No sooner had the polls closed in Moscow a week ago Sunday than U.S. television audiences were informed that Boris Yeltsin had won election to the Congress of People's Deputies. The votes weren't counted until the following Monday.

Welcome, comrades, to that scourge of modern democracy, the exit poll.About 2,300 Moscow voters were interviewed by reporters from Western news organizations after they left polling places in about 20 election districts. No one has yet complained about the canvassing or blamed it for the shockingly low turnout - 80 percent, as opposed to the customary 100 percent in a Soviet election. But I can't imagine it will take long for some alarmists in the Kremlin to raise the dirty question: Did the reporting of early returns from Moscow discourage some voters from coming out in Minsk?

The other leading explanation for low turnout - that the voters were reasonably sure of the outcome even before election day - can be dismissed out of hand. After all, this was the first Soviet election time in 72 years where there was any doubt about the outcome. When they were racking up all those 100 percent turnouts, there was only one name on the ballot.

Now that we have imparted our exit polling technology to the Soviet Union, the least we can do, in the true spirit of glasnost, is export the experts and strategies we have accumulated to cope with the supposed problems.

First, Congress can share its plan for uniform poll closings - 9 p.m. in the East, 8 p.m. in the Central time zone, 7 in the Mountain and Pacific zones. It accomplishes this feat in the Pacific states by keeping them on daylight-saving time for the first two weeks of November, when the rest of the country goes back on standard time.

Admittedly, the Soviet Union, with 12 time zones, might have a little trouble with this sort of plan. But what are legions of superannuated nomenklatura good for if not to solve planning problems like this?

If the Soviets can't get their election house in order, they may find themselves confronting the ultimate threat: a Moscow branch office of the Committee for the Study of the American Electorate or a similar, civic-minded organization that browbeats legislators about negative campaigning and the media about exit polls.

In truth, the Soviet electoral system has a long way to go before its worst problems will begin to match those that the American watchdogs so solemnly and endlessly deplore in our own system. But that exit poll in Moscow is a great beginning.