WEBVTT 00:00:00.000 --> 00:00:02.160 Welcome back to the Deep Dive. Today we are focusing 00:00:02.160 --> 00:00:06.280 all our attention on April 26th, 1986. A date 00:00:06.280 --> 00:00:08.519 etched in history. Definitely. The location. 00:00:08.800 --> 00:00:11.259 The Chernobyl nuclear power plant, specifically 00:00:11.259 --> 00:00:15.599 Unit 4, right beside the planned city of Pripyat. 00:00:15.660 --> 00:00:18.399 And what happened there in the early hours was 00:00:18.399 --> 00:00:22.149 just... Seismic. Yeah. An explosion. So catastrophic, 00:00:22.210 --> 00:00:24.890 it remains one of only two incidents ever rated 00:00:24.890 --> 00:00:27.089 level seven. That's the absolute maximum severity 00:00:27.089 --> 00:00:29.129 on the international nuclear event scale. Right. 00:00:29.170 --> 00:00:31.050 And, you know, when you look at the sheer cost, 00:00:31.390 --> 00:00:33.649 Chernobyl is in a league of its own. You mean 00:00:33.649 --> 00:00:36.530 financially? Yeah, absolutely. Our sources confirm 00:00:36.530 --> 00:00:38.929 it's the single most expensive disaster in history. 00:00:39.009 --> 00:00:41.609 Yeah. Total estimated costs, containment, health 00:00:41.609 --> 00:00:44.920 fallout, economic impact. It's staggering. Over 00:00:44.920 --> 00:00:47.780 700 billion U .S. dollars. Wow. That number is 00:00:47.780 --> 00:00:49.740 hard to even grasp. It really challenged everything, 00:00:49.880 --> 00:00:52.399 didn't it? Political systems, science. Fundamentally, 00:00:52.399 --> 00:00:54.600 it forced a reckoning. So our mission today is 00:00:54.600 --> 00:00:56.640 to take this, well, this mountain of source material, 00:00:56.920 --> 00:00:59.780 the reports, the declassified files, scientific 00:00:59.780 --> 00:01:02.659 analyses, and try to piece together a clear narrative. 00:01:02.920 --> 00:01:05.640 It's complex. How did a safety test? A test designed 00:01:05.640 --> 00:01:08.700 specifically to improve safety. Exactly. How 00:01:08.700 --> 00:01:11.859 did that lead to the reactor's complete destruction? 00:01:12.430 --> 00:01:15.209 The core meltdown. And releasing, what was it, 00:01:15.290 --> 00:01:18.670 400 times more radioactive material than Hiroshima 00:01:18.670 --> 00:01:21.390 and Nagasaki combined. That's the estimate. It's 00:01:21.390 --> 00:01:23.609 almost unbelievable. It wasn't just one mistake, 00:01:23.709 --> 00:01:26.329 though. That's key. Right. It was systemic. Systemic 00:01:26.329 --> 00:01:30.409 flaws, yeah. Institutional denial is where engineering 00:01:30.409 --> 00:01:33.349 failure met, well, a kind of human arrogance, 00:01:33.549 --> 00:01:35.989 almost. So to understand the catastrophe, we 00:01:35.989 --> 00:01:38.120 have to start at the beginning. We have to. with 00:01:38.120 --> 00:01:41.159 the reactor itself, the RBMK design, and the 00:01:41.159 --> 00:01:43.560 dangers literally built into it. Okay, let's 00:01:43.560 --> 00:01:45.719 get into this. Nuclear reactors make heat through 00:01:45.719 --> 00:01:48.420 fission, obviously. But the critical thing, even 00:01:48.420 --> 00:01:51.599 after shutdown, you still need cooling. Absolutely 00:01:51.599 --> 00:01:54.200 critical. It's because of decay heat. Explain 00:01:54.200 --> 00:01:56.640 that a bit. Decay heat. So even when the main 00:01:56.640 --> 00:01:58.980 chain reaction stops, the leftover bits, the 00:01:58.980 --> 00:02:00.519 fission products, and the fuel, they're still 00:02:00.519 --> 00:02:02.980 radioactive. They keep decaying and releasing 00:02:02.980 --> 00:02:05.180 heat. And that's significant? Yeah, yeah. About 00:02:05.180 --> 00:02:08.400 6 % of the reactor's full thermal power. Now, 00:02:08.400 --> 00:02:11.639 6 % sounds small, maybe. But in a massive reactor 00:02:11.639 --> 00:02:14.939 like Chernobyl's Unit 4. Which was 3 ,200 megawatts 00:02:14.939 --> 00:02:18.439 thermal. Yeah. That 6 % is more than enough energy 00:02:18.439 --> 00:02:21.199 to cause a core meltdown if your coolant stops 00:02:21.199 --> 00:02:24.199 flowing. Catastrophic overheating. And the RBMK 00:02:24.199 --> 00:02:26.520 needed a lot of coolant flow. Just immense amounts. 00:02:26.699 --> 00:02:30.199 These RBMK -1000s were giants. They used ordinary 00:02:30.199 --> 00:02:33.080 water circulated by these huge electrically driven 00:02:33.080 --> 00:02:35.680 pumps. How much water are we talking? The documentation 00:02:35.680 --> 00:02:39.719 points to over 45 million liters per hour per 00:02:39.719 --> 00:02:42.460 reactor, just to keep things stable across all 00:02:42.460 --> 00:02:44.639 those individual fuel channels. It's a staggering 00:02:44.639 --> 00:02:47.599 volume, which demands constant, reliable electricity. 00:02:47.919 --> 00:02:49.960 Exactly. And that brings up the nightmare scenario. 00:02:50.680 --> 00:02:52.780 A station blackout. What happens if the grid 00:02:52.780 --> 00:02:54.500 goes down? How do you keep those vital pumps 00:02:54.500 --> 00:02:56.539 running? Okay, so that's the safety gap they 00:02:56.539 --> 00:02:58.960 were worried about. Precisely. In a total blackout, 00:02:58.960 --> 00:03:01.360 you've got backup diesel generators, but there's 00:03:01.360 --> 00:03:04.500 a lag. How long? Between 60 and 75 seconds for 00:03:04.500 --> 00:03:07.060 them to spool up to full power. And you needed 00:03:07.060 --> 00:03:09.919 that full power 5 .5 megawatt just for one main 00:03:09.919 --> 00:03:12.500 pump. A whole minute or more with potentially 00:03:12.500 --> 00:03:14.870 no cooling. That's the window of vulnerability, 00:03:15.189 --> 00:03:18.389 that minute where decay heat could just skyrocket 00:03:18.389 --> 00:03:21.110 temperatures. And bridging that specific 60 -second 00:03:21.110 --> 00:03:25.030 gap, that was the entire point of the test on 00:03:25.030 --> 00:03:27.590 April 26th. That was the goal. It was purely 00:03:27.590 --> 00:03:30.169 theoretical at that stage. Could the turbine 00:03:30.169 --> 00:03:34.229 itself help? The idea was harnessing the turbine's 00:03:34.229 --> 00:03:37.949 rotational momentum, its inertia. As it spins 00:03:37.949 --> 00:03:40.389 down after the steam is cut off, could it generate 00:03:40.389 --> 00:03:43.139 enough leftover electricity? Enough to power 00:03:43.139 --> 00:03:45.979 those main coolant pumps. For at least 45 seconds. 00:03:46.039 --> 00:03:48.740 That was the target. To cover most of that diesel 00:03:48.740 --> 00:03:51.560 startup time. Okay, makes sense in theory. But 00:03:51.560 --> 00:03:53.159 this wasn't the first time they'd tried this 00:03:53.159 --> 00:03:55.879 test. No, far from it. The sources highlight 00:03:55.879 --> 00:03:58.080 a really troubling history here. Attempts in 00:03:58.080 --> 00:04:02.939 82, 84, 85, they all failed. Failed how? Like 00:04:02.939 --> 00:04:05.759 explosions? No, not catastrophically back then. 00:04:05.860 --> 00:04:08.460 More technical glitches. Problems keeping the 00:04:08.460 --> 00:04:10.860 excitation voltage stable on the generator. Or 00:04:10.860 --> 00:04:12.539 sometimes the recording equipment just didn't 00:04:12.539 --> 00:04:14.479 work properly. But the fact that they kept trying. 00:04:14.759 --> 00:04:17.019 It suggests a strong push from somewhere. Maybe 00:04:17.019 --> 00:04:19.360 pressure to just pick the box, show full safety 00:04:19.360 --> 00:04:21.439 compliance, you know. What's really alarming, 00:04:21.500 --> 00:04:24.040 though, is the note that the people writing the 00:04:24.040 --> 00:04:26.639 test procedure, they didn't even know how the 00:04:26.639 --> 00:04:29.899 RBMK behaved under these specific low power conditions. 00:04:30.339 --> 00:04:32.620 That's more than just a glitch. That's a systemic 00:04:32.620 --> 00:04:35.300 failure. Yeah. A huge institutional blind spot, 00:04:35.399 --> 00:04:37.720 almost denial. And the whole environment. The 00:04:37.720 --> 00:04:40.600 sources mention a general... Lack of safety culture. 00:04:40.899 --> 00:04:42.819 Yeah. And we see chilling proof of that with 00:04:42.819 --> 00:04:45.319 the emergency core cooling system, the ECCS. 00:04:45.399 --> 00:04:47.899 The failsafe. What happened there? It's designed 00:04:47.899 --> 00:04:50.019 to flood the core with water if a major pipe 00:04:50.019 --> 00:04:52.579 breaks. Standard procedure. But they manually 00:04:52.579 --> 00:04:55.079 disabled it for the test preparations. But then 00:04:55.079 --> 00:04:57.420 the test got delayed. The key of grid controller 00:04:57.420 --> 00:05:00.839 asked them to wait. And that ECCS system, it 00:05:00.839 --> 00:05:03.540 was left disabled for 11 hours. 11 hours running 00:05:03.540 --> 00:05:06.160 without that ultimate safety net. Exactly. Yeah. 00:05:06.240 --> 00:05:09.040 Now, the ECCS being off didn't cause the explosion 00:05:09.040 --> 00:05:12.279 directly, but operating a reactor like that without 00:05:12.279 --> 00:05:15.060 its fundamental last line of defense for half 00:05:15.060 --> 00:05:18.079 a day, it's just blatant disregard for protocol. 00:05:18.600 --> 00:05:20.500 cutting the seatbelt before a risky maneuver. 00:05:20.720 --> 00:05:23.060 Which brings us to the reactor's core design 00:05:23.060 --> 00:05:25.959 flaw, the thing that made the RBMK so uniquely 00:05:25.959 --> 00:05:28.899 dangerous. The positive void coefficient, yeah. 00:05:29.019 --> 00:05:31.500 Let's break that down. Why was this feature so 00:05:31.500 --> 00:05:34.040 hazardous? Well, first, you need to understand 00:05:34.040 --> 00:05:37.149 why it was built that way. Unlike Western reactors 00:05:37.149 --> 00:05:40.250 using water for both cooling and moderating neutrons. 00:05:40.589 --> 00:05:43.310 Moderating means slowing neutrons down for fission, 00:05:43.410 --> 00:05:45.870 right? Correct. The RBMK was different. It was 00:05:45.870 --> 00:05:49.149 a dual -purpose design. Not just power, but historically 00:05:49.149 --> 00:05:51.769 it was good for making weapons -grade plutonium. 00:05:51.850 --> 00:05:54.550 Ah. So it used graphite blocks as the main moderator. 00:05:54.769 --> 00:05:57.389 Big stacks of it. Okay, graphite moderates. What 00:05:57.389 --> 00:06:00.269 about the water then? In this setup, the water 00:06:00.269 --> 00:06:02.250 flowing through the fuel channels was primarily 00:06:02.250 --> 00:06:04.879 the coolant. but it also absorbed a significant 00:06:04.879 --> 00:06:07.839 number of neutrons. So water took neutrons out 00:06:07.839 --> 00:06:10.240 of the reaction. Yes. And here's the deadly quirk. 00:06:10.300 --> 00:06:12.620 A positive void coefficient means that when that 00:06:12.620 --> 00:06:15.819 water coolant boils and turns into steam, steam 00:06:15.819 --> 00:06:19.459 bubbles or voids, that steam is much less effective 00:06:19.459 --> 00:06:21.720 at absorbing neutrons than the liquid water it 00:06:21.720 --> 00:06:25.199 replaced. Oh, I see. So less water or more steam 00:06:25.199 --> 00:06:28.560 means fewer neutrons get absorbed. Leaving more 00:06:28.560 --> 00:06:32.439 neutrons free to cause more fission. Which generates 00:06:32.439 --> 00:06:35.860 more heat. Which causes more boiling, more steam. 00:06:36.240 --> 00:06:39.379 Exactly. A positive feedback loop. More boiling, 00:06:39.519 --> 00:06:42.740 more steam voids, higher reactivity, more heat, 00:06:42.759 --> 00:06:45.500 even more voiling. A runaway train. In certain 00:06:45.500 --> 00:06:48.240 situations, especially at low power, yes, it 00:06:48.240 --> 00:06:51.379 could accelerate catastrophically. Most modern 00:06:51.379 --> 00:06:55.259 reactors have a negative void collector. Boiling 00:06:55.259 --> 00:06:58.910 slows things down. a natural brake. The RBMK, 00:06:58.990 --> 00:07:01.589 in certain modes, had a built -in accelerator 00:07:01.589 --> 00:07:03.870 pedal for when things started to go wrong. So 00:07:03.870 --> 00:07:06.009 you have the dangerous design, the disabled safety 00:07:06.009 --> 00:07:08.949 systems, and bad timing throws another wrench 00:07:08.949 --> 00:07:11.779 in the works. The human element. That delay from 00:07:11.779 --> 00:07:14.199 the Kiev grid controller pushed the test off 00:07:14.199 --> 00:07:16.579 the experienced day shift. And onto the night 00:07:16.579 --> 00:07:18.639 shift. Who had much less time to prepare for 00:07:18.639 --> 00:07:20.980 this really delicate, complex experiment. It 00:07:20.980 --> 00:07:23.360 was actually in the control room. Key players. 00:07:23.819 --> 00:07:26.980 Anatoly Dyatlov, the deputy chief engineer. He 00:07:26.980 --> 00:07:29.319 was supervising, reportedly putting immense pressure 00:07:29.319 --> 00:07:31.759 on the crew to get the test done. Then Alexander 00:07:31.759 --> 00:07:34.269 Akimov, the unit shift supervisor. responsible 00:07:34.269 --> 00:07:37.050 for the reactor itself, and crucially, Leonid 00:07:37.050 --> 00:07:39.250 Toptunov, the senior reactor control engineer. 00:07:39.470 --> 00:07:41.930 How experienced was he? Barely. He was only 25 00:07:41.930 --> 00:07:44.310 and had just three months of working independently 00:07:44.310 --> 00:07:47.029 on that console. Inexperience plus high pressure. 00:07:47.529 --> 00:07:50.209 The recipe for disaster. And the first problem 00:07:50.209 --> 00:07:53.050 they hit wasn't instability. It was the power 00:07:53.050 --> 00:07:55.290 dropping like a stone. Right. They were aiming 00:07:55.290 --> 00:07:59.110 for 700 to 1 ,000 megawatts thermal for the test. 00:07:59.269 --> 00:08:02.209 They got down to 720 milliW, which was fine. 00:08:02.389 --> 00:08:04.829 But then. It just plummeted. Yeah. Unexpectedly. 00:08:04.829 --> 00:08:07.709 Down to maybe 30 milliW thermal or even less. 00:08:08.170 --> 00:08:10.610 Practically shut down. Why? What caused that? 00:08:10.810 --> 00:08:13.269 Something called xenon poisoning. Xenon, like 00:08:13.269 --> 00:08:16.430 the gas? Yeah, xenon -135. It's a byproduct of 00:08:16.430 --> 00:08:18.870 fission, and it's really good at absorbing neutrons, 00:08:18.910 --> 00:08:21.110 kind of like control rods do. It poisons the 00:08:21.110 --> 00:08:24.129 reaction. Okay. Normally, at high power, the 00:08:24.129 --> 00:08:26.529 neutron flux is so intense, it burns off this 00:08:26.529 --> 00:08:30.230 xenon as fast as it's created from decaying iodine 00:08:30.230 --> 00:08:32.830 -135. But when they lowered the power... The 00:08:32.830 --> 00:08:35.309 neutron flux dropped too. Exactly. So the xenon 00:08:35.309 --> 00:08:37.190 wasn't being burned off quickly enough. It built 00:08:37.190 --> 00:08:39.179 up... rapidly choking the reactor, soaking up 00:08:39.179 --> 00:08:40.840 all the neutrons. So the reactor just died down. 00:08:41.019 --> 00:08:42.419 Pretty much. And this is where the really bad 00:08:42.419 --> 00:08:44.960 decision started. Under pressure to get the power 00:08:44.960 --> 00:08:47.500 back up for the test. Demense pressure from Dyatlov. 00:08:47.960 --> 00:08:51.240 They decided to basically brute force it. Override 00:08:51.240 --> 00:08:54.480 the xenon poisoning. By pulling out control rods, 00:08:54.700 --> 00:08:57.879 lots of them, manually removing them far beyond 00:08:57.879 --> 00:09:01.120 safe limits to flood the core with enough neutrons 00:09:01.120 --> 00:09:03.879 to overcome the xenon absorption and get the 00:09:03.879 --> 00:09:06.620 power level back up. That sounds incredibly risky. 00:09:06.960 --> 00:09:10.080 It was beyond risky. It was reckless. By 12 .39 00:09:10.080 --> 00:09:12.860 a .m., they managed to nurse the power back up 00:09:12.860 --> 00:09:16.039 to about 160 milliJoules. Still way below the 00:09:16.039 --> 00:09:18.460 700 milliW they needed for the test. Way below. 00:09:18.700 --> 00:09:21.720 But the cost was stability. To get even that 00:09:21.720 --> 00:09:23.940 160 millioad, they had pulled out almost every 00:09:23.940 --> 00:09:27.500 single control rod. Out of 211, maybe only six 00:09:27.500 --> 00:09:29.220 or eight effective rods were left in the core. 00:09:29.379 --> 00:09:31.799 Wow. Plus, to try and manage temperatures, they 00:09:31.799 --> 00:09:33.919 were running the main coolant pumps way too fast. 00:09:34.240 --> 00:09:36.000 Excessively high flow rate. What did that do? 00:09:36.240 --> 00:09:38.139 It meant the water entering the core was already 00:09:38.139 --> 00:09:40.580 very close to boiling point. So you had almost 00:09:40.580 --> 00:09:43.139 no control rods left. And the coolant was prying 00:09:43.139 --> 00:09:45.200 to turn into steam at the slightest provocation. 00:09:45.620 --> 00:09:48.279 The reactor was hypersensitive to that void effect. 00:09:48.580 --> 00:09:51.639 A ticking time bomb. And the worst part, they 00:09:51.639 --> 00:09:54.279 didn't even know how dangerous it was. That's 00:09:54.279 --> 00:09:58.279 the damning institutional failure. The RBMK design 00:09:58.279 --> 00:10:02.039 lacked a crucial safety feature, real -time monitoring 00:10:02.039 --> 00:10:05.039 of the operational reactivity margin, the ORM. 00:10:05.240 --> 00:10:08.299 The ORM. Basically, a measure of how many effective 00:10:08.299 --> 00:10:10.860 control rods are inserted and how quickly the 00:10:10.860 --> 00:10:13.080 reactor could be shut down if needed. It tells 00:10:13.080 --> 00:10:14.700 you your safety margins. And they didn't have 00:10:14.700 --> 00:10:16.799 that reading. No real -time calculation available 00:10:16.799 --> 00:10:19.240 to them. They had absolutely no idea their ORM 00:10:19.240 --> 00:10:22.019 had dropped way below the mandatory minimum, 00:10:22.179 --> 00:10:24.500 which was equivalent to having at least 15 rods 00:10:24.500 --> 00:10:27.500 fully inserted. Regulations required an immediate 00:10:27.500 --> 00:10:30.720 shutdown if the ORM fell that low. But they couldn't 00:10:30.720 --> 00:10:32.639 see it. They were flying blind. Totally blind. 00:10:33.179 --> 00:10:35.340 On the very edge of criticality without a functioning 00:10:35.340 --> 00:10:37.899 speedometer or safety gauge. And in that state, 00:10:38.039 --> 00:10:42.059 they started the test. At 1 .23 and 4 seconds 00:10:42.059 --> 00:10:44.779 AM, they shut off the steam supply to the turbine. 00:10:44.879 --> 00:10:47.200 It started to coast down, just like the test 00:10:47.200 --> 00:10:49.720 plan intended. But the power to the pumps? Immediately 00:10:49.720 --> 00:10:52.240 started dropping as the turbine slowed, which 00:10:52.240 --> 00:10:54.019 slowed the water flow through the core. Less 00:10:54.019 --> 00:10:57.169 water flow. More steam. Those voids started forming 00:10:57.169 --> 00:10:59.610 rapidly. And that positive void coefficient, 00:10:59.970 --> 00:11:02.470 which had been sort of held in check by the massive 00:11:02.470 --> 00:11:04.830 water flow. Now it took over. It started driving 00:11:04.830 --> 00:11:07.409 the reaction rate up. Yeah. Power began to climb. 00:11:07.629 --> 00:11:08.970 They must have seen it on the control panel. 00:11:09.090 --> 00:11:11.269 Oh, yes. They realized they were losing control. 00:11:12.409 --> 00:11:16.889 At 1 .23 and 40 seconds, Akimov slammed the AZ 00:11:16.889 --> 00:11:20.429 -5 button. The emergency shut down. Scram. The 00:11:20.429 --> 00:11:22.389 last resort. Witnesses said the control room 00:11:22.389 --> 00:11:25.360 was calm, though. Maybe they thought, OK, test 00:11:25.360 --> 00:11:28.419 failed, shut it down, believing the AZ -5 would 00:11:28.419 --> 00:11:30.919 work. But it didn't. It did the exact opposite. 00:11:31.159 --> 00:11:33.419 And this is where the design flaw becomes utterly 00:11:33.419 --> 00:11:35.700 lethal. Even if the reactor hadn't been unstable, 00:11:36.000 --> 00:11:39.120 the AZ -5 itself was fundamentally flawed. OK, 00:11:39.220 --> 00:11:41.860 this is the core of it, the control rods. Why 00:11:41.860 --> 00:11:44.539 did pushing the shutdown button trigger the explosion? 00:11:44.940 --> 00:11:47.220 It's one of the most horrifying design flaws 00:11:47.220 --> 00:11:50.340 imaginable. The RBMK control rods weren't solid 00:11:50.340 --> 00:11:52.840 boron carbide, the stuff that absorbs neutrons. 00:11:53.000 --> 00:11:55.799 No. What were they? They had tips, about 1 .3 00:11:55.799 --> 00:11:58.059 meters long, made of graphite, the same stuff 00:11:58.059 --> 00:12:00.340 used as the moderator. Graphite tips on the neutron 00:12:00.340 --> 00:12:02.799 -absorbing rods. Why? It was meant to enhance 00:12:02.799 --> 00:12:05.019 the neutron economy when the rods were fully 00:12:05.019 --> 00:12:06.960 withdrawn, pushing water out of the channel. 00:12:07.740 --> 00:12:09.980 But when the rods were almost fully out, like 00:12:09.980 --> 00:12:12.840 they were that night, the space below the absorber 00:12:12.840 --> 00:12:14.639 part of the rod and the lower part of the core 00:12:14.639 --> 00:12:18.019 was filled with a column of water. Water, remember, 00:12:18.179 --> 00:12:21.480 absorbs neutrons. Right. So when they hit AZ 00:12:21.480 --> 00:12:24.240 -5, the rods start moving down. The graphite 00:12:24.240 --> 00:12:27.539 tip goes in first. It displaces that column of 00:12:27.539 --> 00:12:29.840 neutron -absorbing water below it. And graphite 00:12:29.840 --> 00:12:32.320 moderates neutrons. It doesn't absorb them well. 00:12:32.539 --> 00:12:34.440 Exactly. So for those first critical seconds 00:12:34.440 --> 00:12:36.960 of insertion, the graphite moving into the bottom 00:12:36.960 --> 00:12:39.480 of the core actually increased the neutron population 00:12:39.480 --> 00:12:42.059 and the reaction rate locally. It momentarily 00:12:42.059 --> 00:12:44.509 boosted the power. Instead of shutting it down. 00:12:44.610 --> 00:12:47.929 Precisely. A massive localized power surge right 00:12:47.929 --> 00:12:50.129 at the bottom of the core. This was the positive 00:12:50.129 --> 00:12:52.570 scram effect. Had anyone ever realized this could 00:12:52.570 --> 00:12:55.350 happen? Tragically, yes. It had been observed 00:12:55.350 --> 00:12:58.269 and documented at another RBMK plant back in 00:12:58.269 --> 00:13:02.909 1983. But that information, classified, never 00:13:02.909 --> 00:13:05.309 put into the operating procedures. The operators 00:13:05.309 --> 00:13:07.669 had no warning. Unbelievable. So the power surge 00:13:07.669 --> 00:13:11.870 was... Immediate and huge. Instantaneous. Seconds 00:13:11.870 --> 00:13:14.190 after the button push, the output rocketed. Yeah. 00:13:14.250 --> 00:13:17.330 It went way past 530 millidobby levothermal almost 00:13:17.330 --> 00:13:20.190 instantly. Some models suggest it might have 00:13:20.190 --> 00:13:22.490 spiked to 10 times the reactor's normal operating 00:13:22.490 --> 00:13:25.090 power before things physically broke apart. What 00:13:25.090 --> 00:13:28.070 broke first? The fuel rods themselves fractured 00:13:28.070 --> 00:13:30.870 from the thermal shock. The fuel channels ruptured 00:13:30.870 --> 00:13:33.090 violently. Leading to the first explosion. A 00:13:33.090 --> 00:13:35.710 massive steam explosion. The coolant instantly 00:13:35.710 --> 00:13:38.190 flashed a high -pressure steam mixing with fragmented 00:13:38.190 --> 00:13:41.509 fuel. It blew the reactor vessel apart. And the 00:13:41.509 --> 00:13:44.909 lid? The 1 ,000 -ton upper biological shield, 00:13:45.009 --> 00:13:47.309 they called it Elena, was ripped off and blasted 00:13:47.309 --> 00:13:48.870 straight up through the roof of the reactor building. 00:13:49.409 --> 00:13:51.149 Gone. Shaking all the cooling pipes with it. 00:13:51.230 --> 00:13:53.610 Severing everything. Guaranteeing the core was 00:13:53.610 --> 00:13:56.129 now exposed, open to the air. And then the second 00:13:56.129 --> 00:13:58.230 explosion just seconds later. Yeah, two or three 00:13:58.230 --> 00:14:01.230 seconds later. Even bigger. More powerful. estimated 00:14:01.230 --> 00:14:04.850 maybe 225 tons of TNT equivalent. What caused 00:14:04.850 --> 00:14:07.610 that one? It's still steam. That's debated. The 00:14:07.610 --> 00:14:09.570 consensus is likely further steam explosions, 00:14:09.750 --> 00:14:12.409 maybe hydrogen combustion. But this second blast 00:14:12.409 --> 00:14:15.490 did the final damage. It completely pulverized 00:14:15.490 --> 00:14:18.149 the core, ejected burning graphite blocks and 00:14:18.149 --> 00:14:20.669 fuel chunks hundreds of meters away. Which ironically 00:14:20.669 --> 00:14:22.549 stopped the chain reaction. By dispersing the 00:14:22.549 --> 00:14:25.950 fuel, yes, the nuclear reaction stopped. But 00:14:25.950 --> 00:14:28.759 it started a massive graphite fire. Fueled by 00:14:28.759 --> 00:14:30.759 the superheated graphite hitting the oxygen in 00:14:30.759 --> 00:14:32.480 the air. There are these accounts for people 00:14:32.480 --> 00:14:36.600 outside seeing strange lights. Alexander Yurchenko's 00:14:36.600 --> 00:14:38.860 account is chilling. He was just outside Unit 00:14:38.860 --> 00:14:42.860 4, saw this very beautiful, intense, laser -like 00:14:42.860 --> 00:14:44.940 beam of blue light shooting upwards from the 00:14:44.940 --> 00:14:47.720 destroyed reactor hall, flooding up into infinity. 00:14:48.039 --> 00:14:51.110 What was that? Ionized air glow. just a raw visual 00:14:51.110 --> 00:14:53.549 manifestation of the immense radiation and energy 00:14:53.549 --> 00:14:56.029 release physics made visible and terrifying. 00:14:56.250 --> 00:14:58.149 You mentioned the cause of the second blast is 00:14:58.149 --> 00:15:00.990 debated. What's the alternative theory? The nuclear 00:15:00.990 --> 00:15:03.710 fizzle hypothesis. It suggests the second blast 00:15:03.710 --> 00:15:06.169 wasn't just steam or hydrogen, but involved a 00:15:06.169 --> 00:15:08.889 very brief, uncontrolled nuclear chain reaction, 00:15:09.070 --> 00:15:12.049 a prompt criticality in a small part of the dispersed 00:15:12.049 --> 00:15:14.950 fuel. Like a tiny nuclear bomb? A very small, 00:15:15.009 --> 00:15:18.740 inefficient one, yes. A fizzle. The evidence 00:15:18.740 --> 00:15:23.559 cited is weirdly high. Xenon -135 levels measured 00:15:23.559 --> 00:15:27.299 days later, hundreds of kilometers away in Sharapovets. 00:15:27.379 --> 00:15:30.460 Why is that significant? Xenon -135 decays really 00:15:30.460 --> 00:15:33.710 fast. Half -life is only about eight hours. To 00:15:33.710 --> 00:15:37.210 detect it so far away so soon, proponents argue 00:15:37.210 --> 00:15:39.409 it must have been blasted high into the atmosphere 00:15:39.409 --> 00:15:42.210 very quickly, like in a nuclear event, rather 00:15:42.210 --> 00:15:44.610 than just drifting slowly from the fire plume. 00:15:44.690 --> 00:15:46.570 It's not the mainstream view, but it's out there. 00:15:46.730 --> 00:15:48.750 Meanwhile, back at the plant, firefighters are 00:15:48.750 --> 00:15:51.450 rushing in. Absolute heroes, but completely unaware 00:15:51.450 --> 00:15:53.850 of what they were facing. The first unit, led 00:15:53.850 --> 00:15:56.610 by Lieutenant Voldemar Pravik, they just saw 00:15:56.610 --> 00:15:58.549 a fire at the power plant. Their job was to put 00:15:58.549 --> 00:16:00.789 out the fire. Exactly. Prevented spreading to 00:16:00.789 --> 00:16:02.629 the adjacent Unit 3, which was still operating. 00:16:02.929 --> 00:16:05.090 Yeah. The big danger was the roof it was covered 00:16:05.090 --> 00:16:07.590 in bitumen, which is basically asphalt. Highly 00:16:07.590 --> 00:16:09.389 flammable. So they went up onto the roof of the 00:16:09.389 --> 00:16:11.429 turbine hall. Straight into hell. They found 00:16:11.429 --> 00:16:13.889 chunks of graphite scattered everywhere, burning 00:16:13.889 --> 00:16:17.190 debris, intense heat. And the radiation. Unimaginable 00:16:17.190 --> 00:16:19.690 levels. They described feeling pins and needles 00:16:19.690 --> 00:16:22.009 on their skin, a metallic taste in their mouths. 00:16:22.629 --> 00:16:24.950 Classic signs of massive radiation exposure. 00:16:25.789 --> 00:16:28.800 They didn't know it was a reactor itself. One 00:16:28.800 --> 00:16:30.820 firefighter famously said, we didn't know it 00:16:30.820 --> 00:16:32.240 was the reactor. Is it the reactor or not the 00:16:32.240 --> 00:16:34.740 reactor? They were getting fatal doses in minutes. 00:16:35.019 --> 00:16:37.860 Compounding this tragedy was the failure to even 00:16:37.860 --> 00:16:40.799 measure the radiation accurately at first. Utter 00:16:40.799 --> 00:16:43.159 chaos and denial. The control room instruments 00:16:43.159 --> 00:16:46.340 were useless off the scale. Most portable decimeters 00:16:46.340 --> 00:16:49.299 they had were low range, only up to about 3 .6 00:16:49.299 --> 00:16:52.279 rungens per hour. They maxed out instantly. Were 00:16:52.279 --> 00:16:55.610 there any high range detectors? Yes. One capable 00:16:55.610 --> 00:16:58.049 of reading up to 1 ,000 R -second, a lethal dose, 00:16:58.190 --> 00:17:00.889 very quickly. But it was either locked away, 00:17:00.990 --> 00:17:02.669 couldn't be found, or was buried in the debris. 00:17:02.850 --> 00:17:04.430 They couldn't get an accurate reading. Which 00:17:04.430 --> 00:17:06.910 led Akimov, the shift supervisor... To refuse 00:17:06.910 --> 00:17:08.730 to believe the reactor core was actually destroyed. 00:17:08.809 --> 00:17:11.950 He saw the damage, the graphite, but the available 00:17:11.950 --> 00:17:14.750 low readings contradicted it. He clung to the 00:17:14.750 --> 00:17:16.829 idea the reactor vessel was intact. And sent 00:17:16.829 --> 00:17:19.849 his men. Sent his crew members totally unprotected 00:17:19.849 --> 00:17:22.789 into highly radioactive areas to manually open 00:17:22.789 --> 00:17:25.450 water valves, trying to pump cooling water into 00:17:25.450 --> 00:17:27.569 what he thought was a damaged but intact core. 00:17:27.769 --> 00:17:30.109 A fatal decision based on bad information. Bad 00:17:30.109 --> 00:17:32.809 astrophic. Those workers received lethal doses 00:17:32.809 --> 00:17:36.210 almost immediately. Akimov himself, Toptunov, 00:17:36.369 --> 00:17:38.430 many of the firefighters and plant workers who 00:17:38.430 --> 00:17:41.750 were there in those first hours. They died agonizing 00:17:41.750 --> 00:17:44.349 deaths from acute radiation syndrome, mostly 00:17:44.349 --> 00:17:47.329 within three weeks. So the immediate horror of 00:17:47.329 --> 00:17:50.549 the explosion gives way to denial, political 00:17:50.549 --> 00:17:53.329 denial from the Soviet Union. A culture of secrecy 00:17:53.329 --> 00:17:55.950 that cost precious time. The explosion was 1 00:17:55.950 --> 00:17:59.509 .23 a .m. Saturday. The world didn't know officially 00:17:59.509 --> 00:18:02.349 until Monday, April 28th. And it wasn't the Soviets 00:18:02.349 --> 00:18:05.190 who broke the news. No, it was Sweden. Workers 00:18:05.190 --> 00:18:07.329 at the Forsmark nuclear power plant over 1 ,000 00:18:07.329 --> 00:18:09.769 kilometers away set off radiation alarms just 00:18:09.769 --> 00:18:11.750 going into work. Their shoes were contaminated. 00:18:12.029 --> 00:18:14.609 Sweden demanded answers, and that forced Moscow's 00:18:14.609 --> 00:18:16.670 hand. And Pripyat, the city built for the plant 00:18:16.670 --> 00:18:19.210 workers, 50 ,000 people living right next door. 00:18:19.349 --> 00:18:22.470 They weren't evacuated for 36 hours. 36 agonizing 00:18:22.470 --> 00:18:25.269 hours breathing contaminated air. And when the 00:18:25.269 --> 00:18:27.230 evacuation finally happened... It was under false 00:18:27.230 --> 00:18:29.490 pretenses. Beased out, told it was temporary. 00:18:29.809 --> 00:18:32.369 Just for three days, they said. Pack only essentials. 00:18:32.730 --> 00:18:36.920 So people left. Everything. Pets, photos, documents. 00:18:37.279 --> 00:18:39.940 Everything. Believing they'd be right back. The 00:18:39.940 --> 00:18:42.680 initial 10 -kilometer evacuation zone quickly 00:18:42.680 --> 00:18:47.079 became 30 kilometers. Eventually, 135 ,000 people 00:18:47.079 --> 00:18:49.559 were permanently displaced. And Moscow insisted 00:18:49.559 --> 00:18:53.539 on the May Day parade. Incredible, isn't it? 00:18:53.539 --> 00:18:55.700 Issued a directive not to cancel the May Day 00:18:55.700 --> 00:18:58.960 celebrations in Kiev, just downwind. Keep up 00:18:58.960 --> 00:19:00.980 the appearance of normality even as invisible 00:19:00.980 --> 00:19:03.779 poison rained down. Peak Soviet denial. Once 00:19:03.779 --> 00:19:05.779 the scale sunk in, though, there was this immediate 00:19:05.779 --> 00:19:08.180 fear of something even worse. A secondary steam 00:19:08.180 --> 00:19:10.500 explosion, yeah. The nightmare scenario 2 .0. 00:19:10.559 --> 00:19:12.660 Explain that. They realized the reactor core 00:19:12.660 --> 00:19:15.519 debris had melted into this lava -like mass corium, 00:19:15.579 --> 00:19:18.299 they call it. A mix of fuel, concrete, sand, 00:19:18.480 --> 00:19:20.720 incredibly hot, maybe 1 ,200 degrees Celsius 00:19:20.720 --> 00:19:22.880 or more. And it was melting downwards. Melting 00:19:22.880 --> 00:19:25.359 through the concrete reactor floor. And directly 00:19:25.359 --> 00:19:27.460 below that floor were huge pools of water. The 00:19:27.460 --> 00:19:29.000 bubble pool is part of the pressure suppression 00:19:29.000 --> 00:19:32.460 system. Thousands of tons of water. If that molten 00:19:32.460 --> 00:19:35.279 corium hit the water. Bang. A massive thermal 00:19:35.279 --> 00:19:38.559 explosion. Like dropping molten metal into water, 00:19:38.700 --> 00:19:42.380 but on a radioactive, gigantic scale. It could 00:19:42.380 --> 00:19:44.319 have ejected vastly more radioactive material, 00:19:44.599 --> 00:19:47.220 potentially destroyed the other reactors. Just 00:19:47.220 --> 00:19:49.519 unthinkable. Which led to this incredibly dramatic, 00:19:49.680 --> 00:19:53.059 heroic moment. The Chernobyl divers. Three engineers. 00:19:53.480 --> 00:19:56.619 Alexey Naninenko, Valery Bezpilov, and Boris 00:19:56.619 --> 00:19:59.400 Barinov. They volunteered. Volunteer for what? 00:19:59.579 --> 00:20:02.259 To go down into the flooded, pitch black basement 00:20:02.259 --> 00:20:05.259 corridors beneath the reactor, wade through highly 00:20:05.259 --> 00:20:07.900 radioactive water, find the valves for the sluice 00:20:07.900 --> 00:20:10.440 gates, and open them to drain those bubbler pools. 00:20:10.759 --> 00:20:12.660 Knowing the risk. They were told it was certainly 00:20:12.660 --> 00:20:15.220 a suicide mission. The radiation levels were 00:20:15.220 --> 00:20:17.319 astronomical. They went anyway, found the valves 00:20:17.319 --> 00:20:20.019 in the dark by feel, opened them, the pools drained. 00:20:20.299 --> 00:20:22.279 Did they survive? Early reports said they died 00:20:22.279 --> 00:20:24.299 quickly. That was misinformation, part of the 00:20:24.299 --> 00:20:27.140 mythology. Amazingly, they all survived. They 00:20:27.140 --> 00:20:29.619 received high doses, yes, suffered health problems 00:20:29.619 --> 00:20:32.980 later, but they lived for many years. Annanenko 00:20:32.980 --> 00:20:35.720 is reportedly still alive today. They were decorated 00:20:35.720 --> 00:20:38.799 as heroes decades later. But was their sacrifice 00:20:38.799 --> 00:20:41.480 actually needed? I read later analysis suggested. 00:20:41.940 --> 00:20:45.240 That's the tragic irony, potentially. Later probes 00:20:45.240 --> 00:20:46.859 found the corium had actually started dripping 00:20:46.859 --> 00:20:49.480 into the water before they drained it. But instead 00:20:49.480 --> 00:20:51.890 of a massive explosion? What happened? When the 00:20:51.890 --> 00:20:54.190 molten corium hit the water, it cooled rapidly, 00:20:54.430 --> 00:20:57.690 fragmenting into this porous, pumice -like ceramic 00:20:57.690 --> 00:21:00.470 material. Relatively stable. Some of it even 00:21:00.470 --> 00:21:03.410 floated. So the giant steam explosion might not 00:21:03.410 --> 00:21:05.549 have happened anyway. But they didn't know that. 00:21:05.670 --> 00:21:08.150 They acted based on the terrifying possibility. 00:21:08.470 --> 00:21:11.130 Absolutely. Heroism based on the best, worst 00:21:11.130 --> 00:21:13.690 -case knowledge they had. At the same time, they 00:21:13.690 --> 00:21:15.470 were worried about the ground under the reactor. 00:21:16.009 --> 00:21:18.029 Yeah, contaminating the groundwater was a huge 00:21:18.029 --> 00:21:20.650 concern, that corium mass sinking deep into the 00:21:20.650 --> 00:21:22.750 earth. What was the plan there? Freezing the 00:21:22.750 --> 00:21:25.029 ground? That was the ineffable wild idea. Use 00:21:25.029 --> 00:21:27.769 oil drilling tech to inject liquid nitrogen, 00:21:28.029 --> 00:21:30.849 create a frozen barrier underneath. Quickly realized 00:21:30.849 --> 00:21:32.829 it was impractical. That's dead. They brought 00:21:32.829 --> 00:21:35.789 in miners, coal miners, subway builders from 00:21:35.789 --> 00:21:39.849 Moscow and Kiev. Their task, dig a tunnel 150 00:21:39.849 --> 00:21:42.750 meters long directly underneath the reactor foundation. 00:21:43.349 --> 00:21:45.930 Why the tunnel? The original plan was to install 00:21:45.930 --> 00:21:49.109 a massive heat exchanger in it, a concrete pad 00:21:49.109 --> 00:21:52.470 cooled by pipes to solidify the ground and draw 00:21:52.470 --> 00:21:54.849 heat away if the corium kept melting down. Did 00:21:54.849 --> 00:21:57.410 they build it? They dug the tunnel, working in 00:21:57.410 --> 00:22:00.309 brutal heat and high radiation. But by the time 00:22:00.309 --> 00:22:02.609 it was ready, they realized the corium had curved 00:22:02.609 --> 00:22:05.410 and stabilized enough on its own. The active 00:22:05.410 --> 00:22:07.450 cooling system wasn't needed. So the tunnel? 00:22:07.630 --> 00:22:09.950 They filled it with thousands of tons of concrete. 00:22:10.799 --> 00:22:12.940 Not for cooling, but for structural support. 00:22:13.660 --> 00:22:15.980 To shore up the foundation of the damaged reactor 00:22:15.980 --> 00:22:18.240 building, prevent it collapsing further. Now 00:22:18.240 --> 00:22:20.440 the cleanup on top. Getting rid of the debris, 00:22:20.579 --> 00:22:22.519 especially on the roofs, that's where the robots 00:22:22.519 --> 00:22:25.980 came in. Or rather, where they failed. They needed 00:22:25.980 --> 00:22:28.599 to clear about 100 tons of intensely radioactive 00:22:28.599 --> 00:22:31.940 debris fuel fragments, graphite chunks off the 00:22:31.940 --> 00:22:33.980 roof surround the reactor, particularly Unit 00:22:33.980 --> 00:22:36.619 3's roof, to prepare for building the first shelter. 00:22:36.819 --> 00:22:39.380 High -tech solution, right. Remote control robots. 00:22:39.700 --> 00:22:42.049 They tried everything. Soviet moon rover chassis, 00:22:42.390 --> 00:22:46.269 German police robots, Japanese models, about 00:22:46.269 --> 00:22:48.549 60 different machines. Sent them up, pushed the 00:22:48.549 --> 00:22:50.809 debris off. How did that work out? Terribly. 00:22:51.109 --> 00:22:53.730 The gamma radiation fields were just too intense, 00:22:53.950 --> 00:22:55.609 fried the electronics, cooked the batteries. 00:22:55.910 --> 00:22:58.950 Most of the robots failed very quickly. Even 00:22:58.950 --> 00:23:00.789 the heavily shielded ones. Oh, so technology 00:23:00.789 --> 00:23:04.470 wasn't the answer there. Not at all. Valery Legasov, 00:23:04.670 --> 00:23:07.170 a key scientist in the response, famously said, 00:23:07.839 --> 00:23:09.740 We learned that robots are not the great remedy 00:23:09.740 --> 00:23:12.119 for everything. The machines couldn't handle 00:23:12.119 --> 00:23:15.599 it. Which left? People? The biorobots. Human 00:23:15.599 --> 00:23:18.680 liquidators. Mostly young military conscripts. 00:23:18.680 --> 00:23:20.920 Doing the roof cleanup manually. 90 % of it, 00:23:20.960 --> 00:23:23.839 yes. Shoveling highly radioactive graphite off 00:23:23.839 --> 00:23:28.000 the roof. 3 ,828 men did that specific job. How 00:23:28.000 --> 00:23:30.220 could they possibly survive that? Extremely short 00:23:30.220 --> 00:23:32.839 shifts. They'd run out, shovel maybe one or two 00:23:32.839 --> 00:23:35.799 loads, and run back. Maximum exposure time was 00:23:35.799 --> 00:23:38.779 40 to 90 seconds. Even then, they absorbed huge 00:23:38.779 --> 00:23:41.619 doses, an average of 25 rem each, for that roof 00:23:41.619 --> 00:23:44.240 work alone. Just incredible bravery or perhaps 00:23:44.240 --> 00:23:46.700 ignorance of the true long -term risk. A mix 00:23:46.700 --> 00:23:49.259 of both, probably. Duty, orders, maybe not fully 00:23:49.259 --> 00:23:51.460 grasping the invisible danger. But it got the 00:23:51.460 --> 00:23:54.539 job done at immense human cost. And all this 00:23:54.539 --> 00:23:56.960 was to prepare for the sarcophagus. The first 00:23:56.960 --> 00:23:59.519 containment structure, built incredibly fast, 00:23:59.619 --> 00:24:03.000 between June and November 1986, a monumental 00:24:03.000 --> 00:24:05.059 feat of engineering under impossible conditions. 00:24:05.319 --> 00:24:08.029 What was its main purpose? Stop the ongoing release 00:24:08.029 --> 00:24:10.789 of radioactive dust, shield the environment from 00:24:10.789 --> 00:24:13.390 the exposed core, and crucially, protect the 00:24:13.390 --> 00:24:15.589 thousands of workers still operating the other 00:24:15.589 --> 00:24:18.410 Chernobyl reactors, especially Unit 3 next door. 00:24:18.650 --> 00:24:21.450 They work in crane cabins heavily shielded with 00:24:21.450 --> 00:24:23.869 lead. But it was never meant to be permanent. 00:24:24.049 --> 00:24:26.609 No, it was a temporary fix designed for maybe 00:24:26.609 --> 00:24:29.410 30 years max. It was rushed, built remotely, 00:24:29.609 --> 00:24:32.390 full of gaps, structurally unsound in the long 00:24:32.390 --> 00:24:35.150 run. Which led to the massive structure we see 00:24:35.150 --> 00:24:37.390 there today. The new safe confinement, the NSC. 00:24:37.839 --> 00:24:42.099 That gigantic arch, 105 meters high, 256 meters 00:24:42.099 --> 00:24:44.640 long, the largest movable land structure ever 00:24:44.640 --> 00:24:46.519 built. When was that put in place? Construction 00:24:46.519 --> 00:24:49.319 started around 2010, finished nearby, and then 00:24:49.319 --> 00:24:51.140 it was slid over the top of the old sarcophagus 00:24:51.140 --> 00:24:54.400 in Unit 4 between 2016 and 2018. An incredible 00:24:54.400 --> 00:24:56.680 project. And its purpose? Designed to last 100 00:24:56.680 --> 00:24:59.960 years. It seals off the site, contains the remaining 00:24:59.960 --> 00:25:03.119 radioactivity, and crucially, houses the remote 00:25:03.119 --> 00:25:05.039 -controlled cranes and equipment needed for the 00:25:05.039 --> 00:25:09.099 next phase. Slowly. carefully dismantling the 00:25:09.099 --> 00:25:11.839 original sarcophagus and the reactor debris underneath. 00:25:12.059 --> 00:25:14.000 When is that cleanup supposed to finish? The 00:25:14.000 --> 00:25:16.680 current schedule aims for completion around 2065. 00:25:17.369 --> 00:25:19.569 A century after the accident. Let's talk about 00:25:19.569 --> 00:25:22.210 that long legacy. 400 times Hiroshima and Nagasaki. 00:25:22.269 --> 00:25:25.150 It's not just the amount, but the type of radioactive 00:25:25.150 --> 00:25:27.869 stuff released. Right. Different isotopes behave 00:25:27.869 --> 00:25:30.329 differently. Their danger depends on volatility, 00:25:30.569 --> 00:25:32.829 how easily they spread, and their half -life, 00:25:32.910 --> 00:25:35.089 how long they stay radioactive. What were the 00:25:35.089 --> 00:25:37.390 main culprits from Chernobyl? Three big ones 00:25:37.390 --> 00:25:40.640 stand out. First, iodine -131. Very volatile, 00:25:40.759 --> 00:25:43.400 spread easily. Short half -life, only eight days. 00:25:43.579 --> 00:25:46.900 So the danger was intense, but brief. Intense 00:25:46.900 --> 00:25:49.700 initial danger, yes. Got into the air, onto grass, 00:25:49.900 --> 00:25:52.519 cows ate the grass, people drank the milk. It 00:25:52.519 --> 00:25:54.960 concentrates in the thyroid gland. Responsible 00:25:54.960 --> 00:25:57.319 for a lot of the initial radiation dose, and 00:25:57.319 --> 00:25:59.799 crucially, the later thyroid cancers. Okay, what 00:25:59.799 --> 00:26:02.079 else? After the iodine decayed... Then you worry 00:26:02.079 --> 00:26:05.420 about the long -haul isotopes. Cesium -137 is 00:26:05.420 --> 00:26:09.160 key. Half -life of 30 years. Released as an aerosol, 00:26:09.319 --> 00:26:11.900 fine particles that drifted far and wide settled 00:26:11.900 --> 00:26:14.059 into the soil. And it stays dangerous for decades. 00:26:14.559 --> 00:26:17.059 Yeah. It gets into the food chain, mimics potassium 00:26:17.059 --> 00:26:19.180 in the body, can accumulate in muscles, including 00:26:19.180 --> 00:26:21.819 the heart. It's a major reason large areas are 00:26:21.819 --> 00:26:24.420 still uninhabitable. And the third one? Strontium 00:26:24.420 --> 00:26:27.759 -90. Half -life of about 29 years. Chemically, 00:26:27.859 --> 00:26:31.180 it behaves like calcium. So it goes to... Bones. 00:26:31.180 --> 00:26:33.440 Exactly. Accumulates in bones, irradiates the 00:26:33.440 --> 00:26:35.460 bone marrow, another long -term hazard. And the 00:26:35.460 --> 00:26:37.700 spread wasn't uniform, was it? It depended heavily 00:26:37.700 --> 00:26:42.400 on weather. Totally. Wind patterns, rain. That 00:26:42.400 --> 00:26:45.259 determined where the worst fallout landed. About 00:26:45.259 --> 00:26:47.420 100 ,000 square kilometers were significantly 00:26:47.420 --> 00:26:49.940 contaminated across Ukraine, Belarus, and Russia. 00:26:50.380 --> 00:26:52.500 But it went much further. Oh, yes. Irregular 00:26:52.500 --> 00:26:54.559 patches, hot spots appeared all over Europe. 00:26:54.740 --> 00:26:57.000 Heavy rain washed contaminants out of the clouds, 00:26:57.099 --> 00:27:00.079 especially over mountains. The Alps, Welsh mountains, 00:27:00.319 --> 00:27:02.799 Scottish Highlands, Norway. Some sheep farming 00:27:02.799 --> 00:27:05.319 restrictions still exist today because of Chernobyl 00:27:05.319 --> 00:27:07.880 cesium in the soil. And the Soviets even tried 00:27:07.880 --> 00:27:10.720 to control the weather. There's documented evidence 00:27:10.720 --> 00:27:14.440 of the Soviet Air Force seeding clouds, deliberately 00:27:14.440 --> 00:27:17.960 causing rain over parts of Belarus. Why? To try 00:27:17.960 --> 00:27:19.759 and wash the radioactive particles out of the 00:27:19.759 --> 00:27:22.220 air before the clouds reach major cities like 00:27:22.220 --> 00:27:26.380 Moscow. It worked in a way, but it meant incredibly 00:27:26.380 --> 00:27:29.160 contaminated, heavy black rain fell on towns 00:27:29.160 --> 00:27:31.920 like Gomel in Belarus instead, just shifting 00:27:31.920 --> 00:27:34.119 the disaster. Let's turn to the human health 00:27:34.119 --> 00:27:37.390 impact. We know about the immediate deaths. 30 00:27:37.390 --> 00:27:39.309 confirmed direct deaths within the first few 00:27:39.309 --> 00:27:42.569 months. Two from the explosions, 28 from acute 00:27:42.569 --> 00:27:45.430 radiation syndrome, ARS, among the first responders 00:27:45.430 --> 00:27:48.190 and plant staff. A handful more ARS -related 00:27:48.190 --> 00:27:50.230 deaths occurred over the next year or so. But 00:27:50.230 --> 00:27:52.680 the long -term effects, especially cancer. That's 00:27:52.680 --> 00:27:54.599 always been controversial. Highly controversial 00:27:54.599 --> 00:27:57.019 and hard to pin down definitively outside of 00:27:57.019 --> 00:27:59.920 one clear link. Which is? Thyroid cancer, especially 00:27:59.920 --> 00:28:01.539 in those who were children or adolescents in 00:28:01.539 --> 00:28:03.980 1986, living in the most contaminated areas. 00:28:04.160 --> 00:28:06.859 That iodine -131 exposure. How many cases? By 00:28:06.859 --> 00:28:09.480 2005, international studies confirmed over 6 00:28:09.480 --> 00:28:13.059 ,000 cases in Belarus, Ukraine, and Russia that 00:28:13.059 --> 00:28:15.880 were attributable to chiroble radiation. Fortunately, 00:28:16.160 --> 00:28:18.619 thyroid cancer is usually very treatable if caught 00:28:18.619 --> 00:28:21.920 early. How many died from it? Sadly, about 15 00:28:21.920 --> 00:28:23.900 deaths were recorded from those thousands of 00:28:23.900 --> 00:28:26.960 cases by the mid -2000s. A tragedy, but the overall 00:28:26.960 --> 00:28:29.660 mortality rate was low thanks to treatment. What 00:28:29.660 --> 00:28:32.819 about other cancers? Leukemia? Solid tumors? 00:28:33.059 --> 00:28:35.160 That's where it gets much murkier. Studies have 00:28:35.160 --> 00:28:37.299 generally not found statistically significant 00:28:37.299 --> 00:28:40.039 increases in leukemia or other cancers in the 00:28:40.039 --> 00:28:42.700 wider population that can be definitively linked 00:28:42.700 --> 00:28:45.539 only to Chernobyl radiation, outside of potentially 00:28:45.539 --> 00:28:47.599 higher risks among the liquidators who receive 00:28:47.599 --> 00:28:50.549 the largest doses. But it's complex, hard to 00:28:50.549 --> 00:28:52.630 separate from other factors. But the health impact 00:28:52.630 --> 00:28:54.609 wasn't just physical radiation effects. There 00:28:54.609 --> 00:28:58.019 was immense psychological damage. Massive. The 00:28:58.019 --> 00:29:00.759 fear of radiation itself caused widespread anxiety, 00:29:01.160 --> 00:29:03.960 stress, psychosomatic illnesses. People were 00:29:03.960 --> 00:29:06.500 terrified, often fueled by sensational media 00:29:06.500 --> 00:29:08.960 or lack of clear information. And this fear had 00:29:08.960 --> 00:29:12.119 real consequences. Devastating ones. Studies 00:29:12.119 --> 00:29:15.339 estimate that perhaps 100 ,000 to 200 ,000 elective 00:29:15.339 --> 00:29:17.539 abortions occurred across Europe in the months 00:29:17.539 --> 00:29:19.579 after Chernobyl. Abortions performed because 00:29:19.579 --> 00:29:22.160 of fear of radiation damage to the fetus. Exactly. 00:29:22.619 --> 00:29:25.180 even in places where the actual radiation dose 00:29:25.180 --> 00:29:28.019 received was negligible from a medical standpoint. 00:29:28.319 --> 00:29:32.339 In Greece alone, an estimated 2 ,500 excess abortions 00:29:32.339 --> 00:29:35.640 were attributed solely to Chernobyl fears. Researchers 00:29:35.640 --> 00:29:38.480 concluded this was a tragic, unjustified consequence 00:29:38.480 --> 00:29:42.000 driven by panic, not medical necessity. Let's 00:29:42.000 --> 00:29:43.839 look at the environment, the exclusion zone. 00:29:44.140 --> 00:29:46.720 2 ,600 square kilometers, what happened there? 00:29:46.920 --> 00:29:49.980 Immediately downwind, disaster. About four square 00:29:49.980 --> 00:29:52.579 kilometers of pine forest died quickly. The needles 00:29:52.579 --> 00:29:55.000 turned reddish -brown, became known as the Red 00:29:55.000 --> 00:29:56.859 Forest. It was eventually bulldozed and buried. 00:29:57.000 --> 00:29:59.559 Water contamination, too. A major worry, especially 00:29:59.559 --> 00:30:02.000 the Pripyat River feeding into the Dunipa Reservoir 00:30:02.000 --> 00:30:04.799 system, which supplies water to Kiev. They built 00:30:04.799 --> 00:30:08.220 huge underwater dikes, silt traps, even a massive 00:30:08.220 --> 00:30:10.980 underground clay wall 30 meters deep to try and 00:30:10.980 --> 00:30:12.519 stop contaminants leaching into the groundwater. 00:30:12.839 --> 00:30:15.019 But paradoxically, the zone today is thriving. 00:30:15.180 --> 00:30:18.339 In terms of wildlife, yes. It's the ultimate 00:30:18.339 --> 00:30:21.779 irony. With humans gone... The lack of competition 00:30:21.779 --> 00:30:24.319 has turned the exclusion zone into a massive 00:30:24.319 --> 00:30:28.640 accidental nature reserve. Wolves, wild boar, 00:30:28.819 --> 00:30:33.759 elk, lynx, Przelski's horses reintroduced. Populations 00:30:33.759 --> 00:30:36.180 are booming. Nature is resilient when people 00:30:36.180 --> 00:30:37.980 leave. But the contamination is still there. 00:30:38.039 --> 00:30:40.450 You mentioned wild boar in Germany. Yeah, it's 00:30:40.450 --> 00:30:43.029 a weird anomaly. Wild boar in some parts of Germany 00:30:43.029 --> 00:30:45.690 still test above the legal limit for cesium -137 00:30:45.690 --> 00:30:48.410 consumption. For decades, everyone assumed it 00:30:48.410 --> 00:30:50.990 was all Chernobyl fallout. That's not. Recent 00:30:50.990 --> 00:30:53.230 studies analyzing isocope ratios, specifically 00:30:53.230 --> 00:30:56.769 cesium -135 versus cesium -137, found that in 00:30:56.769 --> 00:30:58.970 many German boars, a significant chunk of the 00:30:58.970 --> 00:31:00.950 contamination actually matches the signature 00:31:00.950 --> 00:31:03.269 of atmospheric nuclear weapons testing from the 00:31:03.269 --> 00:31:06.089 1950s and 60s. Wow, so Cold War testing fallout 00:31:06.089 --> 00:31:08.130 is still cycling through the ecosystem. Seems 00:31:08.130 --> 00:31:09.960 so. It gets locked in the soil. oil taken up 00:31:09.960 --> 00:31:12.140 by fungi like truffles which boar love to eat. 00:31:12.440 --> 00:31:14.900 It shows just how incredibly persistent this 00:31:14.900 --> 00:31:17.160 stuff is in the environment. A nuclear legacy 00:31:17.160 --> 00:31:19.259 lasting generations. And we can't forget the 00:31:19.259 --> 00:31:22.339 people who went back. The Samosli. The self -settlers. 00:31:22.480 --> 00:31:25.480 Mostly elderly people, maybe around 180 or so 00:31:25.480 --> 00:31:27.920 today, who illegally returned to their ancestral 00:31:27.920 --> 00:31:30.759 homes inside the zone. They refused to leave 00:31:30.759 --> 00:31:33.839 or came back despite the risks. How do they survive? 00:31:34.200 --> 00:31:36.559 Assistance farming, basically. Living off the 00:31:36.559 --> 00:31:39.799 land they know. It's a complex human story, defiance, 00:31:39.880 --> 00:31:42.440 attachment to home, maybe a different perception 00:31:42.440 --> 00:31:45.140 of risk, a testament to resilience of a sort. 00:31:45.279 --> 00:31:47.940 Okay, back to the reactor site itself. Inside 00:31:47.940 --> 00:31:51.500 that huge new safe confinement arch, the danger 00:31:51.500 --> 00:31:54.299 isn't over, is it? No, there's an ongoing scientific 00:31:54.299 --> 00:31:57.410 concern. Deep within the ruins, you still have 00:31:57.410 --> 00:32:00.269 tons of that corium fuel mass mixed with debris 00:32:00.269 --> 00:32:03.269 covered in radioactive dust. And it's still potentially 00:32:03.269 --> 00:32:05.890 reactive. Potentially. Remember, water slows 00:32:05.890 --> 00:32:08.569 neutrons down, making fission more likely. Well, 00:32:08.690 --> 00:32:11.089 rainwater still seeps into the structure as that 00:32:11.089 --> 00:32:13.190 water evaporates or levels change. It changes 00:32:13.190 --> 00:32:15.670 the neutron environment. Exactly. If water levels 00:32:15.670 --> 00:32:18.049 drop in certain areas where fuel debris is concentrated, 00:32:18.390 --> 00:32:20.509 it could theoretically allow neutron activity 00:32:20.509 --> 00:32:23.109 to increase, maybe even leading to self -sustaining 00:32:23.109 --> 00:32:25.549 fission reactions again, not an explosion. but 00:32:25.549 --> 00:32:28.170 the smoldering nuclear reactions. Has this been 00:32:28.170 --> 00:32:31.369 detected? There were worrying signs. Between 00:32:31.369 --> 00:32:34.630 2017 and 2020, instruments detected neutron density 00:32:34.630 --> 00:32:37.470 doubling in one inaccessible subreactor room. 00:32:37.710 --> 00:32:40.539 It seemed to stabilize in 2021. but it's being 00:32:40.539 --> 00:32:43.299 watched very closely. What's the risk if it starts 00:32:43.299 --> 00:32:46.200 up again? The main fear is not a big power surge, 00:32:46.339 --> 00:32:48.460 but that sustained fission would generate heat, 00:32:48.599 --> 00:32:51.420 dry out the remaining material further, and potentially 00:32:51.420 --> 00:32:54.299 release more radioactive dust and aerosols inside 00:32:54.299 --> 00:32:57.460 the NSC, making the plan dismantling incredibly 00:32:57.460 --> 00:33:00.339 difficult and hazardous. It's a simmering threat. 00:33:00.559 --> 00:33:03.059 Finally, the political impact. Chernobyl wasn't 00:33:03.059 --> 00:33:05.720 just a technical disaster. It was a system -shattering 00:33:05.720 --> 00:33:08.849 event. Mikhail Gorbachev himself later said Chernobyl 00:33:08.849 --> 00:33:11.250 might have been the real cause of the collapse 00:33:11.250 --> 00:33:13.730 of the Soviet Union. How so? The sheer scale 00:33:13.730 --> 00:33:15.730 of the disaster, combined with the attempted 00:33:15.730 --> 00:33:18.769 cover -up and the obvious incompetence in managing 00:33:18.769 --> 00:33:21.490 it, completely eroded public trust in the government 00:33:21.490 --> 00:33:24.769 and the entire Soviet system. It forced Gorbachev's 00:33:24.769 --> 00:33:27.450 hand on his policy of glasnost openness. Because 00:33:27.450 --> 00:33:29.569 they couldn't hide this. They couldn't hide something 00:33:29.569 --> 00:33:32.670 impacting half of Europe. Glasnost, intended 00:33:32.670 --> 00:33:34.730 to strengthen the system through transparency, 00:33:35.089 --> 00:33:38.029 ended up exposing all its flaws and contradictions, 00:33:38.130 --> 00:33:40.950 accelerating its demise. And declassified files 00:33:40.950 --> 00:33:43.390 later showed the flaws were known much earlier. 00:33:43.650 --> 00:33:46.880 That was the ultimate indictment. KGB files released 00:33:46.880 --> 00:33:49.019 years later confirmed that scientists knew about 00:33:49.019 --> 00:33:52.240 the RBMK's key design flaws, the positive void 00:33:52.240 --> 00:33:55.400 coefficient, the graphite tips problem, as early 00:33:55.400 --> 00:33:59.019 as 1973. 13 years before the accident. 13 years. 00:33:59.220 --> 00:34:01.099 Reports went up the chain to the Central Committee. 00:34:02.319 --> 00:34:04.319 And they were essentially buried, classified, 00:34:04.680 --> 00:34:07.180 ignored in favor of meeting energy targets and 00:34:07.180 --> 00:34:09.659 maintaining political face. It was a systemic, 00:34:09.820 --> 00:34:13.159 top -down failure long before Dyatlov, Akimov, 00:34:13.159 --> 00:34:15.739 and Topchunov were in that control room. Catastrophe 00:34:15.739 --> 00:34:17.880 wasn't just possible. It was practically baked 00:34:17.880 --> 00:34:20.900 in. And the economic cost still being felt today. 00:34:21.099 --> 00:34:23.980 Hugely. Sources indicate Chernobyl still eats 00:34:23.980 --> 00:34:26.619 up something like 5 -7 % of Ukraine's entire 00:34:26.619 --> 00:34:29.300 national budget every single year. Belarus is 00:34:29.300 --> 00:34:31.659 heavily impacted too. The cleanup, healthcare, 00:34:31.780 --> 00:34:34.059 social support, it's a multi -generational burden. 00:34:34.260 --> 00:34:35.900 It changed the world's view on nuclear power 00:34:35.900 --> 00:34:39.800 too. Absolutely. Triggered a massive global downturn 00:34:39.800 --> 00:34:42.920 in new reactor construction. Fueled anti -nuclear 00:34:42.920 --> 00:34:45.980 movements, especially in Europe. Germany's decision 00:34:45.980 --> 00:34:48.820 to phase out nuclear power has roots in Chernobyl. 00:34:49.230 --> 00:34:51.650 It starkly demonstrated the potential consequences 00:34:51.650 --> 00:34:54.530 when complex technology meets human fallibility 00:34:54.530 --> 00:34:58.510 and institutional secrecy. The cost of that secrecy 00:34:58.510 --> 00:35:00.690 was infinitely higher than the cost of openness 00:35:00.690 --> 00:35:02.590 would have been. It really underscores the terrifying 00:35:02.590 --> 00:35:05.050 intersection of technology, human factors, and 00:35:05.050 --> 00:35:07.289 political systems. You had the human errors pulling 00:35:07.289 --> 00:35:09.889 rods, disabling safety systems. You had the catastrophic 00:35:09.889 --> 00:35:12.829 technical flaws, the void coefficient, the graphite 00:35:12.829 --> 00:35:15.389 tips. And amplifying it all was the political 00:35:15.389 --> 00:35:18.050 failure, the culture of secrecy, the denial. 00:35:18.730 --> 00:35:21.050 A perfect storm on every level. So the cleanup 00:35:21.050 --> 00:35:24.210 continues until 2065, potentially. The environmental 00:35:24.210 --> 00:35:26.289 impacts, like on Norwegian sheep farming, could 00:35:26.289 --> 00:35:28.769 last a century. And yet, there's still a chance 00:35:28.769 --> 00:35:30.710 of fission starting up again inside the containment. 00:35:30.989 --> 00:35:32.610 It leaves you with a really profound question, 00:35:32.789 --> 00:35:35.789 doesn't it? In our increasingly complex, interconnected 00:35:35.789 --> 00:35:38.630 world, how do we make sure these hidden institutional 00:35:38.630 --> 00:35:41.409 flaws, these buried warnings, don't turn seemingly 00:35:41.409 --> 00:35:44.369 small errors into global crises that span generations? 00:35:45.599 --> 00:35:47.659 Chernobyl proved the biggest danger wasn't just 00:35:47.659 --> 00:35:50.239 the atom, it was the arrogance and secrecy surrounding 00:35:50.239 --> 00:35:52.980 it. What lesson from all this resonates most 00:35:52.980 --> 00:35:54.780 strongly with you? What's the enduring takeaway?