Mayor Marion Barry, hoping to reduce longstanding racial imbalance in the District's fire department without antagonizing the predominantly white firefighters' union, is expected to nominate Norman Richardson, a black racial moderate, as the next District fire chief, sources said yesterday.

Barry's selection of Richardson, 45, a 23-year veteran who is currently deputy chief in charge of training division, would be a compromise choice, the sources said.

The union Local 36 of the International Association of Firefighters, had preferred John P. Devine, a white who is currently one of two assistant fire chiefs. The Progressive Firefighters Association, a group that represents some black firemen, supported fire battalion chief Joseph A. Kitt, a former equal employment opportunity officer in the department who is black.

But, according to several sources, Kitt was unacceptable to the union and had the reputation of being too militant on affirmative action. Devine, the sources said, was judged to be opposed to using special procedures to place more blacks and other minorities in upper echelon positions in the department.

The choice of Richardson, who has had little involvement with the black firefighters group but is acceptable to both groups, would provide Barry with the best resolution of a sticky political issue.

He could maintain the presence of a black in this top position that many blacks in the city are sensitive about, sources said, and not alienate the union, the firemen's bargaining unit and a group that endorsed Barry's long-shot campaign for mayor in 1978.

City Administrator Elijah B. Rogers said Monday that a final decision has not yet been made, and he refused to either confirm or deny the selection of Richardson. The mayor is expected to announce his choice at a press conference Thursday.

Race relations and affirmative action in the District fire department have been a principal concern of the Barry administration since it took office a year ago.

Although the city is 70 percent black, only about 30 percent of the 1,307 uniformed firefighters are black or Hispanic. Moreover, since March 1978, when Jefferson W. Lewis, who has now retired, took office, there have not been more than six blacks and two Hispanics among the 40 top firefighting positions -- the ranks from which fire chiefs are customarily chosen.

In addition, sources said, blacks are assigned disproportionately to fire companies in areas east of the Anacostia River and west of Rock Creek Park -- areas where there are fewer fires and hence, less experience to be gained. There are, the sources said, 13 fire companies housed in four buildings that on one of three regular shifts have no blacks working in them.

In some respects, the Barry administration's criteria for selection of a chief represented a departure from the stated philosophy used by former mayor Walter E. Washington, who said that he had chosen Lewis in 1978 on narrow grounds. I'm not looking for a planner. I'm not looking for an economist, I'm looking for a chief who can put out a fire," Washington said at the time.

Rogers said Monday, "The role of the fire chief is not to put out fires. He has to be a manager of a department."

Sources said that Devine, 48, who has served as assistant chief of operations and as assistant chief for administration, had the strongest management background.But, sources said, Devine expressed opposition to bending some traditional promotional procedures in order to increase the number of blacks in upper echelon positions.

Florence Tate, Barry's press secretary, was asked yesterday if Devine had been rejected for those reasons. She said only that Rogers had considered recommending Devine, but did not because Devine was "too administratively inflexible." Devine declined to comment.

Kitt, 52, was an administrative trouble-shooter during the time that Joseph H. Mattare, who retired in 19173, was chief. Kitt instituted disciplinary actions against several firefighters then, and incurred the wrath of the union in the process, the sources said.

It was also Kitt who in February 1979 recommended that two high-ranking firefighters be charged with discriminating against one of the city's first woman firefighters, Laura B. Samuel. The D.C. Office of Human Rights affirmed Kitt's allegations. The firefighters union raised money to provide legal assistance to the two officers charged in the case.

A fourth candidate given strong consideration, the sources said, was Deputy Chief Dennis M. Logan, 55, who is also black.

Lewis retired at the end of last year. Since then, Deputy Chief Edward H. Birch has served as interim chief. Birch is not a candidate for the regular post, however.

Richardson was promoted to deputy chief in June 1979, after serving as an assistant chief in the department's planning unit. At that time, 17 white battalion chiefs filed a complaint with the department's equal employment opportunity office, saying they had been unfairly passed over. One of those chiefs, Alphonso Torre, took his complaint to U.S. District Court, where it is still pending.

However, any ruling on that complaint would not affect Richardson's possible appointment as chief, according to Torre's lawyer.