Three Mile Island Verdict

Human error is to blame

For many of the tourists who are flocking daily to Pennsylvania's crippled Three Mile Island nuclear power station, the 15-minute documentary may have the ring of authority. Prepared by Metropolitan Edison Co., the plant's operator, and being shown daily at the Observation Center across the river from Three Mile Island's cooling towers, the script has a glib explanation for last March's near disaster. It resulted, says the Met Ed film, from "a complex combination of equipment failures, ambiguous instruments and operator failures . . ." The production also insists that the amount of radiation released into the atmosphere was insignificant.

Unfortunately for the beleaguered utility, its film may now need some editing. For the past four months, the Nuclear Regulatory Commission (NRC), among others, has been looking into the causes and effects of the nation's worst commercial reactor accident. Last week, in a report that is sure to have wide repercussions, NRC staff investigators said that the most serious aspects of the mishap were almost certainly due to human error. And though they acknowledged that the radiation level was low, they said that one burst was greater than any previously revealed.

Some two inches thick and based on many hours of hearings, the NRC report will be some comfort to those who design and build reactors used to generate electricity. It states categorically that although the Pennsylvania plant was not "fail-safe," its equipment and emergency procedures "were adequate to have prevented the serious consequences of the accident, if they had been permitted to function or be carried out as planned." Trouble is, neither the equipment nor the preprogrammed safety procedures built into the Babcock & Wilcox reactor really got a chance.

The investigators confirmed that the plant's operators overrode the automatic safety systems in their attempts to correct the rapidly developing crisis that occurred when an electricity-generator turbine tripped, or shut itself down. Those actions, says the report, turned what should have been a relatively minor glitch into a potential disaster. Instead of letting the reactor's emergency core cooling system perform its safety functions, the operators paid "undue attention" to keeping the coolant from overfilling the reactor and refused to believe instruments indicating that the plant's fuel core was getting perilously hot.

Critical as the investigators may have been of the utility, the NRC itself got a wrist slap from Congress. In a report approved by a 29-to-2 vote, the House Government Operations Committee severely chided the commission for failing "to demonstrate strong constructive leadership" in developing evacuation plans and related emergency procedures for areas surrounding nuclear plants. Of 25 states that have these facilities, the study said, 16 do not have such NRC-approved plans. As one committee staffer summed up: the NRC just "pretended that accidents could not happen."

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