was being designed, the CANDU 9. ACR was slightly larger but less expensive to build and run. The downside was that it did not have the flexibility of fuels that the original CANDU design offered, and would no longer run on pure unenriched uranium. This was a small price to pay given the low cost of enrichment services and fuel in general.

AECL bid the ACR-1000 on several proposals around the world but won no contests. The last serious proposal was for a two-reactor expansion of the Darlington Nuclear Generating Station,