Everything they had been taught now suggested to Akimov and Leonid that the test should be abandoned and the reactor closed down. It was perhaps possible, if the power could be maintained at this level, to wait another twenty-four hours or so for the xenon gas and iodine to decay. Dyatlov, however, had waited long enough. In a state of high exasperation, cursing the operatives for their incompetence, he ordered them to withdraw the control rods to increase the power. Both Akimov and Leonid hesitated: if they did as Dyatlov ordered, the reactor would be working with a dangerously small number of control rods inserted into the core. They argued with Dyatlov until Dyatlov, apoplectic with rage, threatened to bring back the foreman of the earlier shift, Yuri Tregub.
Faced with the direct orders of a deputy chief engineer who had worked with atomic reactors for more than twenty years, Akimov and Leonid gave way. A further seven control rods were withdrawn, leaving only eighteen in the reactor. This seemed to do the trick. By 1.00 a.m. the power had risen to two hundred megawatts and remained steady. This was below the recommended power level and had been achieved with the same small number of control rods left in the core, but it was enough to proceed with the tests on the turbine.
Soon after 1.00 a.m. the fourth main cooling pump was connected to the heat-transport system. This added to the negative reactivity and meant that Leonid had to withdraw more control rods. Moreover, the low level of power meant reduced resistance to the water flowing through the core; the rate of flow increased, putting pressure on the pumps and causing vibrations in the pipes, and less water turned to steam, which led to a fall in steam pressure in the separator drums.
The operators saw from their dials what was happening and tried to adjust the parameters but did not entirely succeed. Indeed, the steam pressure in the drum separators was falling to a level where it would automatically trigger a shutdown. They therefore overrode the ‘trip’ signals in respect to these variables while Dyatlov telephoned Valeri Perevozchenko, the foreman in charge of the reactor, and summoned him to the control room.
At 1.22 a.m., Leonid saw from a printout of the Skala computer that the reactivity reserve margin was half of what was recommended; in normal circumstances this would have led to an immediate shutdown. He reported the parameters to Akimov at just the moment when the experiment was to begin. At 1.23 the emergency regulating valves to the turbogenerator were turned off so that if necessary the test could be repeated. Metlenko switched on the oscillograph and Kirschenbaum shut off the steam from the turbine. As he did so, Leonid noticed that the reactor’s power had begun to rise. He alerted Akimov, who, glancing at the computer printout, shouted to Dyatlov that he was going to shut down the reactor and pushed the emergency AZ button to lower all the control rods into the core.
There was a thud, followed by further thuds from deep inside the building. At the turbine controls, Igor Kirschenbaum thought the sounds came from the huge tanks of nitrogen installed above the reactor at the same level as the control room. At this moment, Valeri Perevozchenko burst into the control room in a state of great alarm, shouting that while walking along the catwalk high above the top of the reactor, he had seen the heavy caps to the fuel channels jumping up and down in their sockets.
Akimov looked up at the instruments and saw that the descending control rods had stopped. He immediately disconnected the servomotors to let them fall under their own weight. They did not move. Simultaneously there was a terrible tremor, together with a sound like a clap of thunder. The walls shook, the lights went out and a drizzle of plaster dust rained down from great cracks in the ceiling.
At the control panel, the operators looked frantically at their dials and gauges, which were now dimly lit by the emergency circuits. Dyatlov, who had been standing by the electric panel, ran to the main board. He noticed at once that both Akimov and Leonid were in a state of confusion. He looked up at the reactivity gauge; it was positive when it should have been either negative or at zero. Numb with horror, he checked the position of the control rods and saw that they had jammed. He turned and, spotting the two young men who had stayed on to watch the test, Victor and Alexander, ordered them to run to the central hall and lower the control rods by hand. But as soon as they had left Dyatlov realized that it was a nonsensical order because they had jammed still attached to the servomotors. He rushed to the door to stop them but all he could see in the corridor were clouds of dust and smoke.
Dyatlov went back to the control panel, where Akimov had switched on all the emergency pumps to flood the core with water. None of them worked. Both men realized that whatever had caused the explosion – whether it was a separator drum or one of the nitrogen tanks – there was now a real danger of a meltdown. It was vital to get water into the reactor. Akimov turned to Piotr Palamarchuk and Razim Davletbayev and asked them to go to the turbine hall to see what was wrong with the pumps, while Dyatlov ordered Yuri Tregub and Valeri Perevozchenko to open the valves by hand.
In the central hall, before the explosion, Sasha Yuvchenko, accompanied by his immediate superior, Valeri Perevozchenko, had been asked by the operator of the circulation pumps, Ogulov, for some coloured paint to mark the different parts of his equipment. The three then went to Sasha’s storeroom. There the telephone rang; it was Dyatlov calling Valeri to the control room. Valeri told Sasha and Ogulov to wait for him in the storeroom.
It was here that they heard a crash that made Sasha think that a crane had fallen onto the building, and a few seconds later they felt a blast of such force that it threw them both onto the floor and blew down the door of the storeroom. When Sasha got to his feet he saw to his astonishment that the concrete walls of his room, a metre thick, had buckled under the force of the explosion.
He staggered out of the room, followed by Ogulov, groping in the dim light and choking in the dust. Ogulov wanted to go back to unit 3, but Sasha warned him that he might be crushed by slabs of concrete falling from the ceiling. ‘What can have happened?’ Ogulov asked him.
‘I don’t know,’ Sasha replied. ‘It may be a war.’
While Ogulov went back to his post by the pumps, Sasha tried to ring the control room from his office. He could not get through. Then he got a call from the head of shift in unit 3 asking for a stretcher from the first-aid post in his office.
Confused, because he thought the explosion had come from the fourth unit, Sasha snatched up the stretcher and set off towards unit 3. Before he got very far, he nearly bumped into a man whose face was covered with blisters and blood and whose clothes were filthy and wet. Recognizing him by his voice as one of the pump operators, he offered to help him, but the wounded mechanic brushed him aside, telling him to go to the aid of his companion, Gena, who was still by one of the pumps.
Leaving the stretcher, Sasha ran to the room from which the wounded man had come. It was dark, and at first there seemed to be no one there. Then he saw Gena, filthy and shivering with pain and shock. ‘Khodemchuk,’ the wretched man muttered, ‘help Khodemchuk. He’s still trapped up there.’ Sasha looked up and saw that there was nothing above him but the stars in the sky.
Since Gena could walk, Sasha led him out of the ruins of the pump operators’ room and almost at once came face-to-face with Yuri Tregub. ‘I’ve been told by Dyatlov to open the valves for the emergency cooling system,’ Tregub said breathlessly.
Realizing that it required two men to turn the huge valves, Sasha left Gena to go on alone and ran after Tregub. There were two ways of getting to the valves: the nearest one was from above, but there they found that the door had jammed. They went down to the lower entrance; here too the door was stuck, but there was room enough to squeeze through. Water was pouring down from the ceiling and was already up to their knees. They spent some minutes trying to turn the valves, to no avail.
Deciding that they might be able to make out what had happened from outside the building, they went out through a transportation passage and found themselves on the road outside the power station. To their horror, they saw that half of
the fourth unit had disappeared. The machine room no longer existed; in its place there was a huge hole, like a burst belly with a mass of torn metal intestines steaming and quivering in the night air. Sasha searched among the debris for the separator drums, but they no longer seemed to be there. Nor could he see the room where Khodemchuk had been stationed. He could make out the tanks that had contained water and nitrogen, hanging like huge matchboxes above the tangle of concrete and steel, and from amid this chaos there came a strange white glow.
Sasha stood still, hypnotized by the extraordinary sight. Then Tregub brought him to his senses. ‘We’re not sightseeing,’ he said. ‘We must go back.’
Their objective now was to find out what had happened to Khodemchuk, but back in the dim, dust-filled passages of the power station they ran into Sasha’s boss, Valeri, with the two young engineers, Victor and Alexander.
‘Have you got a torch?’ Valeri asked.
‘Yes, but the battery’s low.’
‘Never mind. Let me have it. We’ve been told to lower the control rods but we can’t get up through the machine room. The passage is blocked.’
‘The control rods?’ asked Sasha. ‘There are no control rods. We’ve been outside. The central hall doesn’t exist any more.’
‘An order is an order,’ said Valeri. ‘We have to try.’
The four of them now climbed from the twelfth to the thirty-fifth level, water from the emergency cooling tanks pouring over them like rain. When they reached the top, where the walls were made of reinforced concrete, they found that the huge door, which itself weighed a ton, had shifted on its hinges. Sasha held it open while Valeri, Victor and Alexander crept through onto the steel rafters, searching for the levers that would release the control rods from the servomotors. To light their way, Valeri took the torch from Sasha and handed it to Victor. Then they looked down through the tangle of steam and concrete, and instead of the top of the reactor saw a glowing volcanic crater.
Valeri crept back through the door. ‘There’s nothing to be done,’ he said.
Victor and Alexander followed. Sasha asked Valeri if he could take a look. Valeri would not let him. ‘There’s nothing to see,’ he said. He led them back through the smoke-filled passages to the control room to report to Dyatlov.
5
Back in the control room, after the initial panic, a measure of professional calm had returned. Young Igor Kirschenbaum, at the turbine-control panel, had thought first that the roar of the explosion came from the turbine spinning out of control, then that it was an earthquake; he had felt one once in the southern Ukraine. Nevertheless, he remained at his post, switching off all the circuits and waiting for the dials to tell him that the parameters were normal. When this was done, Dyatlov instructed Akimov to dismiss him, along with all other superfluous personnel.
Strictly speaking, Dyatlov was not in charge. Akimov, as head of the shift of the fourth unit, was responsible to the overall head of the shift, Rogozhkin, who was in unit 3. Akimov had reported to Rogozhkin over the telephone that there had been a serious accident, but Rogozhkin had not turned up to take charge. Moreover, Rogozhkin knew less about reactors than Dyatlov, and it was Dyatlov who had written the programme for the tests on the turbines. It was therefore Dyatlov who took charge, sending Perevozchenko to open the valves and ordering Akimov to start up the emergency cooling pumps. ‘Lads,’ he said calmly, ‘we’ve got to get water into the reactor.’
When Valeri Perevozchenko returned and reported that the reactor had been destroyed, Dyatlov countered calmly that this could not be true. Whatever it was that had exploded, the priority now was to cool the core. He asked Valeri and his three young companions to go up to level 27 and manually open the valves, which would send the water from the turbine hall into the bubbler pool.
Although Dyatlov knew that there had been an explosion, and could see from the dials in front of him that the reactor’s parameters were haywire, it did not occur to him that the explosion could have been in the core. He had worked with reactors for twenty years; he had taken numerous courses to bring his initial training up to date; he had studied the voluminous documentation that had accompanied the new RBMK reactors; he had seen the building of the fourth unit and had supervised its commissioning and never had it been suggested that the reactor itself could explode. He knew that the active zone was dead and realized that the hermetic containment might have been ruptured, but he could not envisage anything worse.
It was time to see for himself. Dyatlov left the control room and immediately ran into three young operators – one, Anatoli Kurguz, with skin peeling off all the exposed parts of his body. He ordered him to report at once to the medical unit. He went up to a window that looked out onto the reactor hall and saw that one of the walls had been completely destroyed.
Still convinced that it must have been a burst tank or drum that had caused the damage, Dyatlov ran along the passage to the end of the unit, down the stairs and out onto the road. The first thing to catch his eye was the fires on the roof of the turbine hall. He ran back up the stairs to the control room, which was filled with dust and smoke. He told Akimov to call the fire brigade and turn on the fans to extract the smoke. Then, noticing Leonid Toptunov and Igor Kirschenbaum, he turned angrily to Akimov: ‘Didn’t I tell you to dismiss them?’
‘They were dismissed,’ said Akimov, ‘but they returned.’
Igor explained that he had volunteered to bring respirators from the third block, and that Leonid, feeling responsible as the reactor’s operator for what had happened, had come back to help. Dyatlov again told them to leave. Igor obeyed, but once Dyatlov’s back was turned, Leonid stayed.
Dyatlov now went back down to the entrance on level 12. Here he could see the damage more clearly. The tanks filled with nitrogen had been destroyed and the emergency core-cooling system would not function. About three hundred square metres of the roof had collapsed, some of the panels and girders crashing onto the two turbines of the fourth unit. At level 6, a pipe had been ruptured, creating a fountain of scalding water, which, falling on torn cables, created a firework display of bright sparks, small fires and minor explosions. Worst of all, from inside the reactor came a terrible glow. It was like Dante’s vision of hell.
There were figures in this inferno, operators with fire extinguishers and firemen on the roof. Dyatlov went to the nearest fire engine and advised the young commander where the hydrants were to be found. Then he walked toward the third unit. At his feet there were some smouldering lumps of … of what? They looked like graphite, but if they were graphite that could only mean … It was dark. How could he tell? Perhaps they were lumps of concrete. He did not pause to inspect them but went back in through a door to the control room of the third unit. There the head of the shift asked him if he should shut down his reactor. Dyatlov said that it was unnecessary, but before returning to the fourth unit he took a dose of iodine from the first-aid kit.
6
Meanwhile, the hefty Piotr Palamarchuk and Razim Davletbayev, asked by Dyatlov to check the pumps, found their way through the dark, dusty passages into the adjacent turbine hall on level 12. The first thing they saw was that part of the roof had collapsed, and even as they stood there pieces of steel and chunks of concrete fell to the ground, together with dripping tar, which formed fires all over the floor. They stayed by the wall, watching the cascade of debris fall on the pipes filled with scalding radioactive water. Then they climbed down to level 5 and stumbled through clouds of steam to look at the pumps. They found the pumps swamped with water; none would function. All around them the ruptured pipes spewed forth their different contents, not just scalding water but hydrogen and oil. The greatest danger came from the hydrogen in the turbines, which could cause a further explosion. Razim began the process of replacing the hydrogen with nitrogen, but first he had to summon electricians to replace the cable that had been destroyed.
Three members of the team that had come from Karkhov to conduct the test on the turbines st
ood as impotent spectators in the midst of this confusion. Razim told them to leave, and Piotr dismissed three of his own engineers who had been there to measure the vibrations of the turbine during the shutdown. Of the two others, one, Shevchuk, was present in the hall, but another, Shashenok, had been in the reactor hall and did not answer the telephone attached to his post. With Shevchuk, Piotr set off to find him. The corridors were dark; the green lights that indicated a permissible level of radioactivity had turned to red, which made him realize that the explosion had done serious damage, but there was no way of knowing what the levels were and no means of obtaining protective clothing. There was debris everywhere; sometimes they could climb over the fallen girders; at other times their route was blocked, and they had to change direction.
Reaching the reactor hall, Piotr ran into Alexander Kudriatsev on his way back to the control room, who told him that everything above them had been blown apart. Only now did Piotr realize that the reactor itself might have been damaged, and seeing that he could not reach Shashenok’s post from where he was, he ran back with Shevchuk to get hold of a dosimetrist, one of the specialists with a Geiger counter responsible for monitoring radiation levels; but when he found one he was told that no one knew the level of radiation because the needles of the dosimeters were permanently fixed at the maximum reading.