The fourth unit of the Kakrapar Atomic Power Project (KAPP-4) in Gujarat, with 700 MWe capacity, started controlled fission chain reaction and thus became critical at 1.17 am on December 17. Kakrapar is situated about 80 km from Surat.
The 700 MWe units are the largest indigenous nuclear power reactors to be built by the Nuclear Power Corporation of India Limited (NPCIL), a public sector undertaking of the Department of Atomic Energy.
The 700-MWe unit-3 of KAPP started generating commercial electricity from August 30.
These reactors are pressurised heavy water reactors (PHWRs), which use natural uranium as fuel and heavy water as coolant and moderator.
The NPCIL is already operating indigenous PHWRs with 220 MWe and 540 MWe capacity at other facilities.
The reactor’s first criticality was ascertained after it met all the conditions set out by the Atomic Energy Regulatory Board (AERB), India’s nuclear safety watchdog.
B.S. Pathak, Chairman and Managing Director of NPCIL, was present in the station’s control room with the site team when KAPP-4 was commissioned, per an NPCIL press release. He congratulated the NPCIL employees and called the criticality of KAPP-4, happening within six months of commercial operation of unit-3, a significant achievement.
It demonstrated the strength of NPCIL in all facets of nuclear power generation – the design, construction, commissioning, and operation of reactors, Mr. Pathak said.
Indian industries supplied the equipment and executed the contract for these two reactors, according to the NPCIL press release. The Kakrapar Atomic Power Station already has two operating PHWRs with a capacity of 220 MWe each, called KAPS-1 and -2.
Earlier, on December 13, Mr. Pathak told The Hindu that the indigenously built 700 MWe reactors are among “the best reactors of this PHWR category”. They have many advanced safety features, including among others a steel-lining from the floor to the wall and a passive decay heat removal system to cool the fuel core, he added.
The NPCIL presently operates 23 nuclear electricity reactors with a total capacity of 7,480 MWe. It has nine units, including KAPP-4, under construction while 10 more reactors, with a total capacity of 7,000 MWe, are in the pre-project phase.
