Ontario Power Generation (OPG) has submitted its operating license application to Canada’s nuclear regulator for the company’s first small modular reactor (SMR) at the Darlington nuclear site in Clarington, Ontario.
The March 25 application also seeks permission for an associated waste storage structure for the Darlington New Nuclear Project, the Canadian Nuclear Safety Commission (CNSC) said in a Tuesday X post. The storage facility will hold low-and intermediate-level waste.
On Monday, CNSC removed its first regulatory hold point for Darlington’s first BWRX-300 SMR, allowing OPG to install its reactor building foundation. Regulatory hold points are checkpoints used by CNSC that require nuclear licensees to demonstrate compliance with safety obligations before proceeding to the next stage of their project.
The first Darlington SMR, GE Vernova Hitachi’s BWRX-300 reactor, was granted a construction permit by CNSC in April 2025.
Construction of the first Darlington SMR is being handled by Aecon Kiewit Nuclear Partners. AtkinsRéalis, which has been involved with the project since 2023, and its subsidiary Candu Energy are also working on the project. AtkinsRéalis is the lead architect engineer.
The first Darlington SMR is expected to be completed in 2030, OPG said.
Following CNSC’s construction permit issuance, the Province of Ontario approved OPG’s venture to build its first BWRX-300 SMR in May 2025. In October 2025, the two Canadian government agencies committed $3 billion CAD ($2.1 billion US) to OPG’s Darlington project to help de-risk the company’s construction and operation of its new small modular reactors.
The Darlington New Nuclear Project aims to build four SMRs at the Darlington site to produce 1,200 megawatts of electricity for the Ontario Province. A BWRX-300 SMR is a boiling water reactor with a generating capacity of 300 megawatts. OPG selected the BWRX-300 SMR in December 2021.