10 | January | 2023

All nuclear reactors run on fuel containing uranium and other isotopes, but filling a nuclear reactor is much more complicated than driving up to them with a dump truck filled with uranium ore and filling up. Although nuclear fission is simple enough that it can happen without human intervention, as happened for example at Oklo’s natural fission reactors, within a commercial reactor the goal is to create a nuclear chain reaction that targets a high burnout rate (fission rate), with a as constant as possible release of energy.

Each different fission reactor design makes a number of assumptions about the fuel rods inserted into it. These assumptions may concern the enrichment ratio of the fissionable isotopes such as U-235, the density of individual fuel pellets, the distance between the fuel rods containing these pellets, the configuration of said fuel rods together with any control, moderator and other elements. and so on.

Today’s light water reactors, heavy water reactors, fast neutron reactors, high-temperature reactors and relatives all have their own fuel preferences as a result, with high-analysis lava-enriched (HALEU) fuel being the new hot thing for new reactor designs. Let’s take a look at what goes into these fuel recipes.

Continue reading “The Intricacies of Making Nuclear Reactor Fuel” →

There is a select group of computer games whose in-game logic is enough to simulate computers themselves. We have seen it in Minecraft and DOOMand now there’s a new player in town from a surprising quarter: Tetris.

One might wonder how the Russian falling block game could do this, since unlike the previous examples it has a very small playing field. And it’s actually not quite that Tetris you are used to playing, but a version that is played over an infinite board. So viewed as a continuous progression of the game, it can be seen as something similar to the tape in a Turing machine.

The various moves and outcomes are referred to through a Tetris scripting language, so states can be represented by different sets of blocks and holes while logical elements can be built up using the different shapes and game logic. From these a computer can be built, represented entirely in Tetris movements and forms. It’s a bit mind boggling and we’d be lying if we said we understood every nuance of it, but apparently it works well enough to run the game on its own.. If it had the catchy music of the NES version, we’d declare it perfect.

Hungry for more? Here is DOOM adds a little, and of course Minecraft has a rich computing history.

Once you’ve seen a beach beast, it’s hard to forget the mesmerizing movement of its mechanical limbs. [Adam Savage] built a pedal-powered beach beast in (more than) a day in full view of the public at the San Francisco Exploratorium.

One of the biggest challenges in building a beach beast is the sheer number of parts required to build a walking machine. It becomes clear quite quickly how big an advantage the wheel is for part counting on a unit. Add in some seemingly minor design flaws and you might not have any forward movement at all.

[Savage]the build takes us through all the ups and downs of this process, including lots of screwing, welding, and more sneakers than Squitter the Spider could use. The end product is unwieldy, impractical and beautiful. What more could a manufacturer ask for?

If you need more Strandbeest goodness, check out this more practical Strandbeest bike, this Strandbeest Venus rover concept, or Jeremy Cook’s talk on designing Strandbeest robots.

Continue reading “Human Powered Strandbeest” →