Disasters

Nuclear Catastrophes


International Nuclear Event Scale

·         Introduced in 1990 by IAEA
·         Enables prompt communication of safety significance in case of nuclear accidents
·         Logarithmic
·         There are 7 levels: 3 incident levels and 4 accident levels
·         Level 7 – Major accident: Chernobyl, 1986
·         Level 6 – Kyshtym disaster (Mayak, Soviet Union), 1957
·         Level 5 – Three Mile Island US, 1979; Windscale Fire (UK), 1957
Chernobyl Disaster
Three Mile Island Disaster

2011 Japan Nuclear Disaster

·         At the three  reactor units at the Fukushima Daiichi nuclear power station
·         Located in the town of Okuma in the Futaba District of Fukushima Prefecture, Japan. Combined capacity of 4.7 GW.
·         What caused it?
o   The earthquake caused a power failure
o   The subsequent tsunami knocked out the generators that produced the power
o   Lack of power in turn caused the cooling systems of the reactors to fail
o   This led to a partial meltdown in the three reactors
·         Background       
o   Fukushima 1 reactor went critical in 1971
o   All the three are Boiling Water Reactors (BWR) and use demineralised water for cooling nuclear fuel
·         Methods that can be adopted to avoid a meltdown
o   Pump sea water to reduce the heat
o   Boric acid is an excellent neutron absorber. Using it would reduce the chances of nuclear reactions restarting even if the fuel is found loose inside the reactor core.
o    

Nuclear Safety

·         The disaster has re-ignited the debate on the safety of nuclear power
·         AERB should be made an independent regulator
·          

Earthquakes

·         Ring of fire in the pacific ocean
·         Largest Earthquakes by Magnitude
o   Valdivia, Chile, 1960: 9.5
o   Prince Sound Willaim, Alaska, 1964: 9.2
o   Sumatra, Indonesia, 2004: 9.1
o   Kamchatka, USSR, 1952: 9
o   Sendai, Japan, 2011: 9

Tsunami

·         Intensity measured by the Soloviev-Imamura tsunami intensity scale.
·         Major Tsunamis
o   2011: Japan
o   2004: Indian Ocean

o   1908: Messina, Italy

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