Speaking of Thorium and Navy Nuclear Power verses Polywell

[jnaujok]

The Thresher sank while being tested after a refit. The refit was flawed, the sub leaked, and sank.

The sub's issue was freezing up of the emergency blow supply valves cutting off air to the tanks while attempting to surface. Bad design.

As I recall reading in the public domain, they tried to blow tanks after a SCRAM and issues making a recovery.

The reason they were blowing the emergency tanks was because the engine compartment was flooding after the refitted piping sprung leaks as they ran at their 1000 ft maximum depth during the shakedown run.

The reactor men, in order to save the reactor, were trained to SCRAM it in the case of any emergency, so they did. This cut all power to the propellers. But in the case of the Thresher, they used the momentum to maintain depth (think airplane). Without forward thrust, they lost their ability to maintain depth, and began to fall to the sea floor. That's when they did the emergency blow. Moisture in the air tank condensed in the valves that blew the ballast tank, and froze to ice, preventing the emergency tanks from blowing clear. The nose of the Thresher lifted, but the back end sank, and it fell tail first towards the bottom. Around 1500 feet of depth, it began to be crushed by the water pressure. As it sits on the bottom, the rear section was telescoped into the main body, and the entire operations center explosively imploded.

The final cause of failure was the implosion of the hull, but it was a whole chain of events that led to the sinking, started by a leak in the newly refitted ship.

[D Tibbets]

No US Navy nuclear accidents?
How about "incidents"?

An interesting read (looks like it was written in the 1980's):

http://oc.itgo.com/kitsap/nuclear/clymer.htm

Dan Tibbets

[ladajo]

The Thresher sank while being tested after a refit. The refit was flawed, the sub leaked, and sank.

The sub's issue was freezing up of the emergency blow supply valves cutting off air to the tanks while attempting to surface. Bad design.

As I recall reading in the public domain, they tried to blow tanks after a SCRAM and issues making a recovery.

The reason they were blowing the emergency tanks was because the engine compartment was flooding after the refitted piping sprung leaks as they ran at their 1000 ft maximum depth during the shakedown run.

The reactor men, in order to save the reactor, were trained to SCRAM it in the case of any emergency, so they did. This cut all power to the propellers. But in the case of the Thresher, they used the momentum to maintain depth (think airplane). Without forward thrust, they lost their ability to maintain depth, and began to fall to the sea floor. That's when they did the emergency blow. Moisture in the air tank condensed in the valves that blew the ballast tank, and froze to ice, preventing the emergency tanks from blowing clear. The nose of the Thresher lifted, but the back end sank, and it fell tail first towards the bottom. Around 1500 feet of depth, it began to be crushed by the water pressure. As it sits on the bottom, the rear section was telescoped into the main body, and the entire operations center explosively imploded.

The final cause of failure was the implosion of the hull, but it was a whole chain of events that led to the sinking, started by a leak in the newly refitted ship.

You do not SCRAM for flooding. I do not recall flooding for the incident, but will look it up. I am not sure what was put out in public, vice not.

For the record, they are not Emergency tanks, they are Ballast Tanks. The blow method is in how you actuate the valves. You can do a partial or full blow. They attempted a full, which is the more drastic of the two blows.
The blow lines were too small by design, and on a full blow, this caused a velocity induced pressure drop which in turn caused freezing. Subsequent to Thresher, all MBT Blow Lines were increased in diameter.

[jnaujok]

You do not SCRAM for flooding. I do not recall flooding for the incident, but will look it up. I am not sure what was put out in public, vice not.

This was part of the investigation's determination, made after the fact. Of course, we don't know exactly what happened aboard the Thresher, as everyone died with the ship. However, standards at the time were to safe the reactor as the first action in nearly every emergency situation. During the inquest, when other reactor operators were asked what they would have done if the engineering compartment was flooding, they said they would have SCRAMed the reactor.

Admiral Rickhoffer (spelling from memory) was often quoted in the press as believing that water from the leak struck the reactor's control panel, causing the reactor to safe itself. Again, lacking any kind of "Black Box" of the incident, there's no way to know exactly how the reactor was shut down or why. I simply was explaining the final findings of the inquest. Your comment of "You do not SCRAM for flooding," well, do you think that maybe it's because of the Thresher accident that your phrase is now the standard action?

For the record, they are not Emergency tanks, they are Ballast Tanks.

For the record, I called them Ballast tanks. The "Emergency Tanks" that I referred to was the compressed air tanks used to blow the Ballast tanks. When the MBT froze, those tanks were the ones that could not empty.

The blow method is in how you actuate the valves. You can do a partial or full blow. They attempted a full, which is the more drastic of the two blows.
The blow lines were too small by design, and on a full blow, this caused a velocity induced pressure drop which in turn caused freezing. Subsequent to Thresher, all MBT Blow Lines were increased in diameter.

Exactly what I said. The Thresher had several design and work flaws that led to its sinking. What I was saying is that it is these design flaws and an incorrect response to the situation -- that may well have been standard practice at the time -- that led to the sinking of the Thresher. It had nothing to do with the reactor.

[ladajo]

You do not SCRAM for flooding. I do not recall flooding for the incident, but will look it up. I am not sure what was put out in public, vice not.

This was part of the investigation's determination, made after the fact. Of course, we don't know exactly what happened aboard the Thresher, as everyone died with the ship. However, standards at the time were to safe the reactor as the first action in nearly every emergency situation. During the inquest, when other reactor operators were asked what they would have done if the engineering compartment was flooding, they said they would have SCRAMed the reactor.

Admiral Rickhoffer (spelling from memory) was often quoted in the press as believing that water from the leak struck the reactor's control panel, causing the reactor to safe itself. Again, lacking any kind of "Black Box" of the incident, there's no way to know exactly how the reactor was shut down or why. I simply was explaining the final findings of the inquest. Your comment of "You do not SCRAM for flooding," well, do you think that maybe it's because of the Thresher accident that your phrase is now the standard action?

For the record, they are not Emergency tanks, they are Ballast Tanks.

For the record, I called them Ballast tanks. The "Emergency Tanks" that I referred to was the compressed air tanks used to blow the Ballast tanks. When the MBT froze, those tanks were the ones that could not empty.

The blow method is in how you actuate the valves. You can do a partial or full blow. They attempted a full, which is the more drastic of the two blows.
The blow lines were too small by design, and on a full blow, this caused a velocity induced pressure drop which in turn caused freezing. Subsequent to Thresher, all MBT Blow Lines were increased in diameter.

Exactly what I said. The Thresher had several design and work flaws that led to its sinking. What I was saying is that it is these design flaws and an incorrect response to the situation -- that may well have been standard practice at the time -- that led to the sinking of the Thresher. It had nothing to do with the reactor.

For flooding, you only SCRAM when you abandon the space, unless the plant dumps itself. It has always been that way. You may be taking "inquest quotes" out of context. For the Operator to flip the switch, it means he had time to do so, and chose to do so. That is easy enough to determine, and there was a lot of time spent on the wreck researching the cause. For water spray to cause a trip in the RPCP, Power Range Instruments, or Protection and Alarm would mean that they were more than likely already evacuating, and the RO flipped the switch. I do not recall that being that case from what was determined. In catastrophic hull failure, you do not have time to flip the switch.
The reason you would not SCRAM during flooding is what you have already mentioned: The most important thing is to keep the shaft turning. Once you drop rods, you are now on residual heat in the primary and steam generators, and that will not last you long. After that you are on battery, and rolling the EPM, and that does not have enough push to over come a significant depth transient. You also want to maintain enough heat in the Primary to facilitate a fast recovery, if you cool to much you lose the option. These are basic integrated plant operations concepts. Again, you do not drop rods for flooding. The hot rock is your life, if you lose it, everything you do is about getting it back as fast as possible. Submarines are not surface ships.
The 4500lb air banks are not called Emergency Air tanks. They are 4500lb air, it is used for many things, but the large size of the banks are to support blowing the MBT's for surfacing evolutions, (however they are done). The Blow Actuators have a backup tank for actuation, it is widely known as the Captain's Air Flask. Punching out the chicken switches for a full ride is a major evolution and not done lightly. The rule of thumb is that you will get up once, staying there is the trick. Submarines are in a long period condition once an HP blow has been done and they are up, but before the LP blow. Until you get the LP done, you are at risk, or should submerge again until you figure out the LP blow. The stability state is such that it does not take much of an up or down angle to lose it. And once you pass the critical angle either way after that, you are done.

[jnaujok]

For flooding, you only SCRAM when you abandon the space, unless the plant dumps itself. It has always been that way. You may be taking "inquest quotes" out of context.

Look, I don't want to keep arguing when we're basically agreeing on 95% of the items.

No, the air tank is not called the "Emergency Tank." I didn't capitalize it that way, and I was only using it as a general term. I'm not a submariner, and I wasn't privy to the code numbers on the parts of the submarine's construction. Nor did I feel that information would have been meaningful to most of the people on this forum. Would it have really helped to say that "The P793 valve on MBT iced up in the scrubber filters during the HP blow?" I had my 16 year old son read my version and he understood what I meant just fine.

Yes, standard procedure says not to SCRAM the reactor unless you're willing to lose the ship, I understand that. Again, I'm not arguing that point. Was it an intentional SCRAM? Was it an accident? Was it part of the effects of the failure of the seawater pipe? I don't know. Neither do you. There were probably 20 people who did know, but they're at the bottom of the ocean with the other 127 people who were on board the Thresher when she sank. The normal reactor officer was at home taking care of his ailing wife during the shakedown run and a greenhorn was at the controls. Was that part of the problem? It's likely it was.

We do know the Thresher knew they were in trouble, because there are audiophone communications from the Thresher that she was attempting to surface and blow ballast. Had she not lost power, they would have been able to surface. They didn't.

All of that is immaterial to the point I was trying to make, which was very simple. The reactor did not cause the sinking. That's where this conversation started, and that's all I wanted to get across.

Here's one summary of the Inquest findings: http://www.disastercity.info/thresher/index.htm

Wikipedia has another decent article which also includes the mention of the junior operator being at the controls and being likely to have SCRAMed the reactor. They also mention the total change of procedure (not shutting the primary steam loop on a SCRAM at depth and allowing steam draw from the secondary loop in emergency conditions) that was instated by Admiral Rickover after the accident. http://en.wikipedia.org/wiki/USS_Thresher_%28SSN-593%29
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Let's just agree to disagree on the details and give this a rest. There's no way to know which of us is right, or if we're both wrong.

[ladajo]

I was a submariner, specifically, a Reactor Operator. I am very familiar with the incident, having trained on it numerous times. I have seen the navy only report, as well as public domain. It is difficult to seperate the two and not get myself in trouble.
The navy has a very good idea what went down on the boat. Yes the old way of business was to shut MS1&2, and not re-open. On a SCRAM you still shut them to preserve the steam and primary temperature. Then you decide on re-opening.
I have been in a situation very similar to what happened to Thresher. We answered bells with poles in the holes to save the boat.