For years, the energy bureaucracy's library was a cork riding the tides of change.

The Atomic Energy Commission came and went. The Energy Research and Development Administration bobbed to the surface and submerged again in the Department of Energy.

Through it all, the technical library remained a faithful guardian of voluminous and esoteric reports on fuel technology and energy dynamics, a helpmate to harried researchers and a friend to chemists, physicists and engineers.

That is, until the Office of Management and Budget decided that libraries are "commercial activities" subject to the cost-comparison provisions of its infamous Circular A-76.

Translation: The energy library is about to be turned over, lock, stock and card catalog, to a private contractor.

The DOE estimates that it will save $217,000 if it lets Informatics General Corp., a California-based firm with offices in Rockville, run its technical libraries at the Forrestal Building and its offices in Germantown under a three-year contract.

That's a 12.6 percent savings, well above the 10 percent mark that the OMB has provided as the guideline for when work should be contracted out.

But the Federal Government Service Task Force, a bipartisan congressional group, has mounted a last-minute effort to get the decision reversed, contending that the DOE erred in its cost calculations.

In a letter last week to Energy Secretary Donald P. Hodel, the group said the DOE had overestimated its in-house costs by nearly $100,000, failed to consider the costs of early retirement for federal employes whose jobs would be abolished and didn't figure in the $28,000 worth of security clearances that would be required for new employes.

With those numbers factored in, the group said, the DOE would save only 1.5 percent by putting the library under contract.

But even without the numbers factored in, the group contended, a technical library-by-contract is not a good idea. There is, for example, even ina city that changes hands every four yearson the average, the matter of institutional memory.

" . . . The majority of the present staff at both libraries have been with the library units since the beginning of the Atomic Energy Commission," the letter to Hodel said. "It appears unlikely that outside contractors would be able to staff the libraries with individuals who have the same degree of expertise."

Informatics has offered jobs to most of the library's current staff of 12--at salaries ranging from 25 to 45 percent less than their present pay. According to the congressional task force, most of the library employes, who have collectively amassed 180 years of government service, say they'll try their luck elsewhere.

This is not the first time the contracter camel has put its nose under a federal library's tent. In fact, Informatics already has more people working in the DOE's libraries than the DOE does.

Newton Parks, manager of contract administration at the firm, estimates that Informatics has 20 people working under a contract to do processing and cataloging for the DOE's technical libraries. It has similar contracts with a num- ber of other federal agencies, including NASA, the Army Corps of Engineers and the Library of Congress.

"There is quite a large market for providing something other than widgets to the government," said Parks, who expressed puzzlement at the contract flap. "We're merely complying with goverment wishes and requirements here. We're going where the business is, I guess."

But to library fans all this amounts to high treason.

Rep. Major R. Owens (D-N.Y.), a former librarian, took to the floor of the House in March, shortly after the OMB suggested putting libraries under contract, to condemn the idea.

"The totality of federal library services and facility operations are considered by OMB to constitute a commercial activity similar to laundry and dry cleaning services," he said.

" . . . At a time when the administration is concerned about the export abroad of scientific and technical knowledge and information, is it prudent to voluntarily relinquish control over federal libraries, a key component of the nation's information infrastructure?"

Owens warned that library services will suffer under such a policy. In fact, he said, Vandenberg Air Force Base already has advertised for a single contractor to run its metal plating and corrosion control operations, calibrate its gauges, analyze its chemical solutions--and run its library.

"What kind of library service is this installation likely to receive?" Owens asked.