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Updated December 9, 2021
Navy Next-Generation Attack Submarine (SSN[X]) Program:
Background and Issues for Congress
Introduction
Procurement Schedule
The Navy wants to begin procuring a new class of nuclear-
Under the Navy’s FY2020 30-year (FY2020-FY2049)
powered attack submarine (SSN), called the Next-
shipbuilding plan, the first SSN(X) would be procured in
Generation Attack Submarine or SSN(X), in FY2031. The
FY2031, along with a single Virginia-class boat. In FY2032
SSN(X) would be the successor to the Virginia-class SSN
and FY2033, the final four Virginia-class boats would be
design, which the Navy has been procuring since FY1998.
procured. Procurement of follow-on SSN(X)s, at a rate of
The Navy’s proposed FY2022 budget requests $98.0
two per year, would then begin in FY2034. The 30-year
million in research and development funding for the
plan’s sustained procurement rate of two SSNs per year
SSN(X) program.
would achieve a force of 66 SSNs—the Navy’s current
SSN force-level goal—in FY2048. A long-range Navy
Submarines in the U.S. Navy
shipbuilding document released by the Biden
The U.S. Navy operates nuclear-powered ballistic missile
Administration on June 17, 2021, proposed a new SSN
submarines (SSBNs), nuclear-powered cruise missile and
force-level goal of 66 to 72 boats and envisaged increasing
special operations forces (SOF) submarines (SSGNs), and
the SSN procurement rate years from now to something
nuclear-powered attack submarines (SSNs). The SSNs are
more than two boats per year.
general-purpose submarines that can perform a variety of
peacetime and wartime missions.
Figure 1. Virginia-Class Attack Submarine (SSN)
Virginia-Class Program
Virginia-class SSNs (Figure 1) have been procured since
FY2011 at a rate of two boats per year. When procured at a
rate of two boats per year, VPM-equipped Virginia-class
SSNs have an estimated procurement cost of about $3.4
billion per boat. For additional information on Navy
submarine programs, see CRS Report RL32418, Navy
Virginia (SSN-774) Class Attack Submarine Procurement:
Background and Issues for Congress, by Ronald O'Rourke,
and CRS Report R41129, Navy Columbia (SSBN-826)
Class Ballistic Missile Submarine Program: Background
and Issues for Congress, by Ronald O'Rourke.
Source: Cropped version of photograph accompanying Dan Ward,
Submarine Construction Industrial Base
“Opinion: How Budget Pressure Prompted the Success of Virginia-
U.S. Navy submarines are built by General Dynamics’
Class Submarine Program,” USNI News, November 3, 2014. The
Electric Boat Division (GD/EB) of Groton, CT, and
caption states that it shows USS Minnesota (SSN-783) under
Quonset Point, RI, and Huntington Ingalls Industries’
construction in 2012, and credits the photograph to the U.S. Navy.
Newport News Shipbuilding (HII/NNS), of Newport News,
VA. These are the only two shipyards in the country
Design of the SSN(X)
capable of building nuclear-powered ships. GD/EB builds
The Navy states that the SSN(X)
submarines only, while HII/NNS also builds nuclear-
will be designed to counter the emerging threat
powered aircraft carriers. The submarine construction
posed by near peer adversary competition for
industrial base also includes hundreds of supplier firms, as
undersea supremacy. Unlike the VIRGINIA Class
well as laboratories and research facilities, in numerous
Submarine, which was designed for multimission
states. Much of the material procured from supplier firms
dominance in the littoral, SSN(X) will be designed
for building submarines comes from sole-source suppliers.
for greater transit speed under increased stealth
SSN(X) Program
conditions in all ocean environments, and carry a
larger inventory of weapons and diverse payloads.
Program Designation
It will also be designed to retain multi-mission
In the designation SSN(X), the “X” means that the exact
capability and sustained combat presence in denied
design of the boat has not yet been determined.
waters, with a renewed priority in the anti-
submarine warfare (ASW) mission against
sophisticated threats in greater numbers.
https://crsreports.congress.gov
Navy Next-Generation Attack Submarine (SSN[X]) Program: Background and Issues for Congress
(Budget-justification book for FY2022 Research,
with an LEU reactor while meeting the Navy’s
Development, Test, and Evaluation, Navy account,
schedule.
Vol. 3 [Budget Activity 5], p. 1301.)
FY2022 Funding Request and
The Navy wants the SSN(X) to incorporate the speed and
Congressional Action
payload the Navy’s fast and heavily armed Seawolf (SSN-
The Navy’s proposed FY2022 budget requests $98.0
21) class SSN design, the acoustic quietness and sensors of
million in research and development funding for the
the Virginia-class design, and the operational availability
SSN(X) program, including $29.8 million in Project 2368
and service life of the Columbia-class design.
(SSN[X] Class Submarine Development) within Program
Potential Procurement Cost
Element (PE) 0604850N (SSN[X]), which is line 154 in the
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 joint explanatory statement for the HASC-SASC-
cost of a VPM-equipped Virginia-class SSN.
negotiated proposal for the FY2022 National Defense
Issues for Congress
Authorization Act (S. 1605) that was released on December
7, 2021, recommends approving the Navy’s research and
Issues for Congress include the following:
development funding requests for the SSN(X) program. The
whether the Navy has accurately identified the
joint explanatory statement states: “We believe that efforts
SSN(X)’s required capabilities and accurately analyzed
to develop any form of alternative naval nuclear fuel system
the impact that various required capabilities can have on
should ensure that such a system can be produced in a
the SSN(X)’s cost;
manner that will not reduce vessel capability, increase
expense, or reduce operational availability as a result of
the potential impact of the SSN(X) program on funding
refueling requirements,” and directs the Administrator for
that will be available for other Navy program priorities;
Nuclear Security to submit a report on activities conducted
whether it would be technically feasible for the SSN(X)
using FY2021 funding for development of an advanced
to be powered by a reactor plant using low-enriched
naval nuclear fuel system based on LEU. (PDF pages 424-
uranium (LEU), rather than the highly enriched uranium
425 of 670)
(HEU) used on other Navy nuclear-powered ships, and
if so, what impact that would have on nuclear arms
The House Appropriations Committee’s report (H.Rept.
control and nonproliferation efforts and SSN(X) costs
117-88 of July 15, 2021) on the FY2022 DOD
and capabilities; and
Appropriations Act (H.R. 4432) recommended reducing
line 154 by $4.98 million for “excess to need” (
page 270)
whether each SSN(X) should be built jointly by GD/EB
and line 48 by $18.082 million for a “Classified
and HII/NNS (the approach used for building Virginia-
adjustment” that may or may not be related to the SSN(X)
class SSNs and, in modified form, is to be used for
program (page 266). The Senate Appropriations
building Columbia-class SSBNs), or whether individual
Committee, in the explanatory statement it released on
SSN(X)s should instead be completely built within a
October 18, 2021, for the FY2022 DOD Appropriations Act
given shipyard (the separate-yard approach used for
(S. XXXX), recommends approving the program’s two
building earlier Navy SSNs and SSBNs).
funding requests. (PDF pages 170 and 172 of 253) The
Regarding the third issue above, a January 2020
explanatory statement also recommends reducing the
Department of Energy (DOE) National Nuclear Security
funding request for line 136—the line that requests funds
Administration (NNSA) report to Congress on the potential
for research and development work for improving the
for using LEU for the SSN(X) that was provided by the
Virginia-class design—by $186.3 million for “Transfer to
project XXX for SSN(X) acceleration only,” and also
Navy to CRS in unclassified form stated:
increasing the funding request for line 136 by $273.3
It is not practical to substitute LEU into existing
million for “Project XXX: Transfer for SSN(X)
naval fuel systems or to design a VIRGINIA Class
acceleration only.” (Page 176)
Submarine (VCS) replacement [i.e., the SSN(X)]
around an unproven advanced LEU fuel concept.
The House Appropriations Committee’s report (H.Rept.
Developing a newly designed submarine capable of
117-98 of July 20, 2021) on the FY2022 Energy and Water
later acceptance of an LEU reactor core would also
Development and Related Agencies Appropriations Act
involve insertion of substantial margin (e.g.,
(H.R. 4549) recommends $20.0 million “within
increased hull size) that would be difficult to
Nonproliferation Fuels Development to develop high-
estimate accurately at present and costly to
density, low-enriched fuels that could replace highly
implement. If future United States policy requires a
enriched uranium for naval applications.” (Page 164)
shift to LEU, at least 15 years of advanced fuel
development and significant investment would be
Ronald O'Rourke, Specialist in Naval Affairs
required. This development timeline makes it
IF11826
impractical to design a lead ship VCS replacement
https://crsreports.congress.gov
Navy Next-Generation Attack Submarine (SSN[X]) Program: Background and Issues for Congress
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https://crsreports.congress.gov | IF11826 · VERSION 12 · UPDATED