# Natrium Reactor

## Overview

345 MW electric sodium-cooled fast reactor coupled to a 1 GWh molten salt energy storage system. Developed by TerraPower with DOE ARDP funding.

## Technical Specifications

- **Base output:** 345 MW electric (constant)
- **Peak output:** 500 MW electric for 5.5 hours
- **Storage:** 1 GWh molten salt thermal storage (borrowed from concentrated solar power industry)
- **Reactor type:** Sodium-cooled fast reactor
- **Load-following capability:** Reactor runs at constant power while storage system enables variable grid output

## Design Intent

- **Original purpose:** Complement intermittent renewables (solar/wind) through load-following capability
- **Design timeline:** Pre-2020 (before AI demand wave)
- **Retrofitted application:** AI datacenter power with training cycle variability

## Economics

- **Total cost:** ~$4B for first unit at Kemmerer
- **Cost per GW:** ~$11.6B/GW (based on 345 MW base capacity)
- **Funding:** DOE ARDP 50/50 cost-sharing (up to $2B DOE contribution)

## Commercial Deployments

- **Meta:** 8 units (agreement signed January 9, 2026)
- **Google/Microsoft:** 2.5-3 GW through NextEra-TerraPower partnership (April 8, 2026)

## Technology Heritage

- **Molten salt storage:** Explicitly borrowed from concentrated solar power (CSP) industry
- **Storage architecture:** Same technology used in solar thermal plants, adapted for nuclear heat input

## Timeline

- **2006** — TerraPower founded
- **2020** — DOE ARDP funding selection
- **2026-03-04** — NRC construction permit issued (first for commercial-scale advanced nuclear)
- **2026-04-23** — Groundbreaking at Kemmerer, Wyoming
- **2030** — Target first power

## Regulatory Significance

First commercial-scale advanced nuclear plant to receive NRC construction permit. NRC safety review completed ahead of schedule and 11% under budget, demonstrating regulatory pathway for subsequent advanced reactor projects.

## Related

- Parent company: TerraPower
- EPC contractor: Bechtel
- Location: Kemmerer Power Station Unit 1, Wyoming