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Reg D 506(c)TRL76.6–7.5Tier IIOpen

Castellan Defense Systems

Castellan Defense Systems

Senior notes on a transportable gas-cooled microreactor under a defense prototyping contract. Accredited only.

Roughly half of the casualties in recent land campaigns occurred in or around fuel convoys. A three megawatt reactor that fits in shipping containers and runs for five years without refueling removes that convoy. Castellan holds a construction permit under Department of Energy authorization and a prototyping contract with options for eight units.

New River Defense Complex · Radford, VAConstruction permit issuedEscrow: Meridian Trust, N.A.
TRL 7 of 9, band 6.6 to 7.5, signed by Dr. Helena Vargas-Mbeki, PE, Nuclear; former NRC senior reactor analyst, on Jun 4, 2026.See the evidence it rests on

$24,900,000 committed of $30,000,000

$17,430,000 released · 83% subscribed

Released to the issuerCommitted, held in escrowRemaining
Minimum
$25,000

$1,000 per unit

Target coupon
7.15%

Annual, fixed

Term
6 yr
Investors
88

Closes November 15, 2026 · 63 days remaining

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No payment processor is connected. The commitment flow runs end to end, through amount, agreement, signature and receipt, and records a simulated position rather than a charge.

Principal risks of this offering

  • Revenue is concentrated in a single government customer whose options are not commitments.
  • Defense contracting timelines and appropriations are outside the issuer's control.
  • Transportable reactor security requirements are still being established and could increase cost materially.
  • Accredited investors only, restricted from resale.

General risks of private securities

Private securities are speculative and illiquid. You should be prepared to hold this position for its full term and to lose the entire amount invested. Nuclear construction has a documented history of schedule and cost overrun. Platforms that sold equity in unbuilt energy projects have mostly failed; those that sold debt against operating assets with contracted offtake have mostly survived. That history is why the TRL tier of an offering matters more than its headline return.

A TRL score is not a prediction and not a rating. Read the offering documents in full before committing capital.