The Advanced CANDU Reactor-1000 (ACR-1000) design is a 1200 MWe pressure tube reactor that retains many essential features of a typical CANDU plant design, including horizontal fuel channel core, a low-tem­perature heavy water moderator, a water-filled reactor vault, two indepen­dent safety shutdown systems, a highly automated control system, on-power fueling and a reactor building that is accessible for on-power maintenance and testing. The key differences from the traditional CANDU design incor­porated into the ACR-1000 are the use of low-enriched uranium fuel (as opposed to natural uranium), the use of light water instead of heavy water as the reactor coolant, and a lower moderator volume to fuel ratio. These features together with a number of other evolutionary changes lead to the many benefits for the ACR-1000 design: a more compact core design, an increased burn-up as a result of the fuel enrichment, increased safety margins, improved overall turbine cycle efficiency through the use of higher pressures and higher temperatures in the coolant and steam supply systems, reduced emissions through the elimination of tritium production in the coolant and other environmental protection improvements, enhanced severe accident management by providing backup heat sinks, improved performance through the use of advanced operational and maintenance information systems, and improved separation of redundant structures, systems and components (SSCs) important to safety through the use of a four-quadrant plant layout. The ACR-1000 design has been reviewed by the Canadian regulatory body and has been given a positive regulatory opinion about its licensability. The generic preliminary safety analysis report for the ACR-1000 design was completed in September 2009. The final stage of the ACR-1000 design is currently underway including documentation and addi­tional confirmatory analysis, and the basic engineering is expected to be completed in 2010.

AP1000

The Westinghouse Advanced Passive PWR (AP1000) is a two-loop 1117 MWe PWR scaled up from that already certified in the USA AP600 design, which was originally compliant with the EPRI URD (EPRI, 1995, 1999). In the AP1000, designers have made an effort to simplify all systems, and to reduce the number of systems and components for easier construc­tion, operation and maintenance. As in other evolutionary concepts, the AP1000 uses prefabrication and modular construction as a way to reduce construction schedule uncertainties. One of the signature characteristics of the AP1000 is the use of passive safety systems, i. e., those that rely on natural driving forces such as pressurized gas, gravity flow, natural circula­tion flow, and convection, for core cooling, containment isolation, residual heat removal and containment cooling. On the other hand, the plant design utilizes proven technology and capitalizes on more than 40 years of PWR operating experience. The AP1000 also incorporates severe accident mitiga­tion features, such as in-vessel retention of core debris following a core melt event, and no reactor vessel penetrations below the top of the core level. Two AP1000 projects are currently under construction in China (Haiyang and Sanmen) and substantial construction and operating experience is expected from these. In the USA, final design certification by the US NRC for the AP1000 is expected by 2011 and there are several applications for its construction starting 2011.