The Demon Core

On the 6th of August 1945, the first nuclear weapon ever used in warfare, codenamed ‘Little Boy’, was dropped over the Japanese city of Hiroshima. Despite technically being considered a failure by only achieving 2% of its potential yield, the initial blast exploded with the force of 15 Kilotons of TNT. In the beat of a hummingbird’s wing, the city was levelled and 80,000 people lost their lives. Over the ensuing weeks and months, a further 90,000 to 166,000 people died slow and painful deaths from radiation poisoning.

This second bomb swiftly followed on the 9th of August code-named ‘Fat Man’ which was dropped over Nagasaki, killing a further 40,000 in the nuclear inferno, with a temperature hotter than the surface of the sun. Up to 80,000 people were then lost to fallout and radiation poisoning. Many of those who died in the blast were literally vaporised, leaving nothing behind except shadows etched into walls.

In the wake of these devastating attacks, the Japanese Emperor, Hirohito, announced Japan’s surrender to the Allies on the 15th of August that year. This would be the first time many of his subjects had heard his voice. Hirohito spoke in classical Japanese, with the pronunciation unfamiliar to many of his subjects. During his address, he never used the word ‘surrender’ and cited the use of a “New and most cruel bomb” as being the reason for the withdrawal of hostilities between the Japanese Empire and the Allies.

The address was made via a recording, and on the 14th of August, a group of officers raided the imperial palace, trying to seize the recorded address before transmission, believing that it would be ‘dishonourable’ for Japan to surrender. The rebels could not find the recordings, hidden in a pile of documents. The tapes were then smuggled out, one in a lunch bag and the other in an ornate lacquer box. As a last-ditch effort to prevent the transmission, Major Kenji Hatanaka went directly to the station where the address was to be broadcast. Eventually, he acceded to the orders of the Eastern District Army.

There was, however, a third bomb planned. Had Japan not surrendered, the third warhead was due to be dropped on Tokyo. The death toll would have been catastrophic. The heart of this device would have been a sphere of subcritical plutonium just 89 millimetres in diameter and weighing 6.2 kilograms, codenamed Rufus. History, however, would give it a much darker moniker: The Demon Core.

The First Incident.

Haroutune Krikor Daghlian Jr, known as Harry to his friends and colleagues, was an Armenian American physicist. Daghlian started his academic career at MIT but switched to Purdue University to study particle physics, where he graduated with a Bachelor of Science degree in 1942. He was hired to work on the Manhattan Project, which developed the first atomic bombs.

With ‘Rufus’ no longer needed as part of the arsenal, Daghlian was conducting critical mass experiments in the project’s birthplace at the top-secret Los Alamos Laboratory in New Mexico.

Rufus was a subcritical mass, and due to its construction, it could not be accidentally detonated. The real danger came from the invisible waves of radiation that it could emit should the mass, which was always poised at 95% of critical mass, ever be tipped towards going ‘super critical. There were no outwardly visible signs of how dangerous this fist-sized sphere of Plutonium coated in nickel was, it didn’t hum or emit an ethereal green glow; the only thing that would hold it apart was that it was said to be unsettlingly warm to the touch. The nickel coating was in place to contain the radiation under normal circumstances.

There was little understood then about the actual processes by which nuclear power and reactions were generated. Although the dangers were known, there was a certain ‘seat of the pants’ attitude towards safety, leading to experiments that were likened to ‘tickling the Dragon’s tail’. On the 21st of August 1945, Harry Daghlian returned to the lab after hours to continue an experiment that involved reflecting neutrons on the core by placing heavy tungsten carbide bricks around it. These bricks would act as a mirror and push the core closer to criticality. As he carefully placed them, a detector went off, warning him that if he put the brick, it would cause the dragon to wake and send Rufus into a dangerous, supercritical state. Freezing, Daghlian started to withdraw the 5kg brick, but it slipped and hit the core. A wave of warmth blew over him, and a sour taste filled his mouth as a bright blue flash emanated from the core. The Dragon had awoken.

Daghlian acted quickly, knocking the brick to the floor and stabilising the core. The whole thing was over in less than a second, but it had been long enough. The warmth that had washed over Daghlian was a wave of radioactive energy. A chest x-ray exposes the patient to around 0.01 rem; 300 rem is a fatal dose of radioactivity. In these fractions of a second, Harry Daghlian absorbed 510 rem. The hand that he had used to knock the brick loose was severely burned, photos taken to document his injuries resemble a hand with a glove melted onto it and peeling away at the palm. Daghlian was the only scientific member of staff present. Still, a security guard, Private Robert J. Hemmerly, sat a few meters away, and, although he escaped immediate radiation sickness, it is believed that the exposure shortened his life. Hemmerly died of acute myelogenous leukaemia 33 years after the accident. Daghlian was rushed to the hospital and treated, but twenty-five days later, he was dead from acute radiation sickness after falling into a coma. His mother and sister were at his bedside. Also comforting him was his friend and fellow scientist Louis Slotin, who would become the Demon Core’s second victim.

The Second Incident.

Louis Slotin, in his blue jeans and cowboy boots, with a devil-may-care attitude towards laboratory protocol, had earned himself the nickname ‘The Nuclear Cowboy’. Quite the showman, he was known for conducting experiments without using the correct safety equipment. Since the accident that had claimed the life of Harry Daghlian the lab at Los Alamos had switched from using tungsten carbide bricks to using a sphere of material that could be manually lowered over the core, used in tandem with safety shims  that would prevent the core from being completely enveloped (and therefore going prompt critical). With these safety precautions in place, the halves of the sphere couldn’t touch. Slotin, to push the sample even closer to critical, didn’t use the spacers. Instead, he used the tip of a flathead screwdriver. Enrico Fermi, physicist and the creator of the world’s first nuclear reactor, warned Slotin that he would be dead within the year if he continued experimenting this way.

On the 21st of May 1946, Slotin’s screwdriver slipped, and the demon core awoke again, letting out a pulse of heat and blue light. Unlike the first instance, Slotin was not alone in the lab. As the core spewed out heat and blue light, the others in the lab ran for safety. Slotin, who was training his replacement at the time, lifted the half sphere off with his hand and shouted for everyone to get back to where they were so they could mark with chalk their positions and calculate how much radiation they had absorbed. In the deafening silence that followed the incident, Slotin was heard to say, “Well, that does it.” Slotin was rushed to the hospital with acute radiation poisoning, and it is thought that he had absorbed more than 1000 rem, well over three times the lethal dose. His injuries were so severe that it was described as ‘Three-dimensional Sunburn’ with his internal organs burnt from the exposure. He would die 9 days after the accident, and he would be treated by the same nurse as his friend, in the same room, and, in a final bit of irony, both accidents would take place on Tuesdays, which happened to be the 21st day of the month.

Following the loss of two of its best minds, the Los Alamos lab forbade further hands-on experiments with radioactive cores. From that point on, everything would be done remotely. The demon core was scheduled for destruction via detonation, but after Slotin’s untimely death, it was safely melted down and re-integrated into the US stockpile.