The Defense Department has decided to recommend that work begin on production of new, low-yield, nuclear 8-inch artillery shells and Lance missile warheads and some, but not all, of the components that could turn them into more powerful neutron nuclear weapons, informed sources said yesterday.

Delay in fabricating some neutron elements would leave a clear differentiation between the newly designed - or modernized - tactical nuclear waepons and the controversial neutron version into which they could easily be turned.

The Defense Department proposal is expected to go to the White House this week, sources said.

If approved, the plan would end two months of bureaucratic arguing over how to implement President Carter's April 7 order that deferred immediate building of neutron shells and war-heads and left open the possibility they never would be made. The president said at the time that if the Soviets responded with a similar arms control gesture, the neutron deferral would become permanent.

At the same time however, the president ordered the Pentagon to "modernize" the 8-inch artillery shells and Lance warheads deployed in Europe. What was not explain then was that modernization meant the proposed neutron versions were to be built but in an "emasculated" form - without their neutron core elements. These were to be fabricated later if the president decided he wanted to build and deploy neutron weapons.

The ease with which a decision to go neutron could be implemented has been at the root of the government debate. The final mix of components to be built and delayed under the defense proposal may be kept classified, sources said.

Althought they do not have the neutron effects, the new nuclear artillery shells would have almost twice the range of those now deployed in Europe and would contain safety and security featurest considered necessary in the face of possible terrorist threats.

Some Defense Department officials, with the backing of Capitol Hill supporters of neutron weapons including Sen. Henry M. Jackson (D. Wash.) and Sam Nunn (D. Ga.), have been pressing to have the new nuclear shells and warheads and the components that would make them neutron-capable built at the same time. With Nunn and Jackson taking the lead, the Senate Arms Service Committee has authorized the Department of Energy to begin that simultaneous production with fiscal 1979 funds.

They have argued that no Soviet response would be forthcoming unless U.S. production of neutron weapons began. Much the same argument had been made, unsuccessfully, to the White House before the president's April 7 statement.

Other officials, reportedly including some White House aides, have countered that simultaneous production would make it appear that the president had dissembled in his deferral statment and would be little different from producing neutron weapons directly.

Should the White House accept the Defense Department recommendation it would have to be taken to Capitol Hill for approval before the Department of Energy, which builds weapons could start production.

The four committees most eager to have neutron weapons built immediately - the Senate and White House Armed Service and Appropriation committees - are the very ones to whom the plan will have to be presented for approval. Thus the debate that has been going on within the administration may be replayed again before one or more of those committees.