The Senate Foreign Relations Committee, opening two days of hearings yesterday on a proposed nuclear cooperation agreement with China, heard closed-door testimony that several members said "raised serious questions" about whether the pact might promote proliferation of nuclear weapons.

Sen. John Glenn (D-Ohio) said he would introduce legislation today to require formal White House certifications allaying those concerns. He described the pact as "seriously flawed but salvageable."

State Department officials said that the agreement is adequate and that any modifying legislation would anger China and nullify it.

Committee Chairman Richard G. Lugar (R-Ind.) said the hearing included "an excellent review" by State Department and Nuclear Regulatory Commission officials of the agreement. It would allow U.S. industry to bid on supplying some of China's future nuclear-power needs, a possible $6 billion market.

Written NRC testimony reiterated "concern regarding the adequacy of certain assurances" from China and said, "We believe they could lead to future misunderstandings." However, these concerns "should not be interpreted as opposing the . . . proposed agreement."

Sen. Jesse Helms (R-N.C.) joined longtime nuclear-industry critic Sen. Alan Cranston (D-Calif.) in questioning whether the agreement guarantees that U.S. nuclear material and equipment are not used for weapons production. "I would vote against it if I don't get satisfactory answers," Helms said after the hearing. "There are a lot of questions in my mind yet."