[en] A programme to assess the airborne radioactivity levels due to natural radon daughter products in underground non-uranium mines was taken up. In India there are more than 500 underground non-uranium mines employing about 6 lakh people. During this study a total of 36 mines covering most of the major sectors of mining from various parts of the country had been surveyed. The coal sector which accounts for more than 300 mines and 3.8 lakh underground miners had shown very low radon levels, mostly below 10 mWL. The underground metal mines, in general, had enhanced levels of radon activity ranging from 10 to 100 mWL. In many copper mines the air activity levels were considerably high, ranging from 100 to 300 mWL and at least in one mine the levels were as high as 900 mWL in some locations. (author). 8 refs., 6 tabs

[en] A number of non-uranium mines in India were monitored for airborne radon daughter product activity. The Equivalent Equilibrium Radon (EER) values were derived from the individual concentrations of RaA, RaB and RaC, calculated from the gross alpha decay of the filter paper air samples. Some of these mines had shown fairly high levels of airborne radioactivity. The EER values in the Ventilation Return Airways (VRA) of these mines varied from a few pCi/l to 20 pCi/l, while at a few underground working areas levels as high as 40 pCi/l were detected

No abstract available

[en] Ten non-uranium mines from various regions of India have been surveyed for airborne radioactivity due to radon daughter products. The average air concentrations of RaA, RaB and RaC in the main ventilation return airways and in some selected areas in different working levels underground were assessed. The average equilibrium equivalent radon values and the RaC to RaB ratios were calculated. In one of these mines activity levels of the order of 500 to 1200 mWl were observed in different working areas. In all other mines the levels observed varied from a few mWL to about 100 mWL. The method of air sampling and analysis is briefly described. (author)

[en] This paper gives a brief account of the various types of continuous air-monitoring instruments designed and used at the Bhabha Atomic Research Centre. The two types of instrument used for continuous monitoring of the airborne particulate radioactivity are the fixed-filter monitor and the moving-filter monitor. The selection of a particular type of monitor for a given area is discussed in detail. The development of a slope-sensitive alarm is described. The feasibility of replacing the comparatively sophisticated moving-filter air monitor by the fixed-filter type monitor fitted with the slope sensitive alarm is discussed. A continuous monitor for iodine-131 in air, which Is fitted with activated-charcoal-impregnated filter paper, is also described and a general analysis of the calibration procedure, accuracy and reliability of air monitors is presented. (author)

[en] Plastic scintillator detectors have been found to be more efficient than GM tubes for continuous air monitoring measurements in areas of high gamma background fields. Several flowcell type detectors filled with plastic scintillator powder or chips have been developed for use as area monitors or on-line monitors for tritium specially. Preparation of thin films, fine powder, chips and turnings of the plastic scintillator material are described. Measurements of beta and alpha activity are reported. (A.K.)

[en] Various types of detectors used for monitoring tritium activity levels in heavy water moderated and cooled reactors and their relative merits are outlined. The recent improvements in monitoring systems have been attempted by using perforated plastic scintillator films. These detectors are 50 to 60% more sensitive and the limit of tritium detection is as low as 2μci/cm³ or 0.002 MPC. Design of a monitoring system incorporating such a detector and experience gained are described. (A.K.)

No abstract available

[en] The Proceedings of the Third National Symposium on Environment with special emphasis on high background radiation areas comprises of the papers submitted for the third symposium whose emphasis is on the high natural background radiation areas in the country. The choice of this special theme is appropriate as the symposium is being held at Thiruvananthapuram, Kerala which is sandwiched between two well-known high background monazite areas around Manavalakkurichy in the south and Chavara in the north. The health effects of these high background radiations are of great public concern. Contributed papers included in this volume spans a wide spectrum of environmental disciplines: epidemiology, ecology, monitoring, control, standards, regulations and so on. Specific to the special theme are studies carried out in high background radiation areas in Chavara, Kalpakkam, Chatrapur and Jaduguda. The proceedings volume also contains several invited papers among them a review paper on epidemiological and dosimetric studies carried out in various countries of the world bestowed with high natural background radiation areas. A careful study of the scientific material presented in this volume immediately reassures the reader that no abnormal health effects have been observed in populations living in the high natural background radiation areas. Directions for future environmental studies have also been indicated variously in the volume for building up an useful database. Papers relevant to INIS are indexed separately

[en] The results of an ongoing study to estimate the inhalation doses due to airborne radon-thoron and their short lived decay products in dwellings located in the high background radiation area (HBRA), Chavara, Kerala State, are presented. Air sampling using a glass fibre filter paper was carried out in 18 houses and the indoor radon-thoron decay product concentrations in air estimated by alpha counting. The ambient dose equivalent (background gamma) in these houses ranged from 100 to 5000 nSv h^-1, the estimated radon and thoron progeny concentrations ranged from 0.1 - 1.5 and 0.3 - 4.5 mWL respectively. The resultant inhalation doses were in the range of 10 - 160 nSV h ^-1. As the radon thoron levels are known to exhibit diurnal and seasonal variations, time integrated measurements covering 90 days were also made in a few houses using solid state nuclear track detectors (SSNTDs). The average dose rates during the 90 day exposure period in these houses ranged from 100 to 900 nSV h^-1. (author). 6 refs., 3 tabs