EVERY NOW AND THEN the Reagan Administration does something so outrageous that it's hard to decide tragicomedy is a seven-year. $4.2 billion plan to relocate millions of Americans in the event of a full-scale nuclear war.

The program, to be administered by the Federal Emergency Management Agency (FEMA), class for the evacuation of more than 150 million people--every one who lives near one of America's 61 military "counterforce" targets or in any of the 319 U.S. cities with a population of more than 50,000. FEMA's plan assumes that the Soviets will give us at least a week's notice before they start shooting: Americans are supposed to begin evacuating their cities as soon as our intelligence reports that Soviets have begun to desert their urban areas.

U.S. city dwellers are to drive in their cars to "host areas" in rural America. According to FEMA, food shortages will present no problem for the refugees. They can "probably" find enough to eat in the host areas, and "we might ask people to take food with them," says FEMA spokesman James Holton. FEMA also plans to spend $600 million annually for the next seven years to supply rural areas with telephones and radios, medicine, and radiation detectors--all for the post-holocaust comfort of their city brethren.

Once these supplies are "deployed," the "resuscitation of life," should be relatively easy. Nor is FEMA concerned about what would happen to residents of cities of New York, who lack the getaway cars FEMA is counting on. "New York City is an oddity." Holton notes. "It is not a typical situation." "If everything is in place and we have enough time to do it," says Holton, about 80 percent of the American people could survive a full-scale nuclear war.

Not that a few bugs don't remain in the Reagan-approved FEMA system. For one, the plan doesn't help at all in the event of a nuclear attack within the next seven years. And imagine what traffic jams would be like if everyone in town got in his car and started heading in the same direction during a nuclear crisis.

We're doubtful that civil defense plans like FEMA's could even begin to protect 80 percent of the American people. For one thing, many experts say the long-term environmental effects of full-scale nuclear war would destroy the U.S. as a political, social and biological entity. The point, although it escapes both FEMA planners and president Reagan, is as horrifying as it is simple: there is just no place to hide from nuclear war.

Fortunately, there are some wiser heads in Washington. Last Thursday, the Senate Armed Service Committee refused to fund the Reagan/FEMA head-for-the-hills plan for the time being. Regrettably, however, the committee declined to examine whether the current modest civil defense plans that they renewed do anything more than propagate the dangerous fiction that post-Armageddon survival is possible.

More dismaying, the committee's temporary rejection of FEMA's plan does nothing to protect the American people from an irresponsible president who, by advising us that we can "drive away" from Soviet missiles, is simply lying to the public. What is more, a president who believes that civil defense makes nuclear war "survivable" might not think it's so terrible to risk a confrontation with the Soviets. And that is not very funny at all.