Movies of Cold War Bomb Tests Hold Nuclear Secrets (wired.com)

An anonymous reader writes: Nuclear weapons specialists are limited in their research today. Prudence and international treaties prevent them from setting off any nuclear weapons, so they have to run tests through other means and interpret the results. But this wasn't always the case. In the '50s and '60s, the U.S. government performed a huge number of nuclear weapons tests, and filmed most of them. As happened with a lot of film from that time, most laid untouched in storage facilities until people generally forgot about them. But physicist Greg Spriggs recently realized they could be a trove of useful information, so he started tracking them down, eventually locating thousands of them. His team has started scanning and analyzing them. They've finished about 3,000 so far, with more than half yet to go. "Now, of course, scientists have computer programs that can analyze every single pixel in a frame over hundreds of frames. What might have taken days by hand takes only minutes. With computer analysis, Spriggs is pinpointing more precise yields. Computer models then use yield to estimate the damage from a bomb in different situations."

Comments

Secrets

[Dan East]

The "secrets" they speak of are higher accuracy measurements of the yield of the weapons. It is done by tracking the speed and size of the shockwave captured in the films, which was originally done by hand. There was up to 20% variation in the results of the measurements made by hand. They are now using computer software to perform the optical per-frame analysis of the shockwaves, and the result is more accurate measurements of the weapons' yield.

Re:Secrets

[KGIII]

It's okay, I must be out of touch. I could have sworn the treaties signed still allowed for underground testing. I seem to recall Dan Rather (quite specifically though I suppose it might have been the News Hour on PBS) talking about it on the nightly news? Have we ratified any treaties since?

Hmm... Unless I am not reading something properly, Wikipedia agrees with me.
https://en.wikipedia.org/wiki/...

I don't think we're strictly prohibited from testing nuclear weapons in and of itself but I do seem to recall that we've only agreed to end atmospheric and above-ground tests. While we're not prohibited, I don't think (from my limited memory and quick scanning), it would be socially unacceptable behavior. Of course, Starfish Prime might indicate that we're not always worried about being polite or responsible. At least I think that's the project name where we decided setting off nukes in space was a brilliant idea.

Re:Secrets

[140Mandak262Jamuna]

Hmm... Unless I am not reading something properly, Wikipedia agrees with me.

No, it does not agree with you. Don't believe me? Give me five minutes and then check wikipedia.

Re:Secrets

[Dins]

It is done by tracking the speed and size of the shockwave captured in the films, which was originally done by hand. There was up to 20% variation in the results of the measurements made by hand. They are now using computer software to perform the optical per-frame analysis of the shockwaves, and the result is more accurate measurements of the weapons' yield.

Fun fact: The vertical smoke trails present in many nuclear test films are there so they can "see" the shockwave on film as it propogates and affects the smoke trails. Right before detonation a row of rockets are launched vertically to create the smoke trails. I only mention it as for the longest time I wondered what these weird lines were from, and thought they might be some weird effect of the bomb or something. So I looked it up and learned the above.

Re:Secrets

[hey!]

The Comprehensive Test Ban Treaty was adopted by the UN General Assembly in 1996, but won't come into force until 44 specific nations with nuclear technology capabilities have ratified the treaty. At present there are eight nations on the list who have not ratified the treaty, including the United States. The US, however, is a signatory to the treaty, and has not conducted a nuclear test since 1992.

So the US abides by the CTBT as a matter of policy, even though the treaty is not in force, and the Obama administration has in the past indicated that it wants to ratify the treaty, although that won't happen with this Senate.

The reason it's smart policy to promote the adoption of the CTBT is that it would discourage nuclear proliferation, and we don't need to perform testing. We already have enough data from half a century of active testing to ensure our bombs go boom.

Re:Secrets

[Richard_at_work]

I wonder what the actual output of Castle Bravo was in the end then, if there was such a variation in original estimates and bearing in mind that Castle Bravo was massively in excess of its prediction.

Clickbait title

[NotInHere]

Its not what you think, there are no actual national secrets that have to be kept disclosed, all researchers can access all material.

The title is clickbait and taken from the press article.

Re:Didn't the US reject the comprehensive treaty?

[tnk1]

Yes, it isn't law. It doesn't prevent us from more or less complying with it unilaterally, it's just that we aren't binding ourselves to it. That gives everyone else a lot less peace of mind about it, but the US often has its own reasons for basically following the gist of treaties it doesn't ratify, so it usually works out. Usually.

Want to calculate nuclear yield? Buy Glasstone

[Nova Express]

If you want to calculate nuclear yields, I suggest picking up a copy of Samuel Glasstone's The Effects of Nuclear Weapons (that's an Amazon link, but there are a fair number of used copies floating around). I have the revised 1962 edition.

Be sure to pick up a copy that still has the yield computer wheel in the back of the book.

Also, this web page lets you map nuclear bursts using Google maps, and seems to be heavily based on Glasstone.