The Madras Atomic Power Station (MAPS) is located at Kalpakkam, 30 kilometres from Chennai City and was the first indigenously built nuclear power station in India. The Department of Atomic Energy (DAE) and the Indian engineering firm Larsen and Toubro built the power station based on experience obtained by working with the CANDU reactors at Kota. The power station consists of two units. MAPS-1 was completed in 1981, but start-up was delayed due to a shortage of heavy water. After procuring the necessary heavy water, the Madras Unit-1 went critical in 1983 and began operating at full power in January 1984. MAPS-2 obtained criticality in 1985 and began full power operations in March 1986. The two Pressurized Heavy Water Reactors (PHWR) are capable of generating 170MWe each. Since 1985, the power station has supplied spent fuel to the Tarapur reprocessing plant. MAPS is also home to a pilot plant for the removal of tritium from heavy water that is used as a moderator in the reactors.