First BWRX-300 reactor basemat lowered into shaft at OPG Darlington

On April 22, 2026, the basemat for the first BWRX-300 small modular reactor at Ontario Power Generation's Darlington site was lifted and lowered into the reactor shaft, according to the American Nuclear Society. The 300 MWe unit is the first of four planned at Darlington and is designed by GE Vernova Hitachi Nuclear Energy. OPG targets grid connection by the end of 2030, and the next milestone is completing the first level of the reactor building by the end of 2026.

• Basemat placed in the reactor shaft on April 22, 2026
• Unit 1 of four planned at Darlington; 300 MWe BWRX-300
• Grid connection target: end of 2030
• Next milestone: first level of reactor building by end of 2026
• Two regulatory hold points remain before fuel-out commissioning