Lucy E. O'Brien and Vijay S. Pande, seniors at Langley High School in McLean, were named local winners yesterday in the annual Westinghouse Science Talent Search -- the only two students in the Washington area to win the prestigious competition.

Both are 17 years old and have been accepted by Ivy League universities.

O'Brien, who will be class valedictorian and has been accepted at Harvard University, struggled to contain her excitement and find the right words to express the importance of the Westinghouse award.

"It's like a good stigma, a mark," she said.

"It's a blessing," added Pande, who hopes this will help him win some academic scholarships to finance his college education. He has been accepted at Princeton University.

O'Brien and Pande are among 40 students nationwide to be named talent search winners. The awards are based on independent research projects done by the students. This year 1,339 high school seniors entered the competition. Five previous winners have gone on to win Nobel Prizes.

The 40 will compete next month in Washington for scholarships totaling $140,000 with the top 10 winners receiving awards ranging from $7,500 to $20,000 and the rest receiving $1,000.

For her project O'Brien developed an assay that determines the amount of paraquat residues on foods. Paraquat is a commonly used herbicide that can be lethal in large quantities. She said her method for determining the presence of paraquat is quicker than current methods.

She worked for more than a year on her project at the National Agricultural Research Center in Beltsville. "It's fun. It's almost like playing," she said of scientific research.

O'Brien describes herself as someone who "can talk on the phone for hours." She also writes poetry and plays violin in the Northern Virginia Youth Symphony. Her parents, James and June O'Brien, are economists at the Federal Reserve.

Pande describes himself as someone who plans ahead and is a worrier by nature.

Trying to decide whether to research the Strategic Defense Initiative or semiconductors for his project, he chose SDI. After all, he reasoned, SDI, or Star Wars, is a topic with which most people can identify.

His computer simulation research showed that it would take 8,000 space-borne lasers to effectively ward off an attack from incoming nuclear missles. That's 8,000 shuttle missions to get the lasers into space and bad news for SDI advocates.

For the last two summers he has worked at the Naval Research Laboratory under a program run by George Washington University. He will work there again this summer doing computer simulations.

His father Chandra is a physicist and his mother Seetar is a chemist. Both work at the naval lab. They did buy him a physics kit when he was in sixth grade, said Pande, but they never pressured him to become a scientist.

"They would also discuss negative aspects, that scientists, like teachers, are not really that well paid," said Pande.

Along with his science prizes, Pande has won several piano competitions and played intramural volleyball.

Both students, who are of Asian descent, shared one fear, that their heritage might be held against them when they applied for college. Some elite schools, faced with a large number of qualified Asian-American applicants, have been accused of using quotas, charges that have been vigorously denied.

"I think if it was between an Asian and an American with the same credentials, {a place} would go to the American or Caucasian person because there's a feeling that Asians are overrepresented" at some elite universities, said O'Brien, whose mother is Chinese.