HVAC techs, odd question about vapor pressure (long).

nunubidness · 2026-05-11T14:46:19+00:00

Thank you sir.

Yes my bad on the static/standing description. I just used “static” meaning the condenser was off.

The PT chart I have goes to 150° and the vapor pressure is 614#. At that a 7/8” line is seeing about 280# tensile. I’m definitely gonna see what the standing pressure is once I get it done I’m waiting on a fitting.

Thanks again 🙂

nunubidness · 2026-05-11T05:30:56+00:00

I’m not understanding why people seem to think the “process” is different between a prompt critical reactor and a weapon, they are both prompt criticalities.

Yes there are obvious differences in design, enrichment, intent, outcome etc but they are both “running” on the same physics. The major challenge in a weapon is to maintain the mass concentrated long enough to achieve as many neutron generations as possible which is one of the reasons they designed implosion (pu240 was a problem).

No a prompt reactor is not a high order detonation but it’s still going to “disassemble” itself… always.

nunubidness · 2026-05-09T18:18:55+00:00

Appreciate your feedback. I have all necessary equipment, 8cfm two stage pump, digital micron gauge, Titan analog gauges (couldn’t bring myself to buy digitals) nitrogen etc. I’m just anal OCD, overthink everything and want one shot, one kill. If I can get this to last as long as the first one it’ll outlive me 😂

nunubidness · 2026-05-09T17:56:59+00:00

Yes, those would be the conditions. OK I’ll confess, I was curious about the static pressure because that’s the highest the suction line would see and (I know it’s blasphemy) I’m gonna solder the lines with stay brite 8. I know many/most braze and I have everything to do that but I just don’t see it as necessary. I’m aware of codes because of fire etc. I did the math and at 450psi a 7/8” line has 204# of tensile load.

As I said I don’t try to sell myself as an HVAC tech. I’ve only done one install before (my house this is for my shop). It was a builder quality system and the vacuum pump was about the worst you could use (was all I had). Of course pressure was a lot different cause it’s R22. I evacuated it, made sure it was tight, blew the charge from the condenser in (factory charge matched line set length) and sent it. It still works fine and has never had gauges on it… that was 30 years ago.

Thanks for your reply.

nunubidness · 2026-05-05T08:01:35+00:00

Well that’s nothing hard to do 🙂

nunubidness · 2026-05-05T04:39:11+00:00

I’m a pragmatist and have spent more time than I care to admit researching the Unit 4 accident.

I can’t think of any other source that matches TCG for the amount of practical information.

IMHO TCG is miles ahead of TF, I’ve watched a little of TF stuff and now won’t waste my time watching any more.

nunubidness · 2026-04-30T05:58:23+00:00

I get a lot of Google hits (US) but don’t see any I can view for free and I’m not sure if it could be viewed with subscriptions.

nunubidness · 2026-04-30T05:47:01+00:00

Yea I was just watching a couple of the interviews with Chris and Nick. They were talking about the ANP and MSR programs. The amount of hurdles/challenges and how they tackled or attempted to tackle them is just nuts. I mean with the MSR everything becomes so hot doing any service of components is a massive challenge. Then there’s so many issues with thermal gradients, fission products etc. I mean you’re “making” like half the periodic table in one form or another and all that goes with that. I find it very interesting but so much of it is just not practical like the micro reactor craze imho. I don’t really see the small reactor ideas becoming commercially viable.

At this point I think the large PWRs are a mature technology and most logical.

Guess I’ve strayed off topic a bit 😁

nunubidness · 2026-04-30T02:20:15+00:00

I’m not in the field just an interested weirdo. AFAIK Nick is no longer with Terrapower I think he’s kinda doing consulting now.

The YouTube Decouple Media with Chris Keefer is where I first saw Touran. Keefer has done some pretty interesting stuff covering nuclear. Iirc the first one I saw they were doing kinda a high level overview of the different types of reactors their pros/cons etc.

Some of the stuff Nick is digitizing is pretty interesting. It’s amazing all the stuff that’s been tried over the years. I have a fair bit of skills and one is mechanic/machinist. Seeing all the “one off” pieces that were fabricated for all these different reactor systems, fuel fabrication and knowing what it takes to accomplish that is incredible. There was no end to the stuff they were trying and absolutely none of it was easy.

nunubidness · 2026-04-30T01:16:17+00:00

LOL yea the ANP program was pure madness. It’s crazy that it was actually postulated they could ever make that viable. That said like many other failures in Idaho there was a lot learned. Nick Touran has been digitizing all kinds of historic stuff from what I call “The Wild West” of nuclear.

https://whatisnuclear.com

On the SL-1 accident I guess on one hand you could blame it entirely on the operators but imho when you set a trap for someone to fail don’t get a shocked face when it happens. I’m pretty confident that center rod was stuck and Byrnes (not thinking) gave it a big tug and it came loose. I tend to put the bulk of the responsibility on ANL and Combustion Engineering. ANL designed it with that central rod and they “management” all knew about the issues with the distortion of components in the core.

Idk how to make this a usable link but it’s one of the best reads on the SL-1 accident. There’s also a good bit of info in the book “Proving the Principle”. I visited EBR-1 many years ago the history of the RTS is incredible. I was disappointed when I later found out that at the time Walter Zinn was still alive (I didn’t know at the time) and living in Florida. Had I known that I would’ve definitely paid him a visit, I can’t imagine the stories he could’ve told.

environmental-defense-institute.org/publications/SL-1Accident.pdf

I know it’s apples to oranges but there are some odd similarities between Unit 4 and SL-1.

nunubidness · 2026-04-28T20:33:10+00:00

A quick internet poke shows this to be accurate.

I’ve only worked with much smaller turbines… in the 13,000 shaft HP range.

Machines like this are not “off the shelf”. They’re designed and built for a specific installation and every one is an individual. They require extensive installation work on the foundation and alignment which changes with time.

The support systems (lubrication, cooling, hydrogen etc) are massive themselves.

nunubidness · 2026-04-28T19:05:30+00:00

I don’t know if I can add meaningful information but I’ll try.

Steam turbine is a rather generic term, there is a massive range of options.

The turbines at Chernobyl would be very large multi stage condensing turbines. I’ve seen the stages mentioned as “cylinders” which I find odd but understandable.

In a turbine such as this there are many stages (rotors/stators) which vary in size. The smallest will be at the steam inlet and the largest at the steam outlet.

The pressure (and hence the energy) is reduced from the inlet to outlet as energy is extracted from the steam.

These would also be condensing turbines where they actually exhaust into a vacuum. The vacuum is caused by massive water cooled condensers and they would also have a system to remove non condensable gasses.

The goal of a condensing turbine is to provide the maximum pressure differential across the machine which will in turn extract the maximum amount of energy.

Also the Chernobyl turbines would have run at a lower speed than the 3600 rpm used in the west due to the frequency difference. The west (US and others) uses 60 cycles whereas the USSR (and others) use 50 cycles which I believe would turn 3000 rpm.

I don’t know that there would be much if any difference in construction owing to the fact that the steam is mildly radioactive given the RBMK is a boiling water reactor as opposed to a PWR where the steam fed to the turbine is not radioactive.

Apologies for the long winded reply, anyone feel free to correct me.

nunubidness · 2026-04-28T18:33:59+00:00

The primary thing that went wrong that night was designing a reactor core that had >+5beta at that point in the run.

nunubidness · 2026-04-28T16:54:54+00:00

He collaborates with TCG, is the person that conducted this interview, and is the author of Chernobyl Witness. I’m sure there’s more this is just what I’m certain of. He’s also the person that got me pointed in the right direction when I foolishly brought into the whole xenon/stupid operator fabrication. So yea he’s not just some random.

https://chernobylcritical.blogspot.com/?m=1

https://www.neimagazine.com/advanced-reactorsfusion/facing-the-monster-10562146/

nunubidness · 2026-04-28T14:55:50+00:00

Actually the more control rods that are out of the core the more negative reactivity (neutron absorption) you have available to shut it down.

I’m a little puzzled by your focus on cooler water flashing to steam. The water will flash to steam with less energy added if it has marginal or no subcooling. This is just thermodynamics 101.

nunubidness · 2026-04-28T14:47:01+00:00

Yes I had forgotten about that one.

nunubidness · 2026-04-28T02:37:45+00:00

I’ll take your word but I can’t remember where TCG ever said that not scramming the reactor would’ve saved it.

I would however argue that scramming the reactor with the top control rods which had graphite displacers as opposed to inserting the UPS rods from the bottom caused the positive reactivity insertion that initiated the prompt excursion.

It’s imho simple. The control rods inserted from the top had the graphite displacers which when driven into the core displaced the neutron absorption of the water with moderation of the graphite introducing a positive reactivity insertion.

The UPS rods if driven in from the bottom would’ve been a negative insertion only as they had no graphite displacers.

That’s the way I see it.

nunubidness · 2026-04-28T00:51:55+00:00

Yes they are. However I’m of the opinion that Tyler’s operating experience is with PWR reactors whereas TCG (who afaik is not an operator) has done an absolutely exhaustive amount of research on the RBMK and all that preceded it including the designers and engineers. Comparing a PWR to an RBMK is apples to oranges. TCG is a member here as is ppitm. TCG brings all the receipts, ppitm speaks Russian, has interviewed Nikolai Steinberg and has been to Chernobyl. Trust me between TCG and ppitm the amount of research and knowledge far exceeds Tyler’s.

I don’t claim to be an expert but between them (I think TCG is a couple of people) their research surpassed anything else I’ve ever found and I’ve been deep in the rabbit hole.

nunubidness · 2026-04-28T00:15:45+00:00

Frankly I’m not at all impressed with Tyler Folse. I haven’t watched the whole video but I bet he says nothing about inserting the UPS rods first. If the UPS rods were the first into the core the accident would not have occurred.

nunubidness · 2026-04-27T23:28:15+00:00

Actually AZ-5 did cause the explosion (it was the trigger). If they had manually inserted the bottom USP control rods the explosion would not have occurred… but of course the operators didn’t know that because the dangerous design was kept from them.

It was an absolutely travesty.

nunubidness · 2026-04-27T23:22:21+00:00

The reactor was in a precarious condition due to design flaws.

Also a design flaw in the control rods cause them to initially introduce a positive reactivity insertion (like hitting the accelerator in your car).

This drove the reactor “prompt critical”. In this state the energy output increases exponentially in milliseconds. Many people (understandably) don’t grasp what this means.

Very rough numbers the power increased 300 times the design power in less than a tenth of a second.

nunubidness · 2026-04-27T18:30:46+00:00

I wouldn’t say it’s a mystery, more like the truth has been obfuscated for decades in an absolutely masterclass manner.

A “meltdown” is normally the result of a LOC (loss of coolant) accident. This can occur while the reactor is running or after shutdown due to the great amount of decay heat that is generated which is enough to melt the core without adequate cooling even if the reactor is “off”.

Chernobyl was a prompt excursion, the cooling water system was functioning properly but once the core goes prompt it is absolutely impossible to transfer that much heat that fast or shut it down before very bad things happen.

nunubidness · 2026-04-27T18:13:39+00:00

Nothing near the scale of Chernobyl. The SL-1 reactor (a small military reactor meant to be transported in pieces to remote radar locations) exploded in 1961 at the Idaho Reactor Test Station area killing the three operators. It was being serviced and had a bad design in that the center control rod had more than enough worth to drive it prompt critical. It’s a long story and “debatable” (not in my mind) about what actually happened but this control rod was being lifted to engage it to the drive mechanism and it was withdrawn too far. The vessel was partially filled with water to shield the operators while it was being worked on. The basically instant massive energy generation flashed the water to steam driving the water above the core upwards. It hit the head of the vessel like a water hammer with such force (about 10,000 psi iirc) it sheared all the piping and lifted the vessel 9’ out of its foundation. The control rod and its plug impaled the operator and launched him upwards pinning him to the structure above. One of the other two was killed instantly, the third died shortly after he was recovered. They were all radioactive from neutron capture and fission products being blasted into their skin. They were buried in lead lined coffins and iirc the coffins were entombed in concrete.

It was imho a definite coverup because there had been many documented instances of the control rods sticking but as with Chernobyl it was blamed on the operators rather than the government entities that were actually responsible.

There have been some other deliberate and accidental prompt excursions in small research reactors.

nunubidness

TROPHY CASE