Nuclear Energy And Its Future In India Environmental Sciences Essay

1. Dr. RK Pachauri while addressing at a national workshop on ” Nuclear energy development in India” organised by The Energy Research Institute ( TERI) and Indian nuclear society on 13 Aug 2009 said ‘India has been dependent on conventional fossil fuels but it is no longer possible to depend on the same for a long time. There is an urgent need to look for substitutes to ensure the energy security of the country, and requires adding significant power generation capacity in the coming years.’

2. Nuclear energy has the potential to address a major portion of the country’s power shortage and climate change worries. According to the Ministry of Power, the share of nuclear power in the country is abysmally low at 2.9% of the total installed capacity. Presently India produces 150,323.41 megawatt of electricity. Of this staggering 96,044.74 MW (64.6%) comes from thermal [that includes coal, gas and oil]; 36,916.76 MW (24.7%) from hydro; 4,120 MW (2.9%) from nuclear; and 13,242.41 MW (7.7%) from renewable sources.

3. However, India is envisaging increasing the contribution of nuclear power to overall electricity generation capacity to 9% within 25 years. In 2010, India’s installed nuclear power generation capacity is likely to increase to 6,000 MW. Experts say that India plans to produce 20,000 MW by 2020 and if everything goes smoothly with Indo-US nuclear deal, it can even produce an additional 25,000 MW by the same year. The country presently has 17 nuclear power plants and six more are under construction with a total capacity of 3,160 MW. Several others are under the various stages of planning.’

4. Nuclear Power is the greatest facilitator of energy security in countries with inadequate domestic energy resources. First commercial nuclear power stations started operation in 1950s. Out of the 440 commercial nuclear reactors operating in 31 countries a total of 360,000 MWe is being generated. This caters to almost 16% of the world’s electricity supply in 56 countries which combined operate a total of 284 research reactors.

5. The comparison of GDP and Electricity Generation ranks more or less match. That is the country that has a strong electricity production has a high GDP. This is a strong correlation. The only exception to this fact is countries with very cold climate such as Russia and Canada. Countries with no active nuclear construction programme today have either high per capita electricity generation or access to alternative energy options (cheaper in the short term). Italy has shut down its nuclear plant however imports nearly 20% of its electricity from France which in turn has nearly 80% of its electricity coming from Nuclear energy. The selection of nuclear reactor technology has a large bearing on the efficient utilization of available Uranium. India (PHWRs) tops the list in this regard.

The Nuclear Reactors

6. Basic Types. In a nuclear reaction is a process in which the uranium nuclei breaks and in the process release large amount of heat. This heat can be captured and used to produce steam and subsequently used to run turbines and produce electricity. There are two basic types of reactors – Thermal Reactors or Slow Neutron Reactors, in which the neutrons produced in the fission process are slowed down using a moderator (graphite, high purity ordinary water- called light water in nuclear parlance or heavy water) and the FBRs, in which the fission process takes place with high-energy neutrons, not requiring a moderator. A brief description of the two types is given below.

(a) Thermal Rectors. Among thermal reactors, there are two types – those that can use natural uranium as fuel and those that require enriched uranium (in which percentage of fissionable U235 is increased artificially). Reactors using natural uranium as fuel were developed by Britain, France and Canada, who did not have large uranium enrichment capability. Enriched uranium was used initially in the nuclear propulsion plants of the nuclear submarines built by the US and USSR. These reactor designs were later scaled up for electricity production and were known as Light Water Reactors (LWR) The LWRs have also been adopted in France, Germany, Japan and Korea, after getting the technology from the US.

(b) Fast Breeder Reactors. Unlike Thermal reactors, Fast Breeder Reactors do not use moderators to slow down the neutrons. A large amount of heat is produced from a small volume in these reactors requiring special materials such as molten sodium to be used as coolant. The greatest advantage of these reactors is that they can utilise up to 50 percent of natural uranium as against less than one percent used by the Thermal reactors. The FBR is thus a fuel conservation measure that makes possible the extraction of about 60 times more energy from uranium than the present day thermal reactors. However, the complicated design and its unsuitability for scaling up to commercial sizes has resulted in FBRs not finding favour with most of the nuclear energy producing countries.

The Nuclear Fuel

7. The material that can be used for nuclear reaction are called fissile material. The main resources for nuclear energy are Uranium isotope U235, U238, U233, Plutonium isotope P239 and Thorium isotope Th 232. Only U 235 (less than 1%) is naturally occurring that can be used directly as a fissile material. U238 which is available in abundance can be used to produce P239 and similarly Th 232 is used to produce U233. Thus U238 and thorium are also valuable nuclear resources, called fertile materials, as they can be converted into fissile material for fuelling nuclear reactors.

8. The Natural Uranium resource found in India is modest and at best can be used to for generating approximately 10,000 MWe of energy in the PHWRs for duration of about 30 years. The country has vast resource of Thorium (about 3.2 lakh tonnes), which if used in the Fast Breeder Reactors, can provide about 10,00,000 MWe of energy for a period of approximately 200 years.

9. Given the abundance of thorium in the country and the potential it holds for the energy generation, the Indian nuclear programme is centred on using thorium as the main fuel for Indian reactors. Whereas Uranium remains the favourite fuel for the LWRs being used the world over, there are certain advantages that thorium offers over uranium based fuel. For this reason, the world nuclear community is increasingly recognising thorium as representing a crucial part of the future of civil nuclear power generation. The key advantages offered by thorium on other isotopes currently being used as nuclear fuels are as follows:-

(a) Abundance. As an element, thorium is at least three times as abundant in the earth’s surface as that of uranium. All mined thorium can be used in a reactor, compared with 0.72 percent of the fissile U235 isotope of the natural uranium. This means that up to 40 times the amount of energy per unit mass could be available from thorium.

(b) Non-Proliferation Benefits. The most advocated reason for using thorium in the nuclear fuel cycle is the non-proliferation benefits that it offers. All uranium fuelled reactors produce a certain quantity of plutonium, which can be used for the weapons programme. But when thorium is used as the dominant fuel, it decays to become U233 and does not yield any utilisable plutonium.

(c) Less Radio Toxicity. There is very low and significantly less radio toxicity from spent thorium fuel than that of spent U235 or U238. Spent U235 and U238 have half-lives of around 700 million years and 4.5 billion years respectively, while the spent U233, from the thorium fuel cycle has a half-life of 160,000 years and would remain radioactive for 500 years only.

(d) Higher Neutron Yield. A further benefit from U233 is its higher neutron yield per neutron absorbed, thus providing for greater fuel efficiency than U235 or U238.

10. The Indian nuclear programme was conceived based on, unique sequential three-stages and associated technologies essentially to aim at optimum utilization of the indigenous nuclear resource profile of modest Uranium and abundant Thorium resources. This sequential three-stage program is based on a closed fuel cycle, where the spent fuel of one stage is reprocessed to produce fuel for the next stage. The closed fuel cycle thus multiplies manifold the energy potential of the fuel and greatly reduces the quantity of waste generated. The salient aspects of the programme are as follows:-

(a) The First Stage. The first stage comprises of Pressurized Heavy Water Reactors fuelled by natural uranium. Natural uranium contains only 0.7% of Uranium235, which undergoes fission to release energy (200Mev/atom). The remaining 99.3% comprises Uranium238 which is not fissile however it is converted in the nuclear reactor, to fissile element Pu 239. In the fission process, among other fission products, a small quantity of Plutonium239 is formed by transmutation of Uranium238.

(b) The Second Stage. The second stage, comprising of Fast Breeder Reactors (FBRs) are fuelled by mixed oxide of Uranium238 and Plutonium239, recovered by reprocessing of the first stage spent fuel. In FBRs, Plutonium239 undergoes fission producing energy, and producing Plutonium239 by transmutation of Uranium238. Thus the FBRs produce energy and fuel, hence termed Breeders. FBRs produce more fuel than they consume. Over a period of time, Plutonium inventory can be built up by feeding Uranium238.

(c) The Third Stage. Thorium232, which constitutes world’s third largest reserves in India, is not fissile therefore needs to be converted to a fissile material, Uranium233, by transmutation in a fast breeder reactor. This is to be achieved through second stage of the program, consisting of commercial operation of Fast Breeder Reactors (FBRs). In the second stage, once sufficient inventory of Plutonium239 is built up, Thorium232 will be introduced as a blanket material to be converted to Uranium233. Consolidation and further growth of the nuclear electric base is planned by means of thorium breeders, which will form the third stage of the programme. The third stage involves breeder reactors using U233 (produced in second stage) in their cores and Th232 in their blankets, thereby producing energy that can meet the demands of the country for many centuries to come.

11. Considering the sequential nature of the indigenous nuclear power program, and the lead time involved at each stage, it is expected that appreciable time will be taken for direct thorium utilization. Therefore, innovative design of reactors for direct use of thorium is also in progress in parallel to three stage program. In this context, the frontier technologies being developed include the Accelerator Driven Systems (ADS) and Advanced Heavy Water Reactor (AHWR). The ADS essentially is a sub-critical system using high-energy particles for fission. One of the significant advantages of this system is small quantity of waste production. The quantity of waste in this system is greatly reduced in comparison to the existing reactors as Actinides produced in ADS are `burnt’ out.

12. The AHWR is another innovative concept, which will act as a bridge between the first and third stage essentially to advance thorium utilization without undergoing second stage of the three stage program. It uses light water as coolant and heavy water as moderator. It is fuelled by a mixture of Plutonium239 and Thorium232, with a sizeable amount of power coming from Thorium232.

13. The Capability Development. The country has developed comprehensive capabilities in all aspects of nuclear power from sighting, design, construction and operation of nuclear power plants. Multidimensional R&D facilities have also been set up along with capability development in front and back ends of the fuel cycle, mining, fuel fabrication, storage of spent fuel, reprocessing and waste management. Infrastructure also exists for miscellaneous components like heavy water, zirconium components, control and instrumentation. The country has also been able to develop excellent Human Resource and training infrastructure for the specialised skills needed for generation of nuclear power. The figure below illustrates the status of power production through various sources. It is evident that the nuclear energy has a great future in the sector of power.

14. The Slow Progress. At the time of country’s independence in 1947 and for several years thereafter, the industry’s capability was limited to manufacturing and supply of equipment for cement and sugar industry. The Indian industry exposure, manufacturing and supply of equipment for high technology requirements was quite limited. Whereas other developed countries at that time had well established industrial infrastructure and capability to manufacture equipment for defence and aviation industry. The nuclear industry development in those countries was a spin-off of the well established industry. The Indian industry development was initiated and achieved maturity with the development of nuclear technology.

15. As per the data of the Economic Survey 2007-08 of the Government of India, nuclear power was one of the slowest growing power-generation industries in the country. The scenario, however, is likely to change now. The Indo-US nuclear agreement signed in Oct 08 and the NSG waiver accorded to India for international nuclear trade would be of a great help to India in its quest for large energy source. The much needed Uranium would bring up the reactors back to its full capacity and give the necessary breathing space for the indigenous nuclear programme using natural thorium to take off.