The brief

Analyst view

• Gravity is a 15 MWe PWR housed in a slim borehole 1.6 km deep, with geology and hydrostatic pressure providing containment.
• Went public September 2025. Series B raised $80M in February 2026. Part of the DOE Reactor Pilot Program with pilot site in Parsons, Kansas.
• First deep-borehole reactor drill began December 2025. Company adjusted timeline beyond July 2026 target.

Technical approach

As reported

Borehole deployment

Underground reactor design simplifies containment

Fits in a slim borehole 0.75m diameter, 1.6km deep. Geology and hydrostatic pressure provide structural containment.

Gravity cooling

Passive cooling via gravity circulation

Water column above provides hydrostatic pressure and passive cooling. On power loss, natural circulation removes decay heat.

Pressurized water reactor core

Proven PWR physics underground

Uses standard pressurized water reactor technology, leveraging 60 years of proven PWR experience.

Modular scaling

Multiple reactors per site via clustering

9m tall, slim design fits boreholes. Multiple boreholes on one site scale from 15 MW to hundreds of megawatts.

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