Adm. Bobby Ray Inman, deputy CIA director, acknowledged yesterday that scientific papers are only a "very small part of the problem" of the "hemorrhage of this country's technology" to the Soviets.

But at the same time, in speaking to two House subcommittees on science and technology, he again warned that there is a "massive Soviet effort" to acquire U.S. technology, and if scientists do not voluntarily censor some of their papers on sensitive technology, "I think in six months, a year, or 18 months, as the government begins to see the full magnitude of what the Soviet Union gets from the West," there may be a decision to impose restrictions.

At a January meeting here of scientists, Inman warned that if they did not voluntarily let the government review some of their sensitive papers, tough restrictions might result.

Yesterday, Inman said he regretted using the phrase "tidal wave of public outrage," but added that then and now he was trying to "goad" scientists into acting before the government does.

Also testifying for the administration yesterday was Lawrence J. Brady, assistant secretary of commerce, whose remarks were restrained compared with what he said later at a luncheon with the Association of Former Intelligence Officers.

There, Brady said the Reagan administration has "aggressively stepped up our enforcement efforts" under the export administration act in the past year. He cited criminal prosecutions in two California cases .

One case involved a shipment of copper water-cooled mirrors used in high-power lasers. The shipment to the Soviet Union was made through an intermediary in West Germany. The California company's president drew a 10-year prison sentence, all but six months of it suspended.

Brady said the Soviet KGB has built an industrial-espionage network of frightening proportions, one that he said has "blanketed the developed capitalist countries . . . sucking up formulas, patents, blueprints and know-how with frightening precision."

He said the administration is still trying to develop a critical-technologies list that it hopes to make "the kingpin of the whole system" of preventing seepage of sensitive data and equipment. But at least a few in the audience of some 450 seemed chagrined by Brady's suggestion that the role of the multinational firms in the transfer process is "going to be a public policy issue in the next decade."

"How long can we wait?" one questioner demanded. "This has been going on since 1956."

At the House hearing, Inman said that he believes that 70 percent of the problem of the "outflow of technology" comes from Soviet espionage activities, and that only a small percentage of the other 30 percent can be attributed to the failure of scientists to keep sensitive work secret.

But he said he expects the Soviets to concentrate on the other 30 percent much more in the future as the administration succeeds in halting more of the Soviet espionage.

Rep. Albert Gore Jr. (D-Tenn.) questioned Inman's arguments and said the United States should "not take even the first step down that road of a closed society that makes Soviet research so pitiful."

Robert Rosenzweig, a vice president of Stanford University, said the premise of the administration--that there is a threat to national security from open scientific exchange--"is wrong. We should reject it . . . . It has always seemed risky to run an open society; perhaps that is why there are so few of them."

In a related development, officials at Commerce said yesterday they are investigating conflicting accounts of a shipment of $960,000 in water-purification equipment to Libya that the Customs Service seized in Brooklyn on Friday.

Customs spokesman Louis Gerig sad his agency determined that the shipment had not reached the Watertown, Mass., loading docks of the exporting firm, Ionics Inc., until after the administration's embargo on high-technology exports to Libya took effect March 12. A Commerce spokesman said "we were given assurances by the firm that the stuff had gone to the docks on March 11."

Staff writer George Lardner Jr. contributed to this report.