Nuclear Regulatory Commissioner Victor Gilinsky issued a blistering indictment yesterday of the owners of the Three Mile Island atomic power plant, saying it was "simply unacceptable that the company responsible" for the nation's worst nuclear accident should be allowed to restart a reactor there.

Gilinsky, in a unilateral declaration opposing the bid by General Public Utilities to put the undamaged Three Mile Island Unit 1 back into operation, said the company has been slower than most to comply with safety standards set since the 1979 accident at TMI Unit 2.

"The conditions that led to the accident at Three Mile Island Unit 2 have not been cured," Gilinsky said.

He said that unless the top management of GPU, including the chairman and president, are replaced, "I am not prepared to approve the return of Three Mile Island Unit 1 to operation."

In a separate statement yesterday, NRC Chairman Nunzio Palladino said that he was dismayed by Gilinsky's declaration and that the commission would not be able to decide the key issue of whether the GPU management is competent to operate Unit 1 "for at least a couple of months."

NRC Commissioners James Asselstine and John Ahearne also issued brief statements agreeing with Palladino that the commission does not yet have all the information needed to decide whether to permit restarting the Unit 1 reactor. There was no immediate reaction from Commissioner Thomas Roberts.

Gilinsky, in a 25-page statement, accused the GPU management of:

* Taking a "narrow and grudging conception of its public responsibilities," and trying to "get by with the minimum, be it in terms of plant equipment, or of staff discipline and training, or of forthrightness with public authorities."

* Withholding "information about the severity of the accident" at TMI Unit 2 from the state of Pennsylvania and the NRC early on the day of the accident, "when public protection was most critical."

* Being "astonishingly tolerant of cheating by its employes, most particularly by senior members of its operating staff," on examininations for reactor operator licenses.

* Being "extraordinarily slow . . . in making the changes to plant equipment and procedures required at all plants by the NRC Action Plan as a consequence of the experience of the Three Mile Island accident."

* Trying to "scrape by in complying with the new emergency preparedness requirements resulting from its own accident."

Gilinsky also expressed concern about the NRC's "own performance in this case.

"Throughout this inquiry, the NRC staff has been inordinately lenient with GPU," Gilinsky said. "The staff's habitual alignment with GPU has been particularly unfortunate as it has undermined the public's confidence in this agency."