The Carter administration has asked Congress to approve funds to develop a new nuclear bomb whose effects are the opposite of the neutron weapon that the president recently deferred - increased blast and reduced radiation.

The new bomb, called the "RRR" bomb for "reduced residual radiation" by the Pentagon, would be used to demolish structures, dig craters or destroy mountain passes, tasks once assigned to the atomic demolition mines in the nuclear stockpile.

"This is the original idea of a 'clean bomb,'" a government nuclear weapons expert said Friday. "It is a blast weapon designed to create a minimum amount of fallout and surpress irradiation of the soil."

During the neutron weapons debate, government spokesmen described that weapon as "clean" because it cut down on blast and heat, producing instead greater radiation.

In the late 1940s and early 1950s public concern about atomic warfare was focused primarily on radioactive fallout. Scientists went to work developing "cleaner" bombs that cut down on radiation produced by each weapon. The bombs and shells built in those years emphasized heat and blast.

All nuclear weapons produce blast, heat and radiation. In recent years, however, scientists at the government's weapons laboratories have been trying to tailor these effects of nuclear explosions to fit specific military missions.

Thus the neutron artillery shell, which detonates above ground, generates deadly doses of radiation that penetrate steel plate and kill or incapacitate tank crews.

The blast bomb, on the other hand, is planned to explode on or under the ground, throwing enormous amounts of debris. Radiation must be limited or the target area would remain contaminated for hundreds or thousands of years.

The "RRR," or blast, bomb is only one of several new nuclear weapons being developed that were described by Department of Energy officials during closed hearings of the House Appropriations subcommittee on public works last month. An unclassified version of the sessions was published last week.

During the hearing, Dr. Donald M. Kerr, acting assistant secretary of energy for defense programs, told the subcommittee "a substantial increase" is proposed in production of nuclear weapons in the coming fiscal year based on a two-year program approved by the president in December 1977.

Under the Atomic Energy Act, the president is required to review and sign once a year a decision paper on nuclear stockpiles and weapons development guidance. In general, the document authorizes the Department of Energy to initiate paper concept of a weapon, advance a weapon from one phase to another in the development process or to begin production of a new nuclear device.

In signing the document in December 1977, President Carter in large measure continued an extensive nuclear weapons building program that President Ford began.

Kerr told the subcommittee that DOE needs $612 million for production and maintenance of the nuclear weapons stockpile. That represents an "increase of $108 million, or about 21 percent," Kerr said.

Overall, the cost next fiscal year for DOE's portion of nuclear weapons research and production was put at $1.5 billion, up $70 million from this year.

"Current production workload planning," Kerr said, "shows that we will require virtually the full capacity of all production facilities in the mid-fiscal 1980s."

To meet the plutonium and tritium requirements of the Carter weapons program, the subcommittee was told, the Energy Department plans to put three of its Savannah River reactors into full production next year.

The December 1977 presidential paper gave production authority through 1980 for the new Trident sea-launched ballistic missile warhead for the Navy, the Mark 12A warhead for the land-base intercontinental Minuteman III ballistic missile, and the warhead for the new air- and sea-launched tactical and strategic versions of the cruise missile.

Approval was also given to four versions of a new tactical nuclear bomb called the B61.

Three new neutron weapons, the Lance warhead and the 8-inch and 155mm artillery shells, were also in the December 1977 production plan, but earlier this month the president deferred them. A revised plan for these tactical weapons is being drawn up by DOE and the Pentagon.

The only production halted by the president in the December paper was the B77, a strategic nuclear bomb that had been developed primarily to be carried by the F1 bomber. Once Carter cancled B1 production, he decided to save money by asking that the B43, the currently deployed strategic nuclear bomb, be modified with new safety devices.

At the same time, Carter agreed to complete the development phase of the B77, leaving open the possibility of production at a later date.

The House Armed Services Committee has told the White House it does not approve of Carter's halting B77 production. The committee, which has yet to mark up its nuclear weapons procurement bill, may include B77 funds.

Although the amount of money involved is classified, figures presented during last month's hearing show that almost $195 million has already been spent on development of the B77.

According to Kerr, the president has also given DOE planning authority for several other new weapons through 1985.

In addition to the blast bomb, other new nuclear weapons expected to enter the development phase are the Pershing II, a warhead for the Army's 400-mile tactical missile now in Europe, and a warhead for a ground-launched cruise missile.

Development of a warhead for the proposed MX mobile ICBM, according to Kerr, is not expected to be requested by the Pentagon before fiscal 1980.

Other new nuclear weapons that have undergone initial concept and feasibility studies include the Navy's MK-500 maneuverable reentry vehicle and its long-range Trident II missile. The Air Force has under study warheads for an advanced strategic air-launched missile and a stand-off missile.