THE EVIL SPIRIT that watches over the affairs of the Nuclear Regulatory Commission -- its job is to ensure that everything that can go wrong does -- has been at work again. For a while after Three Mile Island, it got nervous: if the right inferences could be drawn from that accident, many of its efforts would be undone. But now the evil spirit can relax, for changes are being planned that will make things worse.

The NRC's newest problem is the president's proposed reorganization plan. What makes it so troublesome is that its subject -- lines of authority and bureaucratic organization -- is so inherently boring, hardly the stuff that can capture the attention of busy congressmen. The flaws in the president's plan are subtle, but if it is approved it will surely tie the NRC into knots that no one can untangle.

The trouble began with a recommendation made by the President's (Kemeny) Commission on Three Mile Island that the NRC be abolished and reconstituted with a single administrator inside the executive branch. However, the Kemeny report did not provide a persuasive explanation of why the NRC's undeniable organizational problems could not be solved without sacrificing the substantial advantages of a five-member commission. These are: continuity, independence from the Department of Energy and diversity among the commissioners in attitude and technical background. There was, therefore, widespread opposition to the proposal on Capitol Hill, and the president wisely decided to reject it.

However, there were many who opposed that decision, including -- this may surprise you -- the current chairman of the NRC, who believes the group he leads should be abolished. These dissenters devised a "compromise" solution, which combines the worst features of both possibilities -- keeping five commissioners, but giving virtually all power to one.

Under the president's plan -- which is criticized today in an article by NRC Commissioner Victor Gilinsky on the opposite page -- the NCR's 2,500 member technical staff would report not to the commission as they do today, but to the chairman only. The chairman would individually appoint the staff director and all but two of the staff members. The other four commissioners would participate in the licensing of nuclear reactors, but would have no say over the rest of the reactors' 30-year life, thereby encouraging the NRC's historic tendency to spend too much of its time on licensing and not enough on actual safety -- that is, on operations, inspection and enforcement.

What then are the other four commissioners going to do? The plan makes them responsible for certain rule-making and adjudicatory functions, and for "policy formulation." But where does policy begin and end? The NRC is likely to spend a solid year tied up in a debate on that one -- if it actually can ever be answered. The argument can be made that any important decision is "policy."

The plan does have a few redeeming features. Some of its proposed changes -- for example, that giving the chairman full powers during an actual emergency -- are important and worth preserving. However, Congress can only approve or disapprove the plan; it cannot amend it. The president should therefore use his option to amend the plan, restoring the equal responsibility of all five commissioners for substantive matters and their equal access to all relevant information, while retaining the chairman's new executive powers to manage the agency. The president should have the staff report to the full commission, and return the commission's power to appoint the key staff members. If he doesn't, the evil spirit is going to have a field day.