By dropping a nuclear reactor 1.6 kilometers (1 mile) underground, Deep Fission aims to use the weight of a billion tons of rock and water as a natural containment system comparable to concrete domes and cooling towers. With the fission reaction occurring far below the surface, steam can safely circulate in a closed loop to generate power.

Deep Fission’s small modular reactor (SMR), called Gravity, is designed to stand 9 meters tall while remaining slim enough to fit inside a borehole roughly three-quarters of a meter wide. The company says its modular approach allows multiple 15-megawatt reactors to be clustered on a single site: A block of 10 would total 150 MW, and Deep Fission claims that larger groupings could scale to 1.5 GW.

"We are unique in that we’ve combined three existing mature technologies in a way that nobody had ever thought of before". The company claims that "using geological depth as containment could make nuclear energy cheaper, safer, and deployable in months at a fraction of a conventional plant’s footprint. Still, independent experts say the underground design introduces its own uncertainties, both regulatory and practical."

If you use Gmail, you need to be aware of an important change that’s quietly rolling out. Reportedly, Google has recently started automatically opting users in to allow Gmail to access all private messages and attachments for training its AI models. This means your emails could be analyzed to improve Google’s AI assistants, like Smart Compose or AI-generated replies. Unless you decide to take action.

The reason behind this is Google’s push to power new Gmail features with its Gemini AI, helping you write emails faster and manage your inbox more efficiently. To do that, Google is using real email content, including attachments, to train and refine its AI models. Some users are now reporting that these settings are switched on by default instead of asking for explicit opt-in.