Two new investigations have found that managers of the Three Mile Island nuclear power plant failed to pass on information that showed a deteriorating situation on the morning of the 1979 accident there. For the first time, however, one of the probes has determined that the information was deliberately withheld.

The Nuclear Regulatory Commission last week cited the Three Mile Island owner, Metropolitan Edison Co., for a "clear failure" to collect, analyze and release information about what was going on in the plant reactor as the accident developed.

However, the NRC's lengthly report of its investigation, found no evidence that anyone at Met Ed had lied about the situation either. "Met Ed was not fully forthcoming," the report said, while at the same time noting that "information was not intentionally withheld" from the Pennsylvania state government or the NRC. Instead, the report said, there was no system at Met Ed for gathering and evaluating all the information that everyone had.

But Rep. Morris K. Udall (D-Ariz.), chairman of the House Interior Committee, released the report of an investigation into the disclosure question by his committee majority staff, and it reached different conclusions. It found Met Ed officials "presented state and federal officials misleading statements . . . that conveyed the impression the accident was substantially less severe and the situation more under control than what the managers themselves believed and what was in fact the case."

Udall expressed concern in a letter to the NRC that its report "does not provide adequate support for its conclusions" that information was not intentionally withheld.

In the notice of violation to Met Ed management, NRC's inspection and enforcement director Victor Stello said "issues which were not reported to the NRC or the Commonwealth of Pennsylvania" included the utility's "uncertainty of core cooling and potential for degradation."

In other words, Stello said in an interview, Met Ed "did have questions" about whether the uranium core of the reactor was adequately cooled and whether things might get worse. "But they didn't come forward with that and they should have," he said, and therefore deserved the citation.

He characterized the management attitude as "hesitancy about casting things in the worst light, especially if you really thought that things were just about to get better," but said that did not mean the management lied.

"It wasn't intentional nondisclosure. It was that they didn't believe the information so they didn't pass it along," he said.

The March 28, 1979, nuclear malfunction caused some radiation to float over the Middletown, Pa., area, amid great confusion at the NRC and among state and local officials as to what was happening and how serious the problem might be. The NRC report said much potentially frightening information, including high temperature readings and a sudden burst of pressure in the containment building, indicated a serious problem but were outside the operators' training and experience. As a result, they were written off as faulty instrument measurements, Stello said.

Udall's report disagreed. "Managers did not communicate information in their possession that they understood to be related to the severity of the situation," it said in its conclusions. In the main report, it said, "TMI plant managers were aware of information indicative of a situation much more perilous than was reported to state and federal officials."

Stello's investigating team recommended against citing Met Ed for violation of the rules, but he overruled that recommendation because, he said, of his concern over the uncertainty question: "There was enough information for them [the Met Ed management] so that they should have started out by saying, 'We've got a lot of uncertainty and here's the things we're worried about.'"

Stello's letter stressed that all nuclear power plant license holders have the primary responsibility to "obtain, evaluate and communicate information" within the plant and to outsiders. "It is in this particular area that . . . there was a clear failure in Metropolitan Edison's response," the letter said. Two other probes of the accident agreed with the NRC that there was no deliberate coverup of information.

The NRC did not impose any penalty for the violation since the utility has already paid the statutory limit of $155,000 in fines for other rule infractions linked to the accident.

Doug Bedell, a Met Ed spokesman, said that the citations "return to previously identified problem areas that are already being addressed," including training, information flow systems, changes in instruments and revamped control room layout. He called the overall report "encouraging" in its findings that there was no willful withholding of information.