The accident happened in a student machine shop at the Sterling Chemistry Laboratory located at 225 Prospect Street.
"By all reports, Michele was an exceptional young woman, and outstanding student and young scientist, a dear friend and a vibrant member of this community," wrote Lorimer in a statement.
The university told the U.S. Occupational Safety and Health Administration that Dufault was operating the machinery for a senior project when she was killed, according to Kang Yi, an assistant area director for OSHA in Bridgeport, Conn.
OSHA was reviewing jurisdiction in the case and evaluating whether it would conduct an inspection, said Ted Fitzgerald, an agency spokesman in Boston.
According to chemistry department's website, the state-of-the-art laboratory is strictly limited to students, faculty and staff who have completed a shop course and is used to construct or modify research.
Dufault, a native of Massachusetts, was an astronomy and physics major at the university, and a member of the Yale Precision Marching Band.
She was graduating in a month, said her grandfather Robert Dufault. She studied constantly and loved sports, he said.
"She was a living saint," the grandfather said. "She was a good, smart girl."
An uncle called her brilliant.
"She's a wonderful, wonderful kid and that should be celebrated. There's nothing but good things to say about her," said Frederick Dufault of Holliston, Mass.
As a result of the accident, the lab was closed today for investigation and all other classes in the building were canceled.
Yale University is offering 24-hour counseling for anyone grieving.