North India earthquake fails to hit functioning of Narora N-power unit

Nuclear Power Corporation’s (NPC) atomic power station at Narora, in Bulandshahr district of UP, about 120 km from Delhi, continued to operate without a problem as an earthquake of 5.7 magnitude on the Richter scale rocked North India this evening.

The plant has two nuclear reactors of 220 Mw each. It is the lone plant situated in Seismic Zone IV. The other 18 reactors at five other plants are all in Seismic Zones II and III.

NPC chairman and managing director S K Jain told Business Standard: “All systems at Narora are working totally normally and both the units are operating and supplying power. The actual eqarthquake felt at Narora was much lower than the value for which the plant is designed to operate safely. Otherwise also, there are seismic instrumentations in the plant for the purpose of taking care of such incidents.”

He recalled that Narora had withstood earthquakes in the past of higher magnitude. Narora has withstood several hundred tremors in the past two decades since its commencement of operation in 1989. All nuclear power plants in the country have operated safely during earthquakes, informed NPC executive director N Nagaich. Adding: “The power generation from one reactor (at Narora) is 175 Mw and 145 Mw from the other. NPC is monitoring the situation.”

Today’s incident occured against the backdrop of the Japanese nuclear crisis, wherein four reactors at Fukushima in the North Japan were seriously damaged due to an earthquake and tsunami.

An NPC official said scientific studies are conducted for each location before deciding the grade level of nuclear plants. “We have a very large land area and a 7,500-km coast line. We do not need to have reactors in high seismic areas. The project site is selected on various criterias, including availability of sufficient wate for condenser cooling, low population density, grade level of the place and seismicity. After selection of the site, a detailed seismic survey is carried out, considering the earthquakes in that region for the past 300 years. Based on the major and inferred data, the magnitude of possible earthquakes and ground acceleration is calculated. Further, as per a formula, the magnitude of the assumed earthquake is enhanced.”

The structures of the plant and equipments mounting inside are designed in line with the enhanced magnitude of quake and corresponding ground acceleration. An NPC official said Indian nuclear plants are designed for magnitudes of quakes ranging from 5.5 to 6.7 on the Richter scale.