Nuclear Weapons

Navy Builds Underground Nuclear Weapons Storage Facility; Seattle Busses Carry Warning

06.27.16 | 5 min read | Text by Hans Kristensen
30x144 KING

Seattle busses warn of largest nuclear weapons base. Click image to see full size.

By Hans M. Kristensen

The US Navy has quietly built a new $294 million underground nuclear weapons storage complex at the Strategic Weapons Facility Pacific (SWFPAC), a high-security base in Washington that stores and maintains the Trident II ballistic missiles and their nuclear warheads for the strategic submarine fleet operating in the Pacific Ocean.

The SWFPAC and the eight Ohio-class nuclear-powered ballistic missile submarines (SSBNs) homeported at the adjacent Bangor Submarine Base are located only 20 miles (32 kilometers) from downtown Seattle. The SWFPAC and submarines are thought to store more than 1,300 nuclear warheads with a combined explosive power equivalent to more than 14,000 Hiroshima bombs.

A similar base with six SSBNs is located at Kings Bay in Georgia on the US east coast, which houses the SWFLANT (Strategic Weapons Facility Atlantic) that appears to have a dirt-covered warhead storage facility instead of the underground complex built at SWFPAC. Of the 14 SSBNs in the US strategic submarine fleet, 12 are considered operational with 288 ballistic missiles capable of carrying 2,300 warheads. Normally 8-10 SSBNs are loaded with missiles carrying approximately 1,000 warheads.

To bring public attention to the close proximity of the largest operational nuclear stockpile in the United States, the local peace group Ground Zero Center for Nonviolent Action has bought advertisement space on 14 transit buses. The busses will carry the posters for the next eight weeks. FAS is honored to have assisted the group with information for its campaign.

The Limited Area Protection and Storage Complex

Although the new underground storage complex is not a secret – its existence has been reported in public navy documents since 2003 – it has largely escaped public attention until now.

The new complex is officially known as the Limited Area Protection and Storage Complex (LAPSC), or navy construction Project Number P973A. The complex was originally estimated to cost $110 million but ended up costing nearly $294 million.

The US Navy describes the complex as “a reinforced concrete, underground, multi-level re-entry body processing and storage facility” with “hardened floors, and hardened load-bearing walls and roof.” Glen Milner at the Ground Zero Center helped locate some of the budget documents. Other construction details provided by the navy further describe the complex as:

A 16,000-m2 [180,000 square feet] multi-level, underground, hardened, blast-resistant, reinforced concrete structure, with approximate dimensions of 110 meters long by 82 meters wide. Two tunnels (approximately 122 meters long, 6 meters wide, and 6 meters tall) will provide heavy vehicle access to and from the LAPSC. An aboveground portion of the facility will provide administrative and utility support spaces. Special features of the facility include: power-operated physical security and blast-resistant doors, TEMPEST shielded rooms, seven (7) overhead bridge cranes (2 ton capacity), three (3) elevators, lightning protection system, grounding system, liquid waste collection/retention system, emergency air purge system, fire protection systems, and multiple HVAC systems. This project will also provide a new 1000 kW emergency generator (enclosed within a new hardened, reinforced concrete structure), two security guard towers, lightning protection, utilities, and other site improvements. The existing Limited Area perimeter fence, security zone, and patrol roads will be expanded to encompass the new LAPSC.

The underground complex is similar to the general design of the large underground nuclear weapons storage facility Kirtland AFB in New Mexico, known as Kirtland Underground Munitions Storage Complex (KUMSC) – except KUMSC appears to be four times bigger than the SWFPAC complex. It appears to include 10 weapons storage bays (each 30 x 8 meters; 98 x 26 feet) where nuclear W76 and W88 warheads in their containers will be stored when they’re not deployed on submarines (see image analysis below).


New underground nuclear weapons storage site at Naval Base Kitsap. Click to view full size.

The primary building contractor, Ammann & Whitney, describes the unique blast doors and gas-tight features intended to ensure the safe storage and handling of the nuclear weapons:

The structures are reinforced concrete containment structures designed to withstand both interior and exterior explosions. All exterior penetrations and blast doors are gas-tight. There are a total of 24 blast doors; 12 are located in the above ground structures and 12 in the buried structure. All 12 doors in the above ground structures are subject to exterior blast loads while seven are subject to additional internal gas loads. Of the 12 doors in the buried structure, six doors are subject to blast loads from both sides, the remaining six are subject to blast loads from one side only but three must be gas-tight. Penetrations from the buried structure are blast resistant and gas-tight.

Design of the complex began in 2002, construction in 2007, and by 2009 the excavation and main outlines were clearly visible on satellite images. The complex was completed in 2012. Construction required enormous amounts of concrete. Over an 18-month period between December 2008 and mid-2010, for example, two hundred cement trucks entered the base every two weeks.

Nuclear weapon at SWFPAC were previously stored in above-ground earth-covered bunkers, or igloos, from where they were transported to two above-ground handling facilities for maintenance or for loading onto Trident II sea-launched ballistic missiles for deployment on operational SSBNs.


Click to view full size.

But the navy has concluded that a “single underground protected structure provides the most robust protection for fulfilling this mission against all threats.” With the completion of the underground complex, the old surface facilities (2 handling buildings and 21 igloos) will be demolished (see site outline above).

The Future


The US Navy plans to operate nuclear-armed ballistic missile submarines at Naval Base Kitsap at least through 2080.

Over the next could couple of years the navy will “convert” four of the 24 missile launch tubes on each SSBN. The conversion will remove the capability to launch missiles from the four tubes, which no longer count under the New START treaty. The 384 excess warheads associated with the 24 missiles will likely be dismantled, leaving roughly 1,000 warheads at SWFPAC.

In the longer term (in the 2030s), the US Navy will transition to a new fleet of 12 SSBNs that will replace the current 14 Ohio-class SSBNs. Each of the new submarines will only carry 16 missiles, a reduction of an additional four tubes from the 20 left on the New START compatible SSBNs. Assuming seven of the 12 new SSBNs will be based at Bangor, that will leave 112 missiles with an estimated 896 warheads at SWFPAC and Bangor submarine base, or a reduction of about one-third of the warheads currently stored there.

Despite these expected reductions, the Naval Base Kitsap complex (the SWFPAC and Bangor submarine base) will remain the largest and most important nuclear weapons base in the United States for the foreseeable future.

This publication was made possible by a grant from the New Land Foundation and Ploughshares Fund. The statements made and views expressed are solely the responsibility of the author.

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