There is not enough reserve water inside the Koodankulam nuclear power plants complex for cooling the reactor cores and the spent fuel pools.
Links:
[1] http://admin.indiaenvironmentportal.org.in/feature-article/koodankulam%E2%80%99s-reserve-water-requirements
[2] http://admin.indiaenvironmentportal.org.in/category/author/v-t-padmanabhan
[3] http://admin.indiaenvironmentportal.org.in/category/author/r-ramesh-0
[4] http://admin.indiaenvironmentportal.org.in/category/author/v-pugazhendi
[5] http://admin.indiaenvironmentportal.org.in/category/journal/economic-and-political-weekly
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/koodunkulam-aps
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/water-demand
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/nuclear-power-corporation-india-npcil
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/nuclear-power-plants
[10] http://admin.indiaenvironmentportal.org.in/category/thesaurus/environment-impact-assessment-eia
[11] http://admin.indiaenvironmentportal.org.in/category/thesaurus/pechiparai
[12] http://admin.indiaenvironmentportal.org.in/category/thesaurus/reservoirs
[13] http://admin.indiaenvironmentportal.org.in/category/thesaurus/kanniyakumari
[14] http://admin.indiaenvironmentportal.org.in/category/thesaurus/drinking-water
[15] http://admin.indiaenvironmentportal.org.in/category/thesaurus/desalination
[16] http://admin.indiaenvironmentportal.org.in/thesaurus/atomic-energy-regulatory-board-aerb
[17] http://admin.indiaenvironmentportal.org.in/category/thesaurus/water-resources