tubes for storing and
Program Designation
launching Tomahawk cruise missiles or other payloads.
In the designation SSN(X), the “X” means that the exact
When procured at a rate of two boats per year, VPM-
design of the boat has not yet been determined.
equipped Virginia-class SSNs have an estimated
procurement cost of about $3.4 billion per boat.
Procurement Schedule
Under the Navy’s FY2020 30-year (FY2020-FY2049)
For additional information on Navy submarine programs,
shipbuilding plan, the first SSN(X) would be procured in
see CRS Report RL32418, Navy Virginia (SSN-774) Class
FY2031, along with a single Virginia-class boat. In FY2032
Attack Submarine Procurement: Background and Issues for
and FY2033, the final four Virginia-class boats would be
Congress, by Ronald O'Rourke, and CRS Report R41129,
procured. Procurement of follow-on SSN(X)s, at a rate of
Navy Columbia (SSBN-826) Class Ballistic Missile
two per year, would then begin in FY2034. The 30-year
Submarine Program: Background and Issues for Congress,
plan’s sustained procurement rate of two SSNs per year
by Ronald O'Rourke.
would achieve a force of 66 SSNs —the Navy’s current
Submarine Construction Industrial Base
SSN force-level goal—in FY2048. A long-range Navy
shipbuilding document released by the Biden
U.S. Navy submarines are built by General Dynamics’
Administration on June 17, 2021, proposed a new SSN
Electric Boat Division (GD/EB) of Groton, CT, and
force-level goal of 66 to 72 boats and envisaged increasing
Quonset Point, RI, and Huntington Ingalls Industries’
the SSN procurement rate years from now to something
Newport News Shipbuilding (HII/NNS), of Newport News,
more than two boats per year.
VA. These are the only two shipyards in the country
capable of building nuclear-powered ships. GD/EB builds
Design of the SSN(X)
submarines only, while HII/NNS also builds nuclear-
The Navy states that the SSN(X)
powered aircraft carriers . The submarine construction
industrial base also includes hundreds of supplier firms, as
will be designed to counter the emerging threat
well as laboratories and research facilities, in numerous
posed by near peer adversary competition for
states. Much of the material procured from supplier firms
undersea supremacy. Unlike the VIRGINIA Class
for building submarines comes from sole-source suppliers.
Submarine, which was designed for multimission
For nuclear-propulsion component suppliers, an additional
dominance in the littoral, SSN(X) will be designed
for greater transit speed under increas ed stealth
https://crsreports.congress.gov
Navy Next-Generation Attack Submarine (SSN[X]) Program: Background and Issues for Congress
conditions in all ocean environments, and carry a
later acceptance of an LEU reactor core would also
larger inventory of weapons and diverse payloads.
involve insertion of substantial margin (e.g.,
It will also be designed to retain multi-mission
increased hull size) that would be difficult to
capability and sustained combat presence in denied
estimate accurately at present and costly to
waters, with a renewed priority in the anti-
implement. If future United States policy requires a
submarine warfare (ASW) mission against
shift to LEU, at least 15 years of advanced fuel
sophisticated threats in greater numbers.
development and significant investment would be
required. This development timeline makes it
(Budget-justification book for FY2022 Research,
impractical to design a lead ship VCS replacement
Development, Test, and Evaluation, Navy account,
with an LEU reactor while meeting the Navy’s
Vol. 3 [Budget Activity 5], p. 1301.)
schedule.
The Navy wants the SSN(X) to incorporate the speed and
payload the Navy’s fast and heavily armed Seawolf (SSN-
FY2022 Funding Request and
21) class SSN design, the acoustic quietness and sensors of
Congressional Action
the Virginia-class design, and the operational availability
The Navy’s proposed FY2022 budget requests $98.0
and service life of the Columbia-class design. (Justin Katz,
million in research and development funding for the
“SSN(X) Will Be ‘Ultimate Apex Predator,’” Breaking
SSN(X) program, including $29.8 million in Project 2368
Defense, July 21, 2021.)
(SSN[X] Class Submarine Development) within Program
Element (PE) 0604850N (SSN[X]), which is line 154 in the
Potential Procurement Cost
Navy’s FY2022 research and development account, and
An April 2021 Congressional Budget Office (CBO) report
$68.1 million in Project 2370 (Next Generation Fast Attack
states that in constant FY2021 dollars, the SSN(X)’s
Nuclear Propulsion Development) within PE 0603570N
average unit procurement cost is estimated at $5.8 billion
(Advanced Nuclear Power Systems), which is line 48.
by the Navy and $6.2 billion by CBO—figures that are
substantially higher than the $3.4 billion unit procurement
The House Armed Services Committee’s report (H.Rept.
cost of a VPM-equipped Virginia-class SSN.
117-188 of September 10, 2021) on the FY2022 National
Defense Authorization Act (NDAA) (H.R. 4350)
Issues for Congress
recommended approving both of these funding requests.
Issues for Congress include the following:
The Senate Armed Services Committee’s report (S.Rept.
117-39 of September 22 [legislative day, September 21],
whether the Navy has accurately identified the
SSN(X)’
2021) on the FY2022 NDAA (S. 2792) recommended
s required capabilities and accurately analyzed
increasing line 154 by $25.8 million for “Navy UFR
the impact that various required capabilities can have on
[unfunded requirement]—SSN(X) non-propulsion
the SSN(X)’s cost;
development.” (Page 446)
the potential impact of the SSN(X) program on funding
that will be available for other Navy program priorities;
The House Appropriations Committee’s report (H.Rept.
117-88 of July 15, 2021) on the FY2022 DOD
whether it would be technically feasible for the SSN(X)
Appropriations Act (H.R. 4432) recommended reducing
to be powered by a reactor plant using low-enriched
line 154 by $4.98 million for “excess to need” (page 270)
uranium (LEU), rather than the highly enriched uranium
and line 48 by $18.082 million for a “Classified
(HEU) used on other Navy nuclear-powered ships, and
adjustment” that may or may not be related to the SSN(X)
if so, what impact that would have on nuclear arms
program (page 266). The Senate Appropriations
control and nonproliferation efforts and SSN(X) costs
Committee, in the explanatory statement it released on
and capabilities; and
October 18, 2021, for the FY2022 DOD Appropriations Act
whether each SSN(X) should be built jointly by GD/EB
(S. XXXX), recommends approving the program’s two
and HII/NNS (the approach used for building Virginia-
funding requests. (PDF pages 170 and 172 of 253) The
class SSNs and, in modified form, is to be used for
explanatory statement also recommends reducing the
building Columbia-class SSBNs), or whether individual
funding request for line 136—the line that requests funds
SSN(X)s should instead be completely built within a
for research and development work for improving the
given shipyard (the separate-yard approach used for
Virginia-class design—by $186.3 million for “Transfer to
building earlier Navy SSNs and SSBNs).
project XXX for SSN(X) acceleration only,” and also
increasing the funding request for line 136 by $273.3
Regarding the third issue above, a January 2020
million for “Project XXX: Transfer for SSN(X)
Department of Energy (DOE) National Nuclear Security
acceleration only.” (Page 176)
Administration (NNSA) report to Congress on the potential
for using LEU for the SSN(X) that was provided by the
The House Appropriations Committee’s report (H.Rept.
Navy to CRS in unclassified form stated:
117-98 of July 20, 2021) on the FY2022 Energy and Water
It is not practical to substitute LEU into existing
Development and Related Agencies Appropriations Act
naval fuel systems or to design a VIRGINIA Class
(H.R. 4549) recommends $20.0 million “within
Submarine (VCS) replacement [i.e., the SSN(X)]
Nonproliferation Fuels Development to develop high-
density, low-enriched fuels that could replace highly
around an unproven advanced LEU fuel concept.
enriched uranium for naval applications.” (Page 164)
Developing a newly designed submarine capable of
https://crsreports.congress.gov
Navy Next-Generation Attack Submarine (SSN[X]) Program: Background and Issues for Congr ess
IF11826
Ronald O'Rourke, Specialist in Naval Affairs
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https://crsreports.congress.gov | IF11826 · VERSION 11 · UPDATED