Nuclear Power plants in India have been designed for earthquake resistance by the methods of analysis & testing. Many of the electrical & instrumentation equipment have been tested on shake tables available in India. The performance of the civil structures, piping systems, cable trays, ducting and mechanical, electrical, instrumentation & control equipment in industries around Koyna (1967, 6.5 M), Bhuj (2001, 7.6 M) & Muzaffarabad (2005, 7.6 M) which have witnessed the earthquake is also available. Contrary to the common perception that Koyna, Bhuj and Muzaffarabad earthquakes were a complete disaster, the data collected on equipment performance from the industries around the area was that the equipment and piping failure due to inertial load were rather nil and wherever the failures were there, they were due to total collapse of the civil structure in which they were installed or falling of brick wall on to the equipment or piping or failure of equipment due to improper or no anchorage of the equipment or due to seismic anchor movement. Apart from the failures of transformers on wheels, battery banks on wooden stillage, false ceiling, lighting fixtures and brick walls the performance of other equipment was good (tanks, pumps, valves, compressors, DGs, fans and blowers, chillers, HVAC ducts, cranes, transformers, switchgears, MCCs, battery chargers and inverters, battery banks, distribution panels, MG sets, cable trays, false ceiling, glass partition, lighting fixtures, brick walls, piping system, instrumentation and control panels, instrumentation devices like relays, temperature and pressure sensors, switches, meters etc) Indian experience on equipment which have witnessed earthquake is from the general industry, although not from the Nuclear Power Plants, viz. thermal & hydro power plants, chemical & fertilizer industry, cement plants, petrochemical plants, electrical substations etc. and is very similar to the experience at Kashiwazaki-Kariwa NPP on soft rock (Vs30-400m/sec) and Shika NPP on hard rock (Vs30 1500m/sec) in Japan. Earthquake experience data from USA, European countries, Russia, Japan etc. as available in the form of Generic Implementation Procedure GIP-DOE, GIP-SQUG, GIP-VVER, FEMA, ASME-QME 1-2000, IEEE-628 etc. as collected by various institutes e.g. EPRI, EERI, LLNL etc from USA have also been used. The performance of the equipment during the shake table tests or during the real earthquake forms the data base of equipment, which can be used by general industry as well as by nuclear industry for their design and forms the part of the experience based data. Fom the experienced based data on the piping system, the major conclusion is to arrive at the support to be provided in the piping system. The supports for the piping in conventional industries are rod hanger or spring hanger type. The piping and cable trays supported with rod hangers have frequency less than 1 Hz and should experience an acceleration of about 0.03g on hard rock site; however, the spectra on soft soil used for the design of piping necessitated the piping and cable trays to meet an acceleration of 0.3g instead of 0.03g. As the rod hangers could not meet the qualification requirement for this acceleration, the supports were changed to angle and channel sections, thereby increasing their stiffness & frequency and being in ascending part of the spectra, resulted in attracting more acceleration, requiring further increase in the support section size, till the frequency of the system went in the descending part of the response spectra. Presently, this process of increased support stiffness is being reverted back to meet the low accelerations in low frequency region of the ground motion spectrum of SCR by using flexible supports or by having supports at 3 to 4 dead weight spans.
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