High Carter administration officials said tonight that the President, moments before leaving Washington yesterday for the summit here, approved resumption of shipments of highly enriched uranium to a number of countries.

Carter's decision was welcomed here, on the eve of the two-day meeting of heads of state, as a gesture that bodes well for the success of the meeting. Countries dependent on highly enriched uranium as a source of energy had been pressing such a step on Carter.

White House press secretary Jody Powell, in response to questions, said that Carter's decision "is the first concrete demonstration of the [American] commitment to be a reliable source of supply of highly enriched uranium to meet other nations' legitimate requirements."

The nations specified in Carter's decision, which must be formally approved by the Nuclear Regulatory Commission, are Canada, the Netherlands, Belgium, West Germany, Japan and a multi-national group that includes France among others.

Another administration source said that these countries "meet the standards" of Carter's new nuclear program.

powell said that the U.S. decision did not alter Washington's disagreement with West Germany over that country's plans to export nuclear technology to Brazil.

The decision to resume uranium shipments appeared to confirm that the Carter strategy for the summit is to push hard for concrete achievements, and avoid a final communique drenched in platitudes.

"He [Carter] doesn't want another heads-of-state meeting to end with just a burst of rhetoric," one of his closest advisers said in an interview.

American officials anticipate that in a meeting with six other national leaders, most of whom have extensive political and economic problems. Carter should be able to exert strong leadership, if not a dominant role.

The two-day session, which begins formally Saturday morning at 10 Downing St., includes host Prime Minister James Callagham of Britain, Carter, French president Valery Giscard d'Estaing, West German Chancellor Helmut Schmidt, and Prime Ministers Pierre Trudeau of Canada. Giulio Andreotti of Italy and Takeo Funkuda of Japan.

During the flight to London yesterday. Carter told reporters that he would offer "new initiatives" in his talks with other heads of state. Highly placed sources said today that Carter has these areas in mind:

A U.S. proposal that the major nations with strong economies pledge to take whatever actions are necessary to meet their stated economic growth targets. Weaker ones would pledge stabilization efforts.

Endorsement of increased financial resources for the International Monetary Fund and other international institutions.

Acceptance of the notion that all nations have common problems, especially unemployment, that require common solutions.

A commitment to get stalled trade negotiations "off-the-ground." This would involve not only reiteration of a stand against protectionism, but identification of specific problems among the big powers that need to be resolved.

A worldwide endorsement of strict energy conservation, ratifying, it is hoped some of the principles of the Carter energy programs.

A common appraoch to aid for the Third World, without endorsing a multibillion-dollar "common fund," as proposed by the poor nations. Carter favors individual commondity stabilization to assist countries whose economies are vulnerable to rapid price changes in a key raw material export.

It has also been learned that special U.S. Trade Negotiator Robert Strauss has met with Japanese officials in an effort to work out a "special marketing agreement" on color television exports to the United States. Strauss, in an interview, defended such agreements, which would have the effect of limiting Japanese sales, "as the best available course."

Whatever the results of the two-day summit, Carter ordered that they be made plain in language that people can easily understand. The President has told aides, that there should be special emphasis on the important link between international economic decisions and the creation of jobs in the United States.

Sources in all of the delegations - including the U.S. team - concede that Carter agenda is ambitious, and that a "realistic" expectation is that there would be no dramatic break-throughs.

Not the least of the problems is the series of disputes between West Germany and the United States. It involves not only differences over issues, but a personal coolness between Carter and Schmidt.

"One of the most important results of this summit, you might never see in a communique," said a U.S. insider, "and that would be if Carter and Schmidt, with a chance to talk to each other, hit off well."

American policy has stressed the need for faster economic growth in both West Germany and Japan as a way of spreading strength through the rest of the Western World. Expansion in the United States, West Germany and Japan, according to the theory, would reduce the smaller countries' deficits because more imports would naturally flow into the big three.

The West Germans have rejected this strategy, not only because of a fear of inflation, but because they feel they have done enough.