WHERE DO YOU begin to try to raise the demonstrably deficient standards by which nuclear reactors are currently built and operated? This is the question at the heart of the Nuclear Regulatory Commission's debate over whether to allow Unit 1, the undamaged reactor at Three Mile Island, to begin operating again. By coincidence, Unit 1 was shut down for refueling at the time of the accident in Unit 2, and it has not been allowed to operate since.

At first, Unit 1 had to be kept shut down until the immediate effects of the accident had been assessed and dealt with. Then changes in the plant had to be made to correct deficiencies that became apparent during the accident. The final reason for the delay in allowing Unit 1 to start up again has proved by far the most difficult to deal with. This is the question of whether the management of the plant's owner, Metropolitan Edison, and its parent company, General Public Utility (GPU), is competent to operate a nuclear reactor.

The issue is an urgent one because GPU, facing billion-dollar clean-up costs for the damaged reactor, is on the verge of bankruptcy. The utility is spending $14 million per month to purchase replacement power for what Unit 1 might be generating. And GPU insists that Unit 1 is physically ready to go, as safe as other operating reactors of the same type.

Others feel differently. A number of investigations have found numerous technical failings at Unit 1, including safety features that should have been installed after the accident, but have not been. Last spring it was discovered that GPU employees had cheated on reactor operators' exams. At the re-examination last month, 14 of the 34 who took the test failed. On balance, however, if enough competent operators can be found and the necessary physical corrections made, Unit 1 does not seem to be significantly less safe than other reactors. It is an unfortunate, but apparently accurate observation, that the closer one examines the management and operation of nuclear utilities, the more flaws appear. GPU has been examined with great care.

A more serious charge, raised by a House interior committee investigation and by NRC Commissioner Victor Gilinsky, is whether the utility's management and employees lied to the NRC during and after the accident. The record of the accident and the numerous investigations that followed are still replete with contradictions and unexplained discrepancies. The NRC's most recent staff investigation concluded that the utility "knowingly" withheld information, but only because it was uncertain of its meaning, not with the intent to deceive.

Past bad behavior may seem minor in the light of GPU's effort to correct past failings while it struggles to regain financial solvency. Certainly the public interest will not be served if the utility goes bankrupt. But the past cannot be pushed aside, because the handling of this case will give the whole industry an indication of the standards of honesty and accountability the NRC expects in the future. The best solution for the NRC is to allow Unit 1 to operate as soon as it is physically ready, while vigorously pursuing the question of possible deception during and after the accident.