Demon Core: The Nuclear Bomb Without An Explosion!

Do you know what the Demon Core is? Rest assured that, despite its name, it’s nothing like a superstitious group. It was a deadly nuclear bomb core that was supposed to be used in World War II as the third bomb on Japan. It was a plutonium pit that killed Russian scientists, Daghlian and Slotin.

The demon core was a sphere of subcritical plutonium with a diameter of 3.5 inches that was created as the fissile core for an early atomic bomb by the Manhattan Project of the United States during World War II.

Despite being one of the most poisonous chemicals known to man, plutonium cannot enter the human body while it is in this solid, monolithic state. The moderate, continuous heat produced by its radioactive decay is the only hint of the immense destructive force that the core contains. A plastic sandwich bag may readily block even the radiation it emits.

However, a plutonium core may become extremely unstable and cause a terrible death under very particular conditions, as two scientists would sadly learn in the immediate wake of the Second World War.

The Demon Core looks like a silver ball; at first glance, nothing looks suspicious about a metal ball. But in the heart, it has fissionable plutonium with tungsten carbide around it. A reflector that excites the core and makes it unstable only takes one touch to kill people without exploding!

It sounds scary enough, but it really happened in the past and was never actually used in the war after gauging the kind of damage it could cause to both sides if detonated. Although it is a genuine scientific tale, it is not the only spectacular instance of radiation poisoning during that period. Let’s take a detailed look at it!

History of the Demon Core

Radioactive material: Demon Core
Image by: Satakorn/ UnlimPhotos

There were instances when the periodic table ended at Uranium, element number 92, when Lisa Meitner, an Austrian physicist and radiochemist who is a magnificent scientist and the first female professor in the history of the University of Berlin, appeared.

She, of all people, could solve the riddle that tormented everyone – how does nuclear fission take place? She also described where the energy originates and how it may create new elements by bombarding Uranium with neutrons.

Lisa believed she was advancing science and serving the greater good by solving this puzzle. But as soon as the former US President, Mr. Roosevelt, learned about this, he ordered the scientists to keep quiet. Instead, he went to the military with the idea of secretly weaponizing nuclear power with this discovery.

They spent millions on Project Y. They took the best foreign scientists and engineers to Los Alamos closed laboratory in the New Mexico desert – where they put Lisa’s discovery into practice, and the demon core obtained a vessel! But who woke it up?

The Criticality Experiment: A Brief Explanation

Image by Nadin Schukina from Pixabay

The atoms of plutonium-239 spontaneously release neutrons from their nuclei since it is inherently radioactive, known as neutron radiation. As far as atomic particles go, neutrons are incredibly massive; if one neutron from one atom strikes another atom, it can literally “break” the other atom, causing it to release some of its neutrons.

The whole point of nuclear weapons is to trap those neutrons within the plutonium. Typically, this process moves along quite slowly since most emitting neutrons fly away. Consequently, the atom splitting process will spiral out of control, with neutrons smashing atoms, emitting more neutrons. It is how a nuclear bomb works.

This chain reaction involves statistics that are virtually impossible to comprehend. Nuclear fuel atoms in an explosion are split by neutrons hundreds of billionths of a second of time trillions of times. The combined breaking of trillions of atoms in such an improbable short period produces a great quantity of energy since each split of an atom releases energy, which explains the strength of atomic weapons!

The purpose of the demon core experiments was to test if the core had the right density and size to support a chain reaction, allowing it to be used in a real nuclear bomb. Also, determine the extent to which they could push the core before the unstoppable chain reaction could get triggered.

The First Burst of Power Shown by the Demon Core

The Demon Core was ready, waiting to be fired to a dumbfounded Japan that was still experiencing new catastrophe due to the bloodiest strikes anybody had ever witnessed on August 13, 1945. It had been less than a week since the bomb Little Boy was detonated over Hiroshima, followed by Fat Man in Nagasaki.

Harry Daghlian encircled the plutonium sphere with tungsten carbide bricks while he tried to reflect the neutrons the core released back at it, bringing it closer to criticality. He placed the nuclear ball between the tungsten carbide blocks, which acted as a reflector for neutrons hurtling from the core. His primary goal was to determine the ideal assembly that would cause the core of a finished cube to go very critically.

Daghlian constructed these reflecting barriers surrounding the core brick by brick. With the addition of each new block, the core was approaching a dangerous state when neutrons had nowhere to go. He continued the experiment until his neutron-monitoring apparatus warned him that any more block would cause the plutonium to become supercritical.

As he started to add the last brick to the critical assembly, he received a warning from his monitoring equipment that doing so would make the arrangement extremely critical. Daghlian took the brick out of the assemblage slowly and delicately. But he accidentally dropped it on top of the sphere, which triggered an uncontrolled chain reaction. It caused it to reach the supercritical point and produce a wave of heat.

It shot a blue light that hit the ceiling. At this point, Daghlian tried to destroy the block structure to appease the core, but it was too late! Fatal doses of radiation had burned his skin inside out due to the contact with the deadly core.

Harry fell into a coma and died 25 days later from severe radiation sickness, including nausea and excruciating pain. He became the first victim of the demon core while he was just 24! The skin on his hands was blistered and finally peeled off, exposing the muscles beneath.

Demon Core Shows its Destructive Power Again

Image by M from Pixabay

The afternoon of May 21, 1946, was at a secret laboratory in Los Alamos, New Mexico. Louis Slotin, a Canadian physicist, demonstrated to his colleagues how to bring a nuclear weapon’s exposed core close to the brink of criticality, a difficult procedure known as “tickling the dragon’s tail.”

The core was an ordinary metal hemisphere with a plutonium nub protruding from its center that was warm to the touch owing to radiation. It was sitting alone on a little table. After the bombing of Nagasaki, it had been hurriedly shaped to be used in another assault on Japan, but when it became clear that it would not be required for the war effort, they redistributed it.

Slotin was regarded as the top authority on handling hazardous amounts of plutonium. A modern photo shows him standing next to the first atomic weapon’s inner workings with his shirt undone and sunglasses on, looking calm and collected. He had assisted in its construction just a year before. He had conducted the same experiment 12 times before this particular event, contributing to his confidence.

Slotin followed an easy process. He would place a beryllium half-shell, known as the tamper, over the core, halting just before it was firmly in place. The neutrons ejecting from the plutonium would be reflected by the tamper, igniting a weak and fleeting nuclear chain reaction that would allow physicists to collect data.

Slotin held the tamper in his left hand. He held a screwdriver in his right hand and planned to wedge it between the components so the two parts would remain apart.

One of his coworkers, Raemer Schreiber, moved away to concentrate on other tasks as Slotin started the lengthy and laborious process of lowering the tamper. Schreiber anticipated that the experiment wouldn’t be fascinating until a few more seconds had gone.

The tamper had entirely fallen over the core when Slotin’s screwdriver slipped, causing a noise to be heard behind him. Schreiber saw a burst of blue light and experienced a heat wave on his face.

Slotin reacted quickly to remove the tamper from over the core, but it did the damage. At first, after being nauseous and vomiting, Slotin seemed to recover in the hospital. However, within a few days, he began losing weight, experiencing abdominal pain, and showing signs of mental confusion. He received the highest doses of radioactivity from fission and died 9 days later in unimaginable agony.

It covered his whole body with blisters and fluid built up beneath the layers of his skin. His white blood cells dropped dramatically, and his organs shut down, sending him into a coma. He died looking like a zombie! They shipped the military casket containing his body to Winnipeg for burial.

Other scientists assisting Slotin inside the room received serious doses of radioactivity and died from various radioactive cancer-like terminal diseases.

What Happened to Lisa Meitner?

You must be wondering whether Meitner ever came to know about this incident. No, she didn’t. She was chased by the Nazis away from everyone. They never told her about this incident till her death. She lived the remainder of her life in England; she received many awards and taught until her last day.

All her life, she regretted that they used her discovery that way. She had no family, no children. She was possessed only by the spirit of exploration. Lisa Meitner died at the age of 89.

What Causes the Blue Light to Flash?

The powerful neutron radiation burst that occurred when the core achieved its supercritical condition and was completely blanketed is thought to have lasted for roughly a half second. The most lethal phenomenon generating chaos was the blue light brought on by this.

Ionizing radiation is energy that affects things, including air, water, and biological tissue, by eliminating electrons from their atoms and molecules. Ionizing radiation can pass through these materials and move undetected. When the experiment temporarily became supercritical, ionizing radiation was released, which is likely what caused the blue light to flash.

This ionizing effect is similar to what we can see during a heavy lightning storm. The lightning appears to be blue in the sky, indicating an ionizing effect when it passes through certain parts of the clouds.

Why Didn’t the Demon Core Explode During these Experiments?

It is rare for nuclear energy released in criticality accidents to be explosive. The excess reactivity is relieved through ordinary physical processes without intentional confinement, as in nuclear weapons.

Increased temperature causes expansion, Doppler widening of neutron capture cross-sections, and finally, deformation, melting, and burning. These are all examples of negative feedback processes that have the potential to stop a chain reaction peacefully.

Rapid heating can occasionally allow nearby, more volatile components, such as water, to evaporate or expand, which negates the positive reactivity and blows the system apart rather gently.

Thermal feedback likely ended the response in the precise instance of Slotin’s tragedy, allowing him to detach the reflector. Depending on the temperature characteristics of the materials involved, supercritical would have likely continued if he hadn’t taken it out, and an oscillating pattern of chain reaction and suspension would have followed.

It could have taken a very long time to reach ultimate, permanent subcritical, potentially by melting or permanent deformation of the relevant materials. If Slotin had not intervened, the accident would have continued, and the consequences would have been more severe.

Image by Enrique from Pixabay

Does the Demon Core Still Exist?

No, the demon core had been demolished after such accidents and was deemed “cursed.” In the fourth nuclear bomb explosion in history, which took place on July 1, 1946, the softball-sized core of Pu-239, which had already claimed the lives of two of America’s most significant scientists, exploded in the Pacific Ocean not far from the Bikini Islands.

The Bikini bomb test that destroyed the Demon Core used a far greater proportion of its nuclear fuel than its forerunners. It was more dramatic by several kilotons, equivalent to the explosive force of 1,000 tonnes of TNT.


It’s easy to see why the scientists gave the Demon Core the superstitious nickname they did, even if the deaths of two scientists are incomparable to the unimaginable atrocities that would have occurred if they had used the core in a third nuclear assault against Japan.

These Demon Core occurrences and many lesser-known World War II tragedies are terrible reminders that we should never take nature’s powers lightly. We can only read this and imagine the horrors scientists have to go through for the sake of experiments and inventions back then.

If you liked this article, check out: ‘What if All the Extinct Animals Could Be Brought Back to Life? The Consequences of Such A Miracle.’



About Author

Leave a comment

Your email address will not be published. Required fields are marked *

You may also like


The 6 Best High Schools in Cardiff

When choosing a high school, students and their families must make a significant choice. A solid education lays the groundwork

4 Top High Schools in Nottingham for Your Kids

While deciding on the top high schools in Nottingham for your kid, there are various variables to consider. Finding the