eVinci Microreactor by Westinghouse: status and timeline

Milestones

Next · Lunar flight test (NASA partnership)

Test reactor achieves zero-power criticalityAug 2026Complete.
Lunar flight test (NASA partnership)Target 2028Not yet reached.

Most important, last 3 months

Westinghouse eVinci microreactor completes zero-power criticality test at NCERC26 Aug 2026

Upcoming

2028Lunar flight test (NASA partnership) (next)

Current obstacles

Regulatory path for civilian and military useLicensing a new reactor type requires NRC approval for civilian use and DoD safety certification for military bases; timelines are uncertain.
Manufacturing scale-up for modular unitsTransitioning from a prototype to factory production of multiple eVinci units in parallel requires new manufacturing infrastructure and supply chains.

Physics limits

Size and weight for portabilityEven at 5 MWe, the reactor plus turbine, radiator and fuel systems are heavy and large; lunar and airborne applications face stringent payload constraints.
Radiator thermal rejectionA closed Brayton cycle radiator must reject tens of megawatts of waste heat in vacuum (lunar) or extreme environments; larger systems need larger radiators.

How it works

4 parts

Heat pipes

Passive heat transport from core to power cycle

Fluid evaporates at hot end, condenses at cold end, moving heat without pumps.

Closed Brayton cycle

Gas turbine with no cooling water needed

High-pressure helium or nitrogen gas spins a turbine directly, then rejects residual heat via air radiators. No water cooling means it works anywhere.

TRISO fuel

Ceramic-coated particles prevent meltdown

Each fuel particle is coated with multiple ceramic layers that contain fission products and resist damage up to very high temperatures, enabling passive safety.

Control drums

Rotating absorbers instead of movable rods

Drums with absorber material control reactivity without penetrating core, simplifying design.

Spec sheet

Spec	eVinci Microreactor
Electrical power output	5 MWe^R (reported)
Thermal power output	15 MWth^R (reported)
Refueling cycle	8+ years^R (reported)
Test reactor scale	One-fifth commercial design^R (reported)
NASA lunar variant power	40 kWe^R (reported)

^R reported by the company

Update log

1 update

Wed 26 Aug

Major: Westinghouse eVinci microreactor completes zero-power criticality test at NCERCPressTest

About Westinghouse

The team behind eVinci Microreactor

Westinghouse

AP1000, AP300, nuclear reactors, APX platform, small modular reactor

Westinghouse develops the AP1000 (1200 MW) and AP300 (300 MW) reactors. US deployment backed by $17.5B DOE loans and Amentum partnerships.

Westinghouse is headquartered in Cranberry Township, Pennsylvania and is led by President and CEO Dan Sumner (appointed April 2026).
Six AP1000s operating globally; 11 under construction; selected for Poland, Ukraine and Bulgaria.
DOE committed $17.5B (June 2026) for long-lead items on up to 10 AP1000s across five utilities.

westinghousenuclear.com (opens westinghousenuclear.com)Company profile →

Founded: 1886140 yrs
Headquarters: United States
Status: Private
Valuation: private
Works in: EnergyFission
Coverage: 3 programs · 3 updateslatest 26 Aug 2026checked 10 Oct
Customers: Tennessee Valley Authority (opens tva.gov)
Partners: U.S. Department of Energy (opens energy.gov)Amentum (opens amentum.com)
People: Dan Sumner (opens info.westinghousenuclear.com)President and CEO

Spec

eVinci Microreactor

Electrical power output

5 MWe^R (reported)

Thermal power output

15 MWth^R (reported)

Refueling cycle

8+ years^R (reported)

Test reactor scale

One-fifth commercial design^R (reported)

NASA lunar variant power

40 kWe^R (reported)