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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)
for using LEU for the SSN(X) that was provided by the
to incorporate the speed and payload of the Navy’s fast and
Navy to CRS in unclassified form stated
heavily armed Seawolf (SSN-21) class SSN design, the
It is not practical to substitute LEU into existing
acoustic quietness and sensors of the Virginia-class design,
and the operational availability and service life of the
naval fuel systems or to design a VIRGINIA Class
Columbia-class design. These requirements will likely
Submarine (VCS) replacement [i.e., the SSN(X)]
result in an SSN(X) design that is larger than the original
around an unproven advanced LEU fuel concept.
Virginia-class design, which has a submerged displacement
Developing a newly designed submarine capable of
of about 7,800 tons, and possibly larger than the original
later acceptance of an LEU reactor core would also
SSN-21 design, which has a submerged displacement of
involve insertion of substantial margin (e.g.,
9,138 tons. Due to technological changes over the years for
increased hull size) that would be difficult to
improved quieting and other purposes, the designs of U.S.
estimate accurately at present and costly to
Navy submarines with similar payloads have generally been
implement. If future United States policy requires a
growing in displacement from one generation to the next.
shift to LEU, at least 15 years of advanced fuel
development and significant investment would be
Potential Procurement Cost
required. This development timeline makes it
A November 2022 Congressional Budget Office (CBO)
impractical to design a lead ship VCS replacement
report on the Navy’s FY2023 30-year shipbuilding plan
with an LEU reactor while meeting the Navy’s
states that in constant FY2022 dollars, the SSN(X)’s
schedule.
average unit procurement cost is estimated at $5.6 billion
by the Navy and $6.2 billion to $7.2 billion by CBO.
FY2024 Funding Request and
CBO’s estimate is about 11% to 29% higher than the
Congressional Action
Navy’s estimate. The CBO report states that CBO’s
The Navy’s proposed FY2024 budget requests $544.7
estimate assumes that the SSN(X) design would have a
million in research and development funding for the
submerged displacement about 11% greater than that of the
SSN(X) program, including $361.6 million in Project 2368
SSN-21 design.
(SSN[X] Class Submarine Development) within Program
Issues for Congress
Element (PE) 0604850N (SSN[X]), which is line 154 in the
Navy’s FY2024 research and development account, and
Issues for Congress include the following:
$183.1 million in Project 2370 (Next Generation Fast
• whether the Navy has accurately identified the
Attack Nuclear Propulsion Development) within PE
SSN(X)’s required capabilities and accurately analyzed
0603570N (Advanced Nuclear Power Systems), which is
the impact that various required capabilities can have on
line 47.
the SSN(X)’s cost;
The House and Senate Armed Services Committees, in their
• the potential impact of the SSN(X) program on funding
reports on the FY2024 National Defense Authorization Act
that will be available for other Navy program priorities,
(NDAA) (H.R. 2670/S. 2226), recommended approving the
particularly if CBO’s estimate of the SSN(X)’s
Navy’s funding requests for the program. The House
procurement cost is more accurate than the Navy’s
Appropriations Committee, in its report on the FY2024
estimate;
DOD Appropriations Act (H.R. 4365), recommended
• whether it would be technically feasible for the SSN(X)
approving the request for line 47 and reducing the request
to be powered by a reactor plant using low-enriched
for line 154 by $82.35 million. The Senate Appropriations
uranium (LEU), rather than the highly enriched uranium
Committee, in its report on the FY2024 DOD
(HEU) used on other Navy nuclear-powered ships, and
Appropriations Act (S. 2587), recommended reducing the
if so, what impact that would have on nuclear arms
request for line 47 by $27.0 million and reducing the
control and nonproliferation efforts and SSN(X) costs
request for line 154 by $39.754 million.
and capabilities; and
Section 1640 of H.R. 2670 would prohibit funds from being
• whether each SSN(X) should be built jointly by GD/EB
used for research or development of a naval nuclear fuel
and HII/NNS (the approach used for building Virginia-
system based on LEU. Section 3111 of S. 2226 would limit
class SSNs and, in modified form, for building
the use of FY2024 funds for conducting research and
Columbia-class SSBNs), or whether individual SSN(X)s
development of an advanced naval nuclear fuel system
should instead be completely built within a given
based on LEU until certain determinations are provided to
shipyard (the separate-yard approach used for building
the congressional defense committees.
earlier Navy SSNs and SSBNs).
Regarding the third issue above, a January 2020
Ronald O'Rourke, Specialist in Naval Affairs
Department of Energy (DOE) National Nuclear Security
IF11826
Administration (NNSA) report to Congress on the potential
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.
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https://crsreports.congress.gov | IF11826 · VERSION 24 · UPDATED