Nuclear Regulatory Commission officials and congressmen questioned the agency's effectiveness in policing the nuclear industry at a briefing yesterday on one of the most serious power plant failures since Three Mile Island.

Early on June 9, the Davis-Besse nuclear plant in Oak Harbor, Ohio, experienced a series of "incidents" similar to the problems that confronted the operators at the Three Mile Island plant in Pennsylvania six years ago.

At least 16 pieces of equipment failed at the Ohio facility, and plant operators pushed the wrong buttons at least once, according to NRC officials. It was the eighth time this year that equipment failure or employe error had caused the plant to shut down.

According to a memorandum prepared by the staff of the House Energy and Commerce subcommittee on energy conservation and power, the NRC has documented numerous shortcomings of the Davis-Besse plant since 1979, often without requiring the owner, Toledo Edison Co., to make the recommended modifications.

NRC officials yesterday were sharply critical of both Davis-Besse management and the NRC itself for not following the commission's recommendations, issued almost annually since 1979, that the plant have a third pump system to supplement the main pump system and the backup system, both of which are steam-powered. The plant's problems began with failure of both the pumping systems.

A 1975 NRC review plan said that auxiliary pumps should be powered by "diverse power sources." The Davis-Besse plant is the only one in the country that does not follow the review plan's suggestion and continues to use only steam-powered pumps.

Subcommittee Chairman Edward J. Markey (D-Mass.) said the incident "was waiting to happen" and "raised serious questions about whether the NRC is guilty of malpractice."

"Why did the NRC drag its feet and chase its tail for six years?" Markey asked commission officials.

NRC Commissioner James K. Asselstine said he agreed with much of Markey's criticism of the agency.

"I wonder why we have gotten so wrapped up in probabilities and cost analysis that we're losing the forest for the trees," Asselstine said. "We spent a lot of time arguing what we should have done a long time ago."

The subcommittee memo also says that during an April surprise inspection of Davis-Besse, the NRC found an unlicensed operator asleep in the main-pump room, a violation of NRC regulations.

Like about two-thirds of all nuclear power plants in the United States, including Three Mile Island, Davis-Besse keeps the uranium in its nuclear core submerged in water under tremendous pressure to avoid boiling.

The heat generated by the pressurized water is absorbed by a separate water system, creating steam that spins a turbine that produces electricity. The steam is then condensed back into water to absorb more heat.

At Davis-Besse, the problems began when the pumps failed that move the condensed steam, called feedwater, back to the reactor building to be boiled again. The auxiliary pumps, which, like the initial pumps, are operated by steam, then failed.

Both failures also occurred at the initial stages of the crisis at Three Mile Island.

Unlike the situation at Three Mile Island, the problems at Davis-Besse were resolved after 12 minutes when plant operators were able to restart the auxiliary pumps from outside of the control room.

The plant has remained closed since the incident.