Deep Fission lowers full-size canister replica 100 feet into a borehole
Deep Fission said on September 10, 2026 that a commercial drilling crew lowered a full-size, non-nuclear prototype of its Gravity reactor canister, 20 feet long, to a depth of 100 feet in a 34-inch borehole and retrieved it on September 3, 2026, using equipment already in commercial drilling service. The company's design places a pressurized water reactor about one mile underground; it said on August 6, 2026 that DOE had approved its Nuclear Safety Design Agreement under the Reactor Pilot Program.
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