Day: November 14, 2024

The Life Cycle Of Nuclear Fission Fuel: From Stars To Burn-Up

November 14, 2024 by 48 Comments

Outdone only by nuclear fusion, the process of nuclear fission releases enormous amounts of energy. The ‘spicy rocks’ that are at the core of both natural and artificial fission reactors are generally composed of uranium-235 (U-235) along with other isotopes that may or may not play a role in the fission process. A very long time ago when the Earth was still very young, the ratio of fissile U-235 to fertile U-238 was sufficiently high that nuclear fission would spontaneously commence, as happened at what is now the Oklo region of Gabon.

Although natural decay of U-235 means that this is unlikely to happen again, we humans have learned to take uranium ore and start a controlled fission process in reactors, beginning in the 1940s. This can be done using natural uranium ore, or with enriched (i.e. higher U-235 levels) uranium. In a standard light-water reactor (LWR) a few percent of U-235 is used up this way, after which fission products, mostly minor actinides, begin to inhibit the fission process, and fresh fuel is inserted.

This spent fuel can then have these contaminants removed to create fresh fuel through reprocessing, but this is only one of the ways we have to extract most of the energy from uranium, thorium, and other actinides like plutonium. Although actinides like uranium and thorium are among the most abundant elements in the Earth’s crust and oceans, there are good reasons to not simply dig up fresh ore to refuel reactors with.

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Smart Thermostats Pitched For Texas Homes To Relieve Stressed Grid

November 14, 2024 by 85 Comments

It’s not much of a secret that Texas’ nearly completely isolated grid is in a bit of a pickle, with generating capacity often being handily outstripped during periods of extreme demand. In a latest bid to fight this problem, smart thermostats are being offered to customers, who will then participate in peak-shaving. The partnership between NRG Energy Inc., Renew Home LLC, and Alphabet Inc. will see about 650,000 of these thermostats distributed to customers.

For customers the incentive would be mostly financial, though the details on the potential cost savings seem scarce. The thermostats would be either a Vivint (an NRG company) or Google Nest branded one, which would be controlled via Google Cloud, allowing for thermostat settings to be changed to reduce the load on the grid. This is expected to save ‘300 MW’ in the first two years, though it’s not clear whether this means ‘continuously’, or intermittent like with a peaker natural gas plant.

Demand curtailment is not a new thing, with it being a big thing among commercial customers in South Korea, as we discussed within the topic of vehicle-to-grid energy storage. Depending on how it is implemented it can make a big difference, but it’ll remain to see how regular consumers take to the idea. It also provides more evidence for reducing grid load being a lot easier than adding grid-level storage, which is becoming an increasingly dire topic as more non-dispatchable solar and wind power is added to the grid.

Building A Reproduction Apple I

November 14, 2024 by 3 Comments

If you think of Apple today, you probably think of an iPhone or a Mac. But the original Apple I was a simple PC board and required a little effort to start up a working system. [Artem] has an Apple I reproduction PCB, and decided to build it on camera so we could watch.

For the Apple I, the user supplied a keyboard and some transformers, so [Artem] had to search for suitable components. He wisely checks the PCB to make sure there are no shorts in the traces. From there, you can watch him build the machine, but be warned: even with speed ups and editing, the video is over an hour long.

If you want to jump to the mostly working device, try around the 57-minute mark. The machine has a basic ROM monitor and, of course, needs a monitor. There was a small problem with memory, but he eventually worked it out by inhibiting some extra RAM on the board. Troubleshooting is half of the battle getting something like this.

Want to look inside the clock generator chip? Or skip the PCB and just use an FPGA.

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