Pentagon planners had hoped to keep secret from the public and the Soviet Union production and deployment of neutron enhanced radiation warheads and artillery projectiles until they were given to U.S. forces in Europe, according to Defense Department officials.

Defense aides yesterday indicated some anger that officials from the Energy Research and Development Administration unilaterally declassified the fact the 56-mile range Lance warhead, for which they sought fiscal 1978 production money, was of the new enhanced radiation variety.

"That was not declassified by joint agreement," a Defense official said yesterday.

Inclusion of a reference to the neutron Lance warhead in ERDA's hearing before a House Appropriations subcommittee led to the first news stories and public disclosure of the new generation of enhanced radiation artillery projectiles and missile warheads being sought by the Pentagon.

Former president Ford approved initial production of the new neutron family of weapons last Nov. 24.

"He knew the concept and application of enhanced radation to these weapons when he made the production decision," Robert Barrett, executive assistant to the former President, said yesterday.

Barrett had asked Ford about allegations in Washington that Ford did not know he was giving the go-ahead for the neutron weapons because the Interagency memorandum he had been sent did not identify them as enhanced radiation devices.

ERDA's Assistant Administration for National Security Alfred D. Starbird said yesterday the declassification of the Lance warheads as an enhanced radiation weapon was made by his agency based on guidelines jointly developed by Defense and ERDA. He could not say, however, why the Lance neutron warhead was declassified because "that would get into design" which itself was classified.

At the White House yesterday, presidential press secretary Jody Powell said President Carter will decide "this Fall" whether to follow Ford's lead and approve production of neutron radiation projectiles for the Army's 8-inch artillery shells and warheads for the lance system.

Funds for those programs, and to develop a neutron shell for the 155-mm howitzer, are in the fiscal 1978 ERDA budget that is part of the public works money bill now before the Senate.

Sen. Mark O. Hatfield (R-Ore.) has introduced an amendment to cut out the neutron production money.

Powell said yesterday that Carter wants the funds approved "to keep his options open."

Powell said Carter "has an abhorrence of nuclear weapons, period, as well as other types of weapons." But he went on to give arguments that "if it (a nuclear weapon) has to be used . . . there will be many fewer civilian casualties (with the neutron variety) than with the standard types of weapons."

Neither Carter nor most members of Congress were aware production money for the new generation of neutron warheads and projectiles bill until news stories appeared two weeks ago.

The fact that planned production of nuclear new 8-inch shells, to replace those already in Europe, are of the neutron variety is still considered top secrety by the Pentagon and ERDA.

Although the public was kept in the dark about the move to neutron warheads, "classified reports were sent to appropriate congressional committees," a Defense official said yesterday.

Those on Capitol Hill who were informed about the program agreed with the decision to produce the first nuclear battlefield weapons specifically designed to kill people primarily through radiation rather than destroy military installation and equipment by heat and blast.

Pentagon officials yesterday strongly defended the neutron radiation concept as the way to turn tactical nuclear weapons now in Europe into "more credible deterrents."

They cut down by a factor of 10 the blast and heat from the present nuclear warheads, these officials argue. Thus the new Lance would be more likely to be used because they would cause less collateral damage to towns or cities adjacent to the battlefield. At the same time the neutrons would kill persons in the target area, even those in tanks and armored personnel carriers.

Another justification for enhanced radiation, according to a top Defense official, is that the Soviet Army in Europe "would have a major re-equipment problem to defend against this [neutron] weapon."

"The Soviets," he said yesterday, "have equipped themselves to live on a present-day nuclear battlefield." Their tanks and fighting vehciles now deployed "have protection against biological and radiological effects," of the type that would exist after tactical nuclear exchange with current weapons.

"They can't handle the prompt radiation," which would be delivered by the proposed new warheads, he added.

Because that neutron radiation would dissipate quickly, friendly forces would be able to occupy that same area within a few hours, according to informed sources.

"Introduction of the new generation of neutron shells and warheads," the Defense official concluded, "would put the Soviets back 20 years in their new military acquisitions."