Cascade Advanced Energy Facility (Energy Northwest) by X-energy: status and timeline

Cascade Advanced Energy Facility (Energy Northwest)

Build 320 MW from four Xe-100 reactors first, with the option to grow to 960 MW, as part of Amazon's aim for more than 5 GW of new US nuclear by 2039.

ResearchStage 1 of 5

In design with Cascade Nuclear Partners; NRC construction permit filing aimed at first half of 2027.

Updated 13 Aug 2026Checked 11 Oct0 updates this week

Milestones

Next · Construction permit application to the NRC

Amazon invests in X-energy; Energy Northwest project agreed16 Oct 2024Complete.
Name and design revealed; plan grows to 12 reactors (960 MW)Oct 2025Complete.
Cascade Nuclear Partners chosen as design-builder23 Oct 2025Complete.
Construction permit application to the NRCTarget 2027Current milestone.
Site construction beginsNot yet reached.
First phase (4 units) operatingNot yet reached.

Most important updates

Upcoming

2027Construction permit application to the NRC (next)

Current obstacles

No permit yetThe NRC construction permit application has not been filed; the project is still in design and feasibility work.
Depends on the first Xe-100 at Long MottNo Xe-100 has been built; schedule and cost lessons from the Dow project in Texas are meant to feed into Cascade.
Fuel supplyThe pebble fuel needs high-assay uranium and X-energy's TX-1 fuel plant in Oak Ridge, due in the first half of 2028, whose output covers about 11 reactors.

Physics limits

Small reactors lose economies of scaleReactor cost does not shrink in step with power: an 80 MW unit still needs containment, safety systems and staff, so savings must come from factory building and repetition.
Gas-cooled cores have low power densityHelium carries far less heat per volume than water, so the core must be large for its output; that buys safety margin at the cost of more material per megawatt.
Graphite wears under radiationThe graphite in pebbles and core structures swells and shrinks under neutron bombardment, limiting how long components last before replacement.

How it works

4 parts

Fuel

Billiard-ball pebbles of coated fuel

Fuel comes as pebbles, each holding thousands of tiny uranium grains sealed in ceramic layers that keep radioactive material in even when very hot.

Cooling

Helium gas instead of water

Helium carries heat out of the core at high temperature to make steam for a turbine. Helium does not become radioactive or boil away.

Layout

Three blocks of four reactors

The site is planned in three 320 MW phases on a few city blocks, far smaller than a conventional gigawatt plant's square mile.

Deal

Amazon pays, the public utility runs it

Energy Northwest, a Washington public power agency, would own and run it; Amazon pays for feasibility and licensing work and has an option on phase-one power.

Spec sheet

Spec	Cascade Advanced Energy Facility (Energy Northwest)
Phase 1 capacity	320 MWe (4 reactors)^R (reported)
Full build-out	960 MWe (12 reactors)^R (reported)
Output per reactor	80 MWe^R (reported)
Construction jobs	Up to 1,000^R (reported)

^R reported by the company

Update log

3 updates

About X-energy

The team behind Cascade Advanced Energy Facility (Energy Northwest)

X-energy

Xe-100 pebble-bed HTGR, TRISO-X fuel

Maryland company developing the Xe-100, an 80 MWe gas-cooled pebble-bed reactor, and making its own TRISO-X fuel. Backed by Amazon and Dow, it went public on Nasdaq in April 2026 in the largest nuclear IPO on record.

A four-unit Xe-100 plant at Dow's Seadrift, Texas site is under NRC review; permit decision targeted late 2026.
Amazon invested in 2024 and plans Xe-100s totalling 5 GW by 2039.
Its April 2026 Nasdaq IPO raised about $1B.

x-energy.com (opens x-energy.com)Company profile →

Founded: 200917 yrs
Headquarters: United States
Status: Public
Listed: XE (opens google.com)NASDAQ
Valuation: public
Works in: EnergyFission
Coverage: 2 programs · 10 updateslatest 17d agochecked 25 Sep
People: Clay Sell (opens x-energy.com)CEO

Spec

Cascade Advanced Energy Facility (Energy Northwest)

Phase 1 capacity

320 MWe (4 reactors)^R (reported)

Full build-out

960 MWe (12 reactors)^R (reported)

Output per reactor

80 MWe^R (reported)

Construction jobs

Up to 1,000^R (reported)

Cascade Advanced Energy Facility (Energy Northwest)

Milestones

Most important updates

Upcoming

Current obstacles

Physics limits

How it works

Billiard-ball pebbles of coated fuel

Helium gas instead of water

Three blocks of four reactors

Amazon pays, the public utility runs it

Spec sheet

Update log

Thu 13 Aug

Thu 23 Oct 2025

Thu 16 Oct 2025

About X-energy

Current obstacles

Physics limits

How it works

Billiard-ball pebbles of coated fuel

Helium gas instead of water

Three blocks of four reactors

Amazon pays, the public utility runs it

Spec sheet

Update log

Thu 13 Aug

Thu 23 Oct 2025

Thu 16 Oct 2025

About X-energy