GAO reviewed eight investigative reports and other supporting material on the nuclear accident at Three Mile Island. Most investigators agreed that the accident was caused by a combination of factors, including equipment malfunctions, inadequate operator training, poor designs, and inadequate operating and emergency procedures. Many of these deficiencies had been known by the Nuclear Regulatory Commission (NRC) for some time, but most were not considered important in view of NRC strategy for reactor licensing and design. The practices, procedures, and attitudes of NRC were challenged to such an extent that a major reorganization and restructuring of the agency was recommended. Previous GAO reports identified many of the same problems as found by the Three Mile Island investigations. Several of the studies of the radiation doses received by the population around Three Mile Island and by plant workers concluded that the accident had a negligible effect on the physical health of these people; however, it had a demoralizing effect on them.