Nine nuclear submarines have sunk, either by accident or by sinking, and the mystery behind their disappearance still remains. The Soviet Navy has lost five, the Russian Navy twice and the United States Navy (USN) two. On April 10, 1963, the nuclear-powered attack submarine USS Thresher was undergoing deep dive tests 220 miles (350 km) east of the city of Boston, Massachusetts. At the time, Thresher was the fastest and quietest submarine in the world, and it had the most advanced weapon system.
It was built to find and destroy Soviet submarines, and was equipped with a new sonar system that could detect other vessels at a much greater distance. It was also equipped with the U. S. Navy's newest anti-submarine missile, the SUBROC.
The UUM-44 SUBROC (SubMarine Rocket) was a type of submarine-launched rocket deployed as an anti-submarine weapon, carrying a 5 kiloton nuclear warhead. The Navy quickly undertook an intensive search, using the oceanographic vessel Mizar, and soon found the shattered remains of Thresher's hull at the bottom of the sea, at a depth of 8,400 feet (2,600 m). The Bathyscaphe of Trieste, fresh from visiting the deepest place on earth, the Challenger Deep in the Mariana Trench, was brought from San Diego, California, to study and photograph the rubble field. A Naval Court of Investigation was convened to determine the cause of the accident and concluded that the Thresher had suffered a failure in the junction of the saltwater piping system, causing high pressure water to be sprayed.
This could have caused a short circuit in an electrical panel, which in turn would have caused the nuclear reactor to shut down suddenly or quickly shut down. Without the nuclear reactor, there would have been a loss of propulsion. Thresher's regular Reactor Control officer, Lieutenant Raymond McCoole, was on the ground caring for a sick wife, and her replacement had just come out of nuclear power school. The replacement followed standard procedures after a “scram”, but this meant that the reactor could not be restarted immediately, which in turn meant that Thresher could not climb out of the depths.
Following the sinking of Thresher, Admiral Hyman Rickover created a rapid recovery start-up procedure that allowed a nuclear reactor to restart immediately after a rapid shutdown. Thresher should still be able to come to the surface by blowing his ballast tanks, but the excess moisture in his high-pressure air flasks had frozen in the cold water at depth, and that ice clogged the flasks. After Thresher, air dryers were installed on submarines to defrost flasks and allow for emergency shocks. On July 29th 1960, 20 days after Thresher's launch, USS Scorpion was launched in Groton Connecticut.
By 1962 its permanent port was Norfolk Virginia. In early 1960s Scorpion participated in numerous naval exercises with US Navy. One story goes that during a Race to North in 1966 Scorpion entered an inland sea of Russia and filmed firing of Soviet missile through its periscope before fleeing ships of Soviet Navy that were chasing it. On February 1st 1967 Scorpion entered Norfolk Naval Shipyard for what should have been nine month review but Navy requirements forced it to be shortened and same emergency system that had condemned Thresher was not corrected in Scorpion.
After deployment in Mediterranean Sea Scorpion left US Naval base in Rota Spain with 99 crew members along with USS John C Davis. Scorpion was sent to observe Soviet naval activities in Atlantic Ocean near Azores. In addition to two fast November class Soviet 32 knot hunter-killer submarines convoy also included Echo II class submarine as well as Russian guided missile destroyer. Scorpion watched and listened to Soviet ships and then prepared to return to Norfolk Naval Station.
The bathyscaphe Trieste II successor to her sister Trieste was also deployed and she collected images of scene of accident. Navy's underwater SOSUS listening system contained sounds of Scorpion's destruction. Navy regularly visits Scorpion wreck site to test release of any fissile material from its nuclear reactor and two nuclear weapons reports show lack of radioactivity indicating that nuclear reactor fuel remains intact and two Mark 45 nuclear tipped anti-submarine torpedoes (ASTOR) are also intact. Ballard's robotic study showed that Thresher had indeed imploded and his 1985 study of Scorpion wreck site revealed large debris field and what Ballard described as ship that appeared to have been put through crushing machine.
In addition in 1985 Ballard located wreck of Titanic. Having been lost at sea neither Thresher nor Scorpion has been dismantled by US Navy on other hand like all lost submarines remain in Eternal Patrol. The nuclear leak that occurred when Russian special purpose pocket submarine sank last year increased concerns about its effects on nature. Of 8 sinks 2 were due to fires 2 were due to explosions of weapons systems 1 was due to floods 1 was weather related and 1 intentionally sank due to damaged nuclear reactor Ingar Amundsen head of international nuclear safety at Norwegian Nuclear Safety and Radiation Authority agrees that it is question of when not if sunken submarines will start leaking radiation into environment.