Low-Background Metal
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Basic Information

Ever since not long after the first atomic bomb test in Los Alamos, New Mexico in 1945, the air everywhere on earth has included tiny amounts of radioactive waste. (This contamination reached its peak in 1963 when the last above-ground nuclear tests were banned by international treaty.)

Smelting metals tends to draw those particles out of the air, and locks them inside the metal.

With a sensitive enough geiger counter you can actually tell if an object made of steel (for example) was manufactured before or after 1945. The radioactive content is so tiny it generally poses no health risk, but sometimes and for certain technologies, you may need materials that don't emit even trace amounts of background radiation. An example would be if you're building a very sensitive radiation detector, you wouldn't want it setting itself off every time you turned it on.

Low-Background Steel is far and away the metal most commonly needed for such applications. This is why old sunken battleships from the first several years of World War Two are so valuable as salvage. While theoretically any source of steel from before 1945 would work just fine, it's hard to beat old warships for the sheer tonnage they contain.

Low-Background Lead is also sometimes needed for the same reasons. Since there are no predominantly-leaden warships at the bottom of any ocean, it often takes acts of iconoclasm or archaeology to procure this. Medieval stained glass windows are a common target, but since people of days gone by didn't necessarily realize how dangerous lead plumbing was, sometimes its possible to just dig up an old set of pipes that once poisoned an early city.


Game and Story Use

  • Some device used in mad science, alchemy, or ritual magic may require Low-Background Metal for its construction or operation.
  • May be necessary to use this if you want to make Depleted Phlebotinum Shells capable of hurting a monster of the week (or demon) that thematically represents: science or technology run amok, the modern age, corruption and contamination, or things man was not meant to know. To slay it, you need a sword that predates the moment of nuclear transformation! (Luckily, that's a pretty decent percentage of the swords ever made in history.)
  • Minor criminals may conduct illegal salvage, wrecker or piracy operations to turn a fast buck on the low-background metal of an old ship.
    • The PCs investigate the wreckage, and can't figure out why this vessel was even attacked. It's so old it was due to be mothballed soon, and wasn't carrying anything that valuable. They spend most of a session searching the hold, tracking down the manifest, investigating the previous owner's insurance claim, etc, convinced there must have been something valuable hidden on the ship. After hitting a few dead ends, they return to the wreck to find that it's been stripped in the night. The old battered hull itself was the prize the crooks were after!
    • The crooks buyer may turn out to be a mad scientist or the like, who later becomes the big bad evil guy of the sequel to your first adventure or mystery. They've made some terrible device from the low-background steel, and it would have been even worse if the PCs hadn't broken up their supply ring.
  • If they minor criminals are after lead, it could be the same basic scenario except instead of wrecking a ship they commit vandalism of a cathedral, or tear up an old sewer system or archaeological dig site.
  • The remains of the Kaiserliche Marine at Scapa Flow are still popular sources of low-background metal. There are several large warships down there in sheltered and relatively shallow (if near Artic) water, and a couple of them were recently put up for auction for salvage rights.
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