Engineers at an Ontario nuclear power station have reached a major milestone in rebuilding a reactor core, finishing a crucial stage almost a month ahead of schedule.Bruce Power says its Unit 4 reactor reached the milestone 25 days faster than the previous unit. The team fitted all 480 calandria tubes, which form the heart of the reactor vessel. Work will now begin on installing the fuel channels.The speed of the work comes at a critical time for Canada’s most populous province. Officials expect electricity demand in Ontario to jump by 90 percent by 2050.Boosting the power outputTo help meet this need, Bruce Power is also boosting the power output of its existing plant. The company has hired Siemens Energy Canada to supply new high-pressure steam turbines for all four Bruce A reactors. Engineers will install the machinery between 2028 and 2031.The upgraded turbines will run more efficiently. They will generate an extra 30 megawatts of electricity from each reactor without burning extra fuel. In total, the deal will inject nearly 125 megawatts of extra clean electricity into the provincial grid.Inside Unit 4, the rapid installation was made possible by advanced automation.Deploying six-axis roboticsTechnicians deployed a state-of-the-art robotic tooling system to seal the reactor components. The machine operates on both faces of the reactor at the same time. It slides an insert into each tube and rolls the metal to an exact diameter. This microscopic cold-working process locks the joint into a permanent, leak-tight seal.The robotic system removed the need for manual work in hazardous areas. It protected tradespeople by sharply cutting their exposure to radiation fields.A domestic partnership built the equipment. Bruce Power developed and tested the tools alongside Shoreline Power Group, ATS Automation, and Calian Engineering. The team first used the system on the Unit 3 reactor. They then used lessons from that job to speed up work on Unit 4. In August, the crew set a single-day CANDU record by fitting 20 tubes in 24 hours, beating the old mark of 16.Stephen Lecce, Ontario’s Minister of Energy and Mines, praised the project: “Ontario’s nuclear sector is demonstrating its world leadership and proven track record of delivering large-scale refurbishments on budget and ahead of schedule.” He added that new nuclear projects across the province would support 150,000 jobs.More than just power supplyUnit 4 is the midway point in Bruce Power’s wider Life-Extension Program. The multi-billion-dollar project will overhaul Units 3 to 8, returning all six to service by 2033 to power the grid for decades. Units 6 and 3 have already returned to commercial service. Technicians will shut down Unit 5 to start its refit this November, with Units 7 and 8 to follow. The refurbished reactors will also support global healthcare.Eric Chassard, the chief executive of Bruce Power, said the plant will supply affordable power for decades. He stressed that the reactors will also provide a dependable supply of cancer-fighting medical isotopes for hospitals around the world.