MAPS allays people’s fear over safety of Kalpakkam nuclear plant

Adequate mechanisms are there during quake to safe shut down reactor: MAPS director

C Shivakumar

Chennai:

Madras Atomic Power Station (MAPS) on Friday allayed people’s fear over safety and security of nuclear reactors during earthquake and said all emergency power equipment and deaerator storage tank and piping have been strengthened from severe earthquake considerations.



Station director of MAPS K Ramamoorthy told Express on Friday that earthquake warning system exists at Madras Atomic Power Station to take mitigating actions for safe shutdown of the reactors to maintain core decay heat removal and to ensure containment integrity.



He was reacting to allegations made by anti-nuclear activists that safety and security of reactors is inadequate as Kalpakkam lies in high risk seismic zone.



Ramamoorthy said MAPS is located in the south-eastern border of peninsular shield and it falls in Zone-3 which is associated with low seismic potential.



“The suitability of the site from the seismic consideration has been studied in detail and design parameters are evaluated for S1 and S2 level of earthquake,” he said.



“The S1 or Operating Babis Earthquake (OBE) is considered to be the maximum ground motion which can reasonably be expected to be experienced at the site area once during the operating life of the nuclear power plant with an estimated return period of 100 years or so. Similarly, S2 level or Safe Shut Down Earthquake (SSE) corresponds directly to the ultimate safety requirement. This level of extreme ground motion has a very low probability of being exceeded and represents the maximum level of ground motion to be used for design purposes,” he said.



“The evaluation is based on seismotectonic model and detailed knowledge of geology and engineering parameters of the strata beneath the site area with a return period of the order of 10,000 years. The geological and seismological investigations reveal that the Kalpakkam site is outside the range of capable fault,” Ramamurthy added.



He said the station is designed to handle the loss supply from grid through onsite power from emergency diesel generator sets and station batteries. “Even in case of failure of diesel generators, design provision exists to maintain the reactor in safe shutdown state with continous core decay heat removal by thermosyphoning mode of cooling,” he added.



“For this, water make up to boilers will be done by operating the diesel engine driven fire fighting pumps. In case of non-availability of these pumps also, provision exists to make up water to the boilers through the hook up points and mobile fire tenders available at site, which will be deployed for pumping water to boilers,” he added.



Other safety features:

--- Station batteries are designed to supply power for a minimum period of 8 hours to operate essential equipments for safe shutdown status of the plant.

--- 37.6 million litres of water stored in MAPs reservoir is adequate for more than seven days.

--- Additional water supply from two more reservoirs of Indira Gandhi Centre for Atomic Research and BHAVINI is also available.