‘It has been moved, certainly, but it has only uncovered about twenty per cent of the opening to the active zone. It’s a narrow crescent shape, and the chances of the sand and boron landing inside are small. It will all end up on the shield.’
‘That doesn’t matter. We’ll bury the whole reactor in sand.’
‘But every load of sand throws heavy particles into the air. If you left it alone, they would stay in the reactor.’
Legasov thought for a moment, then said, ‘But what will people think if we just leave it alone? We have to do something.’
‘And why the lead?’ asked Kalugin.
‘The lead melts and boils and removes heat from the core.’
‘But lead also poisons the atmosphere.’
‘That’s less dangerous than a chain reaction.’
‘In my opinion there’s no danger of that.’
‘So what do you suggest?’
‘Leave things as they are. Let the fire burn out.’
Legasov shook his head. ‘The people would not understand. We have to be seen to be doing something.’
‘But have you considered,’ asked Fedulenko, ‘that if you succeed in covering the reactor with sand, it will increase the heat in the core? At the moment it’s like a furnace. The air comes in from below and cools the lower layer. It cannot fail to do so. It acts like a grate. But if you block the flow of air, then the heat will increase. This is almost certainly what is happening now. At twenty-nine hundred degrees the fuel will melt, possibly burn through the concrete base, and react with the water in the bubbler pool to produce a far greater explosion than we have seen already.’
All the members of the commission now addressed themselves to the horrifying possibility that the molten mass of uranium dioxide fuel, fission products and fuel cladding known as corium, might burn through the concrete base and react with the water below to produce a massive new explosion that would destroy the other three reactors. Even before leaving Moscow, Academician Velikhov had initiated studies at the Kurchatov Institute on the effect of corium on concrete, and he now judged that the corium might already have penetrated halfway through the two-metre slab of concrete.
Even if the bubbler pool could be drained of water, there remained the danger that the candescent corium might burn on down through the foundations and ground to the water table below. This would lead to a further catastrophic thermal explosion, devastating an area of two hundred square kilometres and poisoning the tributaries of the Dnieper River, which provided water for thirty million people in the Ukraine.
The most immediate danger was the water in the bubbler pool. No one knew how much water it contained: the greater the amount, the greater the danger. Someone had to find out, but no one knew how to approach it through the ruins beneath the reactor. The plans of the power station had been lost; the engineers had had to send for those of the similar RBMK at Smolensk. An Armenian engineer volunteered to go on a reconnaissance mission: two soldiers went with him, wearing white protective clothing, respirators and a mask. At 2.00 a.m. on 2 May he returned, haggard, unshaven, wide-eyed, his respirator hanging around his waist. ‘Less than two hundred cubic metres,’ he reported, then sank back exhausted into a chair.
Although it was a relief that there was not more, there remained enough water to cause a further thermal explosion. Brukhanov and Fomin, still responsible for implementing the decisions of the government commission, sent the head of the shift and Vadim Grishenka to make their own assessment of the water level. They too saw that the upper bubbler pool was empty, but said that the water that remained in the lower section could only be drained through the gate valves at the bottom.
These had to be opened by hand, which meant someone had to dive into the highly radioactive water. Shasharin, the deputy minister of energy, came up with wet suits and Silayev asked for volunteers, offering lavish inducements as encouragement: a car, a dacha, a flat and a generous pension for the family of anyone who lost his life in this hazardous operation. A detachment of the chemical troops under a Captain Zbrovsky cut a way for the fire hoses, while Yevgeny Ignatenko, the deputy director of the Nuclear Energy Agency, and two engineers put on wet suits, dove into the bubbler pool and opened the valves. The water poured out and the bubbler pool was emptied.
But the danger was not over. The water that had been fruitlessly directed towards the reactor immediately after the accident had flooded the passages and air vents of the basement. Draining this was a more complex operation, undertaken by the commander of a special unit of the fire brigade in Belaya Tserkov, Major Georgi Nagaevsky, who resembled the French actor Jean Gabin, with an honest, square face and deep blue eyes. He was telephoned on the morning of 3 May by his commander in Kiev and asked to find five volunteers for a hazardous operation.
Thirty-five men from Belaya Tserkov had already been to Chernobyl, but since Nagaevsky was the most familiar with the equipment, he himself was the first to volunteer. With four others he proceeded to Ivankov, where he was briefed on the nature and the urgency of the task. He was warned of the danger; they would be working in an area where the dose could be as much as three hundred rems per hour, and they had to avoid any spillage of the radioactive water.
While a normal fire engine could pump water at a rate of forty litres a second, Nagaevsky’s two special machines could increase this to 110. They also had hoses up to two kilometres long. Before attempting to lay them in the basement of the reactor, Nagaevsky’s men made dummy runs on the uncontaminated ground around Chernobyl, reducing the time it took them to run out the hoses from twenty to seven minutes. They also made precise plans as to how best to approach the fourth unit. There was an entrance designed for the vehicles that delivered the nuclear fuel, and Captain Zbrovsky of the chemical troops cleared this of rubble in one of the armoured reconnaissance vehicles.
The operation was postponed; the firemen were unwilling to proceed while the helicopters were still dropping tons of sand and boron onto the reactor, but they continued their rehearsals. By the evening of 6 May, however, they could delay no longer. Before they set out on their mission, the commander of the fire services gave Nagaevsky three litres of vodka, saying, ‘Give a shot to each of the lads – for courage, better blood circulation and protection against radiation.’ Nagaevsky declined; however, when he got to the bunker at the power station, a doctor repeated the popular line that it was advisable to drink some alcohol before they set out on their mission, but said that unfortunately they had run out.
Remembering the three litres back at the commission’s headquarters in the town of Chernobyl, Nagaevsky asked if anyone would go back to fetch it. A young fireman from Zhitomir volunteered; but when he got back to Chernobyl, his nerve failed him; he said that he had cut his fingers on the plates of the fire engine and so could not return. Another young fireman, Alexander Nemirovsky, was smoking outside in the evening air when the captain on duty came out, shouting, ‘We need a fireman to drive to the station.’ Nemirovsky volunteered and drove with a dosimetrist to join the team.
Nagaevsky and his men now drove their fire engines straight under the reactor. Jumping in and out of the protective reconnaissance vehicles to minimize their exposure to radiation, they laid four hoses – two with a diameter of 1,250 millimetres to pump out the water, two with a diameter of 3,000 millimetres to suck out the debris and dirt. Then the contaminated water was pumped out of the flooded basement into a reservoir adjacent to the power station, from which the uncontaminated water had been pumped into the Pripyat River.
The pumps started at 10.00 p.m. The firemen waited in the bunker along with Brukhanov and Fomin. Every fifteen minutes, two men ran out to check the pumps. After half an hour, Nagaevsky reported to Fomin that the water level had decreased. Fomin telephoned Silayev in Chernobyl, whereupon Silayev passed the information on to Ryzhkov in Moscow. However, half an hour later there was no change. Three hours after they had started pumping, the level had decreased by only one centimetre.
At 3.00 a.m., two firem
en returned breathlessly to the bunker to report that one of the tracked reconnaissance vehicles of the chemical troops had driven over the hoses, cutting them in twenty different places and smashing the sleeves that connected the sections. Nagaevsky ran out to see radioactive water pouring out from the broken hoses only thirty-five metres from the reactor. The operation came to a halt.
Nagaevsky then rang Chernobyl to tell them to prepare twenty new sections of hose, and Nemirovsky drove back to fetch them as fast as his fire engine would go. New men arrived to help. Dressed in rubber suits and wearing gloves, respirators and masks to protect their eyes, but standing knee-deep in radioactive water, the firemen replaced the ruptured hoses. Each hose took two minutes, but they finished in under an hour. They were exhausted, and some already suspected that it was not just as a result of their exertion. From the start, they had had a strange taste of sour apples in their mouths, and each had noticed that the others had dilated, bloodshot eyes. They were afraid; one joked that it would be worse in Afghanistan, but another said he would prefer that because at least he would know where the bullets were coming from; here the danger was intangible and invisible. They only knew that they had been affected when their voices became squeaky or they started to feel sick. One of Nagaevsky’s men from Belaya Tserkov started to vomit during the morning of 7 May. Another man fainted and was sent straight to the hospital at Ivankov.
By midnight on 7 May, thirty hours after it had started, all the water had been pumped out of the fourth unit and the immediate threat of a second thermal explosion had been averted.
7
While the firemen had been working to drain the bubbler pool and basement, the atmosphere in the commission had worsened, for the release of radioactive material from the reactor had risen sharply day by day. The physicists had estimated that only 3.5 per cent of the uranium had been ejected; therefore 96.5 per cent remained. The temperature in the core was estimated to be around 2,300°C. Millions of curies of radioactive isotopes were still rising into the atmosphere – first the noble gases, xenon and krypton, then iodine, caesium and some strontium. Boron was still being dropped by the helicopters, and it was thought to be absorbing some of the radioactivity, but still the emissions increased as the Kurchatov scientists had predicted they would – from two million curies on 1 May to four million curies on the 2nd, five million curies on the 3rd, seven million curies on the 4th and eight million curies on the 5th.
As the emissions increased, so did the anxiety of the commission. Calmer than Scherbina, Silayev nevertheless demanded reports every half hour and passed them on to Moscow. No member of the commission got more than two or three hours of sleep a day. They faced the possibility of not just one but several catastrophes: the pollution of the atmosphere, of the water table, and of the rivers by rain; and further explosions of incalculable force. To avert these disasters, every sinew of the Soviet state was flexed for action. Every branch of the armed forces and its ancillary brigades – the fire department, the civil defence, the troops of the interior ministry, the KGB, the air force, the civilian airline, Aeroflot – were represented at the highest level. Marshals and ministers, chairmen and generals, even the minister of medium machine building himself, the octogenarian Efim Slavsky, all waited on Silayev, straining at the leash to perform acts of heroic valour if only someone would tell them what to do.
But what was to be done? The military engineers under Marshal Oganov had started building a complex system of dams and drains in case rain should wash the radionuclides into the Pripyat. They also drilled boreholes to a level of forty metres where a layer of impermeable clay began, so that if the ground water should become contaminated it could be pumped out before it reached the river; and a start was made on a concrete barrier beneath the ground level to prevent water from seeping out from beneath the damaged reactor.
Such long-term measures, however, did nothing to avert the short-term crisis created by the haemorrhage of radionuclides into the atmosphere. No one seemed to know how to prevent it. While Kalugin and Fedulenko, after estimates made with slide rules in the Pioneer camp, insisted that the graphite fire would burn itself out within a period of between a week and a month, the rotund expert on nuclear fusion, Academician Velikhov, declared that there was no obvious remedy, since they faced a problem of an unprecedented kind. Clearly something that was too hot should be cooled down, so he recommended the construction of a heat exchanger beneath the reactor. But this meant digging under the foundations, building a concrete base, and on this constructing a web of pipes through which water could be pumped from the emergency core-cooling system of the other three reactors. It was not a quick solution.
Velikhov’s tentative approach to the crisis did not impress the military men like Generals Pikalov and Ivanov. To them he was a bumbling Mr Pickwick; Legasov was the man they preferred – lithe, confident, decisive, a leader in the Soviet mould. He backed the idea of the heat exchanger but thought that something more urgent must be done. What about nitrogen? Why not pump it in to freeze the earth beneath the foundations, drive out the oxygen and smother the fire?
For Silayev, it was a matter not of choosing one course of action but of putting all of them simultaneously into effect. The command was given for all available supplies of nitrogen to be brought to Chernobyl. The minister of coal, Mikhail Shchadov, a thickset man with silver hair and a deep, rasping voice, was told to mobilize miners to dig under the foundations of the reactor, and since time was of the essence, metro construction workers, digging the tunnels for the underground railway at Kiev, were summoned to Chernobyl. Every available source of concrete was to be delivered for the construction of the heat exchanger.
8
By this time it had become apparent to the commission that Nikolai Fomin was now incapable of acting as chief engineer. Eventually he was replaced by Taras Plochy, who together with Nikolai Steinberg had come from the Balakovsky nuclear power station to help with the emergency.
Working from the bunker beneath the administrative block, they were made responsible for carrying out the commission’s instructions to pump nitrogen into the reactor. From the beginning, both thought this an absurd idea. If the explosion had been contained within the structure, it might have made sense, but because the whole unit had been ruptured, all the nitrogen would escape into the open air. However, mere operators could not question the decisions of a man as eminent as Academician Legasov. Another engineer, Sergei Klimov, who had been brought back from retirement in the aftermath of the accident, had already ordered the equipment from Odessa that would convert liquid nitrogen into gas. A special shed had been built to house it behind the administrative block, and at 10.00 a.m. word came from the commission that the machinery would arrive at two p.m. that day.
It was delayed. At 4.00 p.m. they were told that it had been brought to the airport at Chernigov by helicopter, and would proceed from there by truck. When it arrived, it would not fit through the door into the shed. They used mallets to smash a wider opening, and by 8.00 p.m. could report to Silayev that they were ready to start pumping as soon as the nitrogen arrived.
This was expected that night but by morning it still had not arrived. They waited all day. At 11.00 that night, Silayev rang Brukhanov: ‘Find the nitrogen or you’ll be shot.’ The wretched Brukhanov traced it to Ivankov, where it had been held up because the tanker drivers were afraid to proceed. The problem was quickly solved by a regional commander, who stationed one armoured car at the front of the convoy and one at the back, with machine guns mounted on each one. Faced with a choice between visible and invisible threats, the drivers proceeded to Chernobyl. The nitrogen reached the power station at 1.00 a.m.
Steinberg was given the task of checking the supply. He found that two of the twenty tankers were empty, and that five, coloured blue rather than yellow, contained oxygen, not nitrogen. Nevertheless, there was enough for the operation to get under way, and by the next evening there was more than enough. Several freight trains had arrived in th
e station yards at Pripyat; thanks to the power of the commission, most of the nitrogen in the western part of the Soviet Union had been diverted to Chernobyl. Little of it was used, however, because after twenty-four hours even Legasov realized that the operation was a waste of time.
But by then the worst was over. On 6 May, for no apparent reason, the emissions of radionuclides from the reactor suddenly dropped from 8 million to 150,000 curies, and remained at a low level thereafter. By 9 May, the fire in the reactor seemed to have gone out. It was Victory Day – the commemoration of the Soviet defeat of the Germans in World War II – and by special government dispensation the restrictions on alcohol that had been ordered to start on 1 May were postponed for the celebration. For the members of the commission at Chernobyl, the struggle to master the reactor had been their own Great Patriotic War, and so it was an appropriate moment to bring out the vodka and celebrate victory in a battle, if not the end of the war.
Still, in the fading light of the evening, a last run by a helicopter over the reactor showed a small but bright spot of red in the crater. Some thought it was just a burning parachute, but Legasov advised Silayev that there might still be a fire in the core. The celebration was postponed. The next day a further eighty tons of lead were dropped into the reactor, after which the luminescence ceased. The vodka was brought out again, and at Ivankov that night victory was celebrated one day late.
VII
1
Working parallel to the Chernobyl commission in Ivankov and the Politburo commission in the Kremlin was the secret medical commission in Moscow. This met daily from 2 May onwards at the Ministry of Health to decide on the measures necessary for the care of the victims of the accident and the welfare of the population at large. It was headed by a deputy minister of health, Oleg Shepin, and included Shulzhenko, the head of the secret Third Division, and the health ministers of the Ukrainian and Belorussian republics, but inevitably the most influential members were those who knew most about the effects of radiation. One of these was Academician Leonid Ilyn, who represented the medical commission at Chernobyl; the other was the director of the Department of Haematology at the Central Institute for Advanced Medical Studies in Moscow, Professor Andrei Vorobyov.