An administration request for funds to start buying production machinery for an Army 155 millimeter neutron artillery shell, the third and most costly of the new nuclear weapons the Army is seeking, has passed the House without debate and will come before a Senate committee this week.

It is the second time this year the administration has tried to win approval of the 155 mm funds from Congress.

The first time, the Department of Energy, which builds warheads for the Army, asked permission to shift $7.5 million of fiscal year 1982 funds to begin purchasing production machinery so the first of a planned 1,000 155 mm neutron shells could be ready by late 1986.

A Senate Appropriations subcommittee led by Mark O. Hatfield (R-Ore.) refused, despite personal letters from Secretary of Defense Caspar W. Weinberger and Secretary of Energy James B. Edwards.

Then last Thursday, with no discussion, the House approved the Department of Energy portion of a fiscal 1982 supplemental bill in which funds were provided for the 155 mm neutron shell production facilities.

In its report on the supplemental, the House Appropriations Committee said it too had earlier held up approval of funds for the 155 mm neutron shell because the Army had not decided on its design and the announced initial deployment date "was unrealistic." But the Army then satisfied the committee by settling on a sophisticated design by the Lawrence Livermore nuclear weapons laboratory and delaying planned deployment 11 months, according to Pentagon sources.

Hatfield's Senate subcommittee reportedly said no to the 155 mm proposal the first time around for different reasons. These were the high cost of each shell, put at over $2 million apiece by some sources compared with $1 million for an eight-inch round and somewhat less for Lance, and the refusal so far of western European countries to permit two other neutron weapons to be stockpiled on their territory.

Those concerns will surface tomorrow when the Senate Appropriations Committee takes up the question of the supplemental bill and the advance funding of the neutron shell.

The government is already producing 380 Lance missile neutron warheads and about 800 neutron shells for eight-inch artillery. These were approved last August by President Reagan.

Neutron shells, unlike previous nuclear weapons, use radiation rather than heat and blast as their main killing mechanism. The tactical virtue of these weapons, called enhanced radiation weapons by the Pentagon, is that they would cause less physical damage to towns adjacent to the battlefield if they were used in heavily populated western Europe.

But critics say they could also make nuclear war more likely, because it would be less damaging.

The new 155 mm neutron shell is supposed to replace more than 2,000 nuclear 155 mm shells that have been deployed in Europe for almost 20 years. The older munitions have a range of only nine miles, are less than a kiloton in yield (the equivalent of 1,000 tons of TNT), have no modern safety devices and are slow in firing since a so-called "spotter" round must be shot off before each nuclear shell to make sure the range is accurate.

The new 155 mm shell will contain the newest safety features for nuclear weapons, will have almost twice the range and nearly twice the explosive yield of the current shell.

In a statement last year supplementing testimony by Army Chief of Staff Gen. Edward C. Meyer, the service said the current 155 mm nuclear round "has limited tactical utility since it has a . . . short range and an inaccurate fuze."

Meyer, however, justified building the new 155 mm shell along with the eight-inch munition because "the preponderance of artillery pieces there in western Europe are 155 millimeter, both United States and allied," rather than eight-inch. By having both weapons with neutron shells, Meyer said, the Army would have "capability to have a flexible response across the full front."

The Army has been working on getting a new 155 mm nuclear artillery shell for over 10 years to replace the one that has been deployed since 1963. It seemed to be stymied in December, 1980, when then-Secretary of Defense Harold Brown ordered all future funds for the 155 mm neutron shell "zeroed out" beginning in fiscal 1982.

The Reagan administration reversed that decision but failed to place the necessary funds in the Department of Energy's 1982 budget. That is the money it is now seeking.