India’s first indigenously built 700 MW reactor connected to grid


India’s first fully indigenously built 700 MW pressurised heavy water reactor (PHWR) was synchronised with the grid at the Kakrapar Atomic Power Project (KAPP) in Gujarat state earlier this week, according to an announcement by a senior official. Unit 3 of the KAPP operated by the state-run Nuclear Power Corp of India Ltd (NPCIL), which achieved its first criticality, or controlled self-sustaining nuclear fission chain reaction, in July last year, was connected to the grid on January 10, 2021.

The former Atomic Energy Commission (AEC) Chairman Anil Kakodkar told Nuclear Asia in this regard that he was extremely pleased about the grid connection of KAPP unit 3, which recorded a global first in attaining criticality during the year of the onset of the coronavirus (COVID-19) pandemic in 2020. “Kakrapar 3 is a true example of indigenous technology developed and built in India with with fifteen more such units to follow in fleet mode”, Kakodkar said.

“Since achieving criticality in July last year, the unit 3 has undergone numerous tests to prove its compatibility with the grid. Now grid-connected, the unit will continue to undergo tests till it is capable of starting commercial operations,” the former AEC Chairman said. “The success of this 700 MW unit comes on the back of India’s nuclear programme that has earlier put on stream indigenously designed reactors with capacities of up to 540 MW”, he added.

Kakrapar 1 and 2 – both Indian-designed PHWRs of 220 MW each – entered commercial operation in 1993 and 1995, respectively. The 700 MW unit 4 at Kakrapar is currently under construction. The Indian government approved plans for the first four of eight planned 700 MWe PHWR units using indigenous technology – Kakrapar units 3 and 4, and Rajasthan units 7 and 8 in Rajasthan state in 2007. The approval for construction and finance was granted in 2009.

In an interview last July, NPCIL Chairman S.K. Sharma had described the criticality attained for KAPP unit 3 as a historic moment, as it is the first of its kind 700 MW PHWR designed by Indian scientists and engineers. “It is unique in that it is our first 700 MW reactor equipped with equipment manufactured indigenously and erected by Indian contractors,” he said. “The mainstay of our nuclear programme, which is now more than half-a-century old, started with reactors with a capacity of 220 MW, which was subsequently increased to 540 MW, and now we have manufactured this 700 MW optimal capacity reactor as our mainstay,” he added. KAPP unit 3 became the country’s 23rd completed reactor.

Elaborating on the near-decade long construction period for unit 3, Sharma said that achieving criticality for 700 MW capacity with totally indigenous capability is not simply a question of “multiplying megawatts” “The entire reactor has been redesigned, concepts have been changed, while the manufacturing of components has faced many challenges, which the local manufacturers have met very competently,” he said. “The new reactor is a first of its kind, and a huge learning curve was involved for the designers, the manufacturers, as well as the construction companies, so it took them more time than earlier”, he added.

Besides, he pointed out the delay caused by the 2011 nuclear accident in Fukushima (Japan) on account of the tsunami, which necessitated a review of safety measures. “We conducted a review of safety measures, paused work in Kakrapar, changed the design in line with the global reviews of safety measures, and, thereafter, incorporated these changes in design for Kakrapar 3 and 4,” he said.

According to Sharma, “safety is our first, second and third priority”. “A safe reactor is a productive reactor, since it is also a reliable reactor. We are employing all the latest, state-of the art safety features in our reactors and have incorporated a lot of both passive and active safety features in our design”, he said.

Noting that Indian reactors have not suffered the kind of accidents comparable to Fukushima, Chernobyl (ex-USSR), or Three Mile Island (US), Sharma said the NPCIL has ensured that India continues to maintain its spotless record on nuclear safety. KAPP-3 has several safety features like a steel-lined inner containment, passive decay heat removal system and a containment spray system, among others.

The Indian government has earlier approved the fleet mode construction of ten PHWRs, each of 700 MW capacity, at a total estimated cost of $16.3 billion. The fleet mode of construction of multiple units ensures standardisation, lower costs and speeding up the setting up of nuclear power plants in the country.

The NPCIL Chairman announced last year that India will construct ten new PHWR units in the fleet mode, thereby facilitating procurement activities, manufacturing and construction of these units. The 10 planned reactors are units 5 and 6 at the Kaiga in Karnataka state, units 1 and 2 at Chutka in Madhya Pradesh, 4 units at Mahi Banswara in Rajasthan and units 1 and 2 at Gorakhpur in Haryana.

Three other PHWRs are already under construction – Kakrapar unit 4, and Rajasthan 7 and 8 in Rajasthan. India currently has 22 reactors in operation with a total capacity of 6,780 MW. Eight reactors are under construction with a combined capacity of 6,200 MW. On completion of these under construction, NPCIL’s capacity will reach 12,980 MW by 2025.