# X-energy

**Type:** Advanced nuclear reactor developer
**Focus:** Pebble bed high-temperature gas-cooled reactor (HTGR)
**Key Technology:** Xe-100 reactor design

## Overview

X-energy develops the Xe-100, a pebble bed HTGR that uses pressurized helium as heat transfer fluid. The design operates at 200 MWt / ~80 MWe per unit.

## Technical Approach

The Xe-100 uses pressurized helium that "remains chemically inert and single-phase at operating temperatures, enabling efficient heat transfer without phase change or material degradation." Hot helium exits the reactor and transfers heat through a steam generator into a separate water loop. Unlike sodium-cooled or salt-cooled intermediate-circuit reactors, the Xe-100 has no salt in primary or secondary circuits and no connection to CSP thermal storage technology.

## Timeline

- **2026-04-27** — Technical documentation confirms helium-based thermal approach with no CSP salt integration

## Sources

- X-energy Xe-100 technical documentation (https://x-energy.com/reactors/xe-100)