---
schema_version: "secwatch.filing_event.v1"
accession: "0001104659-25-114959"
form_type: "8-K"
ticker: "FISN"
cik: "0001918102"
company_name: "DEEP FISSION, INC."
filed_at: "2025-11-21T23:59:59+00:00"
generated_at: "2026-05-16T17:44:08.686819+00:00"
event_type: "regulatory"
sentiment: "positive"
materiality_score: 0.65
calibrated_materiality_score: 0.65
confidence: "high"
source: SEC EDGAR
---

# Deep Fission signs DOE reactor authorization agreement for underground test reactor

## Summary
- DOE and Deep Fission executed Other Transaction Agreement effective Nov 14, 2025, under EO 14301 pilot program.
- Phase I covers safety basis approval and startup authorization; Deep Fission must achieve criticality by July 4, 2026.
- No DOE funding provided; Deep Fission retains all IP and data rights; DOE has oversight and termination rights.
- Either party may terminate on 30 days' notice; DOE may terminate immediately for material breach or insolvency.
- After Phase I, DOE may decide on Phase II (decommissioning or pathway to NRC licensing).

## SEC filing metadata
- accession: 0001104659-25-114959
- form_type: 8-K
- ticker: FISN
- cik: 0001918102
- company_name: DEEP FISSION, INC.
- filed_at: 2025-11-21T23:59:59+00:00
- event_type: regulatory
- sentiment: positive
- materiality_score: 0.65
- calibrated_materiality_score: 0.65
- confidence: high
- sec_items: 1.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1918102/000110465925114959/0001104659-25-114959-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1918102/000110465925114959/tm2531798d1_8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001104659-25-114959
- JSON: https://secwatch.observer/filing/0001104659-25-114959.json
- Plain text: https://secwatch.observer/filing/0001104659-25-114959.txt

## Key facts
- Material Agreements
  DEEP FISSION, INC. entered into Agreement with United States Department of Energy (effective 2025-11-14).
  - Action: entry
  - Counterparty: United States Department of Energy
  - Effective: 2025-11-14
  source text: the Company and the United States Department of Energy fully executed and delivered an Other Transaction Agreement for Reactor Authorization, effective as of November 14, 2025, which we refer to as the “Agreement”
  evidence_url: https://www.sec.gov/Archives/edgar/data/1918102/000110465925114959/0001104659-25-114959-index.htm

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.