Fuel loading begins at India’s second 700 MWe nuclear power unit

Nuclear fuel loading began on Friday at India’s second 700 MWe atomic power plant, setting the stage for “attaining criticality” and commercial electricity production at the fourth unit of the Kakrapar Atomic Power Project (KAPP-4) in Gujarat.

This is the second indigenous 700 MWe nuclear power station that may shortly become operational after KAPP-3 which began producing electricity on June 30 and commenced full power operation two months later.

The two units at Kakrapar are the first two of the 16 such indigenous nuclear power stations that Nuclear Power Corporation of India Ltd is setting up.

In May 2017, the Union Cabinet approved setting up of ten 700 MWe nuclear reactors in “fleet mode” while six such units – two at Kakrapar, two at Rawatbhata in Rajasthan and two in Haryana - were under various stages of approval and construction at the time of the Cabinet approval.

The permission for initial fuel loading at KAPP-3 was granted by the Atomic Energy Regulatory Board after carrying out stringent safety and security reviews. This is a milestone in the setting up of a nuclear power plant as it is the prelude to approaching criticality (start of fission chain reaction) and subsequent start of power generation.

In the case of KAPP-3, there was a gap of three years between the reactor attaining criticality and starting commercial power production as NPCIL faced unforeseen technical challenges.

“During the unit commissioning, following synchronisation with the grid, elevated temperatures were observed in certain areas of the reactor building,” Union Minister Jitendra Singh informed the Lok Sabha in July 2022.

Though the minister said the technical issues were addressed by carrying out “requisite modifications and improvements” and KAPP-3 was likely to start commercial operations by December 2022, it took another six months for the unit to produce electricity for the grid.

Officials said KAPP-4 was unlikely to take such a long time for commercial power production and criticality might happen by December.

“With the successful and stable operation of KAPP-3, the capability of the NPCIL in setting up of indigenous reactors of PHWR technology of this size is validated and paves the path for early completion of the remaining 14 reactors, beginning with Units 7&8 of Rajasthan Atomic Power Project at Rawatbhata,” the NPCIL said in a statement.

All the four big reactors took more than a decade to complete. The construction of the KAPP-3 began in November 2010 while KAPP-4 started in March 2011. The construction of Rajasthan Atomic Power Plant-7 & 8 began in 2011.

The NPCIL claims these reactors have advanced safety features comparable to the best in the world.

Other 700 MWe indigenous reactors will be set up at Kaiga in Karnataka, Gorakhpur in Haryana, Chutka in Madhya Pradesh and Mahi Banswara in Rajasthan.