In an attempt to head off a possible confrontation, federal officials yesterday developed a plan that would let scores of homeless "street people" use the cavernous and empty National Visitor Center at Union Station as a temporary emergency night shelter, it was learned.

High-level Interior Department officials who have been negotiating wth organizers planning to bring large numbers of street people to the visitor center tonight would not formally acknowledge the plan.

But several sources said a flexible, wait-and-see plan includes the option of letting all or some of those who show up tonight stay in the building.

Activists in the Community for Creative Nonviolence, a radical Christian group assisting the inner-city poor here, announced several weeks ago they would "open up" the visitor center near the Capitol for the city's derelict and homeless, starting tonight.

The group estimated that there are 1,000 or more hard-core street people who cannot or will not use available emergency shelter provided by the city government and private missions. With winter coming on, street people are entitled to shelter from the cold, the community group said. Eight persons died of exposure on Washington streets in 1977 and nine in 1976, according to the D.C. medical examiner's office.

The Interior Department, which has jurisdiction over the visitor center, initially responded that the center would be closed to street people. Departmental attorneys cited various legal, legislative and public safety restrictions.

In ensuing negotiations involving Deputy Assistant Interior Secretary Richard Hite and Robert Mendelsohn, special assistant to Interior Secretary Cecil Andrus, city officials agreed to draw up a list of alternative sites and to provide bus transportation to them. A general plan devised yesterday also included Interior's willingness to accommodate some street people at the visitor center for one or two nights if the community group rejects the alternative plans or other hitches arise, night.

Mendelsohn would say only that all concerned want to avoid a confrontation and no arrests are expected tonight.