The Montgomery County school board yesterday reaffirmed an earlier decision to renovate and keep open Bradley Elementary School in Bethesda.

The board opted for a $2.1 million renovation at Bradley and to close nearby Radnor Elementary partly because there would be more space for a day-care center at Bradley.

The decision was made despite concerns of some board members that money might not be available for the renovation and arguments from members of the Radnor community that their school is in adequate shape and that the cost of renovating Bradley would be excessive.

The previous board also cited the larger building at Bradley, and its ability to accommodate a day-care center, as a reason for picking it over Radnor, although Superintendent Edward Andrews wanted to close the 32-year-old Bradley building because of the cost of renovation.

Although yesterday's action was unanimous, board president Blair Ewing expressed reservations about whether money for the renovation would be appropriated by the state and the county.

State facility planners, who are required to provide the bulk of the money, have said they would consider funding the renovation, but have made no decision. Some county council members also have questioned the expenditure of the funds.

"We're going to have real trouble with this," Ewing warned.

Other board members, however, argued that Radnor, a 28-year-old building, also would be coming up for an expensive renovation within the next 10 years and that it was a question of spending money now or later.

Students from both schools now attend Radnor and will remain there until the planned renovation is completed in September 1984, when they will return to Bradley, which will be renamed Bradley Hills.

The board is not required to consider whether there is space available for day-care programs when considering school closings, but several people have urged the board recently to take such programs into consideration.

Several board members acknowledged those concerns yesterday and pointed out that planning figures indicate that because of declining enrollment, one of the two new classrooms to be added as part of the renovation will be available for a day-care program after the first year.