ABSTRACT
The accident at the Three Mile Island nuclear plant dramatically focused attention on the danger inherent in the operation of all large-scale, complex, and potentially hazardous technologies-that is, that the combination of machine and operator performance will fall below the expected level of reliability and pose a threat to public health and safety. The promised benefit of the nuclear-energy economy is a certain supply of electrical power for at least 200 and possibly as many as 2000 years. The incremental approach is best suited to slowly changing situations in which errors can be quickly identified and in which the consequences of errors can be remedied at reasonable cost or are acceptable because of greater benefits. When a technology is rich in benefits but must be operated very carefully to avoid incurring unacceptably high costs, strong pressures arise for trials without error.
