NUCLEAR WAR, says a contemporary, is a the single greatest psychological factor in the minds of a generation that grew up practicing for annihilation. Where previous generations of schoolchildren practiced fire drills, we held air raid drills and civil defense drills and huddled under wooden school desks and shut our eyes as tight as we could so the white fire wouldn't blind us. Back in the 1950s, we all knew someone whose parents had built a bomb shelter. Later, we abandoned bomb shelters -- what good would they do anyway? -- and faced the unthinkable in the only sane way we knew: We didn't think about it.

But nuclear anxiety is back. It is back here and it is back abroad, where the English government has published a hair-raising booklet called "Protect and Survive." The booklet, according to its foreword, would be distributed to every British household if there were an "immediate threat of nuclear war." t

The booklet hardly beats around the bush. "If nuclear weapons are used on a large scale, those of us living in the country areas might be exposed to as great a risk as those in the towns. The radioactive dust, falling where the wind blows it, will bring the most widespread dangers of all. No part of the United Kingdom can be considered safe from both the direct effects of the weapons and the result fall-out. . . .

"Everything within a certain distance of a nuclear explosion will be totally destroyed. Even people living outside this area will be in danger from HEAT AND BLAST, [and] FALL-OUT."

After describing the dangers of radioactive dust, the booklet tells citizens that they should stay at home in the event of nuclear attack and repair to their fallout room, in which they would have already built an "inner refuge." This room should be a place farthest from the outside walls and should be lined with protection against radioactive dust and equipped with enough sealed food and water for 14 days. The "inner-refuge" can be a lean-to made from doors, or it can be a table. Both should be insulated with boxes of clothing, sand or books. How one is to continue breathing while huddled under the table for 14 days is never made clear, but no matter. Apparently, those of us who can hold our breath the longest are going to fare the best, anyway.

"Your radio," advises the pamphlet, "will be your only link with the outside world. So take a spare one with you if you can. . . . You will need to listen for instructions about what to do after the attack while you remain in your fall-out room."

Other essentials are the usual comforts of home, such as a can and bottle opener, clothing, pots, dishes, table and chairs, toilet articles, bedding, first-aid kits, a box of sand and tissues for wiping utensils, writing materials for messages, a clock and a calendar. A special section addresses sanitation when there is no water to waste. And the booklet concludes with information about what to do when you hear a nuclear attack warning, what to do afterward in your home and so on. If someone in the fallout room dies, the body should be placed in another room and covered, and identification should be attached.

This is not a booklet designed to reassure its readers about the future of the world. Ann Allison of the British Information Office in New York City says the booklet reminds her of the civil defense movement in England during the early 1950s, when "housewifes would go to classes to learn all about whitewashing windows. . . . Then it all died down." The Conservative government has put a priority on civil defense, and the Home Office has published two more booklets showing people how to build various nuclear-attack shelters. The preliminary agreement to install 160 NATO cruise missiles in Britian has raised concern about civil defense. According to The Economist, there were six inquiries about fallout shelters in 1979 in England and 1,600 last year.

Almost 30 years have passed since the first hydrogen bomb was exploded at Eniwetok atoll in the Pacific. Our fears are the fears of the 1950s, but now we are dealing with nuclear clear arsenals of unimaginable proportions. Last week, George Kennan, the historian and former ambassador to Moscow, issued a warning about the gravity of what is going on. Accepting the Albert Einstein Peace Prize here, he said the Soviet Union and the United States are on a "collision course," and he called upon both nations to halve their nuclear arsenals. He said that both countries could maintain deterrence with less than 20 percent of their current stock of weaponry, and that the across-the-board reduction in stock should be subject to verification procedures now available to both governments.

Kennan is one of the most widely respected diplomats and experts on the Soviet Union of modern times. His is an idea coming not from a raggle-taggle band of college kids, but from an informed and formidable American mind. It should shock us into thinking about the unthinkable.

That's the only sane thing to do now, it we don't want civilization to end with people hiding out in basements, huddled under tables, listening for signs of life from portable radios.