S. RAGHOTHAM In 2006, former KGB officer Alexander Litvinenko was killed in London by unknown assailants who gave him a tiny dose, less than a microgram, of Polonium-210 : Whether it was accident or "mischief", the 40-50 people who ingested tritiate water at the Kaiga nuclear power plant on November 24 were lucky not to have been radio-poisoned with something more dangerous. Tritium is a mildly radioactive isotope of hydrogen, quite harmless in low concentrations. World over, though, nastier people have played "mischief" with nastier radioactive subIn 2006, former KGB officer Alexander Litvinenko was killed in London by unknown assailants who gave him a tiny dose -- less than a microgram -- of Polonium-210. In Germany, a man attempted to poison his exwife with plutonium caught in rags that had been used to clean surfaces in the reprocessing plant where he worked. During the Cold War, Soviet secret police Stasi are alleged to have used even medical X-ray equipment to induce cancer in political prisoners. Could the mischief maker of Kaiga have laid hands on more lethal substances than tritiate water? NPCIL chairman S.K. Jain told this newspaper that is impossible. "He could have got access only to heavy water or tritiate water since these are routinely moved in small quantities for analyses and their radiation levels are below the range of sensors. The other thing available is the fuel, but that cannot be touched by hand. One would have to have access to specialised handling equipment. That's next to impossible. In any case, the alarms would have gone off if anyone attempted that. Chemicals like polonium is not available in our power reactors," Dr Jain said.