[en] The first stage of Indian nuclear power programme envisages construction of a number of 235 MWe and 500 MWe pressurised heavy water reactors (PHWR). These unit sizes which fall within the small and medium power reactor range have been found to be optimum under Indian conditions. While the primary reason for choosing this system has been our objective to be self reliant in nuclear power reactor technology, the PHWR system also has many advantages from safety point of view. Further through a systematic development programme, a number of new features have been added to this system for better safety and performance. PHWRs have a number of distinctive inherent safety features such as availability of cool moderator within the reactor core, low excess reactivity, locations of reactivity control devices in low pressure regions, two independent shutdown systems, a double containment system with passive vapour suppression pool etc. Availability of such inherent safety features have assumed importance in recent times. An exercise has been carried out to make an assessment of safety characteristics of PHWR system under postulated extreme events scenario. It has been brought out that a small reactor with judiciously engineered safety systems can be developed into a system with effective inherent safety. A number of novel features can also be introduced in such systems to enhance both safety as well as the performance of the reactor system. (author)

[en] The safety concept of the PHWR is principally based on the same safety features as the light water PWR, e.g. reactor building consisting of a spherical steel containment and an outer concrete building with vented annulus inbetween. However, there are some specialities adherent to the heavy water reactor. Safety related systems are designed to be both, diverse and redundant. The moderator cooling system can be used as a high pressure heat removal sysem and thus is an addition to the heat removal via the steam generators. For reactor shut-down a control rod system and a boron injection system exist independently. (orig./HP)

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[en] Electronics devices when designed to meet specific requirements, the designers do not generally envisage the amount of electromagnetic interference that this particular device may give as power line conducted noise and radiated noise. After the product is developed, the quantification of the same is carried out in certified EMI-EMC set-up to get these figures of conducted emissions (CE) and radiated emissions (RE), and its mitigation as per limits of the chosen standard. In the latest TM embodiment of Fault Tolerant Power Distribution System ECPS"T"M (Electronics Corporation Power Supply) developed for NPCIL (PHWR700MW plant) we carried out CE and RE tests and quantified the spectrum obtained for CE and RE, and mitigated them as per CISPR22 standards. In this short article we bring out the CE and RE results of the latest product ECPS, done at EMI-EMC Centre of ECIL Hyderabad. (author)

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