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Radium, thorium, and radioactive lead isotopes in groundwaters: application to the in situ determination of adsorptiondesorption rate constants and retardation factors. Water Resour. Res., 1982Res., , 18, 1663Res., -1675. Kozowska, B., Walencik, A., Dorda, J. and Zipper, W., Radon in groundwater and dose estimation for inhabitants in spas of the Sudety Mountain area, Poland. Appl. Radiat. Isot., 2010, 68, 854-857. 19. Zouridakis, N., Ochsenkühn, K. M. and Savidou, A., Determination of uranium and radon in potable water samples. CATALYSED exchange of deuterium (D) between hydrogen (H) gas and liquid water (liquid phase catalytic exchange (LPCE) reaction) using bi-thermal hydrogen water (BHW) process is receiving considerable attention for heavy water production 1 . This is because it is more energy-efficient and environment-friendly compared to the existing 'girder sulphide' and 'ammonia-hydrogen' processes. The catalysed exchange involves two stepsfirst, deuterium exchange between hydrogen gas and water vapour at the catalytic site and subsequently equilibration of deuterated water vapour with liquid water at gas-liquid interface, which results in the transfer of deuterium from gas to liquid phase. Success of the process requires simultaneous presence of H 2 gas and water vapour at the catalytic site and easy accessibility of liquid water to water vapour involved in isotopic exchange reaction. However, because the solubility of H 2 gas in water is poor, if the catalytic site is covered with liquid water, the exchange of deuterium between hydrogen gas and water vapour is highly impeded 2 . Therefore, a primary requirement for the LPCE process is that the catalyst should allow access of gaseous reactants to the catalytic RESEARCH COMMUNICATIONS CURRENT SCIENCE, VOL. 109, NO. 10, 25 NOVEMBER 2015 1861 However, these show good activity only up to atmospheric pressure and rapidly lose activity as the pressure is increased above atmospheric pressure. This has limited the use of the LPCE process for relatively low-throughput applications like removal of tritium from heavy water of the moderator used in pressurized heavy water reactor operation 10 . The reduction in catalyst activity at higher pressure is believed to arise due to ingression of water at such pressure through pores in the fibrous network or mesh structure of the commonly used hydrophobic binders like PTFE and SDBC. Indeed, the studies carried out by Malhotra et al. 11 showed how the size and distribution of pore in binder contribute to the loss of activity at higher pressure. To address this issue, we have explored different approaches like high-pressure melting of PTFE film, PTFE overcoat, coating of other binders like polyvinylidenedifluoride (PVDF), perfluoroalkoxyalkanes (PFA), etc. to control the porosity of the film. These studies have led us to the successful development of hydrophobic platinumdoped carbon aerogel (PtCA) catalyst that shows good catalytic activity even up to 20 bar.In our earlier studies we had mixed PtCA powder synthesized...

The atmosphere is an important pathway to be considered in assessment of the environmental impact of radioactivity releases from nuclear facilities. The estimation of concentration of released effluents in air and possible ground contamination needs an understanding of relevant atmospheric dispersion. This paper describes the meteorological characteristics of Narora Atomic Power Station (NAPS) Nuclear Power Project site by using the integral parameters developed by Allwine and Whiteman (Atmospheric Environment 28(4):713-721, 1994). Meteorological data measured during the period 2006-2010 were analysed. The integral quantities related to the occurrence of stagnation, recirculation and ventilation characteristics were studied for the NAPS site to assess the dilution potential of the atmosphere. Wind run and recirculation factors were calculated for a 24-h transport time using 5 years of hourly surface measurements of wind speed and direction. The occurrence of stagnation, recirculation and ventilation characteristics during 2006-2010 at the NAPS site is observed to be 33.8, 19.5 and 34.7 % of the time, respectively. The presence of strong winds with predominant wind direction NW and WNW during winter and summer seasons leads to higher ventilation (48.1 and 44.3 %) and recirculation (32.6 % of the summer season). The presence of more dispersed light winds during pre-winter season with predominant wind directions W and WNW results in more stagnation (59.7 % of the pre-winter season). Thus, this study will serve as an essential meteorological tool to understand the transport mechanism of atmospheric radioactive effluent release from any nuclear industry during the pre-operational as well as operational phase.

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