The House Armed Services Committee has found that "there is no basis to assume that large numbers of new nuclear weapons will be produced in the years beyond 1990."

This judgment, laid out in a report on the fiscal 1984 authorization bill for Department of Energy national security programs, led the committee to question the need for a new multi-billion-dollar nuclear reactor to produce tritium and weapons-grade plutonium in the decades to come. The generally pro-defense panel cut study funds for the new reactor to $2 million.

The committee's guess as to future weapons production is in sharp contrast to forecasts by some administration defense officials on one side and nuclear freeze groups on the other. Both have projected that major nuclear weapons programs in the current budget will go into the next century.

But the House committee determined that after production of the land-based MX missile and sub-launched Trident II further nuclear programs would be cut back sharply, sources said.

"Arms control agreements and proposals to build down stockpiles by replacing two old warheads with only one new one," also were cited by a committee source as influencing the decision.

Another reason for the committee's caution, sources said, was its fear that the administration was underestimating the new reactor's cost at $4 billion to $8 billion.

The report said the cost easily could reach $12 billion to $16 billion "because the facility would most likely have to conform to new restrictive standards for ground motion and for hurricane and tornado winds."

The report also pointed out that some of the projected needs for nuclear materials could be met by changing the output of the nation's current production reactors.

Tritium, for example, is a radioactive gas used in making hydrogen weapons. Because it decays at the rate of 5.5 percent a year, tritium in older weapons must be replaced regularly, normally within eight years.

The government now has one tritium production facility, at the Energy Department's Savannah River, S.C., plant. The report notes that there is a $30 million program under way to develop another tritium plant and with an additional $4 million in the fiscal 1984 bill, some results are "expected in the next two to three years."

As for plutonium, one committee source pointed out that this radioactive material does not decay significantly for 24,000 years. Thus, he said, the nuclear material in weapons being retired can be used in new weapons.

The committee's votes made clear that any slowing of weapons production will occur well off in the future. It gave almost 100 percent support to the major nuclear warhead programs begun in the Carter administration and expanded by President Reagan.

The fiscal 1984 authorization bill provides continued funds for building the air and sea-launched cruise missiles, the ground-launched cruise missile, the 8-inch neutron artillery shell, the B83 strategic bomb and the Pershing II medium-range ballistic missile. It also carries funds to purchase production equipment for the MX and a neutron 155-mm artillery shell.

The committee report calls the 155-mm neutron shell "a critical element in the modernization of NATO's nuclear capability." Congress has twice refused to start production of that shell, which European governments have publicly resisted in the past, but which the British, West Germans and Italians now are encouraging; the three countries jointly are building a new cannon that cannot fire the nuclear 155-mm shell now deployed in western Europe.

The committee, however, did turn down administration requests for funds to build production facilities for two other nuclear weapons: a standoff, anti-submarine warhead for the Navy and a warhead for the Army's anti-ballistic missile system nicknamed SENTRY.