Three Mile Island accident incident analysis

These accidents, and many less devastating incidents that continue to occur today, were linked by an incomplete analysis of human factors. The human side of safety was ignored with high costs. Chemical manufacturers have yet to get over the impact of Bhopal, which killed 3,800 and injured over 200,000. Litigation is still in process. It required 4.5 years and 970 million to clean up after the Three Mile Island nuclear plant accident. That cost is hundreds of millions more than the cost to build the plant. Long-term environmental and health impacts of Chernobyl continue to haunt Russia and her neighbors. 

As a result of the analysis of events during the accident at the Three Mile Island nuclear plant (TMI, March 1979), the importance of human error in nuclear plants was better understood. The accident resulted from the confusion of the control room operators with inadequate instrumentation and inaccurate procedures. The most important factor was that they had to act in spite of the weaknesses in the training to respond to unexpected events. Therefore, the United States Nuclear Regulatory Commission (USNRC) called for the improvement of Emergency Operating Procedures (EOPs) and in nuclear reactor operator training. The philosophy of incident response implemented in the improved procedures was to take a symptom-based approach (operators foUow a series of yes - no questions to ensure that the reactor core remains covered and only then determine what was the cause of the problem) (USNRC, 2009). 

This is based on the Kepner-Tregoe method of rational decision-making. Change analysis compares a problem-free situation with a problem (accident) situation in order to isolate causes and effects of change. Change analysis is especially useful when the decision-maker needs a quick analysis, when the cause is obscure, and when well-behaved personnel behave differently from past situations, e.g. the Three Mile Island incident. 

Within process industries characterized by large production units and high levels of automation, risk and accident analysis is focused on the avoidance of low-probability events entailing serious consequences for the plant and its environment. Safety analysis is based here on causal or probabilistic models of the accidental chain of events that can serve to identify deficiencies in the design of the plant and its protective system as well as to predict the level of risk involved in an operation. Methods developed are fault tree analysis, MORT (Johnson 1975) and INRS (Leplat Rasmussen 1984). A detailed analysis of the actual, individual incident or failure is performed to identify these possible weak spots in the plant and its operation. It is a common experience that human acts play an important role in such industrial mishaps so, especially after the reactor incident at Three Miles Island in 1979, much effort has been spent on developing suitable predictive tools for the... 

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