Wednesday was Armageddon, annihilation, holocaust, the atomic fireball towering up from the crater that used to be Washington; the schoolyards of children turned to ash; the overpressure, as the shock wave is described, at 12 pounds per square inch, that being enough to collapse lungs, drive chunks of windows halfway through necks . . . all this assuming merely one 25-megaton surface-burst, an assumption which was very easy for one Bethesda woman who ended up in a phobia clinic because of it.

"I know they test the air-raid whistle on Wednesdays, but I'd want to avoid it, I'd be terrified," she says. Wednesdays were particularly bad, but it could hit her any time -- when she dreaded to open the paper in the morning, or when she rode the bus home from her law practice. "It seemed to me from moment to moment that missiles were on the way. I was terrified. The rational part of me noticed that nobody else was hysterical, but then I'd wonder if they shouldn't be, and if I shouldn't be persuading my husband that we should leave town. It's no longer a phobia for me, but I'm still concerned. I was talking with my doctor psychiatrist Robert DuPont recently, and I said, 'Bob, I hope you've noticed a lot more people are worried now.' "

Welcome to the New Menace, as opposed to the Old Cold War; to life at ground zero; to the view the Soviets see when they look through the "window of vulnerability"; to the worst bout of nuclear fear since we were building fallout shelters in the '50s and early '60s. A brand-new vocabulary is on Washington's lips: "MX," "SS20," "Pershings," "launch on warning," "use 'em or lose 'em" See NUCLEAR, C13, Col. 1 NUCLEAR, From C1 and "demonstration shot." The famed disaster clock of The Bulletin of the Atomic Scientists has jerked forward from 12 minutes to midnight after the SALT I agreement in 1972, to four minutes to midnight in 1981. Atomic war is no longer dismissed as "unthinkable." No, indeed: The strategically unthinkable has become the tactically thought-about. The journals, the experts and the analysts say Americans have lost our old security blanket, which was the doctrine of Mutual Assured Destruction, and replaced it with the doctrine of limited nuclear war.

President Reagan told a group of editors on Oct. 16: "Well, you shoot yours and we'll shoot ours. And if you still had that kind of a stalemate, I could see where you could have the exchange of tactical weapons against troops in the field without it bringing either one of the major powers to pushing the button."

This statement, which he was still footnoting in his press conference Tuesday, got a lot of Europeans as concerned about having American missiles in their back yards as the Mormons were when they lobbied to keep one version of the MX system out of Nevada and Utah.

Yesterday, the Union of Concerned Scientists sponsored one of 153 teach-ins nationwide at the Georgetown Law Center. The crowd was neat, clean and cheering. After his speech to standing-room-only crowd in the moot-court auditorium, Rep. Morris Udall (D-Ariz.) said: "I travel around, and I sense there's a slowly growing increase in the anxiety level. And it isn't a typical liberal-conservative issue -- the Mormons are a very conservative church."

For all the talk of a "limited" nuclear war, a Newsweek Gallup poll published last month had half the people polled saying that a war with the Soviet Union would become "all-out nuclear war." Sixty-two percent of the people polled said there was "some" or "a good" chance that there will be all-out nuclear war between America and Russia in the next 10 years. Twenty-three percent saw the Reagan administration reducing the chances of a nuclear war.

Virtually everybody thinks about it, thinks about strategy or just has an image in his mind. "If you're lucky, you'd be killed immediately," says Ron Murray, head of the medical photography lab at Howard University Medical School. He has a vision of a bleak Bronze Age world in the cities when the radioactivity dies down. "People would be mining the cities for minerals -- they'd pull up the phone wires for copper."

Says Fred Werth, a plumber and contractor in Takoma Park: "I see myself heading out to West Virginia with a gun."

Says Sharon Parks-Mandel, a health-care analyst from Kansas visiting here for a convention, "If I knew it was going to happen, what could I do? I wouldn't want to survive it. I guess I'd just make a drink and watch it all happen."

It is fear, American-style.

"We're finalizing the elements of a franchise. We'll study the market, the income averages, because it's a commodity like campers; you can sell it to everyone -- get 'em out of the crater, give 'em someplace to go to," says Lane Blackmore, president of Survive Tomorrow, a La Verkin, Utah, company that hopes to sell bomb shelters the way McDonald's sells hamburgers. He keeps laughing as he talks about it, as does Robert Firth, of Firth Construction in Ocean City, Md., when he talks about the shelter business. He says he has sold "about 25" housing units built for survival in nuclear war (among other wars), and: "I've been on '60 Minutes,' 'PM Magazine,' 'Evening Magazine,' 'David Susskind,' 'The 700 Club,' the 'ABC Evening News' . . . and now, can you believe it, I've got a Hollywood agent trying to book me for paid speaking engagements!" He laughs and laughs, the kind of laugh that makes you worry that he might not be able to stop.

Why are these men laughing?

"The climate of public opinion certainly changed between 1972 and 1976," says Paul Warnke, former head of the Arms Control and Disarmament Agency. "Detente was badly oversold by Nixon and Kissinger, in part because of the Watergate difficulties. And there's been a lot of disillusionment with the Soviet Union, starting with the Yom Kippur war in 1973. There's also a reluctance to accept the doctrine of Mutual Assured Destruction -- it's awfully uncongenial."

At the National Institutes of Mental Health, Dr. Calvin Frederick, head of the Disaster Assistance and Emergency Mental Health section, can break down fear of disaster, any disaster, by age and sex. But it's just science telling us what we already knew. "The most affected are children, the elderly and young women, especially women with children." The children show a lot of fear of being separated from their parents, not that it would make any difference in a nuclear attack, he says, and the least fearful are the very people who have their fingers on the buttons: "Middle-aged men."

Said President Reagan in 1980: "The Soviet Union does believe that a nuclear war is possible, is survivable and is winnable by them . . . And it has been estimated by military intelligence that the casualties in such a war would be 10 to 1 in favor of the Soviet Union."

Jill Vexler, an anthropologist who lives downtown, pauses at the corner of 17th and M streets NW and says: "I see myself helping people find fallout shelters and calming the panic of people, anguished mothers separated from their children, people separated from their families."

Leslie Guildner, a research scientist who built a fallout shelter when he lived in Bethesda in the early '60s, says now: "I haven't come to any conclusion as whether to build another one or not. I don't believe that people are as worried, but the situation is more serious."

The Federal Emergency Management Agency offers a booklet entitled "In Time of Emergency" whose soothing tones leave the reader hopeful. "Studies show that tens of millions would survive the initial effects of blast and heat . . . Much has been done to prepare for a possible nuclear attack."

This makes the reader feel good. But wouldn't it be bad if everybody felt good? Wouldn't it make it that much easier to push the button?

So read "The Effects of Nuclear War" from Congress' Office of Technology Assessment, with its pictures of Japanese nuclear blast victims, and of a leveled Hiroshima, and its emphasis on our ignorance: "The effects of a nuclear war that cannot be calculated are at least as important as those for which calculations are attempted."

This makes the reader feel bad, but isn't that good? Doesn't that get people concerned? As psychiatrist Robert DuPont says: "Fear is an effective tool in education."

At the Brookings Institution, senior fellow and former ambassador Raymond Garthoff dates current fears to the mid-'70s, "beginning with Schlesinger James, secretary of defense talking about selective targets. In 1976, there was the founding of the Committee for the Present Danger." he says. The committee had members including current Arms Control and Disarmament Agency official Paul Nitze, who published a paper that year asking whether SALT was working, and Richard Pipes, a National Security Council staffer who wrote the much-cited July 1977 piece, "Why the Soviet Union Thinks It Could Fight and Win a Nuclear War."

Also, says Garthoff, "when George Bush was running the CIA he established Team B with both Pipes and Nitze on it." Team B was part of the reevaluation which doubled our estimates of the Soviet Union's military spending as a percentage of gross national product.

It's a litany that seems inevitable as Garthoff recites it: President Ford abandoning the use of the word "detente," President Carter's "abortive effort to get SALT going in the spring of 1977," along with Angola, Ethiopia, Afghanistan, Poland, the development of the neutron bomb.

"For 25 years we had escalation dominance. It's easy to say nuclear war is unthinkable when we have superiority."

Then again, it is conceivable that it is somewhat more thinkable for high government officials than average citizens, given the elaborate government shelters in the countryside outside Washington, and the plan to evacuate the president and his staff to Andrews Air Force Base, where they would take off in E-4Bs before the attack. If this fact is disturbing, be grimly reassured by the reports in 1977 that the procedure was tested with Zbigniew Brzezinski standing in for the president, and proved inadequate. On the other hand, if the fear is of the chaos to follow an attack, then the test failure is disturbing.

As one favorite fact of the New Menace has it, the Russians lost about 18 million people in World War II. They're used to losing a lot of people. They know they can survive.

It might be comforting to think, though, that Russian state television had broadcast anything with the horrible power of the CBS report of June 14. In one segment of its report on American defense, CBS interviewed the family of an Omaha resident, Jerry Allen, and then proceeded to simulate the destruction of his city, house and family in 53 apocalyptic seconds of fire and shock.

It was very real, if it isn't obscene to suggest that anything could compare with the reality of a nuclear attack.

The problem with dealing with nuclear fear, and keeping it from being phobia, is nearly impossible. Three principles, "all irrational, govern risk assessment," writes psychiatrist DuPont in a paper on fear of nuclear power plants. "The first, and most important, is whether the individual thinks he controls the risk . . . The second . . . is whether the health hazard shows up as one big event -- like an airplane crash . . . The third principle . . . is whether the risk is familiar or unfamiliar."

Nuclear fear meets all these criteria for a phobic reaction. Except that it's worse. DuPont points out that one cure for phobias is "necessity." If phobics have to ride the elevators they dread, they can do it.

The question being, as tensions increase, as the arsenals swell, as planners try to guess what the Soviets are guessing about our guesses: What is necessity?

A phobic reaction is not a necessity, a phobia being an affliction that makes ordinary life impossible, which is just what we already fear from nuclear attack. Then again, as bad as Wednesdays were for the woman in Bethesda, they were better than no Wednesdays at all.