Posted on 04/10/2017 6:07:46 AM PDT by Bull Snipe
USS Thresher SSN-593 sinks in 8400 feet of water while conducting sea trials after a yard period at the Portsmouth Naval Shipyard. All 16 officers, 113 sailors and 17 yard civilians are lost.
Yes the welding and the emergency blow system. In tests on another sub it failed because it froze. Also, they were using an older design that did not match to the new class of submarine.
https://en.wikipedia.org/wiki/USS_Thresher_(SSN-593)
“Deep-sea photography, recovered artifacts, and an evaluation of her design and operational history permitted a Court of Inquiry to conclude Thresher had probably suffered the failure of a salt-water piping system joint which relied heavily on silver brazing instead of welding; earlier tests using ultrasound equipment found potential problems with about 14% of the tested brazed joints,[12] most of which were determined not to pose a risk significant enough to require a repair. “
In Enginnering training (nuc training) on the boat I was on a few years later, SUBSAFE was a big deal.
On a 616 class boat I was on, there was a panel that allowed isolating all of the aux seawater valves. It was located between the EOOW (Engineer officer of the Watch) and the Electrical Plant Operator who sat in front of the EOOW.
Another person mentioned the emergency blow capabilities. To prevent the air from freezing when it was dumped to the ballast to expel seawater (the rapid expansion apparently froze the moisture and stopped the expulsion of seawater), air dryers were added. But even more mods were done than that.
Another item mentioned here was the reactor trip. On the Thresher, once the rx tripped, you isolated main steam so that positive reactivity would not be added when cooling the steam generators as steam is drawn off. Back at that time, they were probably still scared of a SL-1 type of restart.
I am sure we were told the Thresher got within about 10 feet of the surface but with loss of blowing the ballast tanks due to freezing, no propulsion due to the rx trip and isolating main steam, no procedures for fast scram recovery, they were doomed to die.
We did fast scram recovery drills so often I still remember that it was easy and boring.
We were told in the yard that workers hung heavy rigging off an aux seawater pipe which stressed the pipe and that probably caused the failure. Hence you made some of the civilian workers go to sea to make sure the yard workers didn't do idiotic things like that.
Lots of things were changed to make a dangerous occupation a lot safer. It's a bad thing to kill over a 100 people AND leave a reactor on the bottom of the ocean with a lots of high level contamination. Adm. Rickover surely wanted to keep his reactors off the front pages of every newspaper in the world.
I heard the rumor that the Thresher got fairly close to the surface.
They invented the tethered, orange emergency buoy that could be deployed from the deck from within the sub. It had about a 1500’ tether if I remember right. I think it had a phone on it and everything. Problem is that the sub operated in waters shallower than 1500’ about 5% of the time. The other 95% of the time the buoy would never reach the surface.
A day or two before we went out on our 70 day patrols welders would come aboard and weld 2 metal straps across it so that it couldn’t be deployed accidently or on purpose as it was basically useless. Not a good feeling.
My Dad worked for the Navy in R&D at the time he got a phone call, packed a bag and Mom took him to the airport. The next day the story broke. Dad didn’t come home for a couple of weeks and said he couldn’t talk about it. We knew better than to ask cause like many other things he wouldn’t talk about it.
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