1 00:00:00,000 --> 00:00:15,480 Chain of events, cause and effect. We analyze what went right and what went wrong, as we 2 00:00:15,480 --> 00:00:20,940 discover that many outcomes can be predicted, planned for, and even prevented. I'm John 3 00:00:20,940 --> 00:00:25,360 Chidgey, and this is Causality. Causality is part of the Engineered Network. 4 00:00:25,360 --> 00:00:29,280 To support our shows, including this one, head over to our Patreon page, and for other 5 00:00:29,280 --> 00:00:38,160 great shows visit https://engineered.network/ today. Fukushima. On Friday the 11th of March 2011 6 00:00:38,160 --> 00:00:46,480 at 2:46pm local time a magnitude 9.0 earthquake occurred under the sea at a depth of approximately 7 00:00:46,480 --> 00:00:57,280 32 km, 72 km east of the Oshika Peninsula off Tōhoku. 8 00:00:57,280 --> 00:01:02,940 It was the most powerful earthquake to ever hit Japan and the fourth most powerful recorded 9 00:01:02,940 --> 00:01:06,520 since 1900 in the world. 10 00:01:06,520 --> 00:01:11,540 This earthquake occurred where the Pacific Plate is subducting under the plate beneath 11 00:01:11,540 --> 00:01:12,540 northern Honshu. 12 00:01:12,540 --> 00:01:21,540 The Pacific Plate moves at a rate of 8-9cm (3.1-3.5in/yr) 13 00:01:21,540 --> 00:01:27,540 That movement pushes the upper plate down until the accumulated stress causes a seismic 14 00:01:27,540 --> 00:01:33,660 slip rupture event, otherwise known as an earthquake. 15 00:01:33,660 --> 00:01:45,180 The Fukushima 1 nuclear power plant consisted of 6 reactors, 1 at 480 MW, 4 of them at 784 16 00:01:45,180 --> 00:01:49,820 MW each and 1 at 1.1 GW. 17 00:01:49,820 --> 00:01:56,300 There were 3 reactors online at the time of that earthquake, those are reactors 1, 2 and 18 00:01:56,300 --> 00:02:03,820 three and all initiated a SCRAM and a shutdown at the time that the earthquake hit. 19 00:02:03,820 --> 00:02:08,100 Now, SCRAM is a unusual acronym. 20 00:02:08,100 --> 00:02:13,820 In fact, some people have suggested it's not an acronym, it's actually a "back-ronym", which is the 21 00:02:13,820 --> 00:02:20,700 the phenomena where people will fit an expression backwards into an acronym to try and explain 22 00:02:20,700 --> 00:02:23,060 the existence of the acronym, hence "back-ronym." 23 00:02:23,060 --> 00:02:24,540 Kind of like that idea. 24 00:02:24,820 --> 00:02:29,620 Anyway, a SCRAM is supposed to be something like Safety Control 25 00:02:29,620 --> 00:02:30,780 Rod Axe-Man. 26 00:02:30,780 --> 00:02:36,780 And it was originally thought to have come, but the phrase was originally coined apparently by Enrico 27 00:02:36,780 --> 00:02:41,580 Fermi, and he was working on the Manhattan Project on the Chicago Pile One reactor, 28 00:02:41,580 --> 00:02:42,940 and that was in the early 1940s. 29 00:02:42,940 --> 00:02:48,740 And the idea behind an "Axe-Man" is that there's a large 30 00:02:48,740 --> 00:02:53,460 collection of control rods suspended above the reactor core by a rope and an 31 00:02:53,460 --> 00:03:01,260 an axe man with an axe is sent to cut the rope in the event of an out of control reaction. 32 00:03:01,260 --> 00:03:05,580 This particular expression and terminology method, whatever you want to call it, of doing 33 00:03:05,580 --> 00:03:10,660 an emergency shutdown of a nuclear reactor is primarily used these days for Boiling Water 34 00:03:10,660 --> 00:03:17,940 Reactors, BWRs, like Fukushima. I don't want to talk too much about the different designs 35 00:03:17,940 --> 00:03:23,860 of nuclear reactors, but suffice it to say that a SCRAM is an emergency shutdown where 36 00:03:23,860 --> 00:03:28,600 you insert a large number of control rods into the core, so many so that it absorbs 37 00:03:28,600 --> 00:03:35,140 all the Neutrons and completely stops the fission reaction. 38 00:03:35,140 --> 00:03:41,020 So the plants are designed to initiate a SCRAM as soon as there is an earthquake above a 39 00:03:41,020 --> 00:03:45,860 certain trip threshold. This one certainly qualified and a SCRAM was initiated on the 40 00:03:45,860 --> 00:03:53,140 online reactors. So reactors 1, 2, and 3 were in operation. So SCRAMs were initiated on each of them. 41 00:03:53,140 --> 00:03:59,220 Now within minutes all those reactors were shut down but reactors 4, 5, and 6 they were already 42 00:03:59,220 --> 00:04:05,060 shut down in actual they're in preparation for being refueled and when you're refueling what 43 00:04:05,060 --> 00:04:09,940 you'll do is sometimes the fuel rods will be withdrawn from the reactor and stored in a large 44 00:04:09,940 --> 00:04:15,380 pool and in this the case of Fukushima it was in an upper level of the reactor building outside of 45 00:04:15,380 --> 00:04:23,120 of the containment vessel. The exact quantity varies depending upon which reports you read. 46 00:04:23,120 --> 00:04:32,260 Some say as many as 1,533 fuel rods, some as little as 1,330. Irrespective of the number, 47 00:04:32,260 --> 00:04:37,620 let's just say a significant quantity, all of them in fact from reactor 4, they were 48 00:04:37,620 --> 00:04:42,620 in a cooling pool above the reactor on the floor above. 49 00:04:42,620 --> 00:04:47,500 So the reactor four cooling pool was full of fuel rods 50 00:04:47,500 --> 00:04:51,140 that were not in use at the time of the incident. 51 00:04:51,140 --> 00:04:53,140 That actually been put there four months earlier 52 00:04:53,140 --> 00:04:54,820 in November of 2010. 53 00:04:54,820 --> 00:04:58,300 Takes a while for them to cool down a bit. 54 00:04:58,300 --> 00:05:02,980 But reactors five and six were still in their reactors 55 00:05:02,980 --> 00:05:06,020 and they had cooling water being pumped through them 56 00:05:06,020 --> 00:05:07,020 to keep them cool. 57 00:05:07,020 --> 00:05:13,500 So, back to reactors 1, 2 and 3. 58 00:05:13,500 --> 00:05:17,820 The earthquake itself doesn't, just because you have an undersea earthquake doesn't actually 59 00:05:17,820 --> 00:05:20,820 mean you're going to get a significant tsunami. 60 00:05:20,820 --> 00:05:25,340 In this particular case, the break caused by the earthquake caused the sea floor to 61 00:05:25,340 --> 00:05:30,540 rise up by several meters and that displaced an enormous amount of water above it. 62 00:05:30,540 --> 00:05:34,960 And liquids aren't compressible, so the energy had to go somewhere and it travels away from 63 00:05:34,960 --> 00:05:40,740 that upthrust region as waves. The deeper the water, the shallower the waves, but as 64 00:05:40,740 --> 00:05:46,880 you approach shallow water, the wave height increases dramatically. In terms of the upthrust 65 00:05:46,880 --> 00:05:54,540 region, it's quite significant. The upthrust region was between six to eight meters along 66 00:05:54,540 --> 00:06:00,300 a 180 kilometer wide seabed, and that was around about 60 kilometers from the shoreline 67 00:06:00,300 --> 00:06:06,120 on average. In fact, the tsunami was so significant it travelled as far as Chile in South America 68 00:06:06,120 --> 00:06:12,240 and there resulted in a 2 metre wave height. Not enough to cause any damage, but certainly 69 00:06:12,240 --> 00:06:22,060 enough to be quite noticeable. Tsunami waves, of course, arrive as sets of waves. It's 70 00:06:22,060 --> 00:06:27,800 not just one, there's a subsequent series of them. But most tsunami wave heights are 71 00:06:27,800 --> 00:06:35,160 measured by the largest or tallest wave. But the first tsunami waves from this incident arrived at 72 00:06:35,160 --> 00:06:43,480 Kamaishi, and I hope I'm pronouncing that correctly. Apologies if I'm not. At 3:12pm local time, the 73 00:06:43,480 --> 00:06:53,240 height was estimated at about 6.8 metres. They arrived at Sōma at 3:50pm with an estimated height 74 00:06:53,240 --> 00:07:01,400 of 7.3 meters, that's 24 feet, and this was around the time at which the tsunami also reached the 75 00:07:01,400 --> 00:07:10,120 Fukushima 1 power plant. At the plant itself, the waves peaked at a staggering 13 meters, that's 43 76 00:07:10,120 --> 00:07:18,200 feet high, and that easily breached the protective seawall, which was only 10 meters or 33 feet high. 77 00:07:20,040 --> 00:07:26,440 Once the water had passed the seawall, the seawater proceeded to flood all of the low-lying 78 00:07:26,440 --> 00:07:33,800 areas of the plant, and this included the turbine hall and the reactor building. Cars and trucks 79 00:07:33,800 --> 00:07:41,240 were all swept away, overturned, the waves destroyed the pipework, and within minutes 80 00:07:41,240 --> 00:07:48,760 affected the backup diesel generators. And understanding why that's a problem, 81 00:07:48,760 --> 00:07:55,720 we first have to understand about fuel rod cladding and decay heat. So let's start with the 82 00:07:55,720 --> 00:08:03,400 cladding. Zircalloy or alloys of Zirconium, they're used predominantly in BWRs for cladding as it has 83 00:08:03,400 --> 00:08:08,200 very low absorption of thermal Neutrons, meaning they just pass through it and don't affect the 84 00:08:08,200 --> 00:08:13,320 material as they pass through. But it also maintains a high hardness ductility and it's 85 00:08:13,320 --> 00:08:20,120 corrosion resistant. And that's important because if the Neutrons actually interact 86 00:08:20,120 --> 00:08:25,680 with the cladding material, then they will change what that cladding material is. And 87 00:08:25,680 --> 00:08:32,120 as you change what the material is, it changes its chemical properties. So you need something 88 00:08:32,120 --> 00:08:36,720 that's going to essentially be invisible, which is what Zircalloys are, and that's why 89 00:08:36,720 --> 00:08:44,640 they are predominantly used in these nuclear reactors. But it's not all positives. Zircalloy 90 00:08:44,640 --> 00:08:51,680 also reacts with water and at high temperatures with steam. The oxidation of Zirconium by water 91 00:08:51,680 --> 00:08:58,560 releases Hydrogen gas as one of its byproducts. The other problem is that once it passes about 92 00:08:58,560 --> 00:09:07,120 400°C the oxidation rate increases dramatically and that increased rate of release 93 00:09:07,120 --> 00:09:14,160 of Hydrogen for example if you're in an enclosed vessel which this is will increase the pressure 94 00:09:14,160 --> 00:09:20,960 as the pressure increases that also further drives that oxidation process forward at an even faster 95 00:09:20,960 --> 00:09:26,800 rate so essentially the higher temperature leads to high pressure the high pressure leads to a 96 00:09:26,800 --> 00:09:32,080 higher oxidation rate which increases the pressure which leads to a higher oxidation rate. 97 00:09:32,080 --> 00:09:37,520 Now in normal operation it's not a problem because the cooling water will keep the temperature well 98 00:09:37,520 --> 00:09:46,320 under control that's fine. Now after a SCRAM event occurs the reactors aren't actually hot 99 00:09:46,320 --> 00:09:52,480 enough anymore to generate steam to make electricity but they still have some latent heat 100 00:09:53,040 --> 00:10:00,160 and more importantly, they have decay heat. So I mentioned this before, decay heat is something 101 00:10:00,160 --> 00:10:09,280 that it's difficult to get your head around, but when we split Uranium or Plutonium 102 00:10:09,280 --> 00:10:16,160 nuclear fission, we get byproducts and those byproducts are themselves radioactive and as 103 00:10:16,160 --> 00:10:23,280 As they decay, they themselves generate heat as part of their decay reaction. 104 00:10:23,280 --> 00:10:27,320 Essentially decay heat is the term that describes the continuing nuclear reaction. 105 00:10:27,320 --> 00:10:31,200 Despite the fact that the main reaction of the Uranium or Plutonium has ended, the beta 106 00:10:31,200 --> 00:10:36,960 decay of the byproducts of the original fission reaction will still occur. 107 00:10:36,960 --> 00:10:42,640 The decay heat fraction is usually expressed as a fraction of the full power of the reactor. 108 00:10:42,640 --> 00:10:49,620 it starts at about 7% of full power at a 1 second post-SCRAM event and then it reduces 109 00:10:49,620 --> 00:10:57,120 logarithmically so about 4% at 1 minute, 2% at 10 minutes but then it really slows down 110 00:10:57,120 --> 00:11:06,140 and it can take about 5 hours to reach 1% of full load and about 0.2% after 10 days. 111 00:11:06,140 --> 00:11:12,020 Now when we consider the size of some of these reactors we're talking about 768 megawatts 112 00:11:12,020 --> 00:11:16,260 That's a lot of power. 1% of 768 megawatts is still a lot of heat. 113 00:11:16,260 --> 00:11:21,300 So if you don't keep it cool, it's going to get very hot. 114 00:11:21,300 --> 00:11:23,020 And that's a bad thing. 115 00:11:23,020 --> 00:11:31,420 And it takes a long time for the decay heat to actually slow down to a point at which these 116 00:11:31,420 --> 00:11:37,660 things, these fuel rods will actually be able to stay cool in free air 117 00:11:37,660 --> 00:11:39,500 quite some time. 118 00:11:41,420 --> 00:11:45,140 Now all those figures and percentages I just quoted, they're all approximations because 119 00:11:45,140 --> 00:11:49,340 since it clearly it varies based on the type of fuel in question, like if it is 120 00:11:49,340 --> 00:11:54,420 Uranium, Uranium or Plutonium, and therefore the byproducts that you will get from the 121 00:11:54,420 --> 00:11:58,860 reaction. It also depends on the concentration of the fuel and the life of that fuel. 122 00:11:58,860 --> 00:12:01,700 Like, for example, newer fuel will have less byproducts. 123 00:12:01,700 --> 00:12:05,820 So therefore, newer fuel will have less decay heat in theory. 124 00:12:05,820 --> 00:12:11,020 So all those numbers are approximations, but it illustrates the problem. 125 00:12:11,060 --> 00:12:12,980 the decay heat is a problem. 126 00:12:12,980 --> 00:12:17,260 So, OK, it's critically important that the fuel rods are 127 00:12:17,260 --> 00:12:19,940 then kept cool after you have a shutdown for at least a week or 128 00:12:19,940 --> 00:12:25,140 two. And so that that happens, external power is required to 129 00:12:25,140 --> 00:12:26,220 keep the system cool. 130 00:12:26,220 --> 00:12:30,420 You need to keep circulating cool water through those fuel 131 00:12:30,420 --> 00:12:31,460 rods to keep them cool. 132 00:12:31,460 --> 00:12:35,220 Now, ordinarily, that would be taking care of power from the 133 00:12:35,220 --> 00:12:38,740 electrical grid that's backfed, what we call in the industry 134 00:12:38,740 --> 00:12:43,140 backfeeding and the idea is that the power grid then supplies the power to 135 00:12:43,140 --> 00:12:49,640 cool the reactors. However in this particular case all six of the high 136 00:12:49,640 --> 00:12:53,780 voltage transmission lines that connected the power plant to the 137 00:12:53,780 --> 00:12:57,820 electrical grid were destroyed by the earthquake following the tsunami and the 138 00:12:57,820 --> 00:13:03,100 following tsunami I should say. Now the so-called Essential Service Water 139 00:13:03,100 --> 00:13:07,420 Systems that keep the cooling water circulating through the reactor they 140 00:13:07,420 --> 00:13:12,900 have several other backups and the backup system installed on 141 00:13:12,900 --> 00:13:17,020 site, the ESS's at Fukushima, they had an independent, 142 00:13:17,020 --> 00:13:23,140 redundant power system of diesel generators. Now, the generators 143 00:13:23,140 --> 00:13:26,100 were regularly tested to ensure they operated when they had to, 144 00:13:26,100 --> 00:13:29,380 their fuel was topped up, everything was maintained. They 145 00:13:29,380 --> 00:13:33,300 were, as far as we are aware, anyhow, in full working order. 146 00:13:34,140 --> 00:13:38,820 When the SCRAM event occurred, the diesel generators were fully functional, 147 00:13:38,820 --> 00:13:42,340 even when they lost mains power. 148 00:13:42,340 --> 00:13:48,260 However, by the time the tsunami had breached the wall, the diesel generators were 149 00:13:48,260 --> 00:13:49,580 inundated with seawater. 150 00:13:49,580 --> 00:13:56,220 Eleven of the 12 diesel generators failed, and with only one 151 00:13:56,220 --> 00:14:00,500 remaining generator off in a distant part of the plant, it was powering reactor 152 00:14:00,500 --> 00:14:06,580 6. The reactor 6 was already online as we offline sorry which we mentioned before. 153 00:14:06,580 --> 00:14:15,460 On a positive note it continued to circulate cooling water through reactors 5 and 6 and 154 00:14:15,460 --> 00:14:22,820 ensured there was no incident in those reactors so that's something. The impact of the tsunami 155 00:14:22,820 --> 00:14:26,980 had already destroyed the seawater lift pumps on the ocean side of the seawall 156 00:14:27,940 --> 00:14:30,660 because they had been mounted lower and closer to sea level. 157 00:14:30,660 --> 00:14:35,700 And there's additional power systems to circulate cooling water. In this case, 158 00:14:35,700 --> 00:14:41,620 there's an emergency backup battery, a UPS system, that was able to power cooling pumps 159 00:14:41,620 --> 00:14:47,780 for eight hours by design. Unfortunately, the flooding from the tsunami destroyed the batteries 160 00:14:47,780 --> 00:14:52,260 in units one and two because they also were in a low-lying area of the plant. 161 00:14:53,460 --> 00:15:01,380 The slightly newer Unit 3 batteries however were not damaged and surprisingly lasted as long as 30 162 00:15:01,380 --> 00:15:05,860 hours before they were depleted which far exceeded their original 8-hour design life. 163 00:15:05,860 --> 00:15:13,860 Now it's common practice for emergency power systems like those at Fukushima that there's 164 00:15:13,860 --> 00:15:20,820 an external power connection point where you could deliver a mobile portable temporary generator that 165 00:15:20,820 --> 00:15:24,740 that you can then connect in to supply power in a true emergency. 166 00:15:24,740 --> 00:15:30,940 Unfortunately, this connection point had been swamped and was severely damaged by the tsunami 167 00:15:30,940 --> 00:15:34,340 and it rendered it inaccessible for several days. 168 00:15:34,340 --> 00:15:40,860 There was also difficulty in getting the portable generator to the plant. 169 00:15:40,860 --> 00:15:49,220 The reactors themselves, for incidents such as this, have two additional layers of protection. 170 00:15:49,700 --> 00:15:54,500 primary containment vessel, which is a steel and concrete reinforced structure surrounding the core 171 00:15:54,500 --> 00:15:57,700 and a secondary containment vessel. 172 00:15:57,700 --> 00:15:59,380 And that's usually just the reactor building. 173 00:15:59,380 --> 00:16:06,940 And whilst the secondary containment is usually sealed well, it's not reinforced to the same extent as the primary containment vessel. 174 00:16:06,940 --> 00:16:10,140 So a bit more about the timeline. 175 00:16:10,140 --> 00:16:12,460 At 7:03pm 176 00:16:12,460 --> 00:16:15,700 local time, the government declared a nuclear emergency. 177 00:16:16,620 --> 00:16:20,940 By 8:50pm that day, the Fukushima Prefecture Office 178 00:16:20,940 --> 00:16:24,700 ordered a two kilometre radius evacuation zone. 179 00:16:24,700 --> 00:16:30,620 By 9:23pm, the government increased this radius to three kilometres and instructed 180 00:16:30,620 --> 00:16:34,580 residents to stay inside buildings in the next 181 00:16:34,580 --> 00:16:37,180 radius up to 10 kilometres away. 182 00:16:37,180 --> 00:16:42,300 The following day at 5:44am in the morning, 183 00:16:43,380 --> 00:16:47,140 the government ordered a full evacuation to a 10km radius. 184 00:16:47,140 --> 00:16:51,180 And then that evening at 6:25pm, 185 00:16:51,180 --> 00:16:56,340 the government then extended this to 20km away from the plant. 186 00:16:56,340 --> 00:17:01,140 Around lunchtime on day four, following the incident, 187 00:17:01,140 --> 00:17:04,660 the government ordered all residents to stay inside buildings in the area 188 00:17:04,660 --> 00:17:06,660 between 20 to 30km from the plant. 189 00:17:06,660 --> 00:17:10,300 Over the next two weeks, 190 00:17:10,740 --> 00:17:16,100 There were a succession of Hydrogen explosions at reactor 1, 2 and 3. 191 00:17:16,100 --> 00:17:22,660 To list the times mentioned relative from the moment of the primary earthquake, 192 00:17:22,660 --> 00:17:24,540 we'll look at some of these events. 193 00:17:24,540 --> 00:17:32,660 Units 1, 2 and 3 lost AC power when the generators died at 51, 54 and 52 minutes out, 194 00:17:32,660 --> 00:17:34,500 respectively, pretty close together. 195 00:17:34,500 --> 00:17:39,700 There were issues with circulating cooling water in unit 1. 196 00:17:40,500 --> 00:17:46,100 So unit 1, it lost its circulating cooling within one hour. 197 00:17:46,100 --> 00:17:51,000 Unit 2 and 3, 70 and 36 hours out respectively. 198 00:17:51,000 --> 00:17:55,500 The water level had dropped to a critical height because of 199 00:17:55,500 --> 00:17:57,600 accelerated evaporation due to high heat. 200 00:17:57,600 --> 00:18:01,200 Which is what happens when you stop circulating fresh cooling 201 00:18:01,200 --> 00:18:05,300 water. And now, at these points, they are only just covering 202 00:18:05,300 --> 00:18:06,400 the top of the fuel rods. 203 00:18:07,100 --> 00:18:11,060 So at three hours out, 74 and 42 hours, 204 00:18:11,060 --> 00:18:13,120 the units one, two and three respectively. 205 00:18:13,120 --> 00:18:16,940 Because of the low coverage of water 206 00:18:16,940 --> 00:18:18,860 and the low amount of cooling, 207 00:18:18,860 --> 00:18:23,540 damage to the cores began at four hours, 208 00:18:23,540 --> 00:18:26,200 77 hours and 44 hours respectively. 209 00:18:26,200 --> 00:18:29,820 So each of the three cores sustained damage. 210 00:18:29,820 --> 00:18:33,820 The reactor primary pressure containment vessel 211 00:18:33,820 --> 00:18:37,020 sustained damage at 11 hours. 212 00:18:37,020 --> 00:18:39,300 Ultimately, we're only certain of the timing 213 00:18:39,300 --> 00:18:41,100 of this for reactor number one. 214 00:18:41,100 --> 00:18:42,360 Damage occurred to all three, 215 00:18:42,360 --> 00:18:45,540 but the timeline for the exact moment of these 216 00:18:45,540 --> 00:18:47,700 is unclear for units two and three. 217 00:18:47,700 --> 00:18:51,620 Fire pumps were used with fresh water, 218 00:18:51,620 --> 00:18:54,700 spraying the core at 15 hours for unit one 219 00:18:54,700 --> 00:18:57,400 and 43 hours for unit three. 220 00:18:57,400 --> 00:19:00,620 Unit two was never sprayed with fresh water, only seawater, 221 00:19:01,460 --> 00:19:06,740 because it was essentially nearly 30 hours later before it had issues. 222 00:19:06,740 --> 00:19:15,060 Hydrogen explosions occurred due to Zircalloy oxidation at 25 hours for Unit 1 223 00:19:15,060 --> 00:19:17,540 and 68 hours for Unit 3, 224 00:19:17,540 --> 00:19:21,660 causing significant damage to their own and adjacent structures. 225 00:19:21,660 --> 00:19:28,660 The offsite electrical supply became available between 11 to 15 days later 226 00:19:29,860 --> 00:19:33,980 and was brought on in stages for different units. 227 00:19:33,980 --> 00:19:38,980 Fresh water cooling was re-established 14 to 15 days later 228 00:19:38,980 --> 00:19:40,620 for all three units. 229 00:19:40,620 --> 00:19:43,540 On the 25th of March, 230 00:19:43,540 --> 00:19:45,780 the government requested a voluntary evacuation 231 00:19:45,780 --> 00:19:47,400 of all residents in the area 232 00:19:47,400 --> 00:19:50,380 from 20 to 30 kilometer radius from the plant. 233 00:19:50,380 --> 00:19:55,780 About a month later, on the 21st of April, 234 00:19:55,780 --> 00:19:58,380 the government set a 20 kilometer radius 235 00:19:58,380 --> 00:20:02,300 as a no-go zone for all residents. 236 00:20:02,300 --> 00:20:07,180 When the water temperature dropped below 100°C 237 00:20:07,180 --> 00:20:08,840 at atmospheric pressure, 238 00:20:08,840 --> 00:20:12,300 the reactor is said to be in cold shutdown. 239 00:20:12,300 --> 00:20:13,340 It's still pretty hot, 240 00:20:13,340 --> 00:20:15,960 but it's technically a cold shutdown. 241 00:20:15,960 --> 00:20:19,420 The reactor reached cold shutdown 242 00:20:19,420 --> 00:20:23,880 on the 16th of December, 2011. 243 00:20:25,660 --> 00:20:28,700 That's quite some time after the incident. 244 00:20:28,700 --> 00:20:31,200 Nine months. 245 00:20:31,200 --> 00:20:33,600 That's how long it took. 246 00:20:33,600 --> 00:20:41,920 What's interesting is the neighboring Daini Plant, 247 00:20:41,920 --> 00:20:48,220 Fukushima 2, is located some 15 kilometers away from Daiichi. 248 00:20:48,220 --> 00:20:52,140 Now, they were hit by a tsunami as well, of course. 249 00:20:52,140 --> 00:20:54,180 It was only nine meters in height. 250 00:20:54,180 --> 00:20:58,740 the height of the tsunami as it crosses the oceans got a lot to do with the profile of 251 00:20:58,740 --> 00:21:02,380 the seabed as it approaches the shoreline. 252 00:21:02,380 --> 00:21:07,860 Now they still had one of their power lines still available into the plant after the earthquake 253 00:21:07,860 --> 00:21:10,220 and the tsunami had passed. 254 00:21:10,220 --> 00:21:14,700 So whilst there were interruptions of the cooling supply post-SCRAM, with some of the 255 00:21:14,700 --> 00:21:19,340 generators damaged, external power didn't really strictly require them. 256 00:21:19,340 --> 00:21:23,980 Power and cooling systems were restored within 30 hours with new pumps fitted for units 1, 257 00:21:23,980 --> 00:21:29,340 and four and no incidents were recorded at this plant and it was only 15 258 00:21:29,340 --> 00:21:35,260 kilometers away a completely different ending. Radioactive releases into the 259 00:21:35,260 --> 00:21:41,900 environment as a result of this incident. The main radionuclide released was 260 00:21:41,900 --> 00:21:47,020 Iodine-131, has a half-life of about eight days. The other main radionuclide 261 00:21:47,020 --> 00:21:55,580 is Cesium-137. Unfortunately, it has a half-life of about 30 years. It's easily carried in smoke, 262 00:21:55,580 --> 00:22:02,540 tends to settle on land, and contaminates that land for decades. Cesium-134 was also released 263 00:22:02,540 --> 00:22:07,740 in smaller quantities, has a half-life of about two years. One of the problems with Cesium is that 264 00:22:07,740 --> 00:22:13,340 it's water soluble, and when it's ingested, has a biological half-life of about 70 days. 265 00:22:14,460 --> 00:22:23,180 Of course, tracking the exact extent of radioactive releases from Fukushima post-incident is very 266 00:22:23,180 --> 00:22:31,100 difficult since the mandatory radiation monitoring stations of which there were 24, well 23 of them 267 00:22:31,100 --> 00:22:41,420 were disabled by the tsunami, so it's hard to be sure. So nuclear fission seems like such a good 268 00:22:41,420 --> 00:22:50,300 idea or does it? A little bit about the history and why we need the water and why we put these 269 00:22:50,300 --> 00:22:57,260 plants where we do so we can understand why on earth they would put a nuclear power plant 270 00:22:57,260 --> 00:23:03,640 where they did. So nuclear power, the first plant was actually built for civilian use 271 00:23:03,640 --> 00:23:10,920 was a 5 megawatt reactor at Obninsk in 1954 that was in the Soviet Union at the time. 272 00:23:10,920 --> 00:23:16,520 Now since then many different designs have been tried many different reactors in operation around 273 00:23:16,520 --> 00:23:22,040 the world. There's actually just under 500 nuclear reactors currently in operation and they generate 274 00:23:22,040 --> 00:23:32,840 2731 terawatt hours and the global total generation as of last year was 20,261TWh 275 00:23:32,840 --> 00:23:38,000 for all forms of energy. So that puts nuclear at about 13% 276 00:23:38,000 --> 00:23:41,040 of the world's electricity generation. Of course, some 277 00:23:41,040 --> 00:23:44,880 countries like France, it's the vast majority and the US it's 278 00:23:44,880 --> 00:23:47,880 about one fifth of its electricity is generated from 279 00:23:47,880 --> 00:23:51,320 nuclear. And nuclear is actually in many respects no different 280 00:23:51,320 --> 00:23:55,000 from coal, oil or gas driven electricity generation insofar 281 00:23:55,000 --> 00:23:58,040 as it requires cooling water. The concept is simple enough, 282 00:23:58,040 --> 00:24:01,800 make heat through some heat source, heat that up, some heat 283 00:24:01,800 --> 00:24:04,720 up some highly cleaned water, chemically cleaned water, so as 284 00:24:04,720 --> 00:24:07,520 pure water as you can make it, and then turn that into high 285 00:24:07,520 --> 00:24:11,440 pressure steam. That steam drives a steam turbine, turbine 286 00:24:11,440 --> 00:24:15,080 spins around, drives an alternator, which then generates 287 00:24:15,080 --> 00:24:20,600 electricity. From there, we need to cool that steam down and 288 00:24:20,600 --> 00:24:24,400 pass it back through the heat source again, because you can't 289 00:24:24,400 --> 00:24:29,680 pump steam. So these sorts of plants are called thermoelectric 290 00:24:29,720 --> 00:24:33,280 power plants. And in the United States, for example, 90% of all 291 00:24:33,280 --> 00:24:36,640 electric electricity is generated by a thermoelectric power plant. 292 00:24:36,640 --> 00:24:41,000 And cooling water is a very big part of the selection process 293 00:24:41,000 --> 00:24:44,880 when you're siting a power plant. Now, not enough water and you 294 00:24:44,880 --> 00:24:47,400 have problems ranging from excessive thermal effects on the 295 00:24:47,400 --> 00:24:51,000 local ecology, depriving the local ecosystem of its minimum 296 00:24:51,000 --> 00:24:54,360 water requirements, or simply not being able to cool the plant 297 00:24:54,360 --> 00:24:59,480 at all, and it's not viable. So obvious choices include large 298 00:24:59,480 --> 00:25:04,760 lakes, large rivers, but if you're happy to deal with the corrosive consequences of living with 299 00:25:04,760 --> 00:25:10,680 salt water, then the most obvious choice is actually the ocean. So much so that with nuclear 300 00:25:10,680 --> 00:25:15,480 reactors about one-fifth of them are located on or within five kilometers of the coastline. 301 00:25:15,480 --> 00:25:24,440 Now you see water for their cooling. So when you consider a nuclear reactor site in particular, 302 00:25:24,440 --> 00:25:29,320 there's a long list of additional potential disasters you need to consider. And clearly 303 00:25:29,320 --> 00:25:34,680 for Japan, the two big ones were earthquakes and tsunami, and there can be very little 304 00:25:34,680 --> 00:25:40,000 doubt based on what happened at Fukushima, that whilst TEPCO may have considered both 305 00:25:40,000 --> 00:25:45,760 of them, arguably the earthquake risk was adequately covered, but the tsunami precautions 306 00:25:45,760 --> 00:25:50,420 were perhaps a little bit less well considered. 307 00:25:50,420 --> 00:25:55,240 So what design flaws were present at this plant? 308 00:25:55,240 --> 00:26:05,940 It's quite disturbing when I was doing the research on this, because I do understand to an extent how they reached the conclusions that they did. 309 00:26:05,940 --> 00:26:11,420 But it doesn't make it that much less terrifying to me personally. 310 00:26:11,420 --> 00:26:18,580 The plant was actually constructed on a bluff, and that bluff was originally 35 metres above sea level. 311 00:26:20,860 --> 00:26:25,860 Well, they decided to take 25 meters off of that height. 312 00:26:25,860 --> 00:26:29,760 It may sound crazy, but I'll tell you why. 313 00:26:29,760 --> 00:26:34,460 The license for the plant and basis of design was that it only 314 00:26:34,460 --> 00:26:38,360 had to withstand a 3.1 meter maximum height tsunami. 315 00:26:38,360 --> 00:26:42,160 But that design basis was based on an earthquake that happened 316 00:26:42,160 --> 00:26:47,160 in Chile in 1960 and that resulted in a 3.1 meter wave 317 00:26:47,260 --> 00:26:53,500 halfway across the world at Japan at the current construction location at Fukushima. 318 00:26:53,500 --> 00:26:59,900 Japanese researchers have increasingly found more evidence of sedimentation layers far 319 00:26:59,900 --> 00:27:05,620 inland from that location and they suggest now that large tsunamis of the size seen in 320 00:27:05,620 --> 00:27:14,100 2011 can actually occur approximately once every thousand years in that area. 321 00:27:14,100 --> 00:27:21,800 As more evidence mounts in recent times, there were concerns raised within TEPCO after the 322 00:27:21,800 --> 00:27:25,840 construction about the tsunami risk to the plant. 323 00:27:25,840 --> 00:27:32,300 In 2008, TEPCO performed some computer simulation modelling and they determined the risk to 324 00:27:32,300 --> 00:27:36,300 the plant may have been underestimated after all. 325 00:27:36,300 --> 00:27:42,340 Now NISA is the Nuclear and Industrial Safety Agency in Japan and NISA were first provided 326 00:27:42,340 --> 00:27:56,340 the details of TEPCO's simulation models, interestingly, 4 days before the tsunami struck. 327 00:27:56,340 --> 00:28:04,340 So 3 years after the analysis was performed, they provided it to NISA. 328 00:28:04,340 --> 00:28:06,100 Back to the construction phase. 329 00:28:06,100 --> 00:28:10,860 During construction, TEPCO decided to lower the height of the bluff by 25m. 330 00:28:10,860 --> 00:28:18,020 That made the base plant level at about 10m above sea level, still well above their 3.1m 331 00:28:18,020 --> 00:28:20,440 maximum design height. 332 00:28:20,440 --> 00:28:24,500 The reasons that they quoted for lowering the bluff included to allow the base of the 333 00:28:24,500 --> 00:28:30,820 reactors to be constructed in solid bedrock and that mitigated earthquake damage. 334 00:28:30,820 --> 00:28:34,500 People that are aware of civil engineering and earthquake prone areas understand that 335 00:28:34,500 --> 00:28:39,700 bedrock is an ideal material for you to be placing your structure because bedrock cannot 336 00:28:39,700 --> 00:28:43,700 go through liquefaction when the ground vibrates. 337 00:28:43,700 --> 00:28:47,700 Not going to talk about liquefaction. 338 00:28:47,700 --> 00:28:51,700 But if you were to put a building on sand 339 00:28:51,700 --> 00:28:55,700 what happens under a high vibration situation like an earthquake 340 00:28:55,700 --> 00:28:59,700 is that that sand essentially starts to act like a liquid and anything in it 341 00:28:59,700 --> 00:29:03,700 tends to sink very quickly in fact. 342 00:29:03,700 --> 00:29:07,700 Sand, dirt, it's a problem. But bedrock is solid 343 00:29:07,700 --> 00:29:15,300 as a, well, rock. How about that? Now, it had to be about something else too, didn't it? 344 00:29:15,300 --> 00:29:20,980 The running costs. The seawater pumps needed to lift the water from the sea to 345 00:29:20,980 --> 00:29:25,940 cool the plant. The higher the plant is, the bigger the pumps needed to be, because 346 00:29:25,940 --> 00:29:29,480 they're pumping against a much higher head pressure, and lifting all that 347 00:29:29,480 --> 00:29:33,900 seawater the much larger distance would have much higher long-term operating 348 00:29:33,900 --> 00:29:39,320 costs. Maintenance costs also would be higher for the pump maintenance and it 349 00:29:39,320 --> 00:29:44,300 would just be more expensive as a long-term operating cost. So by lowering 350 00:29:44,300 --> 00:29:49,320 the height you reduce the distance you have to pump the water makes it cheaper. 351 00:29:49,320 --> 00:29:54,040 Now TEPCO's analysis of the tsunami risk determined a 10 meter high seawall 352 00:29:54,040 --> 00:30:00,560 would provide protection for the maximum tsunami assumed by the design basis. 353 00:30:00,560 --> 00:30:08,560 Hmm. The diesel backup generators that were most likely to be required during an earthquake or tsunami event 354 00:30:08,560 --> 00:30:13,560 were located in the basement of the turbine hall and that was only 10 meters above sea level. 355 00:30:13,560 --> 00:30:19,560 Now, putting generators at those lower heights, it certainly makes them cheaper to construct 356 00:30:19,560 --> 00:30:23,560 and it's easier to maintain them if you have to do any work on them. 357 00:30:23,560 --> 00:30:27,560 And you do have to strip these things from time to time and maintain them. 358 00:30:27,560 --> 00:30:36,560 Now most buildings that I've worked on, the overwhelming majority have their backup gennies in the basement or in the ground floor at least. 359 00:30:36,560 --> 00:30:44,560 But there was one building in particular that I remember, they put their gen set on the 9th floor of the building. 360 00:30:44,560 --> 00:30:53,560 It had a day tank, a day diesel fuel day tank on the 9th floor with enough fuel in it to run for, oddly as the name suggests, a day. 361 00:30:53,560 --> 00:30:56,740 where the bulk fuel tank had nothing to run for a week, 362 00:30:56,740 --> 00:30:58,400 and that was in the basement. 363 00:30:58,400 --> 00:31:00,100 But that was their compromise. 364 00:31:00,100 --> 00:31:02,040 At the time, I remember arguing with them 365 00:31:02,040 --> 00:31:04,800 that with the building's additional reinforcing 366 00:31:04,800 --> 00:31:07,700 to handle the mass of the diesel generator, 367 00:31:07,700 --> 00:31:11,800 putting the bulk fuel tank on or near the ninth floor 368 00:31:11,800 --> 00:31:14,560 would have actually finished the job. 369 00:31:14,560 --> 00:31:17,080 The tanker truck could have had a low lift pump, 370 00:31:17,080 --> 00:31:19,980 a more powerful pump to actually pump the fuel 371 00:31:19,980 --> 00:31:20,920 up to the ninth floor 372 00:31:20,920 --> 00:31:25,080 when it was filling up the bulk fuel tank, but they decided not to do that. 373 00:31:25,080 --> 00:31:31,320 Irrespective of that decision, you would have to put a sealed containment 374 00:31:31,320 --> 00:31:35,640 bund around the bulk fuel tank as they had around the day tank, 375 00:31:35,640 --> 00:31:37,040 but it could have been done. 376 00:31:37,040 --> 00:31:42,080 So in an inundation event, if it ever happened, it would then be totally protected and 377 00:31:42,080 --> 00:31:43,400 isolated. That's not what they did. 378 00:31:43,400 --> 00:31:45,800 Ultimately, though, that's not the point. 379 00:31:45,800 --> 00:31:50,900 It's a common practice to put generators at ground level or in the basement. 380 00:31:50,900 --> 00:31:55,220 and it honestly it's pretty stupid. I've always thought that. I don't get it. 381 00:31:55,220 --> 00:32:00,980 Because when you need it in a flooding event, that's not going to work is it? 382 00:32:00,980 --> 00:32:08,740 Same with switchboards for that matter. Anyway, now if you don't raise the height of the gensets, 383 00:32:08,740 --> 00:32:10,820 it's not the end of the world. There's other things you could do. You could put them in a 384 00:32:10,820 --> 00:32:16,500 watertight bund and by bund I mean it's a wall around the outside without a lid on it essentially, 385 00:32:16,500 --> 00:32:22,500 no roof. But then I think to myself a little bit about the Titanic's interlocking doors. 386 00:32:22,500 --> 00:32:28,260 Now how high is high enough to make that wall high enough to stop becoming inundated? 387 00:32:28,260 --> 00:32:34,580 And the next question is if you do put a wall around it you're stifling the cooling. So are 388 00:32:34,580 --> 00:32:38,420 you going to have enough, are you going to have adequate cooling for the generator trapped inside 389 00:32:38,420 --> 00:32:43,300 its little box? What about access and egress when you need maintenance, you need to pull out the 390 00:32:43,300 --> 00:32:48,340 the alternator, you need to pull out sections of the motor for maintenance purposes. 391 00:32:48,340 --> 00:32:52,100 It makes everything like that more difficult and more expensive. 392 00:32:52,100 --> 00:32:54,500 So they didn't do that either. 393 00:32:54,500 --> 00:33:00,020 Now, the seawater low lift pumps were also a big part of this. 394 00:33:00,020 --> 00:33:06,300 The intake and the building for the low lift pumps was set at four meters above sea level, 395 00:33:06,300 --> 00:33:09,460 which was above the maximum tsunami design height. 396 00:33:10,940 --> 00:33:15,020 But these were the only mechanisms available to draw water in from the ocean 397 00:33:15,020 --> 00:33:18,220 and you needed that cooling water. It was your cooling water source. 398 00:33:18,220 --> 00:33:24,700 They could have added a backup system with multiple intake heights from different depths 399 00:33:24,700 --> 00:33:30,540 with a lower speed, smaller size pumps that are just designed to handle post-SCRAM cooling. 400 00:33:30,540 --> 00:33:34,860 The requirements of post-SCRAM cooling are not as great as when you're in full operation because 401 00:33:34,860 --> 00:33:38,860 you're not at full heat load. So you don't need to cool as much water. So you didn't need as 402 00:33:38,860 --> 00:33:44,260 bigger pump. Well they could have done that but they didn't. The other option of 403 00:33:44,260 --> 00:33:47,360 course they could have mounted them higher with a more reinforced structure. 404 00:33:47,360 --> 00:33:52,100 Mind you that would have cost more money. Refer previous comment about the higher 405 00:33:52,100 --> 00:33:58,820 pumps, higher head pressure. So obviously you want to mount them closer. 406 00:33:59,700 --> 00:34:12,200 So, in the aftermath of this incident, in fact in March this year, the Japanese National Police Agency confirmed 407 00:34:12,200 --> 00:34:24,700 as a result of the earthquake, there were 15,893 deaths, 6,152 people were injured, 2,572 people were reported missing. 408 00:34:24,700 --> 00:34:35,700 A staggering number, though, is 228,863 people displaced from their homes either temporarily 409 00:34:35,700 --> 00:34:38,460 or permanently. 410 00:34:38,460 --> 00:34:44,820 A large number of those relate directly to the exclusion zone around Fukushima. 411 00:34:44,820 --> 00:34:53,700 Now, in amongst those figures will be individuals affected by the incident at Fukushima. 412 00:34:53,700 --> 00:34:58,700 Of course, plenty of other people were affected by the tsunami directly. 413 00:34:58,700 --> 00:35:03,260 And this isn't a show about preventing natural disasters, since you can't. 414 00:35:03,260 --> 00:35:08,220 But in engineering, we design and we construct buildings, roads, control systems, electricity 415 00:35:08,220 --> 00:35:14,300 grids, we design all these things to withstand natural disasters of a certain intensity. 416 00:35:14,300 --> 00:35:21,140 If we build something that can't withstand a natural disaster, I want to know why. 417 00:35:21,140 --> 00:35:26,500 the instance being compared to Chernobyl and TEPCO officially stated that the 418 00:35:26,500 --> 00:35:30,860 amount of radioactive material was only about 15% of that released at Chernobyl 419 00:35:30,860 --> 00:35:35,780 but the truth is that this figure is kind of well I'd say highly questionable 420 00:35:35,780 --> 00:35:41,420 because it's very difficult to accurately determine that. Access to 421 00:35:41,420 --> 00:35:47,780 those cores at units 1, 2 & 3 is still not safe and it won't be for many 422 00:35:47,780 --> 00:35:55,140 years to come. It's going to take 30 to 40 years to clean up the fuel and remediate that site. 423 00:35:55,140 --> 00:36:02,660 In the 20 kilometer no-go zone, it remains in place today, and it's four years after the incident, 424 00:36:02,660 --> 00:36:09,700 and it's going to be in place for a very long time. I came across a very eerie set of photos 425 00:36:09,700 --> 00:36:17,300 taken by a brave, maybe, photographer, and some from an aerial drone as recently as a month ago, 426 00:36:17,300 --> 00:36:22,420 and they're both stunning and terrifying at the same time. There's a link in the show notes and 427 00:36:22,420 --> 00:36:28,820 it's called the Fukushima Wasteland. It shows how nature is taking over again. There's abandoned cars 428 00:36:28,820 --> 00:36:35,620 overgrown by weeds on a freeway it looks like, grasses and sidewalks hidden by foliage, 429 00:36:35,620 --> 00:36:43,380 tables that were still set with half-eaten meals on. It's going to be three decades 430 00:36:43,380 --> 00:36:47,180 at least before they could potentially declare the area safe. 431 00:36:47,180 --> 00:36:50,020 And even then, that's not a certainty. 432 00:36:50,020 --> 00:36:58,060 So there's a lot of conflicting 433 00:36:58,060 --> 00:37:02,660 and disagreeing information about 434 00:37:02,660 --> 00:37:04,300 what happened at Fukushima. 435 00:37:04,300 --> 00:37:09,500 A lot of it is because we're not sure how transparent TEPCO has been. 436 00:37:10,340 --> 00:37:14,100 A lot of it is because of misinformation spread on social media. 437 00:37:14,100 --> 00:37:21,940 Spent quite a bit of time trying to get to the truth of exactly what figures and what happened when, and it's quite difficult. 438 00:37:21,940 --> 00:37:32,100 The reality, though, is that no matter how you slice it, they made the wrong choices when they designed the plant. 439 00:37:32,100 --> 00:37:34,820 But it comes back to the design basis. 440 00:37:34,820 --> 00:37:38,820 A 3.1 metre tsunami, to me, sounds insane. 441 00:37:39,940 --> 00:37:48,500 Japan is perhaps one of the most dangerous countries to live in regarding tsunamis and tsunami risk. 442 00:37:48,500 --> 00:37:59,780 And 3.1 meters is not very big in terms of tsunami wave heights. So whilst it was a huge event, 443 00:37:59,780 --> 00:38:07,300 as the evidence mounted in subsequent decades, it wasn't really reassessed seriously until 2008. 444 00:38:07,300 --> 00:38:12,820 and even when it was, they were considering raising it to I think 5.7 meters or thereabouts 445 00:38:12,820 --> 00:38:17,940 was their design basis adjustment for the maximum tsunami height and even if they had 446 00:38:17,940 --> 00:38:21,220 have taken precautions to protect against that it still would not have been enough. 447 00:38:21,220 --> 00:38:29,860 So the problem is when you say in a design basis I wanted to withstand a storm event of 448 00:38:29,860 --> 00:38:36,820 one in 1,000 years or one in 10,000 years events, so something extreme, how do you know if the 449 00:38:36,820 --> 00:38:38,620 the history doesn't go back that far. 450 00:38:38,620 --> 00:38:46,340 Just because you find sediment 2, 5, 10 kilometers, miles inland, that doesn't tell you how big 451 00:38:46,340 --> 00:38:49,580 the tsunami wave was when it hit the coastline. 452 00:38:49,580 --> 00:38:54,940 I mean, computer modelling will help, sure, but you just don't know for sure. 453 00:38:54,940 --> 00:38:56,460 You know it was bad. 454 00:38:56,460 --> 00:38:57,740 You just don't know how bad. 455 00:38:57,740 --> 00:39:02,180 And if you don't know that, how can you be sure you're meeting that requirement? 456 00:39:02,940 --> 00:39:08,700 So what do we do? We fall back on the most recent sample of history, which is only what? 457 00:39:08,700 --> 00:39:12,540 100 and well, when the plant was designed, it was 1967. 458 00:39:12,540 --> 00:39:14,780 It was first constructed, unit one. 459 00:39:14,780 --> 00:39:20,420 And we only had records going, accurate records, going back to 1900 in terms of earthquakes, 460 00:39:20,420 --> 00:39:23,660 related tsunamis and the height measurements. 461 00:39:23,660 --> 00:39:25,380 We just don't have the history. 462 00:39:25,380 --> 00:39:27,860 How do you know it's enough? 463 00:39:29,740 --> 00:39:34,540 History repeats itself, that's only useful if you're measuring history, if you're recording it. 464 00:39:34,540 --> 00:39:44,540 So, nuclear fission, I guess, is most analogous to an enormous explosion 465 00:39:44,540 --> 00:39:48,940 in extremely agonizingly slow motion. 466 00:39:48,940 --> 00:39:54,140 The problem is that once you start that reaction, that fission reaction, 467 00:39:54,140 --> 00:39:59,660 your goal at that point is to slow it down and keep it under control. 468 00:39:59,660 --> 00:40:05,660 Because if you can control it, you can use the heat to make as much electricity as you like. 469 00:40:05,660 --> 00:40:10,660 Problem is, if you screw it up, it doesn't take very long for it to get out of control. 470 00:40:10,660 --> 00:40:15,660 And once it's out of control, bringing it back under control is extremely difficult. 471 00:40:15,660 --> 00:40:19,660 It takes many, many months, in some cases years. 472 00:40:19,660 --> 00:40:23,660 And there are serious consequences if you get it wrong. 473 00:40:23,660 --> 00:40:33,100 We should be reassessing the protective measures as a result of global warming, because those 474 00:40:33,100 --> 00:40:39,280 effects are starting to be felt, especially with rising sea levels, for plants like this. 475 00:40:39,280 --> 00:40:40,460 And there's a lot of them. 476 00:40:40,460 --> 00:40:46,780 In the last two decades, in case you thought that Fukushima was an isolated case, it's 477 00:40:46,780 --> 00:40:47,780 not. 478 00:40:47,780 --> 00:40:53,620 In the last two decades, there have been several other, call them beyond design basis flooding 479 00:40:53,620 --> 00:40:58,500 if you'd like earthquake related some of them at different nuclear power plants around the world 480 00:40:58,500 --> 00:41:04,740 let's go through some of them December 1999 a storm surge caused flooding at two reactors 481 00:41:04,740 --> 00:41:12,660 at the Blayais nuclear power plant in France on December 26 2004 that was the Indian Ocean 482 00:41:12,660 --> 00:41:17,380 tsunami that flooded the seawater pumps at Madras Atomic Power Station in India 483 00:41:18,660 --> 00:41:23,380 On the 16th of July 2007, an earthquake exceeded the design basis of TEPCO's 484 00:41:23,380 --> 00:41:31,700 Kashiwazaki-Kariwa nuclear power station in Niigata Prefecture. 485 00:41:31,700 --> 00:41:38,100 On August the 23rd, 2011, several months after Fukushima, an earthquake on the east coast of 486 00:41:38,100 --> 00:41:44,500 the United States marginally exceeded the design basis of the North Anna nuclear generating station 487 00:41:44,500 --> 00:41:56,660 in Virginia. None of those led to a significant incident. No radioactivity was emitted. Call 488 00:41:56,660 --> 00:42:07,580 them close calls perhaps, or I don't know, cautionary if nothing else. I guess no matter 489 00:42:07,580 --> 00:42:10,980 how many times I go through this in my mind, I'm just not convinced nuclear fission can 490 00:42:10,980 --> 00:42:16,080 ever be risk free. There will always be risks, there will always be things we just cannot 491 00:42:16,080 --> 00:42:24,860 foresee, we can't account for, and we can't protect against. Ultimately the cost of solar 492 00:42:24,860 --> 00:42:32,200 and wind power is coming down every year. And as we step closer to truly solving the 493 00:42:32,200 --> 00:42:40,080 battery problem for storing that power overnight, maybe we can finally stop playing with nuclear 494 00:42:40,080 --> 00:42:47,080 power and pretending that we're in control of it. Because we're not. 495 00:42:47,080 --> 00:42:51,880 If you're enjoying Causality and want to support the show, you can. Like one of our backers, 496 00:42:51,880 --> 00:42:56,480 Chris Stone. He and many others are patrons of the show via Patreon, and you can find 497 00:42:56,480 --> 00:43:02,520 it at https://patreon.com/johnchidgey So if you'd like to contribute something, 498 00:43:02,520 --> 00:43:09,680 anything at all, it's very much appreciated. This was Causality. I'm John Chidgey. 499 00:43:09,680 --> 00:43:10,680 Thanks for listening. 500 00:43:10,680 --> 00:44:31,380 (gentle music)