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The Thorium Question - An interview with India's nuclear czar

Saurav Jha @SJha1618

Updated: September 16, 2013, 3:51 PM IST
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Dr RK Sinha took over as Chairman of the Atomic Energy Commission (AEC) and Secretary, Department of Atomic Energy (DAE) last year. Besides heading India's nuclear estate he is also known as one of the leading lights of thorium based reactor research globally. 'Geek at Large' caught up with him at his South Block office to get some insights into what lay ahead technologically for India's civil nuclear program in the years to come. A longer version of this interview will appear in the forthcoming October edition of Geopolitics (

What is the status of the Advanced Heavy Water Reactor (AHWR) project ? Has a site been finalized for it?

Well, the consultancy contract for design of conventional systems was awarded three years ago. Most of the design drawings, etc. are ready now. Our validation process is now proceeding on twin tracks.
You would note that the AHWR removes core heat from the system through natural circulation (convection) of the coolant under both normal working as well as shutdown conditions, which eliminates the need for pumps driven by electrical power that we see in most other reactor designs. For this purpose, a single coolant channel of the AHWR design has been tested in BARC for a rating of up to 2.5 - 3 MWt to confirm removal of heat from the system by natural circulation.
I would point out that we are being conservative about the margins here and testing for a higher level of heat removal will be needed to exactly determine the full margin and assess if the rated power of the reactor can be accordingly raised.
To do that we are setting up a large scale AHWR thermal hydraulic test facility (ATTF), with nearly 17 MWt heating capacity for two coolant channels.
The ATTF will validate the AHWR's full potential to remove core heat through natural circulation.
The experiments will thereby also show that much greater levels of decay heat than what can possibly ensue in the event of an emergency shutdown will be removed by the AHWR through natural circulation.
In addition to this, the AHWR has many other passive safety features, including a gravity driven water pool (GDWP) containing 6600 m3 of water that can provide emergency cooling to the core. The GDWP, along with other passive safety measures means that even in a Fukushima type scenario, decay heat can be removed from the AHWR under total station blackout conditions, without availability of any external source of water or operator action for a period of 110 days at a stretch. With such features, the AHWR is considered safe enough to build a case before the regulatory authority for locating the reactor near a population centre.

The other track is, of course, proceeding at the Critical Facility located at BARC Trombay, which was commissioned in 2009 to test the reactor physics side of the design.

Now, as far as site selection for the AHWR is concerned, we haven't identified a site as of now. Given the nature of the AHWR - it is essentially a technology demonstration project- and the fact that it won't contribute a lot of power (about 300 MWe), it doesn't really make sense to have a stand-alone site for it. On the other hand, the small size of the AHWR means that it can be accommodated at an existing site, preferably close to the R&D community.

So what is the time horizon for large scale deployment of thorium based reactors?
The 2040s, I would say. We have to keep in mind the need for optimisation of fissile fuel (uranium and plutonium) requirements for a sustainable path of accelerated growth. Obtaining enough fissile material (since Th-232 itself isn't fissile) before we execute a true thorium based cycle is a key consideration and we estimate that it will become possible by the early 2040s.
What about the AHWR- Low Enriched Uranium (LEU) variant? Could that be deployed faster?
Well yes. Enriched uranium is more readily available. The AHWR-LEU uses 19.75 percent enriched uranium along with Thorium, which comprises 80 percent of the entire mix.
This design has enhanced proliferation resistance owing to the presence of U-232 (with high radioactive decay products) in the spent fuel from the reactor. Using the separated U-233 (along with U-232) is therefore very challenging. Moreover, plutonium generation in this design is less, as compared to other designs. Also, dissolving thorium oxide, a highly stable ceramic, is in itself a stiff challenge. These challenges would make AHWR and AHWR-LEU spent fuel difficult to divert for proliferation objectives.
The burn-up for the AHWR-LEU is about 60000 MW/d (per day) and the reactor is extremely stable.

Coming back to the issue of securing enough fissile material, how is India currently placed in terms of thorium based fuel reprocessing ?

A huge amount of research on the technologies for front as well as back-end of U-233 - thorium fuel cycle has been done in India, and now the efforts are directed towards establishing industrial scale technologies, which will be demonstrated (along with the advanced passive safety features of AHWR), when the reactor and its associated fuel cycle facilities are operational.

Of late there is renewed interest in thorium based nuclear power in other countries as well. China for instance is beginning to prioritize this as a research area, especially the investigation into molten salt reactor (MSR) technology for thorium utilization. Is there any danger of India's lead in the thorium domain eroding?
To the best of my knowledge nobody in the world has, till date, closed the thorium fuel cycle on an industrial scale. I think, our activities in the area of thorium research are more advanced towards that end than anybody else's. Our leadership in the area of scientific publications covering thorium based research establishes that.
India is also investigating Molten Salt Reactor (MSR) technology. We have molten salt loops operational at BARC.

Looking at the second stage now, what is the current status of the Prototype Fast Breeder Reactor (PFBR)? When will we see metallic fuel loaded onto it?
You can say that early commissioning activities are underway. Fuel is being supplied from Tarapur and the testing of equipment, to be eventually installed in PFBR, under 'hot sodium' conditions is underway in the sodium based facilities at IGCAR. The reactor is scheduled to attain criticality by end 2014, but physics and low power experiments will continue beyond that and the rise in power generated by the PFBR will be gradual.
As far as the timing of metallic fuel loading is concerned, this is still an open question as more R&D needs to be conducted in this sphere. R&D activities in this direction have been intensified during the XII Plan (2012-17) period. Our goal is to have this fuel available by the mid 2020's.

Do you think there is now greater appreciation of India's advocacy of closed fuel cycles?
Well, internationally there is a recognition of the need for closed fuel cycles to extend fissile sources.

So what about the India's own Integrated Nuclear Recycle Plant?
The Plan proposal for setting up INRP is currently in the process of government approval.
And the Fast Reactor Fuel Recycle Plant?
That has already received cabinet approval, and the activities at the site should begin very soon.
Is India also researching laser enrichment technologies?
We have a programme for this.
How is India placed in terms of accelerator driven sub-critical systems (ADSS) research since that is seen as one of the ways to use thorium sustainably as well as deal with high level waste including actinides?
A lot of activities are happening in this domain. Again, they are taking place on two fronts. In the first, we are developing the technologies necessary for superconducting radio frequency (SCRF) cavity based linear accelerators (LINACs). The key technologies include cryostats, niobium resonators, RF electronics, test stands etc. On the other front, we are indigenising previously imported equipment common to both normal and superconducting type LINACs, such as klystrons etc.
A 20 MeV 30 mA proton LINAC is being set up in project mode at BARC, Trombay during the 12th Plan period. A large superconducting RF cavity based accelerator will come up in the new Vizag campus.
DAE institutions involved in this domain of activity include RRCAT, VECC and BARC. I think a lot of competence in the ADSS domain is getting developed through projects being executed in these institutions.

Could you give us an update on the Compact high temperature reactor (CHTR) and (High temperature reactor) programmes which are seen as a pathway to delivering process heat requirements at lower cost and generating hydrogen economically?
A cold version of the CHTR with dummy fuel is being set up at BARC, Trombay. It will be moved to the BARC campus at Vizag when the new site gets ready. The reactor will be built there.
The CHTR programme has led to the development of special components and materials needed for high temperature systems like beryllium oxide blocks (which serve as moderator in the CHTR), graphite as well as carbon-carbon composite based tubes (that will contain fuel), molten lead-bismuth alloy (coolant), and Niobium - Zirconium alloy (a structural material).
The HTR development will come up at the new BARC campus in Vizag. The HTR is a design meant for hydrogen production. The design studies for the HTR have been concluded. Investigation currently focuses on different high efficiency thermo-chemical processes for hydrogen production, including the highly challenging iodine-sulphur process.

Incidentally, the Vizag facility will look at a whole spectrum of hydrogen related technologies and not just its production.
First Published: September 16, 2013, 3:51 PM IST

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