Three Mile Island

This document addresses the Three Mile Island accident which resulted in a core partial fusion. It recalls that other reactors of this plant are still being operated. The operation of this PWR is briefly described, and the main events and phases of the accident are briefly presented (failure of the secondary circuit supply pump, failure of a pressurizer component and wrong information about it, mistaken reaction in the control room, core partial fusion due to insufficient cooling means). It shows that the accident occurred because of a combination of technical failures and human mistakes. This situation has put operator education and organisation into question again. The main actors and their mistakes, weaknesses and responsibilities are indicated: Metropolitan Edison (the operator), the NRC (the US nuclear safety authority). Some key figures are recalled, as well as the context of construction of the plant. Impacts and consequences are reviewed: implementation of new standards, population concern. The document outlines that radioactive exposures due to the accident were minor