The Question then arises, Juxtaposing India and Japan, do we too stand a chance of any such breach in the future, when we have already faced some Tsunamis in the past ?
Why Nuclear Plants are mainly situated near coasts (where Tsunami threat is at peak )? All Nuclear plants require a huge supply of coolants and water for cooling purposes of Nuclear Fuel Rods. Constructing them near a coast where large mass of water is available is due to economy reasons.
Firstly, India has 8 nuclear plants(including under construction) as shown in the figure below.
India has two coast-lines. East that contains Kalpakkam Nuclear Plant,Madras and West,that boasts of Kaiga,Tarapur and Kakrapar Nuclear plants. NPCIL(Nuclear Power Corp.) maintains that no reactor should be within 5km radius of fault line while Fukushima was located directly on a fault line (No fault of planners though, Japan has too many fault lines).
Moreover, Only one of the reactors are in Zone-4 (High Probabilty of Seismic Activity Area) which is Narora .Rawatbhata,Kalpakkam and Kudankulam are in Zone-2.Tarapur,Kakrapar,Jaitapur and Kaiga in Zone-3.Though Narora is in Zone-4,We need not fear much by it coz its not near a coast (No chance of rendezvous with tsunami :D) and Reactors do not fear earthquakes (Japan’s nuclear apocalypse started when Diesel Generators and switchgears were ruined by Tsunami Waves)
Out of all Indian nuclear reactors, Kalpakkam has the highest possibility of being stuck by Earthquake + Tsunami Combo. Let us assume that in Dec.2012,there is a tsunami (much like Japan’s) targeting Kalpakkam plant. Then too,We need not fear.Reason : Difference in Design of Japan’s and India’s Reactors.
Basically,there are two types of Nuclear reactors : 1) BWR (Boiling Water Type ) and 2)PWR (Pressurized Water Reactor)
In layman language,A nuclear reactor produces heat with the help of radioactivity. This heat converts water into steam which further rotates the turbine to produce Electricity. In BWR type, The cooling water is maintained at about 75 atm so that it boils in the core at about 285 °C. In comparison, there is no significant boiling allowed in a PWR-type because of the high pressure maintained in its primary loop—approximately 158 atm.
Thus a BWR-type requires a more powerful cooling system. It requires active cooling for a period of several hours to several days following shutdown.At an event of an earthquake,the nuclear reaction is automatically stopped. However, radioactive decay of the fission products in the fuel will continue to actively generate decay heat at a gradually decreasing rate. If active cooling fails during this period, the reactor can still overheat to a temperature high enough that zirconium in the fuel cladding will react with water and steam, producing hydrogen gas. In this event there is a high danger of hydrogen explosions, threatening structural damage to the reactor and/or associated safety systems and/or the exposure of highly radioactive spent fuel rods that may be stored in the reactor building as happened with the Fukushima I nuclear accidents.
In PWR-type there is no such problem. It runs cool. In contrast to a boiling water reactor, pressure in the primary coolant loop prevents the water from boiling within the reactor. So containment of Heat is relatively easier in this case. And so nuclear breach not a problem.
As India employs PWR-type nuclear reactors (Only Tarapur being BWR-type),we do not face any immediate nuclear doomsday like Japan :)
But still there are some Civil Engg. Factors involved that needs to be looked upon too. I,along with some friends, am working on it and will come up with the analysis soon.
