True Story, Issue #5

"How to Survive an Atomic Bomb" by Edward McPherson

True Story, Issue #5

In this issue, we travel back to the anything-goes days leading up to the July 1945 detonation of the first atomic bomb at Trinity Site in Alamogordo, New Mexico. Edward McPherson takes readers on a tour of the site, exploring the history of the atomic bomb, as well as the modern-day challenges still posed by our nuclear arsenal.

From "How to Survive an Atomic Bomb" by Edward McPherson

On the morning of Friday, July 13, 1945, in the master bedroom of a ranch house two miles from ground zero, Canadian physicist Louis Slotin began assembling the bomb’s plutonium core, which was about the size of an orange but weighed a startling thirteen pounds. Slotin Scotch-taped a small neutron initiator made out of polonium and beryllium—called an “urchin”—into a hollow pit in the middle of two plutonium hemispheres. Upon being crushed by the shock wave of the explosions, the urchin would release a burst of neutrons to start the chain reaction.

Slotin would come to be known as the “chief armorer of the United States.” Ten months later, he would be killed after deciding—on a whim—to show some colleagues a criticality demonstration called “tickling the dragon’s tail,” in which he lowered the top half of a tamper onto a plutonium core using nothing but a flat-head screwdriver to hold the hemispheres apart. The screwdriver slipped, the sphere became whole, and there was heat and a bright blue flash. Slotin flung off the tamper, but it was too late—he soon began vomiting. Three of the other seven witnesses would later die from radiation-related diseases.

At 3:18 p.m., the Trinity core arrived at the base of the tower, where it was to be inserted into the two-ton, five-foot ball of explosives. The body of the bomb was a carefully calibrated device: the implosion lenses had been X-rayed, and each tiny air pocket had been drilled and filled with explosives. The blast waves had to arrive at the core in precise synchronicity. Some of the charges were made to fit snugly with tissue and Scotch tape. A declassified film shows the scientists working under a large canvas tent. Oppenheimer leans over his Gadget, hat on, sleeves rolled up. The men—some topless, others in T-shirts and tanks—stick their arms deep into the top of the bomb. There was a moment of panic when the cylindrical plug containing the plutonium core didn’t fit, but someone realized the metal had simply expanded in the heat. Once it cooled off, it slid in perfectly. One step at a time, the scientists followed the painstaking assembly instructions set down for the “hot run”: “Place hypodermic needle in right place. (Note: Check this carefully),” and so on. When they were done, some men went swimming in a water tank. The next morning, a $20,000 winch raised the Gadget to the top of the tower, where the detonators were installed. As it went up, a pile of striped GI mattresses was placed beneath the bomb. A handwritten sign advised WEAR A HARD HAT.