Engineering:IPHWR

Short description: Indian nuclear reactor design

Kakrapar Atomic Power Station with two IPHWR-700 units under construction in the Indian state of Gujarat

The IPHWR (Indian Pressurized Heavy Water Reactor) is a class of Indian pressurized heavy-water reactors designed by the Bhabha Atomic Research Centre. The baseline 220 MWe design was developed from the CANDU based RAPS-1 and RAPS-2 reactors built at Rawatbhata, Rajasthan. Later the design was based on VVER technology which was scaled to 540 MW and 700 MW designs. Currently there are 17 units of various types operational at various locations in India.

IPHWR-220

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. India took help of Soviet Union whose VVER(Pressurised Water Reactor type) technology was used as a design for indigenization 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 c. 1984 under the aegis of BARC in partnership with 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.

IPHWR-700

The IPHWR-540 design was later upgraded to a 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.

Technical specifications

Specifications	IPHWR-220	IPHWR-540	IPHWR-700
Thermal output, MWth	754.5	1730	2166
Active power, MWe	220	540	700
Efficiency, net %	27.8	28.08	29.08
Coolant temperature, °C:
core coolant inlet	249	266	266
core coolant outlet	293.4	310	310
Primary coolant material	Heavy Water
Secondary coolant material	Light Water
Moderator material	Heavy Water
Reactor operating pressure, kg/cm2 (g)	87	100	100
Active core height, cm	508.5	594	594
Equivalent core diameter, cm	451	-	638.4
Average fuel power density	9.24 KW/KgU	-	235 MW/m3
Average core power density, MW/m3	10.13	-	12.1
Fuel	Sintered Natural UO2 pellets
Cladding tube material	Zircaloy-2	Zircaloy-4
Fuel assemblies	3672	5096	4704 fuel bundles in 392 channels
Number of fuel rods in assembly	19 elements in 3 rings	37	37 elements in 4 rings
Enrichment of reload fuel	0.7% U-235
Fuel cycle length, Months	24	12	12
Average fuel burnup, MW · day / ton	6700	7500	7050
Control rods	SS/Co	Cadmium/SS
Neutron absorber	Boric Anhydride	Boron
Residual heat removal system	Active: Shutdown cooling system Passive: Natural circulation through steam generators	Active: Shutdown cooling system Passive: Natural circulation through steam generators and Passive Decay heat removal system
Safety injection system	Emergency core cooling system

See also

• IPHWR-220, first version of the IPHWR class of recators
• IPHWR-700, Generation III+ successor to the IPHWR-220 design
• CANDU, predecessor to Indian PHWR designs
• AHWR-300, thorium fuelled PHWR design for the Indian Three stage nuclear power programme
• India's three-stage nuclear power programme
• Nuclear power in India