[en] After giving a general description of ECCS and its woking and mentioning the factors on which its reliability is dependent, salient features of the ECCS of the Narora Atomic Power Project (NAPP) are described. Light water, instead of heavy water as in the Rajasthan Atomic Power Station, is to be used as an emergency coolant in NAPP, avoiding the possibility of moderator grade heavy water being mixed with primary heat transport system heavy water. Assuming that the recommended frequency of testing valves, switches and relays is adhered to, overall unreliability of the ECCS of NAPP comes to 0.9985x10^-2 which is within set permitted value of 10^-2. (M.G.B.)

[en] The paper describes India's initiative for early detection of nuclear emergency. The various scenarios of nuclear emergency and the criteria for selecting locations for establishing monitoring stations are enumerated. The features of indigenously developed solar powered radiation monitoring system with GSM based data communication are described for getting an insight of the system. (author)

[en] Prediction of downwind tritium air concentrations in the environment around Narora Atomic Power Station was studied on the basis of Gaussian plume dispersion model. The tritium air concentrations by field measurement [measured tritium air concentrations in the areas adjacent to NAPS] were compared with the theoretically calculated values (predicted) to validate the model. This approach will be useful in evaluating environmental radiological impacts due to standard pressurised heavy water reactors. (author)

[en] Zircaloy-2 and Zr-2.5% Nb pressure tubes undergo corrosion upon exposure with the heavy water coolant that flows through it and pick up hydrogen, one of the products of the corrosion reaction, during the in-reactor service leading to hydride precipitation and subsequent deterioration in its mechanical properties. Thus the hydrogen pickup becomes a life-limiting factor for zircaloy-2 pressure tubes and, therefore, the concentration of hydrogen needs to be evaluated periodically. The paper discusses a technique for the estimation of the hydrogen content in the operating pressure tubes by determining hydrogen equivalent (H_eq) profile using in-core scrape sliver sampling and analyzing the silver samples by Differential scanning calorimetry (DSC). The scrape silver sampling was carried out at predetermined locations and the H_eq profile along the length was generated. Analysis of more than 600 samples collected from different Indian pressurized heavy water reactors has been carried out in the past five years. The data generated was utilized in assessing the condition of the pressure tubes for continued safe operation of the reactors. The paper gives a comparison of H_eq content between the zircaloy-2 and Zr-2.5% Nb pressure tubes used in different PHWRs for operating periods ranging from 6.7 to 11.45 hot operating years of reactor operation. (author)

[en] As a part of emergency preparedness programme, environmental radiation monitoring of Emergency Planning Zone (EPZ) (16 km radius) of Nuclear Power Plants (NPPs) is being carried out periodically. An environmental radiation monitoring of EPZ of Narora Atomic Power Station (NAPS) was carried out by installing various state-of-the-art mobile radiation monitoring systems in a vehicle and soil samples were collected from 40 locations. Around 200 important villages within EPZ were monitored and the radiological mapping of the monitored area is shown. The average dose rate recorded was 125 ± 28.8 nGy h"-"1. Analysis of the collected dose rate data and the soil samples indicate normal background radiation level in the area

[en] A short account of the development of prestressed concrete anchorages of 200 tonne capacity for the containment structure of the Narora Atomic Power Station is given. For prestressing, 12 T 13 multistrand system was adopted. The anchorage assembly and the tests carried out are described. (M.G.B.)

[en] The aim of its three-stage nuclear power programme is to ultimately utilize the thorium deposits on a large scale and to maximize the use of modest reserve of natural uranium in PHWRs and also produce plutonium as a by-product to be used in second-stage. The first-stage of PHWRs is already in industrial domain and presently 14 PHWRs having total installed capacity of 3720 MWe are in operation in India. Narora Atomic Power Station (NAPS) falls under first-stage and is situated on right bank of Holy River Ganga in District Bulandshahr of Uttar Pradesh, 160 km east on Delhi-Badaun high way

[en] In the early morning hours on March 31, 1993, a major accident took place in a nuclear power plant located at Narora in Northern India. A huge fire with bright yellow-red flame was seen at both ends of the generator. Extensive damage to the power and control cables and bus ducts took place during this accident. The vertical aluminum ducting above the neutral transformer was completely melted. The ducts ending near the excitation panels had been shattered. All the panels of AVR, Field Breaker and thyristor cubicles were completely damaged in the fire. Mechanical failures include fatigue fracture of Blade No. 52 of the last stage, Bearings No. 4 and No. 5, Generator seals. This paper describes the role of electrical systems in this accident

[en] Atmospheric tritium activity is measured regularly around Narora Atomic Power Station (NAPS) since gaseous waste, which contains tritium, is being released through a 145 m high stack at NAPS site. Atmospheric data collected during 2004-2008 shows a large variation of ³H concentration in air, fluctuating in the range of ≤0.2-91.6 Bq.m^-3. Significantly, higher tritium levels were measured in samples near the site boundary (1.6 km) of NAPS compared to off-site locations. The atmospheric dilution factor was found to be in the range of 1.1x10^-7-7.3x10^-7 s.m^-3. The scavenging of NAPS site was found to be varying from 0.2x10⁴ to 14.1x10⁴ (Bq.m^-3 rain water per Bqm^-3 air). The inhalation dose to a member of general public at different distances (1.6-30 km) from NAPS site was found to be in the range of 0.21 μSv.y^-1. (author)

[en] Narora Atomic Power Station (NAPS) has a Station Training Center (STC). It has been functioning at NAPS since the commissioning stages of the plant and over the years, it has played a vital role in developing the competency of personnel from O and M disciplines