I am sure the crew thought they were going to make it to the surface. There was likely flooding in the engine room, and the submarine was down by the stern, but they were rising. Even though the nuclear reactor had shut down and there was no steam to power the turbines and turn the propeller, compressed air was still blowing water from the main ballast tanks.
But suddenly, there was silence; the blow had stopped. The submarine stopped rising, hesitated, and then began descending, stern first, faster and faster. They were doomed, a crew of 112—including my friends and nuclear power school classmates, Lieutenants (j.g.) Frank Malinski and John Grafton—and 17 civilian technicians. At an unknown depth the Thresher (SSN-593) imploded, creating a searing pressure and heat wave that killed all on board instantly. She continued descending until she crashed onto the ocean floor at a depth of some 8,000 feet on that fateful day, 10 April 1963.
I last saw Frank on 6 April, the Saturday before the disaster. It was a warm spring day, and he came to see me at the New London Submarine Base, where I was living while going to submarine school. Frank was a very bright guy and somewhat unusual in that he was one of the few NROTC graduates in the program who did not have an engineering degree. While we were washing our cars, Frank told me that his boat, the Thresher, was back in dry dock at the Electric Boat shipyard to address a leak in the main seawater cooling system. Neither of us thought this was a big deal.
At submarine school, I was part of a small group of officers who already had completed nuclear power training and would be assigned to nuclear submarines on graduation. Nonetheless, we spent six months studying the intricacies of diesel-electric submarines. I even made a two-week training cruise to Halifax on board the USS Angler (SS-240), a World War II veteran. The Navy was still locked into training officers for duty on diesel-electric boats, even though the boats quickly were becoming obsolete.
The only exposure I had to nuclear submarines was the occasional day cruise when a boat from the base would take congressmen out for “angle and dangle” maneuvers, to impress them with the capability of nuclear-powered submarines. Despite these demonstrations of superiority, the Navy’s operational thinking carried over from diesel-electric boats to the nuclear submarines. The distinction—that one was a surface vessel that could submerge for brief periods on battery power, the other an undersea vessel that had near-infinite power and would seldom need to surface—was not yet recognized or emphasized during submarine school training. This fundamental failure in thinking contributed to the Thresher disaster, after which the Navy finally met the new reality of nuclear-powered submarines with fresh operational thinking.
A Sudden and Swift End
About a month after the loss of the Thresher, the small group of nuclear power–trained officers at submarine school was called together to assess an audio recording of the event.
With the knowledge of reactor plant technology obtained during nuclear power training, we pieced together the sequence of events. The first sound was likely flooding within the engine room that likely led to a loss of power due to an electrically induced automatic shutdown. That meant the loss of AC electrical power from the ship’s service turbine generators, located aft in the engine room. With the resulting loss of reactor coolant flow, the reactor shut down, or “scrammed.” This series of events led us to believe that Thresher was not operating with the reactor coolant pumps at slow speed, a much more reliable lineup. The circumstances of why are still not known today.
At this point, power to the main propulsion turbines and propeller was lost. The Thresher was dead in the water at test depth.
Shortly thereafter we heard the rumble of high-pressure air blowing the water out of the main ballast tanks. This went on for several minutes then suddenly stopped. There was a long silence until we heard the “boom” as the submarine’s pressure hull imploded under the enormous external sea pressure at crush depth. It was a sudden and swift end to a fantastic machine and the men on board her.
After submarine school, I was assigned to the ballistic-missile submarine USS John Adams (SSBN-620). She was under construction at the Portsmouth Naval Shipyard in Kittery, Maine—the same yard that built the Thresher. When I reported in, the executive officer (XO) took me to the dry dock where the John Adams was undergoing reinspection of the silver-brazed joints in the main seawater cooling system. This was part of the SubSafe program put into effect after the Thresher disaster. In addition, all the welds that joined the large diameter rings that made up the submarine’s hull were being reexamined by X-ray. It was somewhat unnerving to see the John Adams with so many white chalk marks on her hull, chalk marks that said, “slag,” “porosity,” “grind out,” “reweld.”
Perhaps the XO sensed my concern, for he offered to have me transferred to another nuclear submarine. He probably was authorized to do this because of the knowledge that two of my good friends had gone down with the Thresher. I declined immediately, knowing that the John Adams had two of the best skippers in the submarine navy. The legendary Lando W. Zech Jr. was captain of the Blue Crew, and Paul J. Early, of Nautilus North Pole fame, was captain of the Gold Crew.
After temporary duty at the Westinghouse Bettis Atomic Power Laboratory outside Pittsburgh, I joined the John Adams as her most junior officer. I served on board from August 1963 to March 1966 in various positions, including as supply officer, auxiliary division officer, diving officer, communications officer, electrical officer, and reactor control officer. Under the command of Commander Early, we made a shakedown cruise to Cape Canaveral, Florida, where we launched four Polaris missiles. Later, we made three Polaris missile patrols out of Holy Loch, Scotland. The John Adams never ventured below 500 feet while I was on board.
After the Thresher disaster, the Navy made significant changes to the nuclear submarine fleet, including to mechanical systems, reactor operating procedures, and submarine operating practices. The main seawater cooling systems and compressed air systems were modified to allow for quick actuation in an emergency. But more important, the filter screens in the high-pressure air piping upstream of the main ballast tank blow valves were removed. These screens were designed to protect the valves from being damaged by any debris in the high-pressure air piping. Instead, they had iced over from moisture in the high-pressure air tanks when the Thresher had attempted an emergency surface from test depth. The ice effectively stopped the flow of compressed air to the main ballast tanks and prevented the Thresher from reaching the surface.
Another significant change was to the reactor operating procedures. After the Thresher disaster, the procedures were modified enabling the reactor to achieve full power quickly once the problem was corrected. Additionally, the residual heat in the reactor system could be used to generate steam for the turbines and propeller to save the submarine in an emergency.
Practices for operating at deep depths also changed dramatically. No longer was a “zero bubble” or level trim desirable. Instead, the submarine would be pumped “light,” so it would rise naturally on a loss of main propulsion. To maintain a steady depth in this condition, the submarine would have to maintain speed and a down angle with the planes. By maintaining speed at depth, the boat could also “plane up” on a loss of main propulsion. And at deep depths, the reactor plant was always to be put in its most reliable condition.
It took the Thresher tragedy to bring about these changes. While there were mechanical failures on the Thresher, the real failure was in not casting off obsolete thinking and recognizing the power and capability of the nuclear submarine.