From 1915 to 1963, the United States Navy lost 16 submarines
to non-combat related causes. Since SUBSAFE began in 1963, only one submarine,
the non-SUBSAFE-certified USS Scorpion (SSN-589), has been lost.
On 10 April 1963, while on a deep test dive about 200 miles
off the northeast coast of the United States, USS Thresher (SSN-593) was lost
with all hands. The loss of the lead ship of a new, fast, quiet, deep-diving
class of submarines led the Navy to re-evaluate the methods used to build its
A "Thresher Design Appraisal Board" determined
that, although the basic design of the Thresher class was sound, measures
should be taken to improve the condition of the hull and the ability of
submarines to control and recover from flooding casualties.
SUBSAFE became the quality assurance program of the United
States Navy designed to maintain the safety of the nuclear submarine fleet;
specifically, to provide maximum reasonable assurance that subs' hulls will
stay watertight, and that they can recover from unanticipated flooding.
SUBSAFE certification is carried out in four areas; Design,
Material, Fabrication, & Testing. The exact procedures are documented in
the initial design & construction for new submarines, while undergoing
routine maintenance in naval depots, and in the fleet maintenance manual for
operating submarines. During each step, quality evidence is collected,
reviewed, approved, and stored for the life of the submarine. This process is
reinforced with external and internal audits.
SUBSAFE covers all systems exposed to sea
pressure or critical to flooding recovery. All work done and all materials used
on those systems are tightly controlled to ensure the material used in their
assembly as well as the methods of assembly, maintenance, and testing are
correct. They require certification with traceable quality evidence.