From CANDU, it took the heavy water moderator, which gave the design an improved neutron economy that allowed it to burn a variety of fuels.
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.
The last serious proposal was for a two-reactor expansion of the Darlington Nuclear Generating Station, but this project was canceled in 2009 when the price was estimated to be three times what the government was budgeting.
With no other sales prospects, in 2011 the AECL reactor design division was sold to SNC-Lavalin to provide services to the existing CANDU fleet.
[2] The original CANDU design used heavy water as both the neutron moderator and the coolant for the primary cooling loop.
It was believed that this design would result in lower overall operating costs due to its ability to use natural uranium for fuel, eliminating the need for enrichment.
At the time, it was believed there would be hundreds and perhaps thousands of nuclear reactors in operation by the 1980s, and in that case the cost of enrichment would become considerable.
This left CANDU in the unexpected position of selling itself primarily on the lack of need for enrichment and the possibility that this presented a lower nuclear proliferation risk.
ACR addresses the high capital costs of the CANDU design primarily by using low-enrichment uranium (LEU) fuel.
The ACR also incorporates characteristics of the CANDU design, including on-power refueling with the CANFLEX fuel; a long prompt neutron lifetime; small reactivity holdup; two fast, independent, safety shutdown systems; and an emergency core cooling system.
The use of LEU fuel with a neutron absorbing centre element allows the reduction of coolant void reactivity coefficient to a nominally small, negative value.
When any 2 of the 3 circuit paths are activated (due to sensing the need for emergency reactor trip), the direct current-controlled clutches that keep each control-rod in the storage position are de-energized.
Gadolinium nitrate (Gd(NO3)3) solution, a neutron-absorbing liquid that shuts down the nuclear chain reaction, is stored inside channels that feed into horizontal nozzle assemblies.
CEO Hugh MacDiarmid is quoted as stating, "We believe very strongly that our best course of action to ensure the ACR-1000 is successful in the global market place is to focus first and foremost on establishing it here at home.
In 2014, SNC announced a partnership with the China National Nuclear Corporation (CNNC) to support sales and construction of the existing CANDU designs.