Note4Students:

Government decision to construct 10 more PHWR Reflects the government’s commitment to prioritise the use of clean power in India’s energy mix.  It is the part of low-carbon growth strategy and to ensure long-term base load requirement for the nation’s industrialisation. So this topic is important.

Introduction

Pressurized heavy-water reactor (PHWR) is a nuclear reactor

1. Using unenriched natural uranium as its fuel,
2. This uses heavy water (deuterium oxide D2O) as its coolant and neutron moderator.
3. While heavy water is significantly more expensive than ordinary light water, it creates greatly enhanced neutron economy, allowing the reactor to operate without fuel-enrichment facilities (offsetting the additional expense of the heavy water) and enhancing the ability of the reactor to make use of alternate fuel cycles.

Advantages of PHWR

1. The use of heavy water as the moderator is the key to the PHWR (pressurized heavy water reactor) system, enabling the use of natural uranium as the fuel (in the form of ceramic UO2), which means that it can be operated without expensive uranium enrichment facilities.
2. The mechanical arrangement of the PHWR, which places most of the moderator at lower temperatures, is particularly efficient because the resulting thermal neutrons are “more thermal” than in traditional designs, where the moderator normally is much hotter. These features mean that a PHWR can use natural uranium and other fuels, and does so more efficiently than light water reactors (LWRs).

Pressurised heavy-water reactors do have some drawbacks.

1. Heavy water generally costs hundreds of dollars per kilogram, though this is a trade-off against reduced fuel costs.
2. The reduced energy content of natural uranium as compared to enriched uranium necessitates more frequent replacement of fuel; this is normally accomplished by use of an on-power refuelling system.
3. The increased rate of fuel movement through the reactor also results in higher volumes of spent fuel than in LWRs employing enriched uranium.
4. since unenriched uranium fuel accumulates a lower density of fission products than enriched uranium fuel, it generates less heat, allowing more compact storage.

Recent Developements

1. Union Cabinet gave its approval for the construction of 10 units of the new indigenous 700 MWe (mega watt electric) pressurised heavy water reactors (PHWRs).
2. The new reactors are of significantly higher capacities compared to the PHWRs currently under operation
3. The standard PHWR being used in India is of 220 MWe though two 540 MWe reactors were installed in Tarapur in 2005 and 2006. The ten reactors will be installed in Kaiga in Karnataka (Unit 5 and 6), Chutka in Madhya Pradesh (Unit 1 and 2), Gorakhpur in Haryana (Unit 3 and 4) and Mahi Banswara in Rajasthan (Unit 1, 2, 3 and 4).

Analysis

Why PHWR

1. The main reasons for selecting PHWRs in the 1960s for the First Stage of the Indian nuclear power programme have been the use of natural uranium oxide as the fuel, the best utilisation of mined uranium in energy production and the prospect of establishing a completely self-reliant technology.
2. The government’s measure seeks to fast track its three-pronged program—developed largely during the country’s almost 30-year-long isolation from international nuclear trade—and also factors in India’s abundant thorium resources, which constitute 25% of the world’s total reserves.
3. The first step of the three-stage program involves building indigenously engineered PHWRs and light-water reactors to produce plutonium. The second stage uses fast-neutron reactors fueled by plutonium to breed U-233 from thorium. In the third stage, using wholly indigenous technology, the country will use advanced heavy-water reactors fueled with U-233 obtained from the irradiation of thorium in PHWRs and fast reactors.
4. India wants to ramp up production of power from low-carbon sources and has outlined plans to install a total of 175 GW of renewables by 2022.
5. As of March 2016, about 61% of the country’s installed capacity was coal-fired, 14% came from hydropower, 14% came from other renewables (mostly wind, followed by small hydro and biomass), 8% from natural gas, 2% from nuclear, and 1% from diesel.
6. 100% of all their components are manufactured by the Indian industry.
7. As far as the safety is concerned, the PHWR technology scores well in terms of its several inherent safety features.
8. The biggest advantage of the PHWR design is the use of thin walled pressure tubes instead of large pressure vessels used in pressure vessel type reactors.
9. This results in a distribution of pressure boundaries to large number of small diameter pressure tubes.
10. The consequence of an accidental rupture of the pressure boundary in such a design will have a much less severity than that in a pressure vessel type reactor
11. In addition, the Indian 700 MWe PHWR design has enhanced safety through dedicated Passive Decay Heat Removal System which has the capability of removing decay heat from core without requiring any operator actions similar with the technology adopted for Generation III+ plants to address the Fukushima type accident.
12. The 700 MWe Indian PHWR has steel-lined containment to reduce the leakages and containment spray system to reduce the containment pressure in case of a loss of coolant accident and for scrubbing radio nuclides in case of their release beyond the design limit.

Research and development

1. Over four decades of relentless research, design and development work in Bhabha Atomic Research Centre and Nuclear Power Corporation and the matching contributions of some of their industry partners who had shown the courage in taking up the challenging manufacturing and construction work have enabled India in establishing the technology in totality.
2. Mastering the entire fuel cycle including prospecting of minerals, mining, processing and manufacturing of fuel and structural materials, reprocessing of spent nuclear fuel and immobilization of radioactive waste has given India a unique position of self-reliance in the atomic energy domain.
3. The constraint of a limited reserve of uranium in the country which earlier impeded a rapid growth in nuclear power has now been eased by augmented production of indigenous uranium and import of uranium under the civil nuclear co-operation agreements with several countries

Clean Energy

1. India is now poised for a rapid growth in the nuclear power capacity which is essential for meeting the demand of clean electricity.
2. The per-capita electricity consumption in India (now close to 1000 KWh) is nearly one-third of the world average and there is an obvious need for a substantial enhancement of non-carbon electricity production to improve the quality of life of our people.
3. The impressive growth in the solar and wind power has made a visible impact in increased availability of electricity in many areas. However, it needs to be emphasized that the distributed and intermittent sources of energy such as solar and wind cannot meet the base load demand very effectively.
4. The nuclear energy source is concentrated, continuous and reliable and, therefore, can be complemented by solar and wind energy in meeting the overall demand of electricity with practically zero carbon foot-print.

Employment

1. Manufacturing orders of close to Rs 70,000 crore are expected to come through to the domestic industry on account of the projects and are expected to generate more than 33,400 jobs in direct and indirect employment.

The merit of the closed fuel cycle

1. Which has been adopted right from the beginning of the Indian programme is not only in multiplying the fuel resource but also in reducing the radio-active burden of the nuclear waste dramatically.
2. In this context, the successful development of separation of minor actinides from the nuclear waste in India, deployed in pilot plant scale, has drawn world-wide attention. Plutonium recovered by reprocessing of spent fuel from operating PHWRs has been used in making the plutonium-uranium mixed oxide fuel for the full core of the Prototype Fast Breeder Reactor (PFBR) which has initiated the commissioning activities before commencing operation.

Challenges

1. The decision to step up the indigenous civil nuclear reactor programme comes amid festering concerns over the deployment of imported light water reactor-based projects in collaboration with global vendors such as Toshiba-Westinghouse and Areva
2. The speed at which we can grow our nuclear power capacity
3. In this context one can examine the experience of France and USA in nineteen seventies and of China in the recent years.
4. They all have achieved very impressive rapid growth by adopting a convoy or a serial mode of installation of nuclear power plants of a few standardised designs. In such a strategy, the industry can gear up their dedicated production lines for sophisticated nuclear components and construction companies can deploy their manpower and skill-set most effectively.

Conclusion

1. With the entry of India in her Second Stage of nuclear power programme in which Fast Breeder Reactors will not only enable the growth of the installed nuclear capacity, but also generate more fissile materials, plutonium-239 and uranium-233 by conversion of fertile isotopes, uranium-238 and thorium-232 respectively
2. An enhanced scope and an accelerated implementation of the First Stage of the programme will make a far- reaching impact on securing the energy self-reliance of the country.
3. By operating multiple recycles in the uranium-plutonium fuel cycle the supply of fissile material is expected to be enhanced by a factor of 60 and by using the huge reserve of thorium, the current estimate being four times that of uranium, India can sustain the supply of clean nuclear energy for several centuries.

Question:

Q.) PHWR will help India to achieve its Paris climate change conference commitments. analyse