President Carter yesterday kept open the option of someday deploying neutron weapons as he made his long-deligred decision to begin production of a new nuclear 8 inch artillery shell and hance missile warhead.

The weapons to be built will be the same nuclear fission type as now deployed in Europe but with the ability to be converted to neutron, or enhanced radiation, effect with the insertion of a special component.

As part of yesterday's decision, Carter ordered that some but not all the elements that make up the insertable neutron component be produced.

"He did the minimum to keep the [neutron] option open," was the way one Carter aide characterized yesterday's announcement.

A different interpretation, however, came from the Department of Energy, the agency that actually builds weapons.

According to a key Carter aide, DOE will now begin production of long-lead-time items for both the neutron components and the fission shells and missiles.

Eighteen months from now, the source said, another decision will have to be made on whether to produce the short-term Parts necessary for final assembly of the neutron components.

"We're doing all we need to do now to fully produce the neutron component," the aide said.

At the White House, officials insisted that Carter's decision yesterday not be interpreted as a signal he would or would not eventually order neutron weapons be produced and deployed.

Neutron weapons are designed to destroy their targets primarily through radiation. The fission weapons now in Europe depend mostly on blast and heat for their killing effects.

Proponents of neutron weapons argue that they are the best weapon to combat the Soviet tank forces in Western Europe - that their radiation would kill crews inside the tanks but their reduced blast would not destroy towns adjacent to the battlefield.

Opponents argue that because the neutron weapons cause less physical damage they would be more likely to be used and thus lower the nuclear threshold.

Word of the proposed U.S. production of neutron weapons first appeared in The Washington Post in June 1977 and set off a Worldwide debate.

Last April 7, after controversy grew around the new weapons, Carter announced he was deferring immediate production of neutron versions but would go ahead with "modernization" of the nuclear artillery shells and Lance missile. At the time he also said he would leave open "the option of installing the enhanced radiation elements."

For the past six months, however, the administration has been wrestling with the problem of how to implement Carter's decision.

Proponents of neutron weapons both within the administration and on Capitol Hill pushed for production of the new shells and warheads and simultaneously the insertable neutron components.

The components were to be stock-piled in the United States; the completed fission shells and missile warheads were to be sent to Europe. Then, it was argued, there would be little delay if the president decided he wanted neutron weapons.

Some Pentagon and State Department officials argued that building all the parts at once was no different from building neutron weapons and would undermine Carter's deferral decision.

In the end, the White House late in the summer was sent a series of production options which ranged from producing the entire neutron component, to producing some of the parts to producing none of them.

A Department of Energy official, who is involved in the nuclear weapons production process, said yesterday Carter's approach showed "a presidential decision to convert to neutron weapons is not there now."

The Carter announcement appeared to be timed to meet both domestic and foreign needs.

The North Atlantic Treaty Organization's Nuclear Planning Group is meeting in Brussels and by raising the decision now, Carter enabled Defense Secretary Harold Brown to inform that group.

If Carter had made his decision earlier, he would have had to take money for the new nuclear weapons from fiscal 1978 funds. An amendment to the fiscal 1978 DOE appropriations bill required him to inform Congress of any decision to go ahead with neutron weapons and allowed 45 days for both houses to veto that action.

By not acting until yesterday, Carter was able to have his decision covered by DOE's fiscal 1979 authorization which does not even require the neutron production actions.

In fact, the While House directive to DOE on neutron component production in classified and thus administration officials will not confirm for the record whether part or all the component elements are to be produced.

This permits various interpretations to be made of the effect of Carter's action yesterday - that he has moved toward neutron production because he is building some neutron parts, that he has maintained his April 7 deferral position, or that he has moved away from neutrons because he didn't build all the neutron parts.

The shells and warheads to be produced will be of lower yield than the weapons now in Europe.

The 8-inch shell, however, is one that U.S. and other NATO military men have been pressing for [WORDS ILLEGIBLE] whether neutron or not. It will replace a shell that is almost 20 years old and lacks the range, safety and capability found in more modern nuclear devices.

For example, the present shell has a range of 10 miles. The new one, with a rocket booster, is supposed to go twice that distance.