Midnight in Chernobyl: The Untold Story of the World's Greatest Nuclear Disaster

by Adam Higginbotham

On October 9 the two thousand tons of graphite in Windscale Pile Number One caught fire. It burned for two days, releasing radiation across the United Kingdom and Europe and contaminating local dairy farms with high levels of iodine 131.

On October 9 the two thousand tons of graphite in Windscale Pile Number One caught fire. It burned for two days, releasing radiation across the United Kingdom and Europe and contaminating local dairy farms with high levels of iodine 131.

threw the tank’s 160-tonne concrete lid twenty meters into the air,

threw the tank’s 160-tonne concrete lid twenty meters into the air,

Within a few hours, a blanket of gray radioactive ash and debris several centimeters thick had settled over the industrial zone.

Within a few hours, a blanket of gray radioactive ash and debris several centimeters thick had settled over the industrial zone.

highly radioactive contamination had begun to spread across the Urals—2 million curies of it—falling in a deadly trace six kilometers wide and nearly fifty kilometers long. The next day, light rain and a thick, black snow fell on nearby villages.

highly radioactive contamination had begun to spread across the Urals—2 million curies of it—falling in a deadly trace six kilometers wide and nearly fifty kilometers long. The next day, light rain and a thick, black snow fell on nearby villages.

The first problem arose from the positive void coefficient, the drawback that made Soviet graphite-water reactors susceptible to runaway chain reactions in the event of a loss of coolant,

The first problem arose from the positive void coefficient, the drawback that made Soviet graphite-water reactors susceptible to runaway chain reactions in the event of a loss of coolant,

A second failing of the reactor resulted from its colossal size.

A second failing of the reactor resulted from its colossal size.

Isolated hot spots of reactivity might build deep inside the core, where they could prove hard to detect.

Isolated hot spots of reactivity might build deep inside the core, where they could prove hard to detect.

A third fault lay in the heart of the reactor’s emergency protection system,

A third fault lay in the heart of the reactor’s emergency protection system,

The AZ-5 emergency protection system was tripped, but before the chain reaction could be stopped, a partial meltdown occurred, destroying or damaging thirty-two fuel assemblies and releasing radiation into the atmosphere over the Gulf of Finland.

The AZ-5 emergency protection system was tripped, but before the chain reaction could be stopped, a partial meltdown occurred, destroying or damaging thirty-two fuel assemblies and releasing radiation into the atmosphere over the Gulf of Finland.

Despite their apparent urgency, the reactor designers failed to act on a single one of these directives, and Moscow promptly ordered more of the reactors to be built.

Despite their apparent urgency, the reactor designers failed to act on a single one of these directives, and Moscow promptly ordered more of the reactors to be built.

a relief valve burst, and superheated steam at 300 degrees centigrade escaped into the annular compartments surrounding the reactor well. Fourteen men were boiled alive.

a relief valve burst, and superheated steam at 300 degrees centigrade escaped into the annular compartments surrounding the reactor well. Fourteen men were boiled alive.

Dyatlov had been involved in a reactor accident in Laboratory 23. There was an explosion, and Dyatlov was exposed to 100 rem, a huge dose of radiation.

But Dyatlov, perhaps assuming that a lower power level would be safer, was adamant that it be conducted at a level of 200 megawatts.

At 200 megawatts, Akimov knew that the reactor could be dangerously unstable and even harder to manage than usual.

And the program for the test stipulated it be conducted at not less than 700 megawatts.

Then, at twenty-eight minutes past midnight, the young engineer made a mistake.

the unit’s computerized regulation system was set to local automatic control,

Toptunov began the process of transferring the system to global automatic—a

Bereft of fresh instructions, the computer defaulted to the last set point it had been given: near zero. Now Toptunov watched in dismay as the glowing gray figures on the reactimeter display began to tumble: 500 . . . 400 . . . 300 . . . 200 . . . 100 megawatts. The reactor was slipping away from him.

Akimov saw what was happening. “Maintain power! Maintain power!” he shouted. But Toptunov could not stop the numbers from falling.

Within two minutes, the power output of Unit Four had plunged to 30 megawatts—less than 1 percent of its thermal capacity.

By 12:30 a.m., the reactimeter display was ...

Yet for at least four more minutes Toptunov ...

While he waited, neutron-scavenging xenon 135 gas began to build in the core, overwhelming what little reactivity remained. The reactor was being poisoned, plunging ...

nuclear safety procedures made the operators’ course quite clear: they should have aborted the test and shut down the reactor immediately.

At this moment, only a careful stabilization of the reactor, followed by a slowly managed shutdown, might have headed off disaster.

The test program closely duplicated one conducted on Unit Three in 1984—which, although it had failed to produce the desired results and keep the circulation pumps running, had nonetheless concluded without incident.

thermal power leapt to more than a hundred times maximum.

As the temperature climbed toward 3,000 degrees centigrade, the zirconium alloy casing of the assemblies softened, ruptured, and then exploded,

thermal power peaked at more than 12 billion watts.

Steam pressure inside the sealed reactor space rose exponentially—eight atmospheres in a second—heaving Elena, the two-thousand-tonne concrete-and-steel upper biological shield, clear of its mountings and shearing the remaining pressure tubes at their welds.

The temperature inside the reactor rose to 4,650 degrees centigrade—not quite as hot ...

Reactor Number Four was torn apart by a catastrophic explosion, equivalent to as much as sixty tonnes of TNT.

Almost seven tonnes of uranium fuel, together with pieces of control rods, zirconium channels, and graphite blocks, were pulverized into tiny fragments and sucked high into the atmosphere, forming a mixture of gases and aerosols carrying radioisotopes, including iodine 131, neptunium 239, cesium 137, strontium 90, and plutonium 239—among the most dangerous substances known to man.

further 25 to 30 tonnes of uranium and highly radioactive graphite were launched out of the core and scattered around Unit Four, starting small blazes where they fell.

Exposed to the air, 1,300 tonnes of incandescent graphite rubble that remained in the reactor c...

As they gazed at the molten crater beneath, the three men realized in horror that they were staring directly into the active zone: the blazing throat of the reactor.

emitting fields of gamma rays reaching thousands of roentgen an hour.

A fatal dose of radiation is estimated at around 500 rem—roentgen equivalent man—or the amount absorbed by the average human body when exposed to a field of 500 roentgen per hour for sixty minutes. In some places on the roof of Unit Three, lumps of uranium fuel and graphite were emitting gamma and neutron radiation at a rate of 3,000 roentgen an hour. In others, levels may have reached more than 8,000 roentgen an hour: there, a man would absorb a lethal dose in less than four minutes.