Screwdrivers And Nuclear Safety: The Demon Core

Harry Daghlian and Louis Slotin were two of many people who worked on the Manhattan Project. They might not be household names, but we believe they are the poster children for safety procedures. And not in a good way.

Harry Daghlian (CC-BY-SA 3.0, Arnold Dion)

Slotin assembled the core of the “Gadget” — the plutonium test device at the Trinity test in 1945. He was no stranger to working in a lab with nuclear materials. It stands to reason that if you are making something as dangerous as a nuclear bomb, it is probably hazardous work. But you probably get used to it, like some of us get used to working around high voltage or deadly chemicals.

Making nuclear material is hard and even more so back then. But the Project had made a third plutonium core — one was detonated at Trinity, the other over Nagasaki, and the final core was meant to go into a proposed second bomb that was not produced.

The cores were two hemispheres of plutonium and gallium. The gallium allowed the material to be hot-pressed into spherical shapes. Unlike the first two cores, however, the third one — one that would later earn the nickname “the demon core” — had a ring around the flat surfaces to contain nuclear flux during implosion. The spheres are not terribly dangerous unless they become supercritical, which would lead to a prompt critical event. Then, they would release large amounts of neutrons. The bombs, for example, would force the two halves together violently. You could also add more nuclear material or reflect neutrons back into the material.

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Retrotechtacular: Better Living Through A-Bombs

Usually, if you are listening to people debate about nuclear issues, it is one of two topics: how to deal with nuclear weapon stockpiles or if we want nuclear power plants in our backyard. But there was a time when the US and the USSR had more peaceful plans for nuclear bombs. While peaceful plans for nuclear bombs might sound like an oxymoron, there was somewhat of a craze for all things nuclear at some point, and it wasn’t clear that nuclear power and explosives wouldn’t take over many industries as the transistor did, or the vacuum tube before it.

You may have heard about Project (or Operation) Plowshare, the US effort to find a peaceful use for all those atom bombs. The Atomic Energy Commission video below touts the benefits “for all nations.” What benefits? Mostly moving earth, including widening the Panama Canal or creating a new canal, cutting highways through mountains, assisting mining and natural gas production, and creating an artificial harbor. There was also talk of using atomic blasts to create new materials and, of course, furthering the study of the atom.

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Retrotechtacular: The Nuclear Cruise Ship Of The Future Earns Glowing Reviews

The average modern cruise ship takes about 250 tons or 80,000 gallons of fuel daily. But can you imagine a cruise ship capable of circling the globe fourteen times before it needed to top off? That was the claim for the NS Savannah, a nuclear-powered cruise ship born out of President Eisenhower’s “Atoms for Peace” initiative.

The ship was a joint project of several government agencies, including the US Maritime Administration. With a maiden cruise in 1962, the vessel cost a little more than $18 million to build, but the 74-megawatt nuclear reactor added nearly $30 million to the price tag. The ship could carry 60 passengers, 124 crew, and over 14,000 tons of cargo around 300,000 nautical miles using one set of 32 fuel elements. What was it like onboard? The video below gives a glimpse of nuclear cruising in the 1960s.

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Getting Into NMR Without The Superconducting Magnet

Exploring the mysteries of quantum mechanics surely seems like an endeavor that requires room-sized equipment and racks of electronics, along with large buckets of grant money, to accomplish. And while that’s generally true, there’s quite a lot that can be accomplished on a considerably more modest budget, as this as-simple-as-it-gets nuclear magnetic resonance spectroscope amply demonstrates.

First things first: Does the “magnetic resonance” part of “NMR” bear any relationship to magnetic resonance imaging? Indeed it does, as the technique of lining up nuclei in a magnetic field, perturbing them with an electromagnetic field, and receiving the resultant RF signals as the nuclei snap back to their original spin state lies at the heart of both. And while MRI scanners and the large NMR spectrometers used in analytical chemistry labs both use extremely powerful magnetic fields, [Andy Nicol] shows us that even the Earth’s magnetic field can be used for NMR.

[Andy]’s NMR setup couldn’t be simpler. It consists of a coil of enameled copper wire wound on a 40 mm PVC tube and a simple control box with nothing more than a switch and a couple of capacitors. The only fancy bit is a USB audio interface, which is used to amplify and digitize the 2-kHz-ish signal generated by hydrogen atoms when they precess in Earth’s extremely weak magnetic field. A tripod stripped of all ferrous metal parts is also handy, as this setup needs to be outdoors where interfering magnetic fields can be minimized. In use, the coil is charged with a LiPo battery for about 10 seconds before being rapidly switched to the input of the USB amp. The resulting resonance signal is visualized using the waterfall display on SDR#.

[Andy] includes a lot of helpful tips in his excellent write-up, like tuning the coil with capacitors, minimizing noise, and estimating the exact resonance frequency expected based on the strength of the local magnetic field. It’s a great project and a good explanation of how NMR works. And it’s nowhere near as loud as an MRI scanner.

Scorched Moon: Secret Project A119

In today’s world, it is hard to realize how frightened Americans were at the news of Sputnik orbiting the Earth. Part of it was a fear of what a rival nation could do if they could fly over your country with impunity. Part of it was simply fear generated by propaganda. While America won the race to the moon, that wasn’t clear in the 1950s. The Soviet Union was ahead in the ability to deliver bombs using planes and missiles. They launched Sputnik on a modified ICBM, while American attempts to do the same failed spectacularly. The Air Force wanted ideas about how to respond to Sputnik, and one of the most disturbing ones was project A119, a project we were reminded of recently by a BBC post.

In all fairness, the Soviets had an almost identical plan, code-named E4. Fortunately, both sides eventually realized these plans weren’t a good idea. Oh, did we forget to mention that A119 and E4 were plans to detonate a nuclear device on the moon?

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If They Fire The Nukes, Will They Even Work?

2022 was a harrowing year in a long line of harrowing years. A brutal war in Europe raised the prospect of nuclear war as the leaders behind the invasion rattled sabers and made thinly veiled threats to use weapons of mass destruction. And all this as we’re still working our way through the fallout of a global pandemic.

Those hot-headed threats raise an interesting question, however. Decades have passed since either Russia or the United States ran a live nuclear weapons test. Given that, would the nukes even work if they were fired in anger?

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New Study Tells Us Where To Hide When The Nukes Are Coming

Geopolitics is a funny thing. Decades can go by with little concern, only for old grudges to suddenly boil to the surface and get the sabers a-rattlin’. When those sabers happen to be nuclear weapons, it can be enough to have you mulling the value of a bomb shelter in your own backyard.

Yes, every time the world takes a turn for the worse, we start contemplating what we’d do in the event of a nuclear attack. It’s already common knowledge that stout reinforced concrete buildings offer more protection than other flimsier structures. However, a new study has used computer modelling to highlight the best places to hide within such a building to maximise your chances of survival.

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