PHWR
Pressurized Heavy Water Reactor
Pressurized Heavy Water Reactor (PHWR) uses heavy water moderator and coolant, enabling use of unenriched natural uranium fuel.
PHWRs operate at 10 MPa pressure with D2O at ~290°C, refuel online unlike LWRs. CANDU design exemplifies with horizontal pressure tubes, calandria vessel separation. Capacity factors exceed 80% in fleets like Ontario Power Generation's 19 units totaling 13.6 GWe. Over 50 units built, mainly Canada/India.
Why it matters now
PHWRs provide fuel flexibility amid 2025 uranium price volatility and HALEU delays. Refurbishments in Canada support baseload power for data center PPAs.