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Kakrapar Unit-4 Power Project Attains Initial Criticality


The Unit 4 of Kakrapar Atomic Power Project (KAPP 4 – 700 MW) marked a historic moment in India’s nuclear power landscape by achieving criticality, signifying the initiation of controlled fission chain reactions. This significant milestone, attained on December 17, 2023, is a testament to the stringent safety standards set by the Atomic Energy Regulatory Board (AERB).

KAPP-4 is part of the ambitious project to deploy sixteen indigenous Pressurised Heavy Water Reactors (PHWR) of 700 MW each across the country.

Criticality Achievement and Safety Compliance

  • Criticality was achieved after meeting all stipulations outlined by the AERB, which conducted a thorough review of the safety measures implemented in the plant systems.
  • The successful criticality establishes KAPP-4 as a model of advanced safety features, placing it among the world’s safest reactors.
  • This achievement reinforces the commitment to AtmaNirbhar Bharat, with the reactors designed, constructed, commissioned, and operated by the Nuclear Power Corporation of India Limited (NPCIL), while equipment supply and contracts execution were handled by Indian industries and companies.

Post-Criticality Experiments and Power Level Increase

  • Following the criticality achievement, KAPP-4 will undergo a series of experiments and tests. The power level will be systematically increased, aligning with the clearances provided by the AERB.
  • This gradual process will ultimately lead to the full-power operation of the unit, showcasing the careful and methodical approach to nuclear power deployment.

Location and Advanced Features

  • KAPP 3&4 (2X700 MW) are situated at Kakrapar in Surat district, Gujarat, adjacent to the existing reactors KAPS 1&2 (2X220 MW).
  • These reactors incorporate advanced safety features, contributing to their reputation as some of the safest globally.
  • The indigenous nature of the PHWRs highlights the self-reliance spirit of AtmaNirbhar Bharat, with NPCIL managing the entire life cycle of these reactors.

Leadership Witnessing the Event

  • The criticality event was witnessed by Shri B.C.Pathak, CMD, NPCIL, who was present in the control room with the site team. Officials at NPCIL Headquarters also observed the event through a video link.
  • Post-event, CMD of NPCIL congratulated all employees and emphasized the significance of achieving criticality within six months of the commercial operation of Unit-3.
  • This accomplishment underscores NPCIL’s strength in all facets of nuclear power, including design, construction, commissioning, and operation.

Future Prospects and NPCIL’s Commitment

  • NPCIL presently operates 23 reactors with a combined capacity of 7480 MW and has nine units, including KAPP-4, with a capacity of 7500 MW under construction.
  • Additionally, 10 more reactors with a total capacity of 7000 MW are in pre-project activities, expected to be completed progressively by 2031-32.
  • The CMD urged everyone to work collaboratively towards the rapid completion of these units, solidifying India’s position as a leader in nuclear power technology.


  • Milestone Achievement: KAPP-4 of Kakrapar Atomic Power Project achieved criticality on December 17, 2023, marking the initiation of controlled fission chain reactions.
  • AERB Compliance: Criticality was attained after meeting all safety stipulations set by the Atomic Energy Regulatory Board (AERB), underscoring the commitment to stringent safety measures.
  • PHWR Series: KAPP-4 is the second unit in a series of sixteen indigenous Pressurised Heavy Water Reactors (PHWR) of 700 MW each being established across India.
  • Strategic Location: KAPP 3&4 (2X700 MW) are strategically located at Kakrapar in Gujarat, adjacent to existing reactors, contributing to India’s energy infrastructure.
  • Self-Reliance: Design, construction, commissioning, and operation of the reactors are handled by NPCIL, with equipment supply and contracts executed by Indian industries, reflecting AtmaNirbhar Bharat.
  • Future Prospects: NPCIL operates 23 reactors with 7480 MW capacity and has nine units under construction, including KAPP-4, along with plans for 10 more reactors, solidifying India’s leadership in nuclear power, set to be completed by 2031-32.

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