Racial desegregation of 18 Montgomery County elementary schools begun by the county school board three years ago has neithr helped nor hindered the achievement of students enrolled in those schools, according to a report released yesterday.

The system's Department of Educational Accountability also found in the study that seating arrangements and playground activities at the schools are well integrated and concluded that "desegregation appears to be functioning smoothly and well and continues to be a viable program."

Those findings parallel national studies of mandatory desegregation and student achievement, according to Charles V. Willie, professor of education at Harvard University who is a recognized expert in the field of school desegregation.

Willie said the goal of desegregation is not higher test scores but rather the "control, understanding and patience" children acquire in integrated settings."

The system's three-year-old desegregation plan, which was adopted to preempt possible court action, has involved about 5,000 pupils in 18 schools that are clustered or paired together in two areas inside the beltway -- Takoma Park and Rosemary Hills.

Three years ago Rosemary Hills Elementary school, for example had a 94 percent minority enrollment. Since the start of the clustering plan, which involves busing, it has become about 46 percent minority.

Officials studied standardized test scores of students currently in the fifth grade at clustered schools, and compared their scores as third-graders, before the integration plan.

It found no significant difference between those scores. Higher achieving white and black students performed generally on the same levels as they had before desegregation.

The scores also were compared with those of pupils in "naturally integrated" schools that were not involved in the desegregation plan. The report found no significant difference in achievement between the two types of schools'

"There was a fear before that higher achievers might suffer under the (school board's) mandatory plan," said Joy Frechling, an educational accountability official. "This proves that the importance of desegregation is... in the human understanding that children acquire."

That sentiment was echoed yesterday by Marian Long, a PTA official at Chevy Chase Elementary School, located in the Rosemary Hills cluster.

"The way the kids get to know each other is really outstanding," said Long, whose son is bused to kindergarten at Rosemary Hills. "And it has such a wonderful effect. During winter vacation we went skiing in Maine and my son came up to me and said 'This is all crazy. There're no black people here.'"