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Water requirements of N-plants
Trends Herod buried among art-work Mammoth DNA mapped
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Water requirements of N-plants
Water is the nuclear power plant’s Achilles heel as they require very large volume of water for their operation. Currently the Government of India is busy with feasibility studies for the possible location of nuclear power plants away from traditional coastal locations. Many in-land locations such as in Haryana and Punjab are being studied and in such studies the critical activity is the water requirements evaluation and how to meet it. During this analysis a comparison is needed as to the nuclear plant’s water requirement vis-a-vis those of a thermal (coal based) plant at the same location.
Nuclear power plants use large volume of water and for this reason they are located near large water bodies. For example, of the 104 nuclear power plants of USA, all but two are located on the shores of rivers, lakes etc. from where they can get their required water demand in an assured mode. At a nuclear power plant water is needed for cooling of the reactor’s core, in addition to the production of steam to drive the turbo-generators to produce electricity. For the latter purpose the volume of water needed is not large because a closed system is used and the spent steam is condensed and water so available re-used to produce steam. But the volume of water needed for cooling of the reactors core is very large. The nuclear plants draw large quantity of water and most of this may be returned to the source which may be used again by the other consumers located downstream. All power plants do consume some quantity of water drawn and this is the water lost as evaporation. Stringent monitoring of the water released is mandatory to avoid any radiation poisoning and consequent contamination of the water body being used. Nuclear power plants need far more volume of water for cooling of the reactor’s core compared to that of a thermal plant. Also a nuclear power plant operates at lower temperatures and pressure level compared to that of a thermal plant, which means that the nuclear power plants are less efficient in use of the heat from the reactor and thus require more water for cooling and other purposes combined compared to thermal plants. The EPRI (Electric Power Research Institute) of USA has carried out a detailed study comparing the water requirements of nuclear plant with thermal plants and some relevant findings are cited below: The EPRI analysis shows that existing nuclear power stations use and consume significantly more water per megawatt hour of energy produced compared to the thermal plants using fossil fuels. The nuclear plants with once trough cycle may use approx. 20 per cent more water and the nuclear plants with closed systems use up to 83 per cent more water than a thermal plant of the same power generation capacity. The actual consumptions of the plants were found to be much higher than the figures worked out by the study carried out by EPRI. Thus the actual consumption of water in the above discussed systems was found to be 33 per cent more in the case of the ‘once-through’ system and 50 per cent more than the calculations in the case of ‘closed system’ both for nuclear and thermal plants. Assuming that the nuclear power plants worked as “base load” station i.e. 24 hours at full capacity, the minimum volume of water needed annually may be 829 million litres per MW in case of the once-through system. In the case of pond-type system using nuclear plant the requirement was found to be 17 million litres per MW. The water requirements of AP 1000 nuclear power plant developed by Westinghouse (USA) was found to vary between 2 and 3.4 million litres per minute which equals to the annual usage of 779 to 1338 Mega litres per MW. In case of the nuclear power plant of 1000 MW capacity proposed in Haryana near Kumaria, district Sirsa, the water requirements are to be met by a 310 cusecs capacity dedicated channel from the Bhakra Main Line Canal which carries waters released from the Bhakra Dam. A standby arrangement is required to be made for feeding the plant in case of an emergency through the Rajasthan Feeder. This would ensure availability of 280 million litres of water per MW annually which, it is hoped, would be sufficient to meet the plant’s requirements. In the case of the 900 MW Harris single-reactor nuclear power plant in North Carolina (USA), the daily requirements of water amount to ~ 150 million litres and nearly 50 per cent of the same is lost as evaporation. In the case of the 2200 MW capacity Duke McGuire twin-reactor nuclear power plant also in North Carolina (USA) the daily requirements amount to about one billion gallons (4.55 billion litres). The water requirements of a nuclear power plant may be as much 80 per cent to 90 per cent more than that of thermal plant of the same capacity and which uses the same type of cooling system. So, with water resource availability already under pressure with domestic, industrial and irrigation demands growing rapidly, we need to undertake a comprehensive water availability audit before going in for the inland nuclear plants.
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Ice that burns
An international research programme has, for the first time, proved the technically feasibility to produce gas from gas hydrate deposits found deep in the oceans and polar regions. The gas hydrates are naturally occurring “ice-like” combination of natural gas and water. The international consortium, including the US, Canada, Japan, India, Germany, and the energy industry has conducted test drilling at a site known as Mallik, supposed to have one of the highest concentrations of known gas hydrates in the world, in the Mackenzie Delta of the Canadian Arctic for extracting the gas hydrates.
It is estimated that there are mega-tons of the gas hydrates at the bottom of the ocean all over the world and in the Arctic permafrost. It is tipped as the cleanest and most abundant source of energy in the world. The amount of gas hydrates is estimated at least twice those of fossil fuels. These hydrates hold great potential as an “environmentally-friendly” fuel for the 21st century. The results of depressurisation and thermal heating experiments at the Mallik site have demonstrated that gas can be produced from gas hydrates. India is not behind any country when we talk of gas hydrates and work is going on a war footing in this direction. India is sitting on the seabed storing an infinite source of energy waiting to be tapped. India’s estimated gas hydrates resources are of the tune of 1,894 trillion cubic metres, which is over 1,700 times as much as the proven natural gas reserves with the country (1.08 trillion cubic metres). Ultrasonographic studies conducted by the National Geophysical Research Institute, Hyderabad, and the National Institute of Oceanography, Goa, have indicated a large presence of gas hydrates in the Bay of Bengal. Realising the potential of gas hydrates, a team of scientists from the National Institute of Ocean Technology (NIOT) is all set to take up seabed coring (a refined and more scientific way of drilling) for gas hydrates on the Krishna-Godavari basin off the Andhra Pradesh coast in six months. One of the thickest and deepest gas hydrate occurrences yet known has been discovered off the shores of Andaman Islands and has revealed gas hydrate bearing volcanic ash layers as deep as 600 metres below the sea floor. For coring and mining of gas hydrates, India has procured from Italian shipbuilder Fincantieri for Rs 232 crore, the state-of-the-art exploration vessel christened as Sagar Nidhi . Carrying the scientists and the US-made autonomous coring system for drilling and retrieving samples, Sagar Nidhi is now on a pilot project near the site. The coring will start in April next and according to S Kathiroli, director, NIOT, this is going to be a big thing for the world and we hope to strike gas hydrate in just one day. He further said that India have the thickest gas hydrates in the world and till now, we have drilled at 20 sites and 11, all of them on off east coast, have found to have gas hydrate. India is likely to do its first gas hydrates production test The writer is Professor of Physics, CCS HAU, Hisar
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Trends
A balloon-borne instrument soaring high over Antarctica has found evidence of a possible large clump of mysterious so-called dark matter relatively close to our solar system, scientists said on Wednesday.
It detected an unexpected amount of very high energy cosmic ray electrons coming from an unknown source within about 3,000 light years of the solar system. A light-year is 6 trillion miles (10 trillion km), the distance light travels in a year. One explanation is that the electrons may have been spawned as dark matter particles collided with one another, triggering their mutual annihilation, according to Louisiana State University physics professor John Wefel. Scientists think perhaps 25 per cent of the universe is made up of dark matter, which responds to gravity the same way as does regular matter such as stars and planets and the like. While the stuff is thought to be strewn throughout the cosmos, it is invisible and poorly understood. Scientists have struggled to find any solid evidence of dark matter, and the new study could represent a major step forward in that effort.
—Reuters Herod buried among art-work King Herod may have been buried in a crypt with lavish Roman-style wall paintings of a kind previously unseen in the Middle East, Israeli archaeologists said Wednesday. The scientists found such paintings and signs of a regal two-story mausoleum, bolstering their conviction that the ancient Jewish monarch was buried there. Ehud Netzer, head of Jerusalem’s Hebrew University excavation team, which uncovered the site of the king’s winter palace in the Judean desert in 2007, said the latest finds show work and funding fit for a king. “What we found here, spread all around, are architectural fragments that enable us to restore a monument of 25 meters high, 75 feet high, very elegant, which fits Herod’s taste and status,” he told The Associated Press in an interview at the hillside dig in an Israeli-controlled part of the West Bank, south of Jerusalem. —AP Mammoth DNA mapped Bringing “Jurassic Park” one step closer to reality, scientists have deciphered much of the genetic code of the woolly mammoth, a feat they say could allow them to recreate the shaggy, prehistoric beast in as little as a decade or two. The project marks the first time researchers have spelled out the DNA of an extinct species, and it raised the possibility that other ancient animals such as mastodons and sabertooth tigers might someday walk the Earth again. “It could be done. The question is, just because we might be able to do it one day, should we do it?” asked Stephan Schuster, a Penn State University biochemist and co-author of the new research. “I would be surprised to see if it would take more than 10 or 20 years to do it.” The million-dollar mammoth study resulted in a first draft of the animal’s genome, detailing the ice age creature’s more than 3 billion DNA building blocks. The research published in Thursday’s issue of the journal Nature also gives scientists new clues about evolution and extinction. —
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