The construction of the Rajasthan Atomic Power Project (RAPP) began in 1963 with two
CANDU (Canada Deuterium Uranium)
pressurised heavy water reactor (PHWR) capable of producing 220
MW of electricity each. Ten years later, in 1973 RAPS-1 was put into service. In 1974 after India conducted
Smiling Buddha, its first
nuclear weapons test, Canada stopped its support of the project, delaying the commissioning of RAPS-2 until 1981.
Unit 1: In the early 1960s, Indian
Department of Atomic Energy (DAE), and Canada's Atomic Energy of Canada limited
AECL signed an MoU to build two reactors of 200 MW each. Construction began in 1963 and unit 1 achieved operational status in 1973. Since the beginning, it faced several technical issues such as cracks in the end shields, leak of the moderator, rupture of fuel channel, etc. To alleviate these issues, it was derated to 100MWe. But issues continued to occur. The unit had low-capacity factor, low availability and caused economic losses. Due to these issues and safety concerns, it was put in a permanent shutdown in October 2004.
Unit 2: When India conducted the 1974 Nuclear tests at Pokhran in Rajasthan, Canada withdrew from the project, leaving the DAE alone to develop the second reactor. Learning lessons from unit 1, and with help of other industries such as Bharat heavy electricals limited
BHEL and
L&T the reactor was completed and put into operation in 1981. It lacked many of the issues that had plagued Unit 1, yielding a capacity factor of 67.2% compared to Unit 1's 21.1% and continues to operate through 2024. In the context of the Indian atomic program, two more PHWR with an output of 220 MW each were built. They cost around 570 million dollars. RAPS-3 became critical on 24 December 1999, RAPS-4 became critical on 3 November 2000. Commercial operations began on 1 June 2000 for unit 3, and on 23 December 2000 for unit 4. Two more reactors (RAPS-5 and RAPS-6) with 220 MWe have also been built, with unit 5 beginning commercial operation on 4 February 2010, and unit 6 on 31 March 2010. One of the new Indian-designed 700 MWe series of the reactor (RAPP-8) is under construction in Rajasthan. One (RAPP-7) was recently commissioned in April 2025. In November 2012, the
International Atomic Energy Agency (IAEA) intensively audited over several weeks two reactors at the Rajasthan Atomic Power Station for safety. It has been concluded that the reactors are among the best in the world, the indigenously made 220 MW atomic plants can withstand a
Fukushima type of accident, even suggesting that the "safety culture is strong in India" and that India emerged a winner with a high global safety rank. First concrete for unit 7 was poured on 18 July 2011, with commercial operation expected by 2016. First concrete for unit 8 was poured on 30 September 2011. Unit 7 and unit 8 will cost together an estimated Rs 123.2 billion (US$2.6 billion). In 2024, the AERB granted permission for unit 7 fuel loading and addition of moderator. The 19 September 2024, unit 7 started a controlled fission chain reaction. In March 2025, unit 7 at Rajasthan site was connected to the grid. It is the 3rd 700 MWe indigenous pressurized heavy water reactor connected to the grid. It entered commercial operations in April of 2025. == Incidents ==