Three Mile Island Nuclear Disaster of 1979

Added on - 16 Oct 2019

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1979: Three Mile Island nuclear disasterBrief:In 1979, in nuclear power plant in USA at Three Mile Island, due to some coolingmalfunction a part of the core melted in a #2 reactor. Due to which the TMI-2 reactor wasdestroyed. A few days after the accident, some radioactive gas was released however, it did notcause any harm to the local residents and no injuries or cases of adverse effects from theThreeMile Islandaccident was seen.Causes:1.)Inadequate failure information system: there were issues with the failure informationsystem present in the control room which caused inadequate emergency response by theiroperators. It was seen that the view of LED was blocked by the warning sign whichindicated the closing of feedwater valve and on closure of the valve a green LED was lit.Furthermore, the level of water was not indicated by the actual amount of water presentin the pressurizer. The operators did not realize that the plant was on the verge ofexperiencing a loss-of-coolant accident and took various actions making the conditionsworse.2.)Lack of reliability assurance: repeated troubles were seen in the malfunctionedpressurizer relief valve and was highly unreliable. In spite of this particular issue, noreplacements were done with the reliable.3.)Inadequate training of operators: All the contract operators lacked proper knowledgeregarding the thermal phenomena and nuclear reactors. They were not even trained forthe accident situation.1
4.)Unexpected event not in the safety design standards: the safety devices of these nuclearplants were designed for handling various nuclear accidents however, the event that tookplace were not assumed and no one gave a thought on how to handle this case.Due to the unplanned automatic shutdown of the reactor, the operators were unable to respond orto diagnose. The root cause of the issue was the deficient control room instrumentation alongwith the inadequate emergency response training. Due to these problems and confusions amongthe officials the accident turned worse and an advisory was issued for evacuating the preschoolchildren and the pregnant women present within the 5-mile radius of the Island.Action taken by the Emergency Response TeamDue to the atmosphere of total confusion among the team, the response lacked all the keyrecommendations. The TMI management as well as the engineering personnel had variousdifficulties while analyzing the events. Significant delays were seen to occur even after thesupervisory personnel took the charge even before the core damage. The key TMI-2 operatingand the emergency procedures took place including LOCA procedure and the operation ofpressurizer were found to be inadequate causing confusion among the operators. During the firsttwo days of the disaster the communication channel between the site and the NRC IncidentResponse Center in Maryland where all the senior management people were located was foundto be extremely difficult so as to obtain all the up-to-date data and information. Therefore thesenior management did not develop a thorough understanding of the site conditions. Thereforethe decision of evacuation which was recommended by the NRC senior staff was done on thebasis of the erroneous information which was highly partial and even fragmentary(ThePresident's Commission On The Accidental Three Mile Island, 1979).2
Lessons Learnt:1.)Responsibility for operation belongs to the management, and not to any federal or stategovernment or regulators.2.)The operating crew and its competence is highly vital. The dangerous technologies likenuclear power and chemical plants.as all these include human in their operation it canlead to the financial damage along with the societal damage. Therefore care must netaken.1984: Bhopal India Union Carbide incidentBrief:The Bhopal disaster is also known as the Bhopal gas tragedy which is a gas leak incidentin India and is the world’s worst industrial disaster. This incident took place on the night of 2-3December 1984, at a pesticide plant Union Carbide India Limited (UCIL) in Bhopal, MadhyaPradesh. Due to the exposure from the methyl isocyanate (MIC) gas and other chemicals. Theshanty towns which were located near the plant were surrounded by the toxic substance(Nair,n.d.).Causes:1.)Underinvestment:The UCIL managers considered high cost cutting leading to the lowerattention being paid towards the maintenance and the safety standards. Due tounderinvestment no maintenance supervisor was placed at the night shifts. Furthermore,the plant had introduced a careless washing method which started a powerful exothermicreaction in the plant and its construction in a place with dense population.2.)Adequacy of equipment and safety regulations:3
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