THE OUTLOOK FOR NUCLEAR power is, post-Kemeny, somber at best. But burning coal throws toxic gases into the atmosphers and, while technology can lower the risks to health, it cannot entirely eliminate them. Natural gas is needed for higher uses than firing utility boilers. As for oil, you have only to follow events in Iran to perceive that it has become the least certain of all sources of energy.

Uranium, coal, gas and oil: the country's four principal ways of generating electricity each lies under a shadow. Each is, for its own reasons, dangerous, uncertain or unavailable. How does the country avoid being left in the dark?

The first truth is that there is no entirely safe way to generate electricity. Any large power station, regardless of its technology, carries with it some degree of damage to the environment and some element of risk to public health. It's not a matter of finding a safe solution -- but of finding the safest among several choices.

The second truth is that the choices have to be made. The idea of at least a conditional moratorium on new reactors seems to be gaining momentum in Congress. But if you don't like nuclear power, what kind of power do you like? The most available alternative is coal -- but there is a death rate associated with the heavy use of coal. That is a thought for Congress and its constituents to keep in mind during the coming debates on nuclear regulation.

Fortunately, in most of the country, the need for new generating plants is not immediate. There is time -- although not unlimited time -- for reflection. It is the result, quite simply, of rising prices for power. Before the first oil crisis, six years ago, consumption of electric power in this country was rising 7 percent a year -- a phenomenal rate at which the total load doubles every 10 years. At that pace, utilities were under ferocious pressure to keep building plants and to keep building them constantly bigger.

But in the past several years, the pattern has sharply changed. The load is currently rising less than 4 percent a year -- hardly more than half the pre-1973 rate. That's why some companies have, temporarily, excess capacity. It's also why a lot of companies have cancelled some of their construction plans. For purely economic and financial reasons, sales of nuclear reactors had dropped off sharply even before the Three Mile Island accident. Utilities are now being pushed toward building smaller plants -- easier to locate and easier to manage safely.

Low rates of increase in consumption mean easier choices of power sources. A wise public policy for power will insist on a balance among different kinds of sources, avoiding total reliance on any one of them. But wise public policy will also recognize that conservation, to hold down consumption, reduces the risk from all of them.