[en] The data on cesium-137 content of rice, wheat, pulses, leafy vegetable and fish or mutton samples collected from Bombay market during 1970 to 1979 period is presented in the paper. The samples after ashing were measured by gamma spectrometric techniques. The assessment of daily intake of this isotope was made on the basis of average daily intake of these food items and then compared with daily intake calculated from the results on ¹³⁷Cs in composite diet samples called Thali. The average daily intake of ¹³⁷Cs by people of Bombay for the 1961 and 1964 period of high fallout deposition is given

[en] Coal is the most abundant naturally occurring resource for electricity generation in India. At present about 65% of total electricity generated in the country is through the use of coal as fuel. However, Indian coal available for electricity generation is characterised by very high ash content (up to 55%). This results in large amount of residual fly-ash and in large emissions to the environment of not only gaseous pollutants but also of particulates. Several thermal power stations do not either have fly-ash control equipment like electro-static precipitators and even those which have such equipment, are not able to control atmospheric emissions to the extent desirable because of high ash content. Since all coals contain natural radioactivity of primordial origin which gets concentrated in fly-ash emitted from the stacks of power stations, thermal power stations utilizing coal produce adverse environmental impact due to radioactivity release as well, in addition to gaseous and particulate pollutants. Extensive studies have been carried out in this country on radioactivity content of coal and fly-ash and this presentation briefly summarises findings of this study. Utilization of ash is mainly considered for 3 applications viz. cement manufacture, brick making for building houses and mixing with asphalt for road construction. The single largest application suitable for India can be for brick making. Due to higher levels of natural radioactivity in the fly-ash, structures built with fly-ash have been found to have higher levels of indoor radon exposures. However, these additional exposures are only a small fraction of the natural dose received by man and it is possible to minimise them by appropriate technology. Detailed results of country-wide survey have been summarized. (author). 14 refs., 5 tabs

[en] This paper presents results of gamma spectroscopic measurements of natural radioisotopes in some foodstuffs that form the principal ingredients of a composite Indian diet. A brief description of sampling and measurement procedures is given, along with the natural radioactivity from ⁴⁰K, ²²⁶Ra, and ²²⁸Th. The assessment of daily intakes of these isotopes was made on the basis of average daily intake of foodstuffs for the people of Bombay and its environs. The average daily intakes of ²²⁶Ra, ²²⁸Th, and ⁴⁰K were 3.8, 3.6, and 1960 pCi, respectively, for the period from 1970 to 1974

[en] This paper presents the results of the gamma spectrometric measurements of ¹⁴⁴Ce, ¹²⁵Sb, ¹⁰⁶Ru and ¹³⁷Cs of fallout origin and the natural radionuclides of uranium, thorium and potassium in soil samples collected from Bombay region. Soil samples have been collected from two undisturbed sites as well as from disturbed sites on a quarterly basis in and around Bombay region. A brief description of the sampling and counting procedure employed is given. The results have been compared with the global reported values. The external gamma radiation dose due to fallout and natural radionuclides present in the samples have been computed and compared with the global averages. (author). 12 refs., 5 tabs

[en] Studies on natural background radiation is a topic, which evoked curiosity and concern between the scientist and layman alike in recent years due to the shift in focus of health effects due to exposure of radiation from acute high level to chronic low level. Ever since studies on uranium miners established the presence of a positive risk coefficient for the occurrence of lung cancer in miners exposed to elevated levels of ²²²Rn and its progeny, there was a great upsurge of interest in the measurement of ²²²Rn in the environment. Subsequently, considerable data is being generated on the levels of ²²²Rn in the environment across the worlds and is being periodically reported by UNSCEAR reports. In contrast to this, data pertaining to ²²⁰Rn in indoors and workplace environment is scare due to the general perception that its levels are negligible due to its shorter half life, and subsequently its contribution to the total inhalation dose is ignored, in the presence of other significant sources of natural radiation. This may not be true from the recent studies resulted in observing high ²²⁰Rn levels in living environments and work places in various countries and it is increasingly felt that it may be necessary to have data on ²²⁰Rn levels in environment for obtaining a complete picture of inhalation dose. Globally many locations have higher levels of natural background radiation due to elevated levels of primordial radio nuclides in the soil and their decay products, like radon (²²²Rn), and thoron (²²⁰Rn) in the environment. Of late, technologically enhanced naturally occurring radioactive material has also contributed to the burden of background radiation. It is estimated inhalation of ²²²Rn, ²²⁰Rn and their short lived progenies contribute more than 54 % of the total natural background radiation dose received by the general population. Due to this it was necessary to supplement the external component with inhalation component. This component is not adequately estimated for any country so far on a national level. ²²⁰Rn problem will also be a problem in industries which uses thorium nitrate. Including India, lamps using thoriated gas mantles are being still used for indoor and outdoor lighting and hawkers in rural as well as urban areas. Considering the fact that large amount of thorium nitrate is being handled by these industries, contribution to the inhalation dose of workers from ²²⁰Rn gas emanated and build up of the progeny in ambient air may also be quite significant. In this paper current status of ²²⁰Rn levels in the indoor environment and workplaces as well as in other industries where large amount of ²³²Th is being handled are being summarized. Methods of measurement and reported levels are also summarized. (author)

[en] Environmental problems concerned with the use of coal as a fuel in thermal power plants (TPS) is due to the production of fly ash. Coal contains tracers of primordial radionuclide and its burning is one of the sources of technologically enhanced exposure from natural radionuclides. When it is burnt in TPSs, the fly ash, emitted through the stack is enriched in radionuclide and so combustion of coal on a large scale for thermal power generation assumes importance. Many of these TPSs are located in thickly populated areas. Radioactivity content of the coal from the coalfields of eastern parts of the country is found to be higher than that of other coalfields. In India coal combustion accounts nearly 73% of the total installed capacity for power generation. A sample study was carried out by this center on coal and fly ash samples collected from more than 35 TPS spread all over the country with a total installed capacity of 10000 MW(e), for their-radioactivity content. Radiation doses to the population residing within 90 km radius of each TPS have been computed. Besides another set of 15 TPSs were studied for thermal pollution emission and trace element concentration. Operation of these TPSs has resulted in effective dose commitments from doses to bones, lungs and thyroid of 200 man-Sv.y^-1 and from doses to the whole body, of 70 man-Sv.y^-1. Dose commitments to the population living within 90 km radius of the TPSs and NPPs in India have been computed and have been compared. Attempt is made to assess the inhalation dose from the radioactivity released from a typical 500 MW(e) TPS and its impact related to chemical pollutants. Impact in terms of Environmental Quality Index (EQI) due to conventional pollutions have been computed and compared with those due to the nuclear power plants (NPPs). Paper gives the summary of the study. (author)

[en] Coal contains naturally occurring radionuclides arising from the uranium and thorium series and potassium-40. Coal burning is, therefore, considered to be on e of the sources of technologically enhanced exposures to man from natural sources . Combustion of coal results in the release and redistribution of its natural radioactivity in the vicinity of the power plants. Emissions of thermal power plants (TPS) in gaseous and particulate form contain radioisotopes which are discharged to the environment causing radiation exposure to the population. This paper gives the results of the measurements carried out for estimating the natural radioactivity discharges to the atmosphere from the power stations operating in India. Radiation dose arising from airborne effluent of a model coal-fired power plant (1000 Mw) was developed for the study. Assuming Environmental Protection Agencies (EPA) regulations for flyash release as guidelines, the population dose committments are assessed. It has been observed that the average population dose committments from the operating coal-fired powe r plants are higher than those from nuclear power plants operating in the same type and capacity. Higher radionuclide contents and ash releases are common and would result in the increased doses from the thermal power plants. The present study evaluates only the radiological impact of airborne effluents. The esimated maximum individual dose committments for various body organs in mrem are: bone: 20.1, whole body: 2.6, lungs: 2.6, thyroid: 2.0, kidney: 3.2, liver: 2.7, and spleen: 2.9. The estimated population dose committments from the airborne releases for various body organs in man-rem are : bone: 23.0, whole body: 214.8, lungs: 31.7, thyroid: 27.8, kidney: 41.8, liver:27.8, spleen:27.8. (author). 4 tabs., 14 refs

[en] The details about the natural radiation sources and a summary of various sources of radiation exposures from different sources to the population in the normal areas of the world is given

[en] Many locations around the world have higher levels of natural background radiation due to elevated levels of primordial radio nuclides in the soil and their decay products, like radon (²²²Rn), and thoron (²²⁰Rn) in the environment. Of late, technologically enhanced naturally occurring radioactive material has also contributed to the burden of background radiation. Since the contribution from inhalation of ²²²Rn, ²²⁰Rn and their short lived progenies contributes more than 54% of the total background radiation dose, it was necessary to supplement the external component with inhalation component. This component is not adequately estimated for the country so far on a national level. With this in mind, a national survey has been executed by this center involving a large number of universities and other allied research institutions from different parts of the country for the estimation of inhalation component of the dose rate arises from ²²²Rn, ²²⁰Rn and their short-lived progenies. This survey has been carried out using a twin cup radon-thoron dosimeter with solid state nuclear track based dosimeter developed and standardized at Bhabha Atomic Research Centre, Mumbai using LR-115 Type-II, of 12μm thick cellulose nitrate film as a detector. In this paper the contribution from ²²⁰Rn and its progenies to the inhalation component is presented. Present study reveals that ²²⁰Rn and its progeny contributes nearly 20% of the total dose rate to radon, thoron and their progenies. Paper presents the method measurements and the results obtained. Data available in literature is also compared. (author)

[en] Inhalation dose rate due to radon (²²²Rn) and its progeny contribute more than 50% of the natural background radiation exposure. International data base on ²²²Rn in the environment has been well documented in the periodic publications of UNSCEAR. In India, external gamma radiation levels have been well mapped by earlier measurement. Country wide survey of outdoor radiation levels using thermo luminescent dosimeters carried out has revealed a national average value of external gamma radiation dose as 775μGy/y including the cosmic ray component. Of this, 48.7% contribution is from ⁴⁰K and the remainder is from the thorium (33.6%) and uranium series (17.7%). Good data base on the concentration of ²³⁸U, ²³²Th and ⁴⁰K in geological materials is also exists for the country. Thus there exists a good data base on total external gamma radiation levels across the country. Since the contribution due to ²²²Rn and its progeny is estimated to be about 50% of the total natural background radiation, there is a need to supplement the external exposure with the inhalation dose component. As a part of the on going survey of mapping of the country for ²²²Rn, Bhabha Atomic Research Centre has initiated national survey of mapping the country for indoor ²²²Rn in dwellings around normal background radiation levels. Measurements in about 1772 dwellings of different types of construction scattered over 126 locations in India using cup with membrane mode dosimeter based on Solid State Nuclear Track Detectors (SSNTDs) were carried out. LR-115 Type-II, 12 μm thick (pelliculable) films were used as detector. ²²²Rn levels varied from 6.3 to 156.0 Bq m^-3 with an overall geometric mean (GM) of 23.0 Bq. m^-3 (GSD 2.61 ). Annual effective inhalation dose rate due to ²²²Rn and its progeny in Indian dwellings using UNSCEAR (2000) dose conversion factors gave a GM value of 0.61 mSv/y. Contribution due to ²²²Rn gas and its progeny; while that due to ²²²Rn progeny works out to be 86.5% of the total inhalation dose rate. Contribution due to ²²²Rn progeny works out to be 21.4 times that of ²²²Rn gas. Any possible relation between indoor ²²²Rn levels and dwelling types has been examined by comparing the relevant means statistically. Most significant difference is found between mosaic and wooden floor dwellings having plastered whitewash walls. Combination of whitewash walls and mosaic floors leads to high levels of ²²²Rn. In this paper the concentrations due to ²²²Rn levels in dwelling in normal background regions of the country are presented. Paper discusses the methodology used and the results obtained. Levels are also compared with the reported values in literature. (author)