[en] Effects of ethanol on phosphorylation of microtubule associated protein (MAP 2) were investigated. Extract from rat brain homogenate was exposed to varying concentrations of ethanol (U-384 mM) at 37⁰C for 30 minutes. Microtubules and MAPs were isolated by assembly and disassembly procedure. Proteins in these preparations were phosphorylated and phosphorylation of MAP 2 was examined by SDS-PAGE and autoradiography. Ethanol (4-24 mM) increased phosphorylation of MAP 2 as well as protein kinase activity in a dose dependent fashion. Higher concentrations of ethanol (> 24 mM) inhibited both phosphorylation of MAP 2 and protein kinase activity. In the presence of 2 μM cAMP or 24 mM ethanol, increased phosphorylation of MAP 2 was observed over control. Much higher phosphorylation of MAP 2 was observed in the presence of both cAMP (2 μM) and ethanol (24mM) than the sum of phosphorylation of MAP 2 by cAMP and ethanol separately. Kinetic studies of the influence of ethanol on MAP 2 phosphorylation reveal an increased rate of phosphorylation of MAP 2 and a decreased Km in the presence of ethanol. These studies suggest that protein kinase(s) other than cAMP dependent protein kinase are influenced by ethanol and the enzyme(s) phosphorylate at distinct sites on MAP 2

[en] Pressurized Heavy Water reactors have been adopted for the first phase of the Indian nuclear power programme. The major use of robots has been in the area of fuel handling. Details are given of the overall control scheme, the use of fluid power controls with oil, water and heavy water. (author)

[en] Graphite comprises about 2% of some of the 3.8-AE metamorphosed sedimentary rocks of Isukasia, west Greenland. Delta¹³Csub(PDB) of carbon in this graphite ranges from -16.0 to -9.3%. For those samples that contain both graphite and siderite, Δsub(carbonate-graphite) is about 6; this fractionation is consistent with an inorganic equilibrium between siderite and graphite at roughly 400-500⁰C. It is likely that graphite found in thise rocks formed by the reaction: 6FeCO₃=2Fe₃O₄+5CO₂+C in which case it is of little help in determining whether or not organisms were active 3.8 AE ago. The presence of quartz-magnetite-cummingtonite-iron formation in the Isukasia metasedimentary sequence may, ultimately, be one of the most powerful environmental indicators remaining in these rocks. (Auth.)

No abstract available

[en] The earliest concrete evidence regarding the existence of an ocean comes from sedimentary rocks 3.8 X 10⁹ years old. Oxygen isotope evidence suggests that the temperature of this body of water was less than 150⁰C and probably less than 80⁰C. The ¹⁸O enrichment of rocks indicates that recycling of water through the mantle is an important geological process. It is, however, difficult to evaluate whether net fluxes of water are causing the ocean to increase or decrease or remain the same size. Helium fluxes from the interior of the earth show that some volatile material is still coming out to the surface of the earth for the first time. The gradual increase in delta¹⁸O of cherts with time has been interpreted either as gradual increase in ¹⁸O of ocean or progressive cooling of the earth's surface. The present state of knowledge does not permit an unequivocal statement in favour of either one of the possibilities. (author)

[en] The control and instrumentation (C and I) system of an NPP is required to perform not only plant control functions but also safety related and shutdown functions. The C and I safety system has to be operative even when the plant is permitted to be shut down. This requires that the C and I system be ultrareliable. With increasing complexity of NPPs, operator information systems now have a direct bearing on safe operation of the plants. The paper discusses the evolution of the safety related C and I systems in NPPs, of the pressurized heavy water reactor (PHWR) type, in India. Beginning with the Rajasthan atomic power plant, a description is given of the safety and operator information systems backfitted and work done in C and I systems to improve the safety and reliability of the plant. Also, on the basis of experience gained in Rajasthan, improvements have been made in the Madras atomic power plant. These improvements and the ways in which they have contributed to safer and better performance of the plant are reviewed. For the Narora atomic power plant the extensive changes made by updating of technology, increased computerization, and improved operator information systems are discussed. The quality requirements have been made far more demanding for Narora, and the equipment has to meet more stringent operating, environmental and seismic requirements. The problems faced in building equipment and control systems to meet these requirements are outlined. C and I is a field undergoing rapid technological change. How this feature affects standardization in design and retrofitting particularly with respect to safety implications is discussed. The paper concludes with a discussion of the options available to the C and I engineer for the design of systems that will be able to meet the safety and reliability requirements of the NPPs of the 1990s. (author). 2 figs, 1 tab

[en] India has a comprehensive nuclear power programme with great emphasis on indigenization and self-reliance. In the field of control and instrumentation systems, the challenges faced by a developing country are best met by development of technology and transfer of technology for production and utilization in a reactor. Bhabha Atomic Research Centre and the Electronics Corporation of India Ltd have both been playing crucial roles as R and D organizations, generating the technology and as a production organization respectively. The various problems faced are illustrated by the example of development of fuel handling control systems for one of the power reactors under construction. The lessons learned are being utilized for spreading technology transfer to the industrial sector, outside the Department of Atomic Energy, to generate greater participation of industry in the Indian nuclear power programme. (author)

[en] Primary coolant pumps (PCPs) are the most critical equipment in PHWR and stuffing box is one of the critical parts of the PCP. The stuffing box houses the mechanical seals, radial bearings, throttle bushings and stationary part of wearing ring. During overhauling of PCPs it was observed that the cracks are developing on the inside face of the stuffing box and at the bolt holes where the lower bearing housing is fixed. Since consequence of failure of stuffing box will be a break in primary system boundary a detailed investigation was carried out to find out cause of failure. An immediate procurement of these from OEM (Original Equipment Manufacturer) was not feasible and indigenous procurement of such a large and precision-machined PCP component would have called for extensive development work. Under the circumstances, the only immediate option left was to repair and re-use these failed stuffing boxes. However, repair of these stuffing boxes was considered to be very difficult job as weld repair could cause distortion and any other option was not found suitable. Since the industry was not geared up to produce such components, a decision to carry out a heavy weld build up after removing the cracks up to root, was taken after considering various other options. Major weld repair and subsequent machining was carried out successfully on four stuffing boxes and subsequently these have been put in to service. The paper covers the investigations done, various options considered, how the weld repairs were carried out and the salient features of the indigenous development taken up. (author)

[en] Full text: The Nuclear Power Corporation of India Limited (NPCIL) is responsible for design, construction and operation for all nuclear power plants in India. Currently, it has fourteen (14) reactor units under operation and another eight units are under various stages of planning and construction. India has adopted Pressurised Heavy Water Reactors (PHWRs) for the initial phase of its nuclear power program. In the earlier PHWRs zircaloy-2 has been used as coolant tube material. Subsequent studies and experience have shown their life to be considerably lower (about 10 full power years) than originally estimated. This meant that reactors at Rajasthan - 1 and 2 Madras - 1 and 2 Narora - 1 and 2 and Kakrapara-1 would require en-masse coolant channel replacement at least once in their lifetime. Subsequent reactors from Kakrapara-2 onwards would not need this en-masse coolant channel replacement as the coolant tube material has been upgraded to Zr 2.5% Nb. En-masse coolant channel replacement and other life extension work have been carried out successfully in Rajasthan Unit-2 (RAPS-2). Madras unit-2 (MAPS-2) has been shutdown since January 2002 and preparatory work for en-masse coolant channel replacement and plant life extension is in progress. This paper discusses in brief the experience of RAPS-2 in carrying out the above jobs as well as the strategies being adopted for MAPS-2. Since the coolant channel replacement work requires a plant outage of about 18 months, this opportunity is used to extend life of existing systems as well as upgradation work. This life extension and upgradation program is based on the results of detailed in service inspection, evaluation of performance of critical equipment, obsolescence and other strategic reasons. This paper discusses in detail some of the major areas of work done, for example introduction of supplementary control room, process control, computer based plant information and event analysis systems, provision of enhanced emergency core cooling system, inspection and replacement of heat exchangers and steam generators, and enhancement of emergency power supplies. It needs to be recognised that RAPS was built in the 1970s. Thus considerable upgrades have been done to meet latest safety requirements. Hence jobs like segregation of safety related power supplies and cables to meet more stringently groups and channel philosophy, installation of fire barriers and modernisation of fire detection system have also been carried out. The paper discusses the tools developed including remote tooling, mock-ups done and special training given to ensure that the work is done safely in the shortest possible time and with the lowest man-rem consumption. For RAPS-2 results are compared with the original planned values and it will be noticed that considerable savings were achieved in man-rem, monetary expenditure and time taken for the job. One significant aspect of the coolant channel replacement and upgradation work has been that all the work was done within the department of atomic energy. This included theoretical work, experimental studies, actual execution of the jobs and inspection and testing. The role of industry has been limited to supply of equipment. For MAPS outside agencies have been invited to participate in actual execution of the jobs at site. This has considerably changed the method of planning and execution of the jobs. For future reactors greater role of industry in development and actual site work is envisaged. The paper discusses the options being considered by NPCIL. Plant life extension and upgradation of older plants throws up several issues related to safety regulatory criteria that the upgraded plant should meet. This paper discusses the methodology formed by the utility and regulatory authority to meet agreed criteria for safety. Also discussed are special areas of concern like configuration control, documentation, training and re-qualification of operations staff. This paper concludes with a discussion of the strategies of plant life extension for future reactors where the emphasis will be on better and more automated tooling preparation, modular replacement, detailed planning, engineering, configuration control and management of outage. (author)

[en] During the time of enmasse coolant channel replacement program, undertaken at Rajasthan Atomic Power Station and Madras Atomic Power Station, upgradation and ageing management activities of these units were also taken up with a view to improve the performance of the station. This paper presents the approach followed for handling the issues, pertaining to the ageing management and obsolesce of various components of Control and Instrumentation systems of these stations. Ageing related issues for field instruments, control room instruments and hardware like cables, terminal blocks and relays will be covered in this paper. It will also cover various aspects of ageing management like assessment of degradation due to ageing, policy followed for identifying the instruments that are to be replaced, selection procedure for items for assessment of residual life, testing method followed for life assessment and problems faced during replacement. From the experience gained, the issues to be addressed during design and construction stages of future plants to minimize the ageing related problems are also discussed in this paper. (author)