The nuclear industry would like to forget April 26, 1986, the day the worst nuclear disaster hit the world. Ironically, the Chernobyl accident occurred when an experiment to improve the reactor safety system went terribly wrong. The operators wanted to find out whether an electrical system they made by using the kinetic energy of the slowing turbo-generator, could provide enough electrical power to operate the emergency equipment and the core cooling water circulating pumps until the diesel emergency power supply kicks in.
Writing in The Guardian on April1, 2016 Dr David Robert Grimes, a scientist at Oxford University, aptly noted that “the mixture of flawed design, disabled redundancies and a tragic disregard for experimental protocol all feature heavily in the blueprint of the disaster.”
A massive steam explosion blew the 1,000-ton top steel case through the roof of the reactor building. A second explosion threw out burning fragments of nuclear fuel and graphite starting fires at five locations on the roof made of bitumen! The unprepared and unprotected firemen became the first victims of the accident. Investigators estimated that about six tonnes of uranium dioxide fuel and solid fission products including many radio-nuclides escaped.
Health effectsThe authentic report of the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR-2008) published in 2011 stated that 28 out of 134 heavily exposed plant staff and emergency workers died due to radiation exposure. Further 19 of the survivors died by 2006. They died due to various reasons, usually not associated with radiation exposure.
“Among the several hundred thousands of recovery workers, apart from an indication for an increase in the incidence of leukemia and cataracts among those who received higher doses, there is no evidence of health effects attributable to radiation exposure,” UNSCEAR noted.
Since authorities did not initiate prompt countermeasures against contamination of milk with iodine 131, some members of the general public received large doses to their thyroid; this led to a substantial fraction of the more than 6,000 thyroid cancers observed to date among people who were children and adolescents in April 1986 (15 of them died by 2005).
“To date, there has been no persuasive evidence of any other health effect in the general population that can be attributed to radiation exposure,” UNSCEAR concluded. In “NucNet Chernobyl Fact File,” NucNet, a global nuclear news agency updated the grisly details of the disaster this month.
Authorities evacuated about 45,000 inhabitants of Pripyat, the nearby town, on April 27, never to return; the town remains how it was left. Later they resettled 210,000 people into less contaminated areas, The accident resulted in the radioactive contamination of 18,000 square kilometre of agricultural land, of which people could no longer farm 2,640 square kilometre.
Present statusInternational Atomic Energy Agency (IAEA) noted that “since 1986, radiation levels in the environment have fallen by a factor of several hundred, due to natural processes and counter-measures and most of the land contaminated with radio-nuclides has been made safe and returned to economic activity.” Except in areas very close to the stricken reactor, increase in doses were low, often within natural background radiation present everywhere.
About 2,500 workers are assembling at site a humongous 36,000-ton new containment shell (cost $2.45 billion) 350-foot high and 500-foot long with a design life of 100 years. This marvellous piece of engineering will be slid over the stricken reactor and the old shelter (sarcophagus).
The Chernobyl accident forced Russia to eliminate the deficiencies that caused the accident in 15 similar reactors. There are no such deficient reactors operating in any country.
A study led by Prof. J. T. Smith, University of Portsmouth, U.K. has revealed abundant wild life populations at Chernobyl ( Current Biology, October 5, 2015).
“Chernobyl led to a leap forward in global cooperation on nuclear safety. Countries with nuclear power began sharing information and experience in a way they never had before. The IAEA’s mandate on nuclear safety was enhanced. IAEA Safety Standards were expanded,” Mr. Yukiya Amano, the Director General, IAEA stated on April 26.
He listed other notable developments: IAEA adopted important international legal instruments including the Convention on Nuclear Safety; the agency set up an international coordinated response system, with the IAEA's Incident and Emergency Centre at its heart and an IAEA peer-review system which involves the deployment of international teams of experts to advise countries on the operational safety of their nuclear reactors or the effectiveness of their regulatory system.
K.S. PARTHASARATHY
ksparth@yahoo.co.uk
(The writer is a former Secretary of the Atomic Energy Regulatory Board.)
