I do want to respond, because in a sense the design process for a large sophisticated machine like this, as you can imagine, involves the interplay of many design factors that go into optimizing it.
The design objectives for the ACR-1000 were to achieve the safest possible reactor we could, built on a CANDU architecture, and to achieve the lowest lifetime unit electricity cost we could and be competitive with the global market requirements.
In order to do that, there were several important design adjustments made from the CANDU 6 starting point to the ACR-1000 evolution. Those included the move to slightly enriched uranium and also the move to a mixture of heavy water moderation and light water coolant, as opposed to the CANDU 6's being a pure heavy-water-based reactor. A number of other factors went into the desire to achieve a reactor with high productivity: high on-time reliability, serviceability—you name it, a number of design considerations.
The fuel design is a very important component of the lifetime economic performance of the reactor, and the use of slightly enriched uranium brings significant benefits when you optimize it with the other elements of the design.