IPHWR

The first PHWR units built in India (RAPS-1 and RAPS-2) are of Canadian CANDU design similar to the first full-scale Canadian reactor built at Douglas point, Ontario. The reactors were set up in collaboration with Government of Canada. Starting in 1963, 100 MWe RAPS-1 was mostly built with equipment and technology supplied by AECL, Canada. RAPS-1 was commissioned in 1973 but the cessation of Canadian cooperation in light of successful development of nuclear weapons by India as part of Operation Smiling Buddha the RAPS-2 commissioning could only be completed by 1981. Later on higher capacity derivatives were developed by Bhabha Atomic Research Centre in partnership with Indian manufacturers Larsen & Toubro and Bharat Heavy Electricals Limited. Successively, a totally Indian design of 220 MWe power capacity was designed and two units were built at Kalpakkam in Tamil Nadu state christened MAPS-1 and MAPS-2. MAPS-1&2 design was evolved from RAPS-1&2, with modifications carried out to suit the coastal location and also introduction of suppression pool to limit containment peak pressure under loss of coolant accident (LOCA) in lieu of dousing tanks in RAPS-1&2. In addition, MAPS-1&2 have partial double containment. This design was further improved and all subsequent PHWR units in India have double containment. With experience of design and operation of earlier units and indigenous R&D efforts, major modifications were introduced in NAPS-1&2. These units are the basis of standardized Indian PHWR units later designated as IPHWR-220. The design of subsequent units i.e. KGS-1, KGS-2, RAPS-3, RAPS-4, RAPS-5, RAPS-6, KGS-3 and KGS-4 is of standard Indian PHWR design. The major improvements in these designs include valve-less primary heat transport system and a unitized control room concept. In addition, the design of these units included improvements in Control and Instrumentation system and incorporation of computer based systems to match with the advancement in technology. == IPHWR-540 ==

Upon completion of the design of IPHWR-220, a larger 540 MWe design was started under the aegis of the Bhabha Atomic Research Centre (BARC) in partnership with the Nuclear Power Corporation of India Limited (NPCIL). Two reactors of this design were built in Tarapur, Maharashtra starting in the year 2000 and the first was commissioned on 12 September 2005. Only two such reactors i.e. Tarapur-3 & Tarapur-4 were built. The design was later upgraded to a 700 MWe design. == IPHWR-700 ==

The IPHWR-540 design was later upgraded to 700 MWe with the main objective to improve fuel efficiency and develop a standardized design to be installed at many locations across India as a fleet-mode effort. The design was also upgraded to incorporate Generation III+ features. The 700 MWe PHWR design includes some features, which are introduced for the first time in Indian PHWRs which include partial boiling at the coolant channel outlet, interleaving of primary heat transport system feeders, passive decay heat removal system, regional over power protection, containment spray system, mobile fuel transfer machine, and a steel liner on the inner containment wall. ==Reactor fleet ==

IPHWR-220 2 at Narora Atomic Power Station 2 at Kakrapar Atomic Power Station 4 at Kaiga Atomic Power Station 2 at Madras Atomic Power Station 4 at Rajastan Atomic Power Project IPHWR-540 2 at Tarapur Atomic Power Station IPHWR-700 2 at Kakrapar Atomic Power Station 2 at Kaiga Atomic Power Station 2 at Gorakhpur Nuclear Power Plant 2 at Rajastan Atomic Power Project 4 planned at Mahi Banswara Atomic Power Plant ==Design ==

The IPHWR reactor is a horizontal pressure tube type. It is derived from the CANDU reactor. These tubes are housed in a horizontal vessel called Calandria. It is filled with heavy water moderator. The each independent tubes are in tubes with circulating carbon dioxide gas. The tubes contain 12 fuel assemblies each and circulating pressurized heavy water coolant. This coolant collects heat from the fuel (natural uranium dioxide) and transfers it to the secondary coolant water to generate steam in the steam generators. This steam turns the turbine coupled to a AC synchronous generator producing 11kV or 20kV 50 Hz AC current. This steam is then condensed, reheated, deaerated and pumped back to the reactor. The moderator heavy water is kept circulating and is maintained at around 70 degrees Celsius. The fission chain reaction is controlled using control rods of cadmium or boron. There is a scram system to inject a poison called gadolinium nitrate in the moderator. The reactors can be refuelled while on full power giving additional advantages. The reactor has a efficiency of around 29 to 30 % gross. These reactors are highly safe. They have many innovative safety systems. They form the first stage of India's three stage nuclear power program. == Technical specifications ==

NPCIL is developing the Bharat small modular reactor (BSMR) and has asked for orders from private companies for construction of BSR at their manufacturing sites to which till now six companies have responded. It is a 220MWe compact PHWR Small modular reactor derived from the larger IPHWR-220. ==See also==