Primary Loop
The primary loop circulates coolant through the reactor core, transferring fission heat while containing radioactivity.
In PWRs, pressurized water at 15 MPa flows via pumps to steam generators. Volume ~250-300 m³ for 1000 MWe. Isolated from secondary loop for safety.
Why it matters now
Primary loop design affects SMR compactness and passive safety for 2025 NRC approvals.
Related reactors
AP1000