A view of the Tarapur Atomic Power Station, with two pressurised heavy water reactors, which generate 540 MW each, visible, Maharashtra, February 26, 2014

An interview with B.C. Pathak on India’s nuclear power plans and strategy

On December 17, 2023, India’s largest indigenously developed 700-MWe pressurised heavy water reactor (PHWR) – the fourth unit in Kakrapar, Gujarat – attained criticality. Six months earlier, another 700-MWe unit in the same facility had started producing commercial electricity. In 2024, another unit with the same capacity is expected to be commissioned in Rawatbhata, Rajasthan. Behind all these reactors is the Nuclear Power Corporation of India Limited (NPCIL). Its chairman and managing director B.C. Pathak told The Hindu NPCIL plans to “commission a nuclear power reactor every year” hence.

Mr. Pathak is a Distinguished Scientist of the Department of Atomic Energy and has more than 30 years of experience implementing the NPCIL’s nuclear power projects, including 220-MWe, 540-MWe, 700-MWe and 1,000-MWe reactors of both PHWR and pressurised water reactor (PWR) technologies. He assumed his current charge in NPCIL in February 2022. On December 13, 2023, he spoke to The Hindu on India’s nuclear power plans and strategy. Excerpts from the interview follow.

In the conference on ‘Nuclear for Clean Energy Transition’ (in December), organised by the Indian Nuclear Society in association with the NPCIL, you made a distinction between electricity generation and energy. You said much of the energy currently comes from fossil fuels. Can you expand on this?

Globally, on an average, the energy composition consists of about 20% electricity and 80% energy from coal, petrol, diesel, gas, lignite, and other components. Efforts are being made to decarbonise the electricity sector by putting up solar power plants, wind energy, renewables, and nuclear power plants. The 80% energy sector consists of fuel that is being directly used as molecules or as a reducing agent. There is a need to decarbonise that sector also.

Efforts are being made globally to replace this fuel by a fuel that does not emit carbon dioxide. That is why the emphasis is being made on the production of green hydrogen. Green hydrogen, to some extent, will help [in decarbonisation].

In future, nuclear power may play a major role in producing hydrogen because nuclear is clean energy. Hydrogen, produced from clean energy sources, is generally termed green hydrogen. That is why nuclear has a dual role – in terms of electricity generation and as a promising potential clean energy source.

But a lot of work has to be done across the globe on this. It will take some time. That is what I was trying to explain by making a distinction between electricity and energy. Electricity is actually a subset form of energy only.

In the COP28 climate talks held in Dubai, many countries agreed to triple their nuclear power generation by 2050 to achieve net-zero emissions. Did India agree to triple its installed nuclear electricity capacity by 2050?

India already has a plan to increase its present installed nuclear power capacity of 7,480 MW to 22,480 MW by 2031-2032 in a progressive manner.

The 700-MWe Kakrapar-3 unit in Gujarat is the largest indigenous PHWR the NPCIL has built. Why did it take more than 18 months to connect it to the grid after it attained criticality? It was generating infirm power for many months, not commercial power.

We made the reactor critical in July 2020 and connected it to the grid in January 2021, in a span of six months. There were some commissioning experiments to be done after that. We had to take care of the commissioning challenges and we have addressed those issues now. Accordingly, it was declared commercial [on June 30, 2023] and started generating its commercial power of 700 MWe [on August 30, 2023].

Since this is the first reactor [to be scaled up] from the 540-MWe reactors at Tarapur, commissioning challenges are bound to occur and we have addressed those issues. This design has many advanced safety features comparable to the best in the world. Commissioning is a sort of validation of design parameters and is completed in phases after obtaining stage-wise clearances from the regulatory authority, i.e. the Atomic Energy Regulatory Board.

What are the new safety features in the 700 MWe reactors? Do they have a fuel core catcher?

These reactors are among the best reactors of this 700-MWe category. Many safety features have been included in them. Basically, the reactor should be made capable of controlling the reactivity. It should be capable of cooling the [fuel] core. It should be capable of containing [the releases] if any.

With reference to that, we have included many additional safety features like the lining inside the containment, passive decay heat removal system, containment filtered venting system, passive autocatalytic recombiners, etc.

Like the steel lining in the Kudankulam reactors?

From the floor to the wall … like in Kudankulam. We have introduced electrical penetration assemblies instead of individual cables. These electrical cables have modular components, which are done at the manufacturers’ end, brought, and assembled here. That will improve leak tightness of the containment.

We have introduced a passive decay heat-removal system. In case of station blackout, if there is no power supply available, it will ensure the cooling of the [fuel] core. We have introduced passive catalytic hydrogen recombiner units.

One of the significant changes we have made in the 700-MWe PHWRs is feeder interleaving. It has been made probably for the first time in the world. It ensures that there is always water in the reactor even in the case of an off-normal condition. This unique feature is available in our reactors.

Our 700-MWe reactors have all the features available based on the operating experience within our country and elsewhere, and lessons learnt from events that took place in other parts of the world. I can say that the 700-MWe PHWRs are among the safest reactors in the world.

You mentioned the NPCIL would build only 700-MWe PHWRs from now on and in fleet mode. What are the reasons for this decision?

I did not exactly say this. The electricity requirement in our country is huge. Our indigenously built largest reactor is 700-MWe. For major capacity addition, we will go ahead with the 700-MWe PHWRs. However, if required, we may go for 220-MWe PHWRs, which are equally proven.

So, at times, not now, there may be requirements from industries for smaller reactors. We are ready for it. But with 700-MWe reactors, we will get the economy of scale.

Until now, we were building two or four reactors at a time. But now, nine reactors are under construction at present. Ten reactors are in various pre-project activities. So 19 reactors are under various stages of implementation.

Are 19 reactors under construction now?

Yes, as I already mentioned, 19 reactors are under various stages of implementation. NPCIL is capable of taking up [for construction] these many reactors. To ramp up our electricity generation capacity, it is better to go for a fleet of reactors at a time. But we are open to 220-MWe and 700-MWe reactors. The ultimate need is to increase the nuclear share in the country at the earliest.

Will these 220-MWe reactors be small modular reactors (SMRs)? The trend is to go for SMRs but nothing has been built so far.

A small reactor of 220 MWe per se is not a small modular reactor. But yes, we can go for SMRs based on our experience in designing power reactors. Today, we have the proven technology of 220 MWe and they can be deployed at the earliest. The manufacturing sector is mature for it. If a requirement comes for 220 MWe, it can be installed.

A large number of 700-MWe units are under construction now. But we are open to 220-MWe units as well.

When will Rajasthan Atomic Power Station-7 (RAPS-7) of 700 MWe go critical?

I am expecting commissioning of RAPS-7 in the next year.

How is the availability of natural uranium in the country? To my knowledge, no new mines have been opened. If enough natural uranium is not available in the country, will you put the indigenous 700-MWe reactors under the International Atomic Energy Agency’s (IAEA) safeguards so that they can get uranium from abroad?

We do not envisage any problem for supply of fuel for our nuclear power reactors.

What is the problem with Madras Atomic Power Station -1 (MAPS-1) reactor at Kalpakkam? It has been shut down for a long time.

MAPS-1 is a very old reactor. MAPS-1 and -2 were operating satisfactorily for a long time. MAPS-2 was operating at nearly 230 MWe. [Its capacity is 220 MWe]. Since they are old units, age-related issues are there. We are addressing them. A little upgradation needs to be done. I am expecting MAPS-1 to come online this financial year.

The TAPS-1 and -2 reactors in Tarapur are older reactors and they have been operating for more than 50 years…

Yes, TAPS-1 and -2 are the oldest operational nuclear power reactors in the world. Presently, both are shut down and undergoing life extension and upgradation works. The first unit will come on line next year.

What is the latest progress on Kudankulam-3,4, 5 and 6? Enriched uranium fuel bundles reached Kudankulam recently from Russia.

The construction work in these reactors is progressing well. A large [workforce] is engaged there, say, to the tune of 10,000 people. We are expecting these reactors to come online progressively. We are getting supplies from the Russian Federation for these projects.

As far as fuel is concerned, we are operating units 1 and 2 on a 11-month fuel cycle. With the new fuel added now in Kudankulam unit 1, it is operating on an 18-month fuel cycle. It means once we load the new type of fuel, the reactor will operate continuously for 18 months.

We are getting the fuel supply regularly. Both the reactors are operating at good capacity factors. These units are generating a good number, of million units of clean electricity, for the country.

The PWRs that we have developed and which use enriched uranium as fuel propel our two nuclear-powered submarines. Will we build commercial PWRs? A big uranium enrichment facility is coming up at Chitradurga in Karnataka.

As far as NPCIL is concerned, we are mainly mandated to work on the PHWRs. But the NPCIL now has the experience of construction, commissioning, operation, and maintenance of VVER-1000 type reactors [at Kudankulam], which will be useful for working on PWR technology.

Why is there so much delay in implementing the nuclear power projects at Jaitapur in Maharashtra and Kovvada in Andhra Pradesh, where the French and the Americans were to build reactors? Are they insisting they will not pay damages if there are accidents?

Discussions with the EDF [of France] and Westinghouse [of the U.S.] on technical issues for Jaitapur and Kovvada are in progress.

The West Bengal Government has said it will not allow a nuclear power project to come up at Haripur. Have you found an alternative site to Haripur?

Site selection for establishing a nuclear power plant is an ongoing activity. Accordingly, the potential sites are identified and evaluated in accordance with the regulatory codes and guides for their suitability.

Homi Bhabha envisioned a three-stage nuclear power programme for India: the PHWRs in the first stage, the breeder reactors using plutonium in the second, and the reactors using thorium as fuel in the third. Why the delay of so many years in building the 300-MWe advanced heavy water reactor, which will use thorium and uranium-233 as fuel?

Nuclear is an evolving technology. Many changes are taking place. In my experience, in nuclear, one has to go slow and steady. We have matured the technology in stage one of our three-stage nuclear power programme. We are going into the second stage. Once we mature that technology, we will enter the third stage. It should be a gradual process…

I don’t think there is any delay. We are on the right track. Our three-stage programme is the best in the world. It is self-sustaining. For the first stage, everything is available for the Indian PHWRs.

Once we go to the third stage, we won’t have to get even fuel [from outside]. Everything will be available in India. The idea is we should be self-sufficient in energy security. This is a gradual process and a sequential process.