Physics

You can now watch 100+ declassified US nuclear explosion videos on YouTube


The US has conducted more nuclear weapons tests than any other nation in history. The official count of 1,054 tests includes 210 atmospheric nuclear tests between 1945 and 1962 – with cameras capturing every one.

 

This week, a team at the federal Lawrence Livermore National Laboratory (LLNL) has released 62 of these atmospheric nuclear test videos on YouTube.

An estimated 10,000 of these videos have languished for decades, forgotten in archives around the country, slowly degrading in storage.

LLNL’s weapon physicist Greg Spriggs and a team of film experts, archivists and software developers are working to restore these videos and make them available to the public, before the hard copies of the films are lost forever.

Over the last five years, they’ve located around 6,500 videos, and have been slowly working on restoring them. To date, 4,200 films have been scanned, and 750 have been declassified.

This is the second batch to go onto YouTube, after the first release in March of this year.

To date, the LLNL playlist on YouTube has 125 declassified atmospheric nuclear test videos.

But the videos aren’t just interesting to look at – they’re helping develop the simulations for virtual nuclear testing. The US hasn’t tested an actual nuclear weapon since 1992, so simulations are the best option.

When Spriggs was asked a decade ago to write simulations, he found his calculations didn’t match records of nuclear tests in the 1950s and 1960s.

 

It was only by reanalysing videos of these tests that he was able to ascertain that those original measurements were incorrect, sometimes off by 20 to 30 percent.

“It was driving me nuts,” Spriggs said. “No matter what I did, I couldn’t get my calculations to agree. Eventually, I came to the conclusion that the data must be off. To prove our simulations are correct, we rely on quality benchmark data.

“That’s why this project is so important. It is providing the data our physicists need to ensure our deterrent remains viable into the future.”

He also said in March that the team was finding things in the videos that they hadn’t known before, which were helping the nuclear forensics field make new correlations.

The tests were actually extraordinarily well documented. Over 50 cameras would film each explosion, from all angles, at up to 2,400 frames per second.

So, even though we can’t conduct these tests any more – as is only right, since they have a devastating effect on the environment, spewing radioactive pollution into the atmosphere – we can still benefit from the tests performed decades ago.

There are several key things a physicist can look for in one of these videos to take measurements of the amount of energy released (known as the yield) in each explosion.

 

One of these is the two light pulses typical of nuclear detonations, clearly seen in a video of Operation Dominic in 1962.

“The first pulse peaks almost immediately as the shockwave first forms. The brightness then decreases as the superheated air, which is opaque when heated to above 3,300 degrees Kelvin – or 5,480.33 degrees Fahrenheit – shields the light from inside the fireball.

“As the shockwave cools to below 3,300 Kelvin, the air becomes transparent and the hot gasses begin to show through, creating the second pulse.”

The fireball that precedes the mushroom cloud, the speed at which it grows, and the amount time it glows can all contribute to calculating the yield. In the 50s and 60s, these were all calculated by eye.

Today, we can take more accurate readings.

Spriggs estimates that it may take another couple of years to scan the rest of the codes, and longer still to analyse and declassify them – but that the work is important for safeguarding the US nuclear weapons stockpile to ensure that they never need to be used.

“It’s just unbelievable how much energy’s released,” Spriggs said. “We hope that we would never have to use a nuclear weapon ever again. I think that if we capture the history of this and show what the force of these weapons are and how much devastation they can wreak, then maybe people will be reluctant to use them.”

You can check out the playlist on the Lawrence Livermore National Laboratory’s YouTube channel.

 



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