Christian Badea, who will conduct the National Symphony Orchestra in 30 Young People's Concerts this season, in addition to Family Concerts, Concerts in the parks and programs on the orchestra's Encore Series of pops concerts, held his first press conference here yesterday.

Badea - whose name is pronounced "body-ah," with the accent on the first syllable - is the National Symphony's new Exxon/Arts Endowment Conductor. That means he is one of 10 young conductors who are working with American orchestras. The program is designed to give working experience to the country's most promising young conducting talents.

Yesterday Badea said he would like to stay in Washington with the orchestra for more than this one season, which is the term of his present contract - depending on a number of factors.

Badea, who is 30, is Romanian-born, but now he is a permanent resident of the United States.

He said that he had just received an invitation to conduct the BBC Symphony in London for several weeks next season, and he was also recently named music director of the Spoleto Festival in Italy.

With major engagements like that already in hand, Badea is strongly attracted by Washington, thanks to the presence here of NSO music director Mstislav Rostropovich, with whom, he says, he gets along very cordially.

"Just a few minutes before this conference," Badea said, "I knew Rostropovich might want me in the hall to listen to the orchestra, to check the balance for tonight's concert.

"As soon as I put my nose in the door, Rostropovich saw me and called me up to the stage.

"He just told me to step in and conduct the end of the Tchaikovsky 'Manfred' Symphony while he went out into the hall to hear if the organ and orchestra were balanced right."

That seemed a very definite answer to the question of whether Badea studies every score that Rostropovich conducts here in order to be able to step in at any time might be necessary.

In regard to the Young People's Concerts, he said, "I would like to feel . . . that there could be some continuity - that those who come to one concert would be back again at the next one, so I could plan some definite growth during the season.

"This is a difficult time to plan music for young people. There is rock and pop music. I might decide to try one idea and fall on my face with it. I know the things that Bernstein had done; believe me, I have read his lectures and books."