Russia has declassified footage of the world’s biggest nuclear bomb blast, Science Alert reported. The bomb was detonated in 1961 in the Arctic Circle and was “thousands of times stronger” than the bombs dropped on Hiroshima and Nagasaki. There are several ways to build a nuclear bomb.
According to Science Alert, Rosatom State Atomic Energy Corporation—Russia’s state atomic agency—recently shed light on a historic event by declassifying its video footage. “In October 1961, the Soviet Union dropped the most powerful nuclear bomb in history over a remote island north of the Arctic Circle,” the article said.
“Onlookers saw the flash more than 600 miles away, and felt its incredible heat within 160 miles of Ground Zero. Last week, Rosatom State Atomic Energy Corporation released 40 minutes of previously classified footage, showing the bomb’s journey from manufacture to mushroom cloud.”
Two ways to build nuclear bombs include gun-type bombs and implosion bombs.
A gun-type bomb is the simplest way to make a nuclear bomb. So how does it work?
“We shoot one subcritical mass of uranium onto another subcritical mass to make a critical mass,” said Dr. Lawrence Weinstein, Professor of Physics at Old Dominion University. “So, the Little Boy bomb, what they did was [they] shot an 86-pound hollow cylinder of uranium at a 60-pound spike of uranium. The uranium was about 80% enriched, it was a six-foot-long barrel, and they hit at 300 meters per second—that’s about 600 miles an hour—and they went critical at about 10 inches away.”
According to Dr. Weinstein, since 10 inches is about three-tenths of a meter, and the cylinder was traveling at 600 mph, it only took a millisecond to shoot the uranium cylinder at the spike. However, scientists had to ensure that there would be very few spontaneous nuclear fissions in that time. In nuclear fission, the nucleus of an atom splits into two lighter nuclei.
“They had to make sure there were almost no spontaneous fissions because that would have meant that it detonated prematurely and fizzled,” he said. “They didn’t test this design—they were so sure that it would work. This design would not work with plutonium because too much plutonium spontaneously fissions.”
Dr. Weinstein said the other kind of nuclear bomb is an implosion bomb, in which engineers compress plutonium with a shockwave. This kind of bomb uses explosive lenses to produce the compression.
“The shockwave travels at 5,000 meters per second, so what you need is a very symmetric wave; otherwise, you squeeze the plutonium out through the hole,” he said. “That means you need to use specially shaped, high-explosive lenses and absolutely perfect timing. If one piece of explosive goes off a little bit before the other, it shoots the plutonium out through the other side without compressing it symmetrically.”
When the plutonium is compressed, it has a higher density. Dr. Weinstein said this higher density gives the plutonium a lower needed point of critical mass.
“So by compressing a subcritical mass of plutonium or uranium, you can make it critical,” he said. “You need less plutonium or less uranium, but you need to make sure that the ignition starts when it’s fully compressed and not an instant before. This was the design of the Fat Man bomb that was dropped in Nagasaki with an energy release of 21,000 tons of TNT.”
The 1961 video footage of the Russian nuclear bomb RDS-220, also known as the Tsar Bomba, is available for public viewing online.
Dr. Lawrence Weinstein contributed to this article. Dr. Weinstein is a Professor of Physics at Old Dominion University (ODU) and a researcher at the Thomas Jefferson National Accelerator Facility. He received his undergraduate degree from Yale University and his doctorate in Physics from the Massachusetts Institute of Technology.