Focus on new technology areas

VIVEK BENDRE

Interview with Dr. Srikumar Banerjee, Director, Bhabha Atomic Research Centre.

Dr. Srikumar Banerjee is the new Director of the Bhabha Atomic Research Centre (BARC), Trombay, which is the nerve-centre of the Department of Atomic Energy and the mother-institution for research in nuclear electricity technology, radiation, nano science, agriculture, biological sciences, artificial intelligence, robotics, human genomes, accelerators, lasers, nuclear fuel and desalination. He took over from B. Bhattacharjee on April 30. In Bhattacharjee's words: "BARC is perhaps the largest R&D [research and development] centre in the world where the widest spectrum of activities in nuclear science and technology is pursued under one roof."

Srikumar Banerjee was Director, Materials Group, BARC, before he was appointed to head the centre. A leading expert in materials science and technology, he has made outstanding contributions in materials-related areas, both basic and application-oriented. After completing his B.Tech. in Metallurgy from the Indian Institute of Technology (IIT) in Kharagpur, he joined BARC's Metallurgy Division in 1968. His work there earned him a Ph.D. in Metallurgical Engineering in 1974 from IIT-Kharagpur. He is the recipient of several awards, including the Shanti Swaroop Bhatnagar Prize in Engineering Sciences (1989), the Acta Metallurgica Outstanding Paper Award (1984) and the Humboldt Research Award (2004).

Banerjee spoke to T.S. Subramanian about BARC's research in nano science and technology, its technology development in the Advanced Heavy Water Reactor (AHWR) and the compact High Temperature Reactor (HTR) and the non-power applications of nuclear energy. Excerpts from the interview:

What is your vision for BARC, as its Director? What will be the thrust areas?

The Bhabha Atomic Research Centre is not just a research and development organisation; it is oriented to research and development, demonstration and deployment. This totality is our activity. Our major thrust today is on entering new technology areas, including new types of reactors such as the Advanced Heavy Water Reactor and the High Temperature Reactor. Our research in energy conversion is focussed in the direction of hydrogen energy. Another big area is the non-power application of nuclear energy in health care, agriculture, desalination and the hygienisation of municipal waste. The thrust in these areas is important because they give us the quickest returns. Some of our research yields results immediately and some after a few years. Others, like the Accelerator Driven Sub-critical System [ADSS], take a fairly long time.

We nurture research in different disciplines and have opened up new avenues in technology development. For instance, in nano science and engineering, BARC has a consolidated view that we should develop specific systems and components based on nano science and technology. These systems and components are of use to us in our programme. While doing this, we are also getting into areas related to nano science and technology.

What is nano science?

Size [miniaturisation]. We develop a variety of sensors and accentuators, and application-specific integrated circuits. These will now be miniaturised to a nano-metre scale. Processing in nano-scale essentially requires processing in vapour-phase, which includes physical and chemical deposition, plasma-processing, molecular epitaxy and several techniques of wet chemistry leading to soft matter such as gel. We have expertise in all these areas and are well placed to enter the nano science and engineering area.

We have strong teams working in machining in extremely fine dimensions. They will work further in designing and manufacturing micro-sized mechanical devices, which will essentially employ fabrication technology of nano-metre scale.

It is an area of many unknowns. Scientists and technologists all over the world are trying to explore new things with the possibility of working in fine scale. The possibilities are inexhaustible and it is the right time for us to join the worldwide effort in developing specific systems for this.

Our focus is on what goes into our immediate applications. It is a two-pronged attack: We get something that is of immediate use and at the same time we enter nano science and technology, which will lead us to further technological development of an unprecedented nature.

What is BARC doing in the area of energy conversion?

When we talk about nuclear energy today, we are talking of steam cycles. That is, we are working at temperatures of around 3000C. Steam at 3000C is utilised for generating electricity [by rolling the turbine]. We want to explore whether we can work at high temperatures - between 8000 and 1,0000C. Obviously, the cooling medium at such temperatures will be liquid metal and bismuth. With liquid metal as coolant, the reactor configuration will be different from that of the present reactors. The fuel, the moderator, the coolant, the structural materials, everything will be different. Ceramics will be used in a variety of applications. High temperature refractory metal alloys will be used. The heat generated at 8000 to 1,0000C can be converted directly into electricity through thermo-electric methods. So development of thermo-electrical materials is an important component of this.

We can use this heat to generate hydrogen. Once we are able to generate hydrogen in an economic manner, we can store it in different configurations for later use, such as in the lattice of metals and inter-metallics. There are many possibilities for developing such hydrogen-storage materials.

How will the development of new materials play an important part in the generation of nuclear electricity?

Development of materials is important for the High Temperature Reactor. In it the fuel is embedded in a carbon-based material. Our initial plan is to produce our fuel in the form of carbides, which will be contained in a three-layered structure. That is why it is called triso. (Iso comes from from isotropic carbon.) The triso-coated particles will be embedded in carbon-based material, which can be pure graphite or a carbon-carbon composite. That will be our fuel configuration. The moderator will be mostly beryllium oxide.

We are actually talking of two possibilities. One is that the HTR will work in the range of 8000 to 1,0000C or in the middle temperature of 5500 to 6150C, maybe using liquid metal as coolant. When we go to 8000 to 1,0000C, we may use a gas coolant, may be helium. It is important to get quality heat. There is heat content even in 500C, the hot water used for bathing. But it is not quality heat that can be converted to perform useful mechanical work. As you go for higher temperatures, you can convert the heat into usable mechanical or electrical energy. The HTR is only a means to get high temperature, which will be used for hydrogen production. This hydrogen can be used in an internal combustion engine, that is, to drive automobiles, or can be converted directly into electricity through solid oxide fuel cells. We, therefore, have a programme for developing solid oxide fuel cells. The HTR will also directly generate electricity by thermo-electric conversion. This is our plan for the HTR.

The HTR is a long-term plan...

We get our returns immediately in the non-power applications of nuclear energy. What are the different applications of radiation isotopes? They are in diagnostics and therapeutics. In diagnosis, it is BARC's responsibility to supply isotopes to hospitals and medical scientists. Many of these radioisotopes are short-lived and we programme them in such a way that they reach the hospitals well within the time of their lives. Iodine-131 and Technitium-99 are used in diagnosing cancer. For treatment of cancer, there is cobalt-60, caesium-137, iridium-192 and Phosphorous-32. It is our job to supply these isotopes. BARC produces them and it is BRIT's [Board of Radiation and Isotope Technology] responsibility to reach them to the different parts of the country.

We recently set up Positron Emission Tomography equipment in our Radiation Medicine Centre at Parel in Mumbai. This is the first Radiation Medicine Centre in the country where positron emission will be used to identify abnormalities in the organs of the human body. You can pinpoint the organ where the positron emission is occurring. It is much better than the conventional CAT (computerised axial tomography).

In agriculture, our track record is impressive. We have so far introduced 23 mutant varieties of seeds, which are certified by the Indian Council of Agricultural Research (ICAR). The National Seed Corporation releases them. Our responsibility is to make mutant variants and check their efficacy. It is not necessary that oilseeds should be as large as peanuts. We have to see what their oil content is, what their storage capacity is, and for how many generations the mutant variety will be effective. This is a complete study that requires decades of research and trials. We have completed them, and these varieties are actually used by farmers.

It is no exaggeration to say that the BARC-developed blackgram mutant constitutes 42 per cent of the blackgram produced in the country and 85 per cent of that grown in Maharashtra. BARC has developed 10 types of pulses, nine types of groundnut, two types of mustard, and one each of rice and jute.

We have made an important contribution to tissue culture. We do cell culture of medicinal plants.

We do radiation processing of food. It took many years to get accepted. Radiation processed food has been approved by the ICAR, the Indian Council of Medical Research, and the World Health Organisation. Irradiation of spices is important because there is tremendous value addition. If you want to export spices, it is mandatory that the bacteria count should not go above a certain number. The reduction of bacteria count is possible only by irradiation. For potatoes and onions, the main degradation factor is sprouting. By irradiation, sprouting can be delayed. We are going to set up demonstration plants throughout the country. We have already set up one at Lasangaon [Nashik district] in Maharashtra, which is a centre for the distribution of potatoes and onions, more so onions.

The farmer and the distributor can be sensitised to the technology so that they see the advantage of investing in such radiation processing facilities. We will provide them all the necessary technologies and guarantee them the supply of isotopes necessary to run their units. This is our strategy for radiation processing of food.

In many places, radiation processing of food and radiation sterilisation of medical products are being done in the same place because it is more attractive for an entrepreneur to do so. Our ISOMED [Irradiation and Sterilisation of Medical Products] plant in Trombay has successfully served as the facility for radiation sterilisation for a variety of medical products. Why is radiation sterilisation important? In conventional sterilisation of a medical product, many a time its effect is lost at the time of packing. In radiation sterilisation, the product is first packed and then irradiated. There is no chance of it getting infected. This is extremely popular.

What are the products that undergo radiation sterilisation?

Bandages, internal sutures, catheters, and all disposables.

Another important area that is becoming popular is [municipal] waste hygienisation. You have to make the sewage sludge pathogen-free. If you can do it by irradiation, you can use the sludge in a variety of ways, including generation of energy. But making it pathogen-free is most important and we are doing it at Baroda. It is catching on. The Union Urban Development Ministry is interested in taking it up in different urban centres. It will be useful in smaller cities. You can have multiple units in bigger cities.

At Anushaktinagar (Trombay) we have set up a five-tonne-a-day plant, which can convert biodegradable waste, kitchen waste, market waste and agricultural residue into high quality methane and manure. Methane is an energy source. It can be burnt anywhere. We have already set up three plants and many more are in the pipeline. This is a cost-effective means of converting waste into wealth.

BARC wanted to set up a desalination plant at the Ennore Thermal Power Station in Chennai. But the proposal fell through. The Tamil Nadu government now wants to set up a huge desalination plant near Chennai. Why has BARC not been able to grab this project? After all, you were the pioneer in the country in setting up desalination plants.

We have waste heat available from nuclear power stations. We can use the heat [to desalinate water] through flash evaporation. Water boils at temperatures above 100C and in vacuum at a much lower temperature. I have low-grade heat, say between 60 and 80C, which can be used to evaporate saline water in vacuum. We want to combine this technique of flash evaporation with the technique of reverse osmosis. Nobody else has done this kind of a hybrid plant. That is the novelty of our programme.

You are trying this at Kalpakkam, home to the Madras Atomic Power Station.

We are trying it at Kalpakkam. We want to establish its techno-economics and the techno-economics is determined by operating the desalination plant for months/years, seeing its life, the exact economics and so on. We have a 1,800 cubic metres [18 lakh litres] a day reverse osmosis plant operational at Kalpakkam. The multi-stage flash plant is under construction. It will be of 4,500 cubic metres [45 lakh litres a day] capacity. With them, we will have a substantial desalination capability.

When will the multi-stage flash plant be operational?

In another few months. During [Vikram] Sarabhai's time, desalination was a popular topic. At that time, desalination plants were expected to come up in areas such as Kutch. But today, when we see the scarcity of water in various coastal regions, including Tamil Nadu and Andhra Pradesh, desalination may eventually become an important activity.

At what stage is the development of a barge-mounted desalination plant?

We are taking it up as an important project. But it does not use nuclear heat. It will use diesel heat. We will have a reverse osmosis plant on a barge by December 2005, with a capacity of 50 cubic metres of desalinated water a day. This will be an important demonstration unit for us in many ways. One is that we are trying to set up our own [barge-mounted] plants where there is water shortage. We can take the barge there and it can supply water. The second is that if there is a calamity and there is acute water shortage in a coastal area, the barge-mounted desalination plant can be used to supply potable water.

What work is BARC doing on the ADSS? What kind of reactor is it?

The ADSS is a new concept in which the European Union is quite active. We have taken it up as an important step. In all nuclear reactors today, you have to have a sustained chain reaction, which means you have a fissile atom or nucleus. The neutron hits it, the nucleus breaks up, and generates more neutrons, typically two or three. Some are lost, and at least one is kept alive. That strikes the next nuclei, which splits. It strikes at least one more surviving neutron, and it is a sustained process like that. It is called a sustained chain reaction and what we call a critical system. There is a controlled fission process. If it is uncontrolled, there is a sudden release of energy and it is not all right. If it is below that [criticality], then the chain reaction will not be sustained. So all our effort is to maintain the criticality or the sustained chain reaction in the nuclear reactors.

But the ADSS is a sub-critical system and can never release energy very fast. These are spallation neutrons, not fission neutrons. These are neutrons stripped from nuclei by very high-energy incident particles. Incident particles are protons. When the neutrons come out, they can be pushed into the sub-critical system and that can continue the chain reaction. So there are two different applications. One is that they give us power. It is actually called energy amplifier. Although you have to put a lot of energy into them, you get more energy than you put in.

The second application is that it is an incinerator for the long-lived isotopes in our nuclear waste. In the long run, our waste management techniques will involve burning of these long-lived isotopes in the ADSS. This is a long-term agenda and we have started work on it. It is not just BARC, but the Centre for Advanced Technology (CAT), Indore, the Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam and others that are working together in tackling this waste management problem.

This gamut of activity cannot be supported without doing basic research. This is one area in which we are strong and we are strengthening it further. We do huge experiments in engineering also. We are building a synchrotron at CAT, which will be the centre for a variety of research. We have expertise in many accelerator areas and laser technology. Basic research in biological sciences is another important component of our work. This includes the influence of radiation on the biological cell and the complete spectrum of work related to it, and the programme on the human genome.

You are working on the human genome?

We are working on it. Obviously, working on these new technologies is essentially based on the development of new materials. Our big emphasis in the last decade or two was on developing the Pressurised Heavy Water Reactor technology. Today, the PHWR technology is almost an industrial process. We are also doing major engineering development of qualifying systems that will survive seismic events, and this requires detailed stress analysis.

One major technology development area is the AHWR. We will use thorium-uranium 233 in the third stage of our nuclear power programme to generate electricity. [The first stage consists of PHWRs and the second stage breeder reactors]. We want to enter the third stage without waiting for the second stage to be completed. This short-circuiting is done by the AHWR. Our second ambition is to develop a reactor system based on passive safety features. That is, it is intrinsically safe. Even if there is a total station blackout there will be no problem.

Will there be no moving parts in the AHWR?

We don't have the main pump. Instead, there is a thermo-siphon. We want to design it in such a way that we won't need an exclusion zone. For a nuclear reactor today, we have an exclusion zone of 1.6 km radius [nobody can live in that area]. In this AHWR, we have technological and engineering developments at every stage. In all these systems, we have people working on thermal-hydraulics, stress-analysis, tribology, materials development, welding and so on. Everybody is finding a new research avenue, and it will all end up in the development of a new system. So it will employ about 1,000 engineers in innovative engineering research. Through the construction of this reactor [AHWR], we will be in the forefront of technology and engineering practices in a variety of areas. This reactor has been acknowledged by the IAEA [International Atomic Energy Agency] as one of the innovative reactor concepts. When we prove this reactor concept and its overall technology, our centre [BARC] will attain maturity in engineering development in many disciplines such as material science, mechanical engineering, chemical engineering, civil engineering and control systems. The control systems are also innovative. This is our aim in the AHWR.