Plans to evacuate 2 million Washington-area residents to rural Virginia and West Virginia during threat of nuclear war are being studied by the Pentagon's Defense Civil Preparedness Agency. The evacuees would include all those living in Arlington and Fairfax Counties, the city of Alexandria and close-in parts of Loudoun and Prince William Counties.

Six civil defense officials are being hired in Virginia, the District and Maryland, and hundreds nationally, to begin preliminary plans for mass evacuation of Washington and some 400 other likely nuclear targets around the country.

The Pentagon is spending more than $7 million on such plans this year, and expects to spend up to $50 million over the next four years on "Crisis Relocation Planning," the evacuation program initiated in 1974 by former Defense Secretary James R. Schlesinger to counter massive Soviet civil defense spending - now more than $1 billion a year - and a vast Soviet city evacuation plan.

Under CRP, area residents would be relocated for up to two weeks in rural "host" counties of Virginia and West Virginia, primarily in the Shenandoah Valley up to 200 miles away. However, some would be relocated as close as the Charlottesville area and remote parts of Loudoun and Culpepper Counties. Virtually everyone within 15 miles of downtown Washington, which is expected to be destroyed in any nuclear war, would be evacuated to schools, churches and any other public and private buildings that offer certain minimum protection from radioactive fallout.

During the past three years the Pentagon's civil defense agency has been conducting nine pilot evacuation studies in small cities - the closest in Dover, Del., - which will be completed within the next few months. All are finding that mass evacuation is feasible in most parts of the country, say Defense officials, except in California and the North-east, where well over 50 million people would have to be evacuated, and shelter, food and supplies found for them in rural areas.

Such evacuation plans are expected to be take years to develop and may never be feasible for places like New York City - an island metropolis with 8 million people and limited access routes - and will be difficult in Washington and other large urban areas. Evacuation plans for Washington were developed in the 1950s, but were more limited in scope since there were fewer people to evacuate and air-plane-carried nuclear bombs were smaller. Such plans were discarded in the 1960s as impractical in an era of more powerful missiles.

"But it's feasible, absolutely feasible, to evacuate Washington, given a day or two's notice . . . Hell, we do it on a limited scale with 360,000 people every day during rush hour," says John E. Bex, who supervises civil defense efforts for the mid-Atlantic states from a concrete bunker beneath a cow pasture in Olney, Md.The $14 million underground communications center, opened in 1971, would be the local military and civilian command post in the event of war.

The key to such a Washington exodus, in fact the only way it would be possible, is with "a day or two's notice," since in a surprise nuclear attack East Coast citizens would have at most 15-30 minutes warning time to run for the nearest basement, Pentagon officials say.

But many defense planners now believe a nuclear war, should it occur, would come only during a growing international crisis, such as the Cuban missile crisis of 1962, thus giving U.S. officials time to evacuate cities, says John E. Davis, director of the Pentagon's civil defense agency. "Certainly, after the receipt of information that Soviet cities have been evacuated . . . (it) could be considered as one kind of response," says Davis.

Not everyone is convinced. Rep. Les Aspin (D-Wis.) calls plans to evacuate U.S. cities in time of international crisis "extremely dangerous nonsense" which could help trigger the nuclear war it was designed to cope with. "CRP, at best, is a bunch of Pentagon officials trying to make work for themselves," Aspin said recently.

For the moment at least, civil defense in the Washington area and around the nation continues to be what it has been since 1960: a "duck and cover" plan, which means simply that in the event of nuclear war the nation scurries for cover into cellars and the basements of large buildings designated as fallout shelters. Those not immediately killed would have some protection in the shelters from nuclear fallout, the radioactive dust that would filter down over the countryside for several weeks after.

Civil Defense efforts since 1960 have been to expand the number of basements designated as fallout shelters and to improve emergency warning and communications systems, little of which has been very noticeable to Washington-area residents.

The major civil defense issues locally have been whether to destroy the 15-year-old piles of stale survival biscuits and outdated medical supplies - $150 million worth were stockpiled in shelters here and around the country following the 1962 Cuban missile crisis - and indeed whether local jurisdictions today need any full-time civil defense officials at all.

Arlington County has none and and the District City Council only last spring considered closing down its $234,000-a-year, 14-employee civil defense office as a budget-saving device. The Council decided to keep the office after discovering it would cost $313,000 in severance pay and other closing costs to shut it down.

The District receives $100,000 in Pentagon civil defense matching grants to run the Office of Emergency Preparedness - it changed its mane from the Office of Civil Defense about a year ago - but most of the staff is occupied coordinating city snow emergencies and other natural disasters, as well as handling demostrations and logistical support for things like parades and inaugural activites.

It also operates the mayor's command post, the police-fire-civil defense communications center in the Municipal Building 24-hours a day and handles public telephone calls to city agencies at night and on weekends.

In 1972, President Nixon ordered the Pentagon Civil defense agency to help states and localities plan for and cope with natural disasters like floods and hurricanes - and the Pentagon Office of Civil Defense changed its name to the current Defense Civil Preparedness Agency. An attempt last year by the Ford Administration to limit the office strictly to preparing for nuclear war was thwarted by Congress.

Montgomery, Prince George's and Fairfax Counties, as well as Alexandria and the District, all have full-time civil defense coordinators, the Pentagon paying 50 per cent of their salaries, but all devote most of their time and effort to non-nuclear matters. The new CRP employees, while working for city and state civil defense agencies, will be paid entirely with Pentagon funds.

In fact, one of the few civil defense responsibilities care for the emergency food and medical supplies stored in many shelters, was eliminated this fall when the Pentagon recommended their destruction. The food was said to be unfit for human consumption.

So far, however, only Price George's County has disposed of the several tons of 1962 survival biscuits it had been storing in shelters - donating them to farmers for livestock food. The thousands of 1962 medical kits were destroyed or given to local hospitals.

Other civil defense offices here still are keeping many cartons of survival biscuits, however, because they believe the biscuits edible, if not very tasty.

"We seriously challenge the statement that the survival biscuits are unfit for human consumption," says George Rodericks, director of the District's office of emergency preparedness. The federal Center for Disease Control in Atlanta ruled the biscuits inedible last summer after some had been donated to Guatemala and a number of people became ill. The center tested the Guatemala biscuits but Rodericks and a number of civil defense officials insist that batch must have been badly packaged or damaged.

The District donated 7,000 tons of survival biscuits to Bangladesh in 1974 "and I've been feeding plastic-wrapped survival crackers to 20 soup kitchens on a weekly basis for two years and never had a complaint," said Rodericks.

The federal government bought 165,000 tons of biscuits for $70 million following the Cuban missile crisis, plus $14 million worth of medical kits and $10 million in sanitation kits. Only the sanitation kits - plastic toilet seats and bags that fit over carboard drums - are still recommended for use by Pentagon officials.

Much of the civil defense hardware installed in the 1960s, such as radiological monitoring equipment, civil defense sirens, emergency radio and telephone equipment and "hardened" emergency operations centers around many cities are still in operation and have been improved.

Montgomery and Fairfax Counties have underground emergency operations centers in their police stations, paid for largely with federal funds. Prince George's County voters recently approved construction of one although it is being delayed because of a budget pinch, and the District built a temporary center at its Lorton, Va., prison complex. All have extensive communications equipment tied in with major underground Pentagon wartime command posts' and local officials would go there in time of war.

While evacuation of Washington-area residents is again being studied, evacuation of Washington-area officials - including the President, members of Congress, the Supreme Court and thousands of federal military and civilian officials here - has been minutely planned for years, ever since President Eisenhower "fled" Washington with 15,000 federal officials in 1955 during a mock nuclear attack on the nation, as a test of our civil defense system.

Eisenhower ran the country for three days during "Operation Alert 1955" from a bombproof headquarters under Raven Rock Mountain at Fort Ritchie, Md., 65 miles from Wahington, while other government officials were dispersed at 30 other secret shelters. Another wartime underground city - with streets, three-story buildings and a lake large enough for water-skiing - has since been built at Mount Weather, near Berryville, Va., where a TWA jet crashed in December, 1974, giving it unwanted publicity. It is one of the major underground command posts to which officials would be evacuated.

But mass evacuation plans now being studied are one of the major civil defense programs of the next few years, says Davis, and will consume about 20 per cent of the civil defense agency's $82.5 million budget this year, and similar amounts over the next four years.

"That's what we need to study now," says the District's Rodericks. "We owe the citizen an option to evacuate and there's no question in my mind that given 24-48 hours it can be done. The real question is can the rural areas support that many people for more than a day or two. That's what the studies will tell us."