Khondab Heavy Water Research Reactor

IR-40 (officially the Khondab Heavy Water Research Reactor), part of the Arak Nuclear Complex, was an Iranian 40 megawatt (thermal) heavy water reactor near Arak, adjacent to the 1990s era Arak Heavy Water Production Plant. The plant was made unusable in 2015 by removing the core and filling it with concrete, and it was hit by Israel in 2025 to keep it from being restored. The facility would later again be struck by Israel in March 2026. Civil works for the project began in October 2004. It was initially planned that the reactor would begin nuclear operations in 2014.