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Syd Midnight posted:I'm reading Atomic Accidents by James Mahaffey (on the recommendation of the thread) and it's great. I just got through the atomic aircraft bit, and one of their experimental reactors for heating the engine airflow had the first atomic oopsie caused solely by instrumentation error, not human error. The reactor monitored its criticality by measuring gamma ray output, but past a certain threshold the gamma ray detector was drawing so much power that the voltage on its circuit dropped and its weakening output signal was filtered out as line noise, causing a positive feedback loop until the core melted down. The reactor vessel held, but they had to fill the surrounding containment structure with mercury as shielding in order to get close enough to work on it. This required 75% of the world markets supply of liquid mercury, and afterwards they had to resell it slowly to avoid destroying the market. What kind of gamma detector was it? Scintillators with photomultiplier tubes, which were the hottest of poo poo for gamma ray detection in the late 40s and 50s can suffer that problem if the photocurrent gets too high, especially if the dynode supply is just a basic resistor divider. It's more typical for reactor designs to work out their power output from measuring neutron flux in and out of core with instruments that don't really suffer from paralyzation issues at high fluxes, like ionization chambers and unpowered detectors based on neutron capture reactions. I guess all of this stuff had to be learned somehow, sometimes the hard way 
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Jun 13, 2018 15:58
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BattleMaster posted:What kind of gamma detector was it? Scintillators with photomultiplier tubes, which were the hottest of poo poo for gamma ray detection in the late 40s and 50s can suffer that problem if the photocurrent gets too high, especially if the dynode supply is just a basic resistor divider. Ion chamber, apparently. The gamma and thermal flux were so closely correlated that the ion chamber output was amplified and used to automatically operate the control rod motors. The line was filtered so the electric motors starting and stopping wouldn't contaminate the signal. Everything was working fine until quote:That filter in the high-voltage cable had unfortunately limited the number of electrons per second that could travel through the wire. That was fine, as long as not too many electrons were needed to register the number of gamma rays per second that were traversing the ion chamber. At the higher power level, at which the equipment had never been tested, the gamma flux overwhelmed the ability of the power supply to keep up. The current demand from the chamber was so high, the voltage dropped, and the detector stopped detecting. The automatic system interpreted this as a power loss, and it tried to compensate for it by pulling the controls. The power climb accelerated until the engine was, as we say, outside its operating envelope. Syd Midnight has a new favorite as of 20:36 on Jun 13, 2018 |
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Jun 13, 2018 20:33
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Phy posted:A giant airborne aircraft carrier, and it was nuclear? I know we were just joking about Ace Combat, but seriously, this is some motherfucking Belkan poo poo. I think this was a Lockheed study as to what the biggest possible aircraft you could make using the technology of the time.
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Jun 13, 2018 20:41
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Syd Midnight posted:Ion chamber, apparently. The gamma and thermal flux were so closely correlated that the ion chamber output was amplified and used to automatically operate the control rod motors. The line was filtered so the electric motors starting and stopping wouldn't contaminate the signal. Everything was working fine until So it was their filtering scheme that wrecked it. I wouldn't have expected it to be an ion chamber because usually they get easier to work with as the radiation intensity increases.
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Jun 13, 2018 21:00
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I'm just picturing a molten core plopping out the bottom of an aircraft midflight. Uranium is pyrophoric, no? Will liquid uranium ignite on contact with air? Because a BURNING molten core falling out the aircraft would be even more hilariously bad.
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Jun 14, 2018 14:52
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Imagine being the unfortunate motherfucker that lands on.
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Jun 14, 2018 17:58
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MazeOfTzeentch posted:I'm just picturing a molten core plopping out the bottom of an aircraft midflight. Uranium is pyrophoric, no? Will liquid uranium ignite on contact with air? Because a BURNING molten core falling out the aircraft would be even more hilariously bad. Seems quibbling anyway. Noticing an oxidation reaction on a fuel escape is like counting sun spots with your bare eyes.
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Jun 14, 2018 18:06
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Bertrand Hustle posted:Imagine being the unfortunate motherfucker that lands on. i'm more concerned about the unfortunate motherfuckers in the general vicinity of the core when it lands but not directly below it. at least if it a thousand pounds of molten uranium land on your head you probably get spared turning into a walking ghost with all your skin falling off
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Jun 14, 2018 18:29
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I noticed you said "probably."
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Jun 15, 2018 03:56
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You could always get hit at just the right angle that you survive the initial impact. Happens with meteors sometimes. Maybe it just breaks your foot, then you have to deal with a broken foot and nth degree radiation poisoning.
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Jun 15, 2018 14:36
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Oh, just GREAT. I'm a walking corpse AND my new haircut is all hosed up!
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Jun 15, 2018 17:11
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Hremsfeld posted:I noticed you said "probably." It's not like we have a lot of experimental data on what happens if somebody gets brained by molten uranium.
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Jun 15, 2018 17:17
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Wasn't there a dude impaled to a roof by a fuel rod who they determined lived for a bit after it?
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Jun 15, 2018 18:14
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Elmnt80 posted:Wasn't there a dude impaled to a roof by a fuel rod who they determined lived for a bit after it?
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Jun 15, 2018 18:20
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darthbob88 posted:Dunno about how long he lived afterwards, but I'm pretty sure you're referring to the SL-1 incident. Ah, yes. The murder-suicide by nuclear meltdown. wikipedia posted:The most common theories proposed for the withdrawal of the rod are (1) sabotage or suicide by one of the operators, (2) a suicide-murder involving an affair with the wife of one of the other operators, (3) inadvertent withdrawal of the main control rod, or (4) an intentional attempt to "exercise" the rod (to make it travel more smoothly within its sheath).[17][18] The maintenance logs do not address what the technicians were attempting to do, and thus the actual cause of the incident will never be known. The investigation took almost two years to complete.
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Jun 15, 2018 18:37
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darthbob88 posted:Dunno about how long he lived afterwards, but I'm pretty sure you're referring to the SL-1 incident. quote:All three men succumbed to injuries from physical trauma; however, the radiation from the nuclear excursion would have given the men no chance of survival even if they had not been killed by the explosion stemming from the criticality accident. We can at least assume the poor fellow was unconscious.
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Jun 15, 2018 18:37
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Specialists 
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Jun 15, 2018 18:47
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The poor fellow was impaled hard enough he was stuck to the ceiling. I severely doubt he lived very long after that.
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Jun 15, 2018 18:54
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Kazinsal posted:Ah, yes. The murder-suicide by nuclear meltdown. It might have been that, or it may have gotten jammed in place by a piece of boron and he pulled way too hard trying to get it unstuck, but I like James Mahaffey's unusually detailed but extremely believable pet theory: control rod guy was in a bad mood, and was annoyed that the Air Force guy was just standing around looking at his radiation detector and talking about how much more dangerous the Air Force's air-cooled reactor was, so he decided to pull the 80-100 lb. control rod up a few extra inches to make it go critical for a few milliseconds, thereby causing the Air Force guy to poo poo himself. After all, he'd been assured that it was an inherently failsafe reactor design. So he gave it a good heave but the instant it went prompt critical a blast of steam pushed against the control rod causing him to pull it up too far. Like when someone pulling against your grasp and you suddenly let go so they hit themselves in the face. Suicide seems more likely, but that's just the kind of dumb poo poo you'd expect to be the cause of a nuclear disaster. In any case, someone should have seen it coming. When the original BORAX reactor was retired, the engineers decided to blow the control rods out of the core with compressed air just to see what would happen. It's not often you get the chance to do something like that. What happened was not so much an excursion as a fizzle. https://www.youtube.com/watch?v=3zR13v-m7yk&t=708s quote:Lichtenberger hit the EJECT CONTROLS button. KABOOM! Up she went with the force equivalent of 70 pounds of high explosive in the reactor vessel. A total energy release of 80 megajoules had been expected. They got 135 megajoules instead, and this inaccurate prediction instantly qualified the test as a nuclear accident. The little reactor that usually shed energy at the rate of 1 watt ramped up to 19 billion watts with a minimum period of 2.6 milliseconds. In all other tests of explosive steaming, the thing would send up a geyser of water droplets, sparkling in the western sun. This time the core melted instantly and homogenized into a vertical column of black smoke. A shock wave rippled through the floor of the control trailer. They concluded that Boiling Water Reactors were safe enough to be operated by unsupervised military personnel because there is simply no way for them to melt down, catch fire, or have a catastrophic excursion unless someone physically yanks out the main control rod. I don't know why they did not realize that this meant that it was absolutely loving inevitable that sooner or later, someone would do exactly that.
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Jun 16, 2018 03:20
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All the official reporting I’ve ever read about SL-1 includes none of those many many dumb theories about the guy commuting suicide or jealous affairs. Or trying to scare the other guy, what? I’ve had work classes taught on nuclear accidents and each one included SL-1 among the others and each one had the same exact reason for the accident. That reason is a very Occam’s razor answer and not at all flashy or optimistic about the safety of reactor design at the time. But I’m not going to say more because I can’t rememer what details were and were not public.
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Jun 16, 2018 03:34
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M_Gargantua posted:were not public. No one's going to fall for the coy "I know nuclear secrets and you don't" act these days now that we're all grown up and know all of this stuff is in a book or on the internet edit: I'm a civilian nuclear engineer but we definitely studied SL-1 and what could be learned about safety and design from it BattleMaster has a new favorite as of 03:45 on Jun 16, 2018 |
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Jun 16, 2018 03:39
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I say that because I was in the Navy nuclear program and then Bechtel and am bound by NDA's indefinitely. None of the actual public reports talk about the silly theories though.
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Jun 16, 2018 03:55
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Yeah, better to say "no comment" than post totally declassified info that might get you Looked At. (Seriously, my mom's BFF's son is a senior enlisted Navy nuc, and all he'll say to his mother about his job is "I'm a shift foreman in the reactor room on [ship].") But also fun to tell us you know things you can't talk about.
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Jun 16, 2018 05:07
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Bad Angus! Bad!
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So, I looked up SL-1, and holy poo poo, I used to work there. Like, not back when SL-1 existed of course, but the Idaho National Lab. I ended up helping build a road so they wouldn't have to close down the normal ones when removing nuclear waste. This explains why all of the terrain around the roadways has "Danger: Radiation" every 50 feet or so on the fencing.
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Jun 21, 2018 10:14
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I grew up in Idaho and am bothered that it was only after moving out of state that I discovered they did something cool, like make most of the refined plutonium for the nation and NASA or had the highest concentration of nuclear reactors, including the first productive reactors and first nuclear submarine manufacturing facilities. INL has like a $1b/year budget which almost what they spend on education per year for the entire state. Too bad the rest of the state sucks for anything except looking beautiful.
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Jun 21, 2018 14:59
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Metal Geir Skogul posted:I grew up in Idaho and am bothered that it was only after moving out of state that I discovered they did something cool, like make most of the refined plutonium for the nation and NASA or had the highest concentration of nuclear reactors, including the first productive reactors and first nuclear submarine manufacturing facilities. INL has like a $1b/year budget which almost what they spend on education per year for the entire state. Potatoes. That's really it.
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Jun 21, 2018 15:35
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iospace posted:Potatoes. I hear there's a grilled cheese truck in Coeur d'Alene that's worth going to Idaho for. Will report back if I ever get to eat there.
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Jun 21, 2018 16:35
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Metal Geir Skogul posted:Too bad the rest of the state sucks for anything except looking beautiful. I lived down in Pocatello. There is nothing pretty there. The place is in fact so boring that there was a law once upon a time that mandated smiling. It was a legal obligation.
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Jun 21, 2018 19:17
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Rorac posted:I lived down in Pocatello. There is nothing pretty there. The place is in fact so boring that there was a law once upon a time that mandated smiling. It was a legal obligation. Holy poo poo, you're not kidding. Happiness is mandatory, citizens! posted:In 1948, the Mayor of the City of Pocatello, George Phillips, passed an ordinance making it illegal not to smile in Pocatello. The "Smile Ordinance" was passed tongue in cheek as a result of an exceptionally severe winter, which had dampened the spirit of city employees and citizens alike. And as far as I can tell the ordinance was never revoked.
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Jun 21, 2018 19:32
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iospace posted:Potatoes. Idaho has pretty sweet mountain forests and lakes.
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Jun 21, 2018 20:01
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Dirt Road Junglist posted:I hear there's a grilled cheese truck in Coeur d'Alene that's worth going to Idaho for. Will report back if I ever get to eat there. oh really? I'm gonna be heading through there at the beginning of next month
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Jun 21, 2018 20:21
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MazeOfTzeentch posted:oh really? I'm gonna be heading through there at the beginning of next month Meltz Grilled Cheese They look like yet another XXXTREME FOOD trend that you'd see on Diners, Drive Ins and Dives, but they actually pull it together. The potsticker grilled cheese isn't the best, but it's worth trying once because there is no way on god's green earth it should be edible, and instead it's a solid 8/10 sandwich. I can highly recommend the bahn mi, the cubano, and the huckleberry heaven (White cheddar, short ribs, caramelized onions, huckleberry bbq sauce and horshradish aioli). Protip: Do not order a full sandwich unless you're sharing or are EXTREMELY hungry. The 1/2 sandwich combo is a better way to go. Also, they just changed to being closed Sunday's FYI.
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Jun 21, 2018 23:06
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Rorac posted:I lived down in Pocatello. There is nothing pretty there. The place is in fact so boring that there was a law once upon a time that mandated smiling. It was a legal obligation. TooMuchAbstraction posted:And as far as I can tell the ordinance was never revoked. Friend Computer knows best! 
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Jun 21, 2018 23:25
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Relentless posted:Meltz Grilled Cheese Similar PROTIP: if the waitress at the Boryspil Airport pizza place says, in response to your question about the size of the pizzas, "Is not big. A child could eat!" she is lying through her teeth and you should definitely NOT order one per person. It is plenty of pizza for two grown adults and I do not even want to know what kind of mutant children they're growing in loving Ukraine these days.
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Jun 22, 2018 00:56
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I've contemplated moving to Idaho Falls for work (nuclear), from the times I've visited it doesn't seem too bad. Being close to places like Grand Targhee and Jackson Hole is a big plus for me. Also, I've literally never heard the theory about the dude at SL-1 intentionally trying to cause a brief criticality to scare the other guy. That's somehow even dumber than the love triangle / suicide theory.
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Jun 22, 2018 00:57
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LostCosmonaut posted:I've contemplated moving to Idaho Falls for work (nuclear), from the times I've visited it doesn't seem too bad. Being close to places like Grand Targhee and Jackson Hole is a big plus for me. If you're LDS you'll love it.
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Jun 22, 2018 00:58
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Dirt Road Junglist posted:Similar PROTIP: if the waitress at the Boryspil Airport pizza place says, in response to your question about the size of the pizzas, "Is not big. A child could eat!" she is lying through her teeth and you should definitely NOT order one per person. It is plenty of pizza for two grown adults and I do not even want to know what kind of mutant children they're growing in loving Ukraine these days. Maybe she thought you were one of those Americans who is used to routinely downing 2000 calories in a single meal.
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Jun 22, 2018 01:02
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Dirt Road Junglist posted:Similar PROTIP: if the waitress at the Boryspil Airport pizza place says, in response to your question about the size of the pizzas, "Is not big. A child could eat!" she is lying through her teeth and you should definitely NOT order one per person. It is plenty of pizza for two grown adults and I do not even want to know what kind of mutant children they're growing in loving Ukraine these days. She's not a native speaker, it's a common mistake to reverse subject and object.
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Jun 22, 2018 01:02
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Mustached Demon posted:If you're LDS you'll love it. Seriously the only place with more Mormons per capita is Utah.
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Jun 22, 2018 01:04
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TooMuchAbstraction posted:Maybe she thought you were one of those Americans who is used to routinely downing 2000 calories in a single meal. have you seen the loving calorie count on a single Dairy Queen strawberry cheesequake Blizzard?  I mean, I love the things but there's two thirds of your 2k calorie count right there in a cup.
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Jun 22, 2018 01:23
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