# Deep Fission’s Borehole Canister Test: Hardware Milestone, Still Not a Reactor in the Ground — source note

Date checked: 2026-09-13 PDT  
Article slug: `deep-fission-borehole-canister-test-source-card`  
Evidence label: official company release plus World Nuclear News trade reporting and DOE Reactor Pilot Program context. This is a full-size non-nuclear hardware handling demonstration, not fuel loading, criticality, NRC commercial licensing, construction authorization or delivered power.

## Bottom line
Deep Fission says a commercial drilling crew lowered a 20-foot full-size non-nuclear prototype reactor canister to 100 feet inside a 34-inch borehole on September 3, 2026, aligned it, and retrieved it. That is useful evidence for the installation/retrieval part of the company’s one-mile-underground Gravity reactor concept. It does not prove the final one-mile deployment, nuclear operation, NRC licensing, cost, insurance, waste, public acceptance, data-center delivery, or commercial repeatability.

## Facts safely used
- Deep Fission's official September 10, 2026 release says the demonstration used standard commercial drilling equipment and a commercial drilling/rigging crew.
- The company says the canister was 20 feet long, lowered to 100 feet inside a 34-inch-wide borehole, aligned, and brought back to the surface on September 3, 2026.
- The company says the prototype was a full-size, non-nuclear replica designed to house the Gravity reactor core and contained no nuclear fuel.
- The company describes Gravity as a pressurized-water-reactor-based SMR concept installed approximately one mile underground and running on standard low-enriched uranium.
- World Nuclear News reported the same demonstration on September 11, 2026 and framed it as a canister-handling milestone, while noting the broader validation program still includes drilling, system integration, regulatory approvals and commercial operation.
- DOE’s Reactor Pilot Program page says the program is a DOE pathway for advanced reactor demonstration and a larger goal of moving advanced concepts toward criticality outside national laboratories; DOE’s initial-selection release named Deep Fission Inc. among selected companies.

## Evidence labels and cautions
- Official / company-controlled: strong for what Deep Fission says it did, the physical dimensions it reports, and the company’s own target-market language.
- Trade corroboration: World Nuclear News provides independent sector framing but still relies substantially on company-announced demonstration facts.
- Official context: DOE pages verify the Reactor Pilot Program pathway and Deep Fission’s selection, not this specific September 3 canister test.
- Do not overclaim: this is not a fueled reactor, not a one-mile nuclear emplacement, not criticality, not NRC licensing, not grid interconnection, not a data-center PPA and not mine-site electrification.
- Follow-up watch gates: public DOE authorization details, NRC filings, fuel arrangements, full-depth drilling and retrieval records, safety analysis, emergency planning, environmental review, commercial contracts and operating data.

Not investment advice: references to Deep Fission, uranium, drilling contractors, nuclear fuel, SMR developers, utilities, data centers and firm-power demand are infrastructure evidence research only, not a recommendation to buy, sell or hold any security or commodity exposure.

## Source files saved
- `source_official_deep_fission_release.md` — https://www.deepfission.com/newsroom/press-releases/detail/118/deep-fission-installs-and-retrieves-full-scale-reactor-canister-using-off-the-shelf-drilling-equipment
- `source_trade_world_nuclear_news.md` — https://world-nuclear-news.org/articles/deep-fission-completes-borehole-demonstration
- `source_official_doe_reactor_pilot_program.md` — https://www.energy.gov/ne/us-department-energy-reactor-pilot-program
- `source_official_doe_initial_selections.md` — http://energy.gov/articles/department-energy-announces-initial-selections-new-reactor-pilot-program
- `source_urls.txt`, `daily-leads-checked.txt`, `fetch_log.json`