IPHWR-700 Reactor Class
Kakrapar Atomic Power Station reactor units 3 and 4, under construction in the Indian state of Gujarat
GenerationGeneration III reactor
Reactor conceptpressurized heavy-water reactor
Reactor lineIPHWR (Indian Pressurized Heavy-water Reactor)
Designed byNPCIL
Manufactured byNPCIL
  • 2 operational
  • 4 under construction
  • 10 planned
Main parameters of the reactor core
Fuel (fissile material)235U (NU/SEU/LEU)
Fuel stateSolid
Neutron energy spectrumThermal
Primary control methodControl rods
Primary moderatorHeavy water
Primary coolantHeavy water
Reactor usage
Primary useGeneration of electricity
Power (thermal)2166 MWth
Power (electric)700 MWe

The IPHWR-700 (Indian Pressurized Heavy Water Reactor-700) is an Indian pressurized heavy-water reactor designed by the NPCIL.[1] It is a Generation III reactor developed from earlier CANDU based 220 MW and 540 MW designs. It can generate 700 MW of electricity. Currently there is one unit operational, 7 units under construction and 8 more units planned, at a cost of 1.05 lakh crore (US$13 billion).


PHWR technology was introduced in India in the late 1960s with the construction of RAPS-1, a CANDU reactor in Rajasthan. All the main components for the first unit were supplied by Canada. India did the construction, installation and commissioning. In 1974, after India conducted Smiling Buddha, its first nuclear weapons test, Canada stopped their support of the project. This delayed the commissioning of RAPS-2 until 1981.[2]

After Canada withdrew from the project, research, design and development work in the Bhabha Atomic Research Centre and Nuclear Power Corporation of India (NPCIL) enabled India to proceed without assistance. India took help of Soviet Union whose VVER(Pressurised Water Reactor type) technology was used as a design for indigenization. Some industry partners did manufacturing and construction work. Over four decades, fifteen 220-MW reactors of indigenous design were built. Improvements were made in the original VVER design to reduce construction time and cost. New safety systems were incorporated. Reliability was enhanced, bringing better capacity factors and lower costs.

To get economies of scale, NPCIL developed a 540 MW design. Two of these were constructed at the Tarapur Atomic Power Station.

After a redesign to utilise excess thermal margins, the 540 MW PHWR design achieved a 700 MW capacity without many design changes. Almost 100% of the parts of these indigenously designed reactors are manufactured by Indian industry.[3]

By 2031–2032, NPCIL plans to construct 18 more nuclear power reactors, which together have the potential to produce 13,800 MWe of electricity. This will bring the total amount of atomic power in the energy mix to 22,480 MWe.[4]


I-PHWR700 Model installed in GCNEP Office, Haryana

Like other pressurized heavy-water reactors, IPHWR-700 uses heavy water (deuterium oxide, D2O) as its coolant and neutron moderator. The design retains the features of other standardized Indian PHWR units, which include:[5]

It also has some new features as well, including:

The reactor has less excess reactivity. Therefore, it does not need neutron poison inside the fuel or moderator. These designs handle the case of a loss of coolant accident such as occurred in the Fukushima Daiichi nuclear disaster.[6]


The reactor fuel uses natural uranium fuel with Zircaloy-4 cladding. The core produces 2166 MW of heat which is converted into 700 MW of electricity at a thermal efficiency of 32%. Because there is less excess reactivity inside the reactor, it needs to be refuelled continually during operation. The reactor is designed for an estimated life of 40 years.[7]

Unit 3 of Kakrapar Atomic Power Station was connected to the grid on 10 January 2021.[8]

Reactor fleet

IPHWR-700 Reactor fleet
Power station Location Operator Units Total capacity
Status Operation start
In Operation
KAPS-3 Kakrapar, Gujarat NPCIL 700 x 2 700 Operational 2021[8][9]
KAPS-4 Critical 2023
Under Construction
RAPS-7 Rawatbhata, Rajasthan NPCIL 700 x 2 1400 Under construction 2026[10]
RAPS-8 Under construction
GHAVP-1 Gorakhpur, Haryana 700 x 2 1400 Under construction 2032[10]
GHAVP-2 Under construction
KGS-5 Kaiga, Karnataka 700 x 2 1400 Under construction
KGS-6 Under construction
Planned [11]
Mahi Banswara 1 Banswara, Rajasthan NPCIL 700 x 4 2800 Planned TBA
Mahi Banswara 2
Mahi Banswara 3
Mahi Banswara 4
Chutka 1 Chutka, Madhya Pradesh 700 x 2 1400 Planned
Chutka 2
GHAVP-3 Gorakhpur, Haryana 700 x 2 1400 Planned

Technical specifications

Specifications IPHWR-220[12] IPHWR-540[13][14][15][16] IPHWR-700[17]
Thermal output, MWth 754.5 1730 2166
Active power, MWe 220 540 700
Efficiency, net % 27.8 28.08 29.00
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


  1. ^ "ANU SHAKTI: Atomic Energy In India". BARC. Archived from the original on 26 June 2020. Retrieved 13 November 2019.
  2. ^ "Rajasthan Atomic Power Station (RAPS)". Nuclear Threat Initiative. 1 September 2003. Retrieved 18 February 2017.
  3. ^ "Pressurised Heavy Water Reactor". PIB. Dr. S Banerjee.
  4. ^ "India to add 18 more nuclear power reactors with total capacity of 13,800 MWe by 2032: NPCIL". The Indian Express. 25 February 2024. Retrieved 4 March 2024.
  5. ^ "Status report 105 – Indian 700 MWe PHWR (IPHWR-700)" (PDF). IAEA.
  6. ^ "Advanced Large Water Cooled Reactors" (PDF). IAEA.
  7. ^ "Advanced Large Water Cooled Reactors" (PDF). IAEA.
  8. ^ a b "Unit 3 of Kakrapar nuclear plant synchronised to grid". Live Mint. 10 January 2021. Retrieved 18 January 2021.
  9. ^ "Bright prospects for India's future fleet". Nuclear Engineering International. Retrieved 13 April 2020.
  10. ^ a b "India gives update on nuclear construction projects". World Nuclear News. 16 December 2022.
  11. ^ "2023 construction start for Indian reactor fleet". World Nuclear News. 28 March 2022. Retrieved 29 March 2022.
  12. ^ "Status report 74 – Indian 220 MWe PHWR (IPHWR-220)" (PDF). International Automic Energy Agency. 4 April 2011. Retrieved 21 March 2021.
  13. ^ Soni, Rakesh; Prasad, PN. "Fuel technology evolution for Indian PHWRs" (PDF). International Atomic Energy Agency. S. Vijayakumar, A.G. Chhatre, K.P.Dwivedi.
  14. ^ Muktibodh, U.C (2011). "Design, Safety and Operability performances of 220 MWe, 540 MWe and 700 MWe PHWRs in India". Inter-Regional Workshop on Advanced Nuclear Reactor Technology for Near-term Deployment.
  15. ^ Bajaj, S.S; Gore, A.R (2006). "The Indian PHWR". Nuclear Engineering and Design. 236 (7–8): 701–722. doi:10.1016/j.nucengdes.2005.09.028.
  16. ^ Singh, Baitej (July 2006). "Physics design and Safety assessment of 540 MWe PHWR" (PDF). BARC Newsletter. 270. Archived from the original (PDF) on 22 May 2013. Retrieved 23 March 2021.
  17. ^ "Status report 105 – Indian 700 MWe PHWR (IPHWR-700)" (PDF). International Atomic Energy Agency. 1 August 2011. Retrieved 20 March 2021.