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Updated March 23, 2023
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 FY2024 budget requests
Procurement Schedule
$544.7 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 $4.3 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 non-acoustic signatures, and higher
U.S. Navy submarines are built by General Dynamics’
operational availability. SSN(X) will conduct full
Electric Boat Division (GD/EB) of Groton, CT, and
spectrum undersea warfare and be able to
Quonset Point, RI, and Huntington Ingalls Industries’
coordinate with a larger contingent of off-hull
Newport News Shipbuilding (HII/NNS), of Newport News,
vehicles, sensors, and friendly forces. It will retain
VA. These are the only two shipyards in the country
and
improve
multi-mission
(Anti-submarine
capable of building nuclear-powered ships. GD/EB builds
warfare (ASW), Anti-surface warfare (ASuW),
submarines only, while HII/NNS also builds nuclear-
Strike, Special Operating Forces (SOF), Mine,
powered aircraft carriers. The submarine construction
Subsea Seabed Warfare (SSW), Intelligence,
industrial base also includes hundreds of supplier firms, as
Surveillance and Reconnaissance (ISR)) capability
well as laboratories and research facilities, in numerous
and sustained combat presence in denied waters.
states. Much of the material procured from supplier firms
for building submarines comes from sole-source suppliers.
(Budget-justification book for FY2024 Research,
Development, Test, and Evaluation, Navy account,
Vol. 3 [Budget Activity 5], p. 1293.)
https://crsreports.congress.gov
Navy Next-Generation Attack Submarine (SSN[X]) Program: Background and Issues for Congress
Navy officials have stated that the Navy wants the SSN(X)
whether each SSN(X) should be built jointly by GD/EB
to be an “apex predator.” More specifically, they have
and HII/NNS (the approach used for building Virginia-
stated that the Navy wants the SSN(X) to incorporate the
class SSNs and, in modified form, for building
speed and payload the Navy’s fast and heavily armed
Columbia-class SSBNs), or whether individual SSN(X)s
Seawolf (SSN-21) class SSN design, the acoustic quietness
should instead be completely built within a given
and sensors of the Virginia-class design, and the operational
shipyard (the separate-yard approach used for building
availability and service life of the Columbia-class design.
earlier Navy SSNs and SSBNs).
Regarding the third issue above, a January 2020
These requirements will likely result in an SSN(X) design
Department of Energy (DOE) National Nuclear Security
that is larger than the original Virginia-class design, which
Administration (NNSA) report to Congress on the potential
has a submerged displacement of about 7,800 tons, and
for using LEU for the SSN(X) that was provided by the
possibly larger than the original SSN-21 design, which has
Navy to CRS in unclassified form stated
a submerged displacement of 9,138 tons. Due to
technological changes over the years for improved quieting
It is not practical to substitute LEU into existing
and other purposes, the designs of U.S. Navy submarines
naval fuel systems or to design a VIRGINIA Class
with similar payloads have generally been growing in
Submarine (VCS) replacement [i.e., the SSN(X)]
displacement from one generation to the next.
around an unproven advanced LEU fuel concept.
Developing a newly designed submarine capable of
Potential Procurement Cost
later acceptance of an LEU reactor core would also
A November 2022 Congressional Budget Office (CBO)
involve insertion of substantial margin (e.g.,
report on the Navy’s FY2023 30-year shipbuilding plan
increased hull size) that would be difficult to
states that in constant FY2022 dollars, the SSN(X)’s
estimate accurately at present and costly to
average unit procurement cost is estimated at $5.6 billion
implement. If future United States policy requires a
by the Navy and $6.2 billion to $7.2 billion by CBO.
CBO’s estimate is
shift to LEU, at least 15 years of advanced fuel
about 11% to 29% higher than the
Navy’s estimate. The CBO report states that CBO’s
development and significant investment would be
estimate assumes that the SSN(X) design would have a
required. This development timeline makes it
submerged displacement about 11% greater than that of the
impractical to design a lead ship VCS replacement
SSN-21 design.
with an LEU reactor while meeting the Navy’s
schedule.
Issues for Congress
Issues for Congress include the following:
FY2024 Funding Request and
Congressional Action
whether the Navy has accurately identified the
The Navy’s proposed FY2024 budget requests $544.7
SSN(X)’s required capabilities and accurately analyzed
million in research and development funding for the
the impact that various required capabilities can have on
SSN(X) program, including $361.6 million in Project 2368
the SSN(X)’s cost;
(SSN[X] Class Submarine Development) within Program
the potential impact of the SSN(X) program on funding
Element (PE) 0604850N (SSN[X]), which is line 154 in the
that will be available for other Navy program priorities,
Navy’s FY2024 research and development account, and
particularly if CBO’s estimate of the SSN(X)’s
$183.1 million in Project 2370 (Next Generation Fast
procurement cost is more accurate than the Navy’s
Attack Nuclear Propulsion Development) within PE
estimate;
0603570N (Advanced Nuclear Power Systems), which is
line 47.
whether it would be technically feasible for the SSN(X)
to be powered by a reactor plant using low-enriched
Ronald O'Rourke, Specialist in Naval Affairs
uranium (LEU), rather than the highly enriched uranium
(HEU) used on other Navy nuclear-powered ships, and
IF11826
if so, what impact that would have on nuclear arms
control and nonproliferation efforts and SSN(X) costs
and capabilities; and
https://crsreports.congress.gov
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
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