[en] Lead Apron as individual shielding is used primarily in Radiology for protection of personnel against ionizing radiation. Occasionally lead apron of specific design are being used in reactor environment where one-sided radiation fields are encountered. The protection provided by Apron has been evaluated using personnel dosimeter. Based on the results the utility of lead Apron has been discussed in view of ALARA. The paper discusses the results and the recommendations for use in reactor environment. (author)

[en] The paper deals with the special features of VVER-1000 reactors (V-412 design). Also in the paper following are included - loss of electrical load event analysis which is an anticipated operational occurrence (AOO), analysis of reactor safety during station black out upto 24 hrs. (author)

[en] The Indian Nuclear Power programme is seen a promising and sustainable energy source. The maintenance management and associated surveillance programme play a key role in maintaining higher degree of safety and plant availability. The Maintenance Manager has to cope up with the challenging problems such as limited maintenance accessibility, compact plant designs, less available time for field maintenance. Sophisticated instrumentation and complicated operational requirements make the task different from conventional industrial maintenance. (author)

[en] Post-fabrication chemical cleaning was carried out for the cylindrical aluminium calandria vessel of the Critical Facility at BARC, to remove the adherent grease, soil and fine iron corrosion products deposited on the structure in the shop floor environment. A four stage cleaning procedure employing acetone, citric acid phosphoric acid and nitric acid was used. Safety precautions were observed and appropriate safety gears used. The base metal corrosion was evaluated on test coupons. Thirteen hollow cylindrical aluminium jackets for ion chambers were also cleaned in the laboratory using the same basic procedure. (author)

[en] FBTR is operated with well laid out procedures by qualified personnel adhering to the technical specifications. However, in the course of operation of FBTR which is the first LMFBR of our country, anomalies/deviations have occurred and failures/malfunctioning have occasionally led to reportable incidents. These have been attributed to reasons like deficiencies in the systems and procedures, human errors and component/system malfunctioning. These incidents have provided valuable experience to the plant management and personnel to handle the off normal conditions and also served as operational/safety experience feedback for the PFBR design. This paper describes experience of FBTR in identifying the deviations and mitigating the consequences, analysis of events/significant events and restoring the affected system to healthy condition. Some significant events/events are also described. (author)

[en] The instrumentation of Fast Breeder Test Reactor (FBTR) can be classified into Nuclear Instrumentation, Process Instrumentation and the Central Data Processing System (CDPS). In this paper, the experience on the above instrumentation is discussed, detailing various problems faced like noise pick-up and component obsolescence in nuclear channels, spurious actuation of sodium leak-detectors and level-detectors, speed fluctuations in primary sodium pumps etc. Various measures taken and modifications incorporated to overcome the above problems, replacement of first generation neutronic channels, replacement of sub-system-II of CDPS with state-of-the-art embedded systems dedicated PC based systems added due to additional requirements are also discussed. (author)

[en] Experimental studies on the rewetting behaviour of hot vertical annular channels were performed to study the mitigation of consequences of loss of coolant accident (LOCA) for a high flux research reactor. Studies were carried out to study the rewetting behaviour with hot inner tube, for bottom flooding and top flow rewetting conditions. The tube was made of stainless steel. Experiments were conducted for water flow rates in the annulus upto 7 litres per minute (l pm) (11.7 x 10^-5 m³ s^-1). The initial surface temperature of the inner tube was varied from 200 to 500 degC. (author)

[en] Water coolant chemistry and corrosion processes are important in the reliable operation of Nuclear power plants because of the aggressiveness of water at elevated temperatures when it comes in contact with structural materials. The role of the water chemistry is suitably programmed to mitigate the harmful effects of chemical impurities and corrosion on plant systems, ensuring the long-term reliability of plant equipments. The water chemistry control programme is also aimed at reducing radiation fields in the plant and releases of radioactivity to the environment. Water regimes for commercial PHWRs, PWRs, VVERs and BWRs were developed over the years and proved to be satisfactory. Nevertheless, studies of operational experience continues and new R and D work is being conducted for further improvement of the technology and a better understanding of the physico-chemical nature of those processes. Information is presented and discussed on-the water chemistry specifications of PHWRs, PWRs, VVER-1000 and BWRs. (author)

[en] Permissible radionuclide concentrations in drinking water (PRCW) can be used as benchmarks to assess the quality of drinking water with respect to radiation safety. PRCW of selected radionuclides are presented in Table 1. It is derived for a reference dose limits of 0.1 mSv per year based on the drinking water consumption of 3 liter per day. The variation of drinking water consumption at various nuclear sites (in India) with the average consumption rate is less than 24 %. Comparison of PRCW with WHO radionuclide guidance value in drinking water shows that PRCW is more restrictive than the WHO values due to high water consumption rate. To comply with WHO reference dose limits of 0.1 mSv per year through the drinking water pathways, it is desirable that the total dose apportionment to the aquatic discharges of radioactive liquid effluent from any inland nuclear site should be limited. 0.1 mSv per year. (author)

[en] Irradiated fuel rods are transferred under-water from Reactor Building (RB) to Spent Fuel Storage Building (SFSB) for further processing. Fuel transfer buggy is used for transferring irradiated fuel rods from Fuel Discharge Port (FDP) to SFSB. A cutting saw is used for bisecting the fuel assembly under-water. Both the equipments are vital and majority of the components of these are difficult to access. Downtime of these equipments directly affects the reactor operation. Based on the operating experience and feed back, modification and design up-gradation have been done on these equipments resulting in improved performance and availability. This paper describes some of these modification and up-gradation on these equipments. (author)