FIREWOOD, according to one calculation, is now producing much more heat for Americans than all the nuclear reactors put together. That's an arresting thought, but it deserves examination. There has been a sharp trend to the use of wood stoves in the past few years. The atavistic appeal of that crackling fire is powerful. But the comparison with nuclear energy seems to imply that it's possible to dispense with the reactors altogether by turning back to man's earliest fuel.

The federal Consumer Product Safety Commission keeps a count of serious injuries reported by hospital emergency rooms. In 1974 the commission estimated about 40 injuries from fires started by wood stoves or open fireplaces. Five years later the figure was about 400. Those numbers do not count burns to people falling on stoves, or cases of carbon monoxide poisoning.

The National Fire Protection Association in 1980 counted 26 fires started by wood stoves, fireplaces or chimneys, in each of which three or more persons died. Can you imagine the state of the nuclear industry if there had been 26 reactor accidents in which three or more persons had died?

As we have observed before, nuclear power has a very thin future in this country, and in most others, for reasons that are essentially economic. But perhaps it's necessary to repeat that no method of staying warm in winter is entirely safe. Nuclear energy brings with it a well-known catalog of risks. It remains curious that people who are deeply frightened by those hypothetical risks are prepared to shrug off the reports on fatal fires. There's one standard for the familiar and simple; there's another for the unfamiliar and esoteric.

Even the safest and best-managed of reactors produces radioactive wastes, and the country can't make up its mind how to dispose of them. A wood fire is simpler; a lot of the waste simply vanishes into the atmosphere in the form of air pollution. One of the pollutants is carbon dioxide, which, as it accumulates, may eventually begin to change the climate of the planet. Carbon dioxide overloading may ultimately prove to be the compelling reason to work with energy technologies, including nuclear technologies, that do not require combustion.

Or perhaps this country will eventually decide to do without nuclear power altogether. But it would be foolish to think that a wood stove is better than a reactor because it is safer and cleaner. It is neither.