MAINE VOTERS went to the polls Tuesday to face an unusually simple ballot -- a total of 17 words. The issue was posed with typical Down-East terseness: "Shall an act to prohibit the generation of electric power by means of nuclear fission become law?" Specifically, the question was whether Maine Yankee, the state's only nuclear power plant, should be shut down for good. By 60 percent to 40 percent, the voters chose to keep the plant operating.

Despite the lack of any political choices on the ballot, turnout was heavy. Many areas reported more voters than had appeared in the last presidential election. Campaign spending on the referendum was even heavier -- nearly $1 million was spent with the pro-nuclear forces, largely financed by out-of-state industry contributions, outspending the anti-nuclear groups by almost 5 to 1.

The nuclear and utility industries' heavy financial contribution reflected the importance both sides attached to what might have been an unprecedented decision to close down an operating reactor. Montana has voted to keep nuclear power out, and several other states have similar referendums on this fall's ballots, but Maine's choice was a first in this country.

In the wake of the vote, pro-nuclear forces were jubilant, claiming a great victory for nuclear power and calling the outcome a strong vote of confidence in the technology. But was it really? The Maine Yankee plant produces one-third of the state's electricity, so a vote to shut it down would have meant that the voters were not only fearful of nuclear energy but fearful enough to be willing to shoulder the enormous costs that would have been associated with willfully turning it off. Looked at in this light, a victory for the referendum would have been an extraordinary event.

On the other hand, the very heavy voter turnout and the 40 percent who voted to shut down the plant despite the costs are evidence of at least a deep and widespread concern over the safety of nuclear power and whether its long-term problems, especially the handling of radioactive waste, can ever be satisfactorily solved.

All in all, the final result of Maine's vote seems to us right on target. Three Mile Island notwithstanding, the overall safety record of nuclear power in this country does not justify shutting down an expensive operating plant that has no particular safety or siting problems. But the industry's record is nothing to crow about either. The 40 percent of Maine voters who voted to shut down their reactor sent a message to the industry and to its government regulators to do better that is shared by many more Americans.