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Is work in a nuclear power plant risky? Prof Yash
Pal THIS UNIVERSE Trends * Clue to anxiety drug addiction |
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Is work in a nuclear power plant risky? A 24 year old who is about to join the Department of Atomic Energy (DAE) as a scientific officer, is troubled by what he saw on a TV channel. He is unmarried; his parents are worried about the alleged damage to DNA by radiation. I assured him that there is no such harm. TV channels often go overboard and make unsubstantiated claims. A 63 year old person asked me whether the throat malignancy, which, his 33 year old daughter is suffering from, is likely due to the possible radiation exposure he might have received while working in a nuclear power plant when he was 28 year old. Thyroid diseases are not infrequent. No one knows for sure the reason for getting it. But there is no evidence that radiation exposure to father may lead to cancer in their children. Workers in nuclear power plants will receive some radiation dose. Nuclear Power Corporation of India Limited (NPCIL) has instituted strict procedures to keep the doses to workers within the limits prescribed by the Atomic Energy Regulatory Board (AERB) and to values As Low As Reasonably Achievable (ALARA). Their radiation risk is insignificant. ALARA committees with Chief Superintendents as chairmen, section heads as members and health physicists as member secretary review radiation work at each station periodically. Sectional ALARA committees plan work involving radiation exposures. Each Station prepares a work plan, identifies various activities involving radiation exposure and gets AERB's approval for an annual “Radiation Budget”. If any Station exceeds the budget, AERB will not be amused! The interior areas of the plant buildings are categorised into four zones for radiation and contamination control. Healthphysicists record radiation levels and airborne activity with prescribed frequency. Movement of every worker within the zones is controlled. Before entering Zone 2, 3 &4, they must wear lab coat, gloves and shoe covers and personnel dosimeters. They come out through sensitive portal monitors which will detect contamination, if any, present. They check hands and shoes using special monitors. Annual reports published at (www.aerb.gov.in) indicate that the compliance with its stipulations is near total. For instance, during 2001 to 2008, among the annual average workforce of about 14,000 workers, one worker each in Rajasthan Atomic Power Station (RAPS) and Narora Atomic Power Station (NAPS) exceeded the limit in 2001; in 2002, one worker each in Madras Atomic PowerStation (MAPS) and NAPS; in 2007, two workers in NAPS exceeded the limits. This is indeed a creditable record. Dose limits are based on conservative assumptions. It is inconsequential if any one receives, occasionally, a dose above the limit. The Station managements made improvements in ventilation, reduced heavy water leakages, shielded hotspots, filtered crud from heat transport system, promptly detected and removed failed fuel bundles and used cobalt-free materials (Radiation from Cobalt-60, formed by actrivation of cobalt present in certain reactor components increases the radiation field). Many elegant engineering solutions helped to reduce radiation doses to workers. Radiation protection standards assume that any dose of radiation, no matter how small, involves a possible risk to human health (World Nuclear Association, November 2009). After reviewing 200 peer-reviewed publications, Electric Power Research Institute (EPRI) concluded that this methodology may have been over-estimating the risks. (World Nuclear News, December 2). Radiation protection standards are based on studies by scholarly bodies such as the US National Academy of Sciences (NAS)’ Biological Effects of Ionizing Radiation Committee, the International Agency for Research on Cancer (IARC) and United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). They indicate that at low doses, radiation risks, if there are any, are very small. Negligibly small risks are no risks at all. Work in a nuclear power plant is not a risky occupation. The writer is Raja Ramanna Fellow,
Department of Atomic Energy |
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THIS UNIVERSE The audible frequency of human ear is 20Hz to 20,000Hz. The frequency of domestic circuit (A.C. 50Hz) lies within our audible frequency, then why we can't hear it? You cannot hear electrical vibrations. Our ears can hear only sound waves, and a sound wave is a longitudinal wave of compression and rarefaction of a medium through which it propagates. There is no question of hearing electromagnetic vibration. However we can often hear a hum of a transformer at a frequency of 50 cycles. This hum is produced because of mechanical vibration of the lamination of the transformer by the oscillating magnetic field induced by the electric current, that does oscillate at this frequency. Can you tell me about the nine planets which are made in Big Bang. Why are there only nine planets and not more? The planets were not produced in the big bang, nor was our sun. All this happened later. It is believed that our sun was produced through slow collapse of a large cloud of gas and dust due to much gravitational contraction of matter. The condensation of matter led to heating up its interior. The temperature reached such high values that Hydrogen nuclei fused into Helium nuclei - in essence four protons fusing into one alpha particle or a helium nucleus. In this process a significant part of the original mass is converted into energy. This process is called nuclear fusion. That is how our sun became a sun; it is this kind of process that is continuously producing energy. The large cloud that condensed to form our sun must have been slowly rotating. During condensation its speed of rotation increased. This resulted in the fact that our sun is still rotating and so would have been lot of mass that did not form the central core. This left over material kept rotating around the sun and while doing so part of the material condensed into planets. Perhaps the amount of rotating material was nearly exhausted after the known planets were formed. Indeed not only these planets but also an enormous amount of material in comets and asteroids were also formed. You could think of the sun as a central part of metropolis and several planets and comets as the material that was left over and became satellites of the sun. It is difficult to find why our sun was made from a cloud only that big and why various pieces were just this size. What I have given above is a qualitative guess of the origin of the system. No one has written the detailed history of what happened when. However, no magic needs to be invoked.. Readers wanting to ask Prof Yash Pal a question can e-mail him at palyash.pal@gmail.com
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Trends WASHINGTON: Scientists have sequenced the DNA from four frozen hairs of a Greenlander who died 4,000 years ago in a study they say takes genetic technology into several new realms. Surprisingly, the long-dead man appears to have originated in Siberia and is unrelated to modern Greenlanders, Morten Rasmussen of the University of Copenhagen and colleagues found.
Clue to anxiety drug addiction LONDON: Valium-like drugs use the same potentially addictive "reward pathways" in the brain as heroin and cannabis, scientists said on Wednesday, findings which may help in the search for non-addictive alternative anxiety drugs. Researchers from Switzerland and the United States found that so-called benzodiazepine drugs, such as Ativan, Xanax and Valium, exert a calming effect by boosting action of a neurotransmitter called gamma-aminobutyric acid (GABA) in the same way as addictive drugs like opioids and cannabinoids. Stuttering linked to cell waste recycling genes BOSTON: Three genes linked to a rare metabolic disorder may also cause some cases of stuttering, researchers said on Wednesday in a finding that could lead to a new treatment for the speech condition. Two of the genes are used by brain cells as part of a waste recycling process, the researchers reported in the New England Journal of Medicine. A third has no other known role. Why it is so scary to lose money WASHINGTON: People are afraid to lose money and an unusual study released on Monday explains why-the brain's fear centre controls the response to a gamble. The study of two women with brain lesions that made them unafraid to lose on a gamble showed the amygdala, the brain's fear centre, activates at the very thought of losing money. Sex-specific lung cancer genes found WASHINGTON: Lung cancer is often dramatically different in women than it is in men, U.S. researchers reported on Tuesday in another study that suggests ways to tailor treatment for cancer patients. They also found that some elderly patients have forms of lung cancer that make them likely to benefit from chemotherapy, even though the treatments can be harsh. Endeavour docks with space station HOUSTON: The space shuttle Endeavour and its six astronauts arrived at the International Space Station on Tuesday, carrying the station's last two main components. After lighting up the sky in a predawn launch from its Florida space port on Monday, Endeavour spent most of Tuesday closing in on the station, 215 miles above the Earth. Gene variant link to aging cells LONDON: Scientists have found specific genetic variants which may explain why some people age earlier than others and say their findings have important implications for understanding cancer and age-related diseases. Dutch and British researchers analyzed more than 500,000 genetic variations from human gene maps and found that people with particular variants near a gene called TERC were likely to be biologically older by 3 to 4 years. — Reuters
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