BREST-OD-300 by Rosatom: status and timeline

BREST-OD-300

Demonstrate lead-cooled fast reactor operation, prove on-site closed fuel cycle technology, establish base for larger BR-1200 commercial reactors.

ProtoStage 2 of 5

Under construction at Seversk. Startup moved to 2029; major equipment installation ongoing.

Updated Aug 2025Checked 11 Oct0 updates this week

Milestones

Next · Physical startup (first criticality)

Pilot Demonstration Energy Complex (ODEK) construction begins2018Complete.
TVEL fuel fabrication facility begins pilot operationJan 2025Complete.
Major reactor components installed at Seversk site2025Complete.
Physical startup (first criticality)Target 2029+36 mo~~originally 2026~~Not yet reached.
Grid connection and full-power operationTarget 2030Not yet reached.

Most important updates

Upcoming

2029Physical startup (first criticality)+36 mo~~originally 2026~~ (next)
2030Grid connection and full-power operation

Current obstacles

Startup schedule delays2026 startup postponed to 2029 for additional engineering work; long timeline increases cost.
Lead-cooled materials qualificationSpecialized steels must survive 40 years of exposure to molten lead at 540°C and fast neutron irradiation; limited commercial experience exists.

Physics limits

Lead density and weightLead is 11 times denser than water, so piping and support structures must be much heavier and thicker, increasing capital cost and construction complexity.
Lead corrosion of structural materialsMost steels corrode in molten lead at high temperature; only a limited set of alloys (mostly martensitic steels with specific composition) resist corrosion, limiting design flexibility.
Transmutation and radioactive decayLead itself becomes slightly radioactive under neutron bombardment; polonium-210, a volatile alpha emitter, can be produced, requiring strict containment.

How it works

4 parts

Fuel type

Uranium-plutonium nitride

MNUP fuel is made from reprocessed spent fuel; nitride form allows higher density than oxide.

Breeding cycle

Fast neutrons convert U-238 to Pu-239

Fast neutrons split fissile atoms and convert abundant U-238 into fissile Pu-239.

Lead cooling

Passive safety and simplicity

Lead removes heat at atmospheric pressure; high boiling point allows passive decay heat removal.

Closed fuel cycle

On-site reprocessing and re-fabrication

Spent fuel is reprocessed on-site to recover plutonium and uranium for fresh fuel production.

Spec sheet

Spec	BREST-OD-300
Electrical output	300 MWe^R (reported)
Thermal power	700 MWt^R (reported)
Lead inlet temperature	420°C^R (reported)
Lead outlet temperature	540°C^R (reported)
Fuel composition	Mixed uranium-plutonium nitride (MNUP)^R (reported)

^R reported by the company

Update log

3 updates

About Rosatom

The team behind BREST-OD-300

Rosatom

Russia, reactors, fuel, uranium, mining, enrichment, state

Rosatom is Russia's state nuclear corporation founded 2007. Designs, builds and operates reactors worldwide; produces fuel, enriches uranium, decommissions plants. The BREST-OD-300 at Seversk demonstrates closed fuel cycle technology.

Rosatom operates Russia's nuclear industry under state control: uranium mining, enrichment, reactor design and decommissioning.
BREST-OD-300 at Seversk is the world's first lead-cooled power reactor, demonstrating on-site fuel recycling.
Originally planned 2026 startup; postponed to 2029 pending additional development work.

Company profile →

Founded: 200719 yrs
Headquarters: Russia
Status: Government
Valuation: government
Works in: EnergyFission
Coverage: 1 program · 3 updateslatest 1 Aug 2025checked 11 Oct
Partners: Siberian Chemical Combine (SCC) (opens scc.silur.ru)
Suppliers: TVEL (opens tvel.ru)

Spec

BREST-OD-300

Electrical output

300 MWe^R (reported)

Thermal power

700 MWt^R (reported)

Lead inlet temperature

420°C^R (reported)

Lead outlet temperature

540°C^R (reported)

Fuel composition

Mixed uranium-plutonium nitride (MNUP)^R (reported)

BREST-OD-300

Milestones

Most important updates

Upcoming

Current obstacles

Physics limits

How it works

Uranium-plutonium nitride

Fast neutrons convert U-238 to Pu-239

Passive safety and simplicity

On-site reprocessing and re-fabrication

Spec sheet

Update log

Aug 2025

Jan 2025

Jan 2024

About Rosatom

Current obstacles

Physics limits

How it works

Uranium-plutonium nitride

Fast neutrons convert U-238 to Pu-239

Passive safety and simplicity

On-site reprocessing and re-fabrication

Spec sheet

Update log

Aug 2025

Jan 2025

Jan 2024

About Rosatom