Chapter 4

THE ACCIDENT

On April 26th, 1986, just after 1am, a test was about to commence at Chernobyl’s Unit 4 reactor. What followed was the worst nuclear disaster in history. That night, the shift comprised of 176 men and women at the plant, along with 286 construction workers building Unit 5, a few hundred meters to the southeast. Unit 4’s control room operators, along with a representative of Donenergo - the state-owned electricity supplier and designer of the plant’s turbines - were testing a safety feature intended to allow the Unit to power itself for around a minute in the event of a total power failure.

The principal concern of a nuclear reactor - particularly an RBMK reactor, because of its graphite moderator - is that cooling water continuously flows into the core. Without it there could be an explosion or meltdown. Even if the reactor is shut down, the fuel within will still be generating decay heat, which would damage the core without further cooling. Pumps driving the flow of water rely on electricity generated by the plant’s own turbines, but in the event of a blackout the electrical supply can be switched to the national grid. If that fails, diesel generators on site will automatically start up to power the water pumps, but these take about 50 seconds to gather enough energy to operate the massive pumps. There are six emergency tanks containing a combined 250 tons of pressurised water which can be injected into the core within 3.5 seconds, but an RBMK reactor needs around 37,000 tons of water per hour - 10 tons-per-second - so 250 tons does not cover the 50 second gap.99

Thus:100 the test of a ‘run-down unit’. If a power failure occurred, the fission reaction would still be producing heat, while the remaining water in the pipes would continue its momentum for a short time and therefore steam would still be produced. In turn, the turbines would still rotate and generate electricity, albeit at an exponentially falling capacity. This residual electricity could be used to drive the water pumps for a few vital moments, giving the diesel generators sufficient time to get up to speed and take over, and it’s the hardware behind this that was being tested.

Despite initial Soviet claims that the experiment had been intended to test a brand new safety system, this run-down unit is actually a standard feature of the RBMK design, and should have been made operational during Unit 4’s commissioning three years earlier. In order to open the plant ahead of schedule, Chernobyl’s Plant Manager Viktor Bryukhanov, along with members of various Ministries involved with the construction and testing of a new plant, signed off on safety tests that were never conducted, with the unwritten promise of completing them later. As reckless as it sounds, this was fairly routine practise in the USSR, as completing work ahead of schedule entitled everyone involved to significant bonuses and awards. The hardware required precise calibration and revisions, and the test had already been conducted three times before on Unit 3 - in 1982, 1984 and 1985; all failed to sustain sufficient voltage - but engineers had by now made additional alterations to the voltage regulators, and so it was to be attempted again. The run-down test was originally scheduled for the afternoon of the 25th, but Chief Engineer Nikolai Fomin was asked by Kiev’s national grid controller to delay it until after the evening peak electricity consumption period had ended.101 The afternoon staff had been briefed on the test and knew exactly what to do, but their shift ended and they went home. Evening staff took over, but then they too left, leaving the relatively inexperienced night crew - who had never conducted a test before - the responsibility of starting a test they were not prepared for and had not anticipated doing.

To make matters worse, Unit 4 was at the end of a fuel cycle. One of the features of the RBMK design is ‘online refuelling’, which is the ability to swap out spent fuel while the reactor is at power. Because fuel burn-up is not even throughout the core, it was not uncommon for the reactor to contain both new and old fuel, which was usually replaced every two years. On April 26th, around 75% of the fuel was nearing the end of its cycle.102 This old fuel had, by now, been given time to accumulate hot and highly radioactive fission products, meaning any interruption in the flow of cooling water could quickly damage the older fuel channels and generate heat faster than the reactor was designed to cope with. Unit 4 was scheduled for a lengthy shutdown and annual maintenance period upon conclusion of the test, during which all of the old fuel would be replaced. It would have been far more sensible to conduct the test with fresh fuel, but management decided to push ahead anyway.

The test would involve inserting all 211 control rods part-way, creating a power level low enough to resemble a blackout while continuing to cool the reactor to compensate for fission products. Use the residual steam in the system to drive a turbine, then isolate it and allow it to run down, generating electricity through its own inertia. The electrical output would be measured, allowing engineers to determine whether it was sufficient to power the water pumps in an emergency. Because the deliberately low power levels would appear to be a power failure to the control computer, which would then automatically activate the safety systems, these systems, including the backup diesel generators and Emergency Core Cooling System (ECCS), were disconnected in order to re-attempt the test straight away if it proved unsuccessful. Otherwise, the ECCS would automatically shutdown the reactor, preventing a repeat of the test for another year. Astonishingly, these measures were not in violation of safety procedures when approved by a Deputy Chief Engineer, despite many subsequent reports to the contrary.103 It’s debatable how much of an impact these systems would have had on the outcome, but it was nevertheless a very foolish decision. Viktor Bryukhanov, along with Nikolai Fomin, who approved the test, paid the price with a sentence of 10 years’ imprisonment in a labour camp and expulsion from the Communist party.104 Countless others paid for it with their health and their lives.

There were problems from the outset. The test programme left for the night shift was full of annotations and hand-written alterations. A transcript of a telephone conversation between an unidentified operator and a colleague elsewhere in the building makes for scary reading: “One operator rings another and asks, ‘What shall I do? In the programme there are instructions of what to do, and then a lot of things are crossed out.’ His interlocutor thought for a while and then replied, ‘Follow the crossed out instructions.’”105 Then at 00:28, while reducing power to levels low enough to begin - a process which would take about an hour - Senior Reactor-Control Engineer Leonid Toptunov made a mistake when switching from manual to automatic control, causing the control rods to descend far more than intended.106 Toptunov had only been in his current position for a few months, during which the reactor power had never been reduced.107 Perhaps his nerves got the better of him. Power levels - supposed to be held at 1,500-Megawatts thermal (MWt) for the test - dropped all the way to 30MWt. (The reactor’s output is measured in terms of thermal power - the turbogenerator’s in electrical power. Energy is lost during the transfer from steam to electricity, hence the higher thermal figures.) Note that it was stated in the Chernobyl trial that power output dropped to zero, and specifically mentioned that the 30MWt figure was erroneous, but everything else I have ever read has said 30.108 Either way, even 30MWt is near-as-makes-no-difference a complete shutdown and not even enough energy to power the water pumps. At such a low power, an atomic process of ‘poisoning’ the reactor begins - a release of the isotope xenon135, which absorbs and seriously inhibits the fission reaction - and the test was over before it began. Had this massive drop in power never happened, the test would have proceeded without incident and the RBMK’s dangerous shortcomings may never have come to light. Crucially, however, the man in charge of the test, 55-year-old Deputy-Chief Engineer Anatoly Dyatlov, did not stop.

Dyatlov was born into a poor family in central Russia. Through tireless hard work and a determination to do more with his life than his parents, he grew into an intelligent, self-made young man, and in 1959 graduated with Honours from Moscow’s National Research Nuclear University. His work background, before moving to Chernobyl in 1973, involved installing small VVER reactors into submarines near Russia’s eastern shores.109 He was also, however, a man privately disliked by his subordinates due to a short temper, a low tolerance for mistakes and a tendency to harbour resentments.110 Dyatlov had been present earlier in the day when the test was postponed; his patience was running short.111 Instead of accepting that it was futile to continue, he reportedly went mad and rushed around the control room shouting. He did not want another test wasted and his reputation tarnished - he ordered the operators to recover the reactor and bring it back up to power. Continuing the experiment after falling to such a low power level resulted in the reactor becoming unstable enough to explode, and Dyatlov holds all the blame for this one crucial decision.112 His behaviour could be, in part, because no nuclear plant operators in the Soviet Union knew of previous accidents at other nuclear facilities, of which there were many. Authorities covered up all fatalities, while claiming in public that the technology was infallible - the best in the world. At worst, it was believed that an RBMK could only suffer a rupture of one or two water lines; an explosion was laughable.

Toptunov considered Dyatlov’s decision to continue after such a massive drop in power to be a violation of safety procedures, so refused to comply, as did Unit Shift Chief Alexander Akimov.113 Akimov was Russian, like most senior staff at the plant. Born on May 6th 1953, in the country’s third-largest city, Novosibirsk, he graduated from the Moscow Power Engineering Institute in 1976 with a degree in thermal power automation processes, before moving to the Chernobyl plant in 1979 as a turbine engineer.114

Dyatlov grew angry and informed them that if they were not willing to do it, he would find someone who was. Akimov and the relatively inexperienced Toptunov, only 26 years-old, relented, and the test continued. Remember that a nuclear plant operator was a prestigious career with its own perks, and the possibility of losing that would have been a serious threat. Not only that, but Dyatlov may well have been the most experienced nuclear engineer at the entire plant. Even Chief Engineer Fomin was an electrical engineer - a specialist in turbines, like Bryukhanov. They respected his knowledge.

By 01:00, after around half an hour, the pair had succeeded in increasing the power to 200MWt by retracting about half of the control rods, but that was as high as it would go - nowhere near the intended 700MWt. Xenon poisoning had already taken its toll, seriously reducing the fuel’s reactivity. Russian safety regulations have since changed to require that an RBMK reactor be kept at a minimum of 700MWt during normal operation because of thermal-hydraulic instability at reduced power. Knowing 200MWt was still far too low to perform the test, they overrode additional automatic systems and manually raised still more control rods to compensate for the poisoning effect.115 At the same time, they connected all 8 main circulating pumps and increased the flow of coolant into the core, up to around 60,000 tons per hour.116 This volume of water was another violation of safety regulations, since very high water flow could lead to cavitation in the pipes. Increased coolant levels meant less steam, which soon caused the turbine speeds to drop. To counteract negative reactivity from all the extra coolant water, the operators withdrew most of the few control rods still inside the reactor, until the equivalent of only 8 fully inserted rods remained.117 The normal absolute minimum allowed at the time was 15, which increased to 30 after the accident.118

The automatic safety systems would have, under normal circumstances, shut the reactor down a few times by now. At 01:22:30, minutes from disaster, Toptunov noticed the computer readings demanding that the reactor be shut down.119 He and his fellow operators were calm but concerned about the state of the reactor. “At the control board before program execution, some nervousness was seen,” reported Razim Davletbaev, Deputy Chief of the turbine hall, in the 1987 accident trial. “Dyatlov repeatedly told Akimov: ‘Do not procrastinate.’”120 I struggle to understand why Dyatlov wanted to continue from here. The reactor was clearly unstable and not even close to the power levels required by the experiment, so they would not have been able to gather useful readings regardless of what happened. Had Dyatlov accepted the futility of continuing, his men could have shut the reactor down. He didn’t: the test began.

I don’t know for certain Dyatlov’s reasoning behind this decision, but he was pressured from above to get it done. The experiment had failed so many times by this point that Bryukhanov and members of the Soviet Academy of Sciences were eager to see the matter concluded. It may be that Dyatlov did not care if the results were useful. He simply wanted to report that the test had been carried out. This is speculation, of course, but it would explain what appears to be irrational behaviour from an otherwise impeccably rational man.

At 01:23:04, turbine 8 was disconnected and began to coast down.121 The operators still had no idea what was about to happen and began a calm discussion, remarking that the reactor’s task was complete and they could start to shut it down.122 Within seconds of cessation of steam flow into the turbine, the main circulating pumps began to cavitate and fill with steam, reducing the flow of valuable cooling water and allowing steam voids (pockets of steam where there should be water) to form in the core. A positive void coefficient was occurring: the absence of cooling water causing an exponential power increase. In simple terms, more steam = less water = more power = more heat = more steam. Because 4 of the 8 water pumps were running off the decelerating turbine, less and less water was supplied to the reactor as power increased. Toptunov spotted this and shouted a warning to Akimov, who had direct control. He saw no choice: job or no job, the reactor was in a dangerous, unstable state and had to be made safe.123

At 01:23:40 on April 26th, 1986, 32-year-old Alexander Akimov made his fateful decision and announced that he was pressing the EPS-5 emergency safety button to initiate a SCRAM, causing all remaining control rods to begin their slow descent into the core.124 It125 was a decision that would change the course of history. (Note that Dyatlov claimed afterwards the EPS-5 button was pressed in a calm environment, purely to bring the test to a successful conclusion and with no concern about reactor readings, but I find that very difficult to believe under the circumstances and it goes against the testimony of other witnesses.) An emergency shutdown was Akimov’s obvious choice. A large part of the reason why the core was so unstable was that almost all 211 rods had been removed, after all, leaving him and his colleagues with very little control over the reactor. He may even have considered this to be his only choice, given how many safety systems had been disabled, and with power increasing it’s quite possible that there would have been a severe accident either way. Alas, it was, in fact, the worst thing he could have done. Within seconds, the control rods stopped moving.

Throughout the building, ‘knocks’ were heard from the direction of the main reactor hall. Akimov’s control board indicated that the rods hadn’t moved far before freezing, only 2.5 meters from their raised position. Thinking quickly, he released the clutch on their servomotors to allow the heavy rods to fall into the core by their own weight. They didn’t move: jammed. “I thought my eyes were coming out of my sockets. There was no way to explain it,” recalled Dyatlov, six years later. “It was clear that this was not a normal accident, but something much more terrible. It was a catastrophe.126”

Akimov didn’t understand what was happening either. He, like the other poor operators in the control room, was unaware of a devastating fatal flaw in the reactor’s design. While around 5 meters of each control rod was composed of the neutron-absorbing element boron to halt the reaction, the ends of each rod were made of graphite - the same reaction-increasing moderator as was used throughout the core of the RBMK. Between the graphite and boron was a long hollow section. The purpose of the graphite tips was to displace cooling water (which is also a moderator, albeit weaker than graphite) in the rod’s path, thus increasing the boron’s dampening effect on the fuel.127 The moment all those graphite tips began to move inside the reactor, there was a surge in positive reactivity in the lower half of the core, resulting in a huge increase in heat and steam production. This heat fractured part of the fuel assembly, distorting the rod’s tubes and causing a jam. When a control rod is fully inserted, the tip extends below the core, but now over 200 were lodged in the centre.

While the RBMK’s designers were unaware of this flaw when the RBMK was first created, they had, they later admitted, forgotten to mention it, “out of absentmindedness,” once they realised.128 I do not understand at all how such an obvious design flaw can be overlooked by so many people. It blows my mind that the very system intended to prevent a fission reaction increases it in the most severe of emergencies - instances necessitating that the Emergency Protection System button be pressed - because the first stage of the designed emergency response is to introduce a moderator to the core. Anyone who knew anything about fission should have foreseen that this was clearly not how control rods should be designed. It is so obvious, in fact, that I am forced to conclude that I have overlooked a critical piece of engineering information, because no intelligent, rational person would have created such a system.

Within 4 seconds, the reactor’s energy output had soared to several times its intended capacity. Runaway heat and pressure deep inside the core ruptured fuel channels, then water pipes, causing the pumps’ automatic safety valves to close. This stopped the flow of coolant, increasing the rate at which steam was forming from the core’s diminishing water supply. The reactor’s own safety valves attempted to vent the steam, but the pressure was too great and they, too, ruptured.

At that moment, remarkably, there was a man in the expansive reactor hall of Unit 4 who witnessed all this.129 Night Shift Chief of the Reactor Shop Valeriy Perevozchenko saw the top of the reactor - a 15-meter-wide disk comprised of 2000 individual metal covers which cap safety valves - begin to jump up and down. He ran. The reactor’s uranium fuel was increasing power exponentially, reaching some 3,000°C, while pressure rose at a rate of 15 atmospheres per second. At precisely 01:23:58, a mere 18 seconds after Akimov pressed the SCRAM button, steam pressure overwhelmed Chernobyl’s incapacitated fourth reactor. A steam explosion blew the 450-ton upper biological shield clear off the reactor before it crashed back down, coming to rest at a steep angle in the raging maw it left behind. The core was exposed.130

A split second later, steam and inrushing air reacted with the fuel’s ruined zirconium cladding to create a volatile mixture of hydrogen and oxygen, which triggered a second, far more powerful explosion.131 Fifty tons of vaporised nuclear fuel were thrown into the atmosphere, destined to be carried away in a poisonous cloud that would spread across most of Europe. The mighty explosion ejected a further 700 tons of radioactive material - mostly graphite - from the periphery of the core, scattering it across an area of a few square kilometers. This included the roofs of the turbine hall, Unit 3, and the ventilation stack it shared with Unit 4, all of which erupted into flames. The reactor fuel’s extreme temperature, combined with air rushing into the gaping hole, ignited the core’s remaining graphite and generated an inferno that burned for weeks. Most lights, windows and electrical systems throughout the severely damaged Unit 4 were blown out, leaving only a smattering of emergency lighting to provide illumination.132 (Linked Footnote)133

“There134 was a heavy thud,” remembered engineer Sasha Yuvchenko in a 2004 interview with the Guardian newspaper. He was only 24 years-old in 1986. “A couple of seconds later, I felt a wave come through the room. The thick concrete walls were bent like rubber. I thought war had broken out. We started to look for Khodemchuk, but he had been by the pumps and had been vaporised. Steam wrapped around everything; it was dark and there was a horrible hissing noise. There was no ceiling, only sky; a sky full of stars.” Yuvchenko ran outside to see what had happened. “Half the building had gone,” he says. “There was nothing we could do.135” One man was killed in an instant: 35-year-old pump operator Valeriy Khodemchuk was unfortunate enough to be in the main circulating pump room when it was annihilated by the explosion. His body was never recovered, leaving him entombed inside Unit 4.

Measuring radiation is a convoluted exercise. Units have included the curie, becquerel, rad, rem, roentgen, gray, sievert and coulomb. The main unit used for measuring the exposure of ionizing radiation at Chernobyl in 1986 was a Roentgen. It’s now outdated, but I’ll use it for the remainder of this book to keep things simple and because almost all reported measurements from the accident were in roentgens. We are all constantly being exposed to radiation from a variety of sources, such as aircraft, rocks, some foods and the Sun, and a typical human is exposed to ordinary background radiation at a harmless dose of 23 microroentgens-per-hour (µR/h), or 0.000023 roentgens-per-hour (R/h). A chest x-ray will give you a dose of 0.8 roentgens; the annual dose limit for a radiation worker, set by the U.S. Nuclear Regulatory Commission (NRC), equates to 0.0028R/h; the NRC’s limit for the public is 0.1 roentgens for an entire year; aircrews, who receive a higher dose than radiation workers because they work in the upper atmosphere, where protection from solar radiation is lessened, receive 0.3 roentgens/year.136 The137 radiation in Chernobyl’s Unit 4 reactor hall was now at an instantly-lethal 30,000 roentgens-per-hour. 500 roentgens, received over the course of 5 hours, is a fatal dose. 400 is fatal in 50% of victims. Anything even approaching that will hospitalise you for months if you’re lucky, or cripple you if you aren’t. The volume and intensity of radioactive particles thrown into the atmosphere on that night was equal to 10 Hiroshima bombs, not including the hundreds of tons of reactor fuel and graphite that landed all over the plant.

Back in the control room, Akimov attempted to phone the fire brigade - who had responded immediately to the devastation and were already on their way - but the line was dead.138 The explosion tore away water pipes used to supply coolant into the bottom of the core, preventing the reactor from being fed with water by the mangled pumps. Unfortunately, the operators did not realise this - or were in denial, given the horrifying consequences a reactor explosion would entail - and their lack of understanding lead them down the wrong course of action which served only to exacerbate the situation and throw lives away. Instead, Deputy-Chief Engineer Dyatlov became convinced the explosions had been caused by hydrogen in the Safety Control System’s emergency water tank, and that the reactor must still be intact. Even though he had no real basis for this explanation - and if he had looked out of a window he would have seen that he was wrong - he acted on this belief for hours after. There can be no other reason for an otherwise intelligent and rational human being defying the obvious. His version of events was told to everyone who asked, including Bryukhanov’s report to the Government in Moscow, and was believed for almost an entire day. Curiously, despite admitting that he at first thought the explosion had been caused by hydrogen in a water tank, Dyatlov later said, “I don't know how [Bryukhanov] reached that conclusion [that the reactor was not destroyed]. He did not ask me if the reactor was destroyed - and I felt too nauseated to say anything. There was nothing left of my insides by that time.139” Did he lie/mis-remember? I don’t know. This is a narrative contradiction I cannot explain.

Every man in the control room was shocked and confused; they believed they had done everything right, under the circumstances. Akimov, prevailed upon by Dyatlov that the reactor could be saved, tried to start the diesel generators then sent two young trainees - Viktor Proskuryakov and Aleksandr Kudyavtsev - to the reactor hall with instructions to lower the control rods by hand. He sent them to their deaths. Dyatlov spent the rest of his life regretting the moment. “When they ran out into the corridor, I realized it was a stupid thing to do. If the rods had not come down by electricity or gravity, there would be no way of getting them down manually. I rushed after them, but they had disappeared,” he said a few years before his death.140 The trainees made it to the massive reactor hall, having navigated their way past destroyed rooms and elevators, and only remained in the vicinity for a minute - stunned by what they saw - but that was enough. They died a few weeks later. Returning to the Unit 4 control room, tanned deep brown by the massive dose of radiation they had absorbed, the pair reported that the reactor was simply no longer there. Dyatlov refused to believe them, insisting they were mistaken: the reactor was intact, the explosion had come from an oxygen/hydrogen mix in an emergency tank. Water had to be supplied to the core!

The men on duty - particularly Dyatlov - were exhibiting strong signs of a psychological phenomenon often associated with man-made disasters, known as groupthink. Described as ‘the desire for harmony or conformity in the group [which] results in an irrational or dysfunctional decision-making outcome,’ Professor of psychology Doctor James T. Reason believes groupthink was a significant factor in the behaviour of the Unit 4 operators. “Their actions were certainly consistent with an illusion of invulnerability,” he says, in reference to choices made during the hour preceding the explosion, though still relevant here. “It is likely that they rationalised away any worries (or warnings) they might have had about the hazards of their behaviour.141”

Valeriy Perevozchenko, the 38-year-old who witnessed the reactor valve-caps jumping up and down, was the first person of any authority to realise and accept what had really happened. He grabbed a radiometer rated for 1000 microroentgens - far higher than any normal reading. It went off the scale. Unbelievably, apart from one buried under rubble and another locked in a safe, there weren’t any devices for measuring anything higher at the plant, as the explosion had burnt out the powerful sensors around the building.142 Even standard safety equipment was locked up and inaccessible.143 He took a guess, estimating 5 roentgens-per-hour. Not even close. Taking charge, Perevozchenko ordered two men to go and search for several missing people. Together, they managed to find and rescue an unconscious Vladimir Shashenok from under a fallen girder. Shashenok, a young Automatic Systems Adjuster who had been monitoring pressure gauges, received deep thermal and radiation burns over his entire body when the explosion destroyed the room he was in. His two brave rescuers received serious radiation injuries, including a radiation burn on one man’s back where Shashenok’s hand rested as he was carried out. Both miraculously survived the accident, despite one of them receiving far more than an ordinary fatal dose. Vladimir Shashenok, a father of two who celebrated his 35th birthday only four days prior, succumbed to horrendous injuries in hospital four-and-a-half-hours later, having never regained consciousness. He was the second and final man to die on the first day. When his wife saw him, she was shocked. “It was not my husband at all, it was a swollen blister.144”

Perevozchenko, meanwhile, went off in search of the already-deceased Khodemchuk, wading through debris, picking up pieces of fuel and graphite with his bare hands as he struggled to find his friend in the darkness. After an exhausting search turned up nothing but rubble and warped metal, he resigned himself to the fact that his colleague was lost and started back to Unit 4. By now Perevozchenko was suffering from the effects of strong radiation, continually vomiting and lapsing into unconsciousness as he staggered towards the control room. When he finally made it, he reported that the reactor was destroyed to Dyatlov, who rejected his assessment. The operators were already feeding water to the core.

Radioactive reactor fuel and graphite lay everywhere. Part of the roof had collapsed into Unit 4’s section of the turbine hall, setting turbine 7 on fire and breaking an oil pipe, which spread the fire still further and set the hall’s roof alight. Falling debris had broken the pressure valve on a feed pump, which was gushing out boiling, radioactive water.145 Men and women rushed past chunks of uranium fuel as they battled to contain the blaze, isolate electrical systems, and manually open oil-drain and cooling-water valves. Many of these brave souls later died, unaware they had been running among pieces of reactor fuel. For their part, Akimov and Toptunov stayed at the plant after the morning shift relieved them from duty at 6am, choosing to join the desperate effort to salvage the situation. The pair decided water flow to the reactor must be blocked by a closed valve somewhere, so they went together to the half-destroyed feedwater room, where they opened valves on the two feedwater lines. Next, they moved to another room, where they stood knee-deep in a highly radioactive mixture of fuel and water for hours, turning half-submerged valves by hand until the radiation drained their strength and they were evacuated to Pripyat’s hospital.146 Their noble efforts were in vain. The water lines had been destroyed along with the reactor - they were opening valves to nowhere - yet still the control room operators continued redirecting water towards the reactor even six hours after the explosion.

The Chernobyl plant staff were genuine heroes that night, in the true sense of the word. They did not flee when they could have. Instead, they selflessly stayed at their posts and replaced the hydrogen coolant in the generators with nitrogen, avoiding another explosion; they poured oil from the tanks of the damaged turbine into the emergency tanks outside, and spread water over the oil tanks to prevent more fire. Had none of this been done, fires would have spread down the entire 600-meter turbine hall and more of the roof would have likely collapsed. The flames would then have spread to Units 1, 2 and 3, which, in all probability, would have resulted in the destruction of all four reactors.

I would like to lift a paragraph straight out of Medvedev’s Chernobyl Notebook, if I may, because it illustrates the gallantry on display that night. “Aleksandr Lelechenko, protecting the young electricians from going unnecessarily into the zone of high radiation, himself went into the electrolysis space three times in order to turn off the flow of hydrogen to the emergency generators. When we take into account that the electrolysis space was alongside the pile of debris, and fragments of fuel and reactor graphite were everywhere, and the radioactivity was between 5,000 and 15,000 roentgens per hour, one can get an idea of how highly moral and heroic this [47]-year-old man was when he deliberately shielded young lives behind his own. And then, in radioactive water up to his knees, he studied the condition of the switchboxes, trying to supply voltage to the feedwater pumps. His total exposure dose was 2,500 rads [2,851 roentgens], enough to kill him five times. But after he had received first aid at the medical station in Pripyat, Lelechenko rushed back to the Unit and worked there several more hours.” This is just one example of one man’s efforts. There are countless more I have omitted. What makes it so depressing is that a lot of what those men did to save the reactor only made the situation worse. They sacrificed their lives for nothing.

Even after he had gone back to work at the plant - and I cannot fathom how he found the strength - Lelechenko insisted he was fine and refused to go to hospital, instead returning home that evening to eat dinner with his wife. He hardly slept, yet still summoned enough energy to get up the following morning and go back to work, explaining to his wife, “You can’t imagine what’s going on there. We have to save the station.147” He died two weeks later on May 7th, in a hospital in Kiev; the third victim of Chernobyl. He had been so sick that he would not have survived the flight to Moscow’s specialist radiation hospital, where the others would soon find themselves. For his bravery, Lelechenko was posthumously awarded the Order of Lenin medal, the Soviet Union’s highest national decoration.148