Deep Fission Announces Collaboration to Test Underground Reactor Drilling

What Happened
On September 21, 2026, Deep Fission, Inc. (FISN) announced a collaboration with Youngquist Brothers, LLC to evaluate and test drilling and borehole‑construction methods for the company’s underground reactor deployment model. The announcement was made via a press release furnished in a Form 8‑K under Item 7.01 (Regulation FD Disclosure).

Key Details

• Announcement date: September 21, 2026 (Form 8‑K filed the same day).
• Partner: Youngquist Brothers, LLC.
• Purpose: Evaluation and testing of drilling and borehole‑construction methods for Deep Fission’s underground reactor deployment model.
• Documentation: Press release furnished as Exhibit 99.1 to the Form 8‑K.

Why It Matters
This disclosure shows Deep Fission is advancing practical testing related to its underground reactor deployment concept, a technical step toward demonstrating feasibility. The 8‑K does not provide financial terms, test results, or timelines; investors should watch for follow‑up announcements or filings that detail outcomes, costs, contracts, or schedule impacts.