Nuclear Power Technology Development Section

Heavy Water Reactors

Heavy Water Moderated Reactors
In operation 44
Under construction 4
Number of countries with HWRs 7
Generating capacity, GW(e) 22.4

Heavy water reactors are a significant proportion of world reactor installations. They provide fuel cycle flexibility for the future and can potentially burn the spent fuel from LWRs, with no major reactor design changes, thus extending resources and reducing spent fuel arising.

Most of the members of the TWG-HWR are from developing countries, which have HWRs in their nuclear power programmes. The IAEA’s technical aid and initiative via TWG-HWR activities are therefore especially important in assisting these countries.

New HWR designs are being developed mainly in Canada and India.

In China, the Qinshan CANDU project, a partnership between AECL, Canada and the Third Qinshan Nuclear Power Company (TQNPC), is proceeding successfully. The two units went into commercial operation in 2002 and 2003 respectively.

In Canada, AECL is continuing to adapt the basic CANDU design to develop the Advanced CANDU Reactor (ACR), focusing on improvements in economics, inherent safety characteristics and performance, while retaining the features of the earlier family of PHWR nuclear power plants. Goals include lower plant capital and operating costs, plus reduced project schedules, through the use of improved design and construction methods and operational improvements. The design utilizes low enriched uranium (LEU) fuel to reduce the reactor core size, which reduces the amount of heavy water required to moderate the reactor and allows the use of light water in place of heavy water as the reactor coolant.

At the leading edge of the ongoing AECL programme for evolutionary improvements in the CANDU line of reactors is a research and development programme, designated CANDU-X, on innovative CANDU reactors operating at higher thermal efficiencies, which implies high temperature coolant or supercritical water as coolant. Such reactors would also incorporate passive high temperature fuel channels, natural circulation heat removal wherever possible, and passive containment heat removal.

In India, a continuing process of evolution of HWR design has been carried out since the Rajasthan I and II projects. Tarapur 3 and 4, an evolutionary 500 MWe HWR, started commercial operation in 2006 and 2005 respectively. Also a boiling light water cooled, heavy water moderated Advanced HWR is under development in India. This innovative design burns thorium and incorporates many passive features, including natural circulation cooling.