President Carter will ask Congress today to eliminate from the budget all future funding for the so-called fast breeder nuclear reactor, the controversial experimental power plant that would burn plutonium, informed sources said.

He will also declare his opposition to federal funding for another plutonium project, a plant that would produce and reprocess the fuel, the sources said.

The present generation of nuclear power plants uses uranium. Many pronuclear groups want to shift to the more sophisticated plutonium reactors for fear the country will run out of uranium in the future. Nuclear critics say there is no need for this, and point out that plutonium is extraordinarily dangerous, both because it can easily be made into bombs and is extremely poisonous.

Carter's expected announcements today mean he is siding with the antiplutonium groups. Assuming that Congress goes along, they also mean there will be no movement toward a "plutonium economy" in the foreseeable future. Without federal acquiescence and funds, private companies are most unlikely to venture into plutonium on their own.

During his campaign for the presidency Carter pledged that he would develop a new policy to control the spread of plutonium, mainly because it can be used to fabricate nuclear weapons.

The two projects that would not receive additional funding are:

The Clinch River Breeder Reactor Project, a 350- to 400-megawatt demonstration liquid metal fast breeder reactor in Tennessee, which would cost more than $2 billion by the time it became operational in the mid-1980s. The reactor is designed to burn reprocessed plutonium as a fuel, and "breed" additional plutonium, which in turn could be reused as a fuel.

A Barnwell, S.C., reprocessing plant designed to recycle radioactive waste from conventional nuclear plants into plutonium for use as nuclear fuel. The Barnwell plant has been privately financed by Allied General Nuclear Services, a joint venture of Allied Chemical Co. and a Gulf Oil-Royal Dutch Shell combine. The firm has spent an estimated $250 million on the plant, and has sought government assistance to finance part of the project completion cost, estimated at $500 million or more.

The Ford administration last year considered a controversial proposal to provide federal assistance to the privately owned atomic fuel reprocessing plant.

Companies that would be affected by ending funding for the Clinch River project include Westinghouse, the major manufacturer involved, General Electric and Atomics International - a division of Rockwell International - which are the leading subcontractors.

Carter's declaration, one source said, "Is the Ford Foundation report translated into policy."

Last month the Ford Foundation issued a study prepared by the Mitre Corp. and a panel of prestigious scientists. The study recommended that the United States reduce the threat of nuclear proliferation by deferring action on plutonium and fast breeder reactors. Two of the 21 panelists on the Ford study, Secretary of Defense Harold Brown and Deputy Under Secretary of State Joseph S. Nye, are members of the Carter administration and have a voice in the administration's proliferation policy.

Carter's statement - a declaration of domestic nuclear policy - is not expected to discuss U.S. policy regardling nuclear export policy, pending the completion of consultations under way with Japan and West Germany. Japan, which is the most dependent on imported oil of all the industrialized countries, has an aggressive nuclear reactor program.

Carter's long-awaited April 20 energy message is expected to stress increased use of conventional nuclear reactors.