Ground zero -- deep in the heart of Amarillo

This is where they are all put together: the big H-bombs for the B-52s, the warheads for the Minuteman missiles, the US battlefield A-bombs for Europe. Every weapon in the American atomic arsenal is finished here.

That's what makes the dispute over the morality of nuclear weapons so important here -- especially this week as nationwide rallies take place all over the United States for Ground Zero week.

To some citizens in Amarillo, the issue is strictly a moral one: Should local workers continue to build weapons collectively capable of such vast destruction?

To others equally concerned, the issue is one of national security: Should a tiny group of protesters, perhaps (say some) financed by the Soviet Union, be allowed to undermine America's vital commitment to and responsibility for defending the free world?

Well-orchestrated rallies this week in support of nuclear disarmament could involve up to 20 million Americans organized by Ground Zero, a self-styled grass-roots organization convinced that nuclear war is a no-win option that must be ruled out. The term itself is the technical designation for the point directly beneath a nuclear blast.

Ground zero in this dispute is a somewhat rundown World War II munitions factory on the outskirts of Amarillo. Surrounded by 7,000 acres of gently rolling wheat and sorghum fields farmed by Texas Tech University is the government's 3,000-acre Pantex plant.

For people here, President Reagan's weekend radio talk on nuclear weapons policy sharpened the line dividing those favoring and those opposing current policy. Those convinced that Mr. Reagan has brought the world closer to nuclear war came away more convinced. Others said the President's five-minute talk confirmed their view that the Soviets are leading the nuclear race and that the US must do all it can to close the gap.

This conservative town weighed the President's words carefully because nuclear weapons have been a hot topic here for over two years. Rather than seeing the issue as theoretical and long term, Amarillo has very practical and immediate concerns.

Assembling nuclear weapons provides regular paychecks for 2,400 Amarillo workers -- and puts the area on the map as a prime target in the event of a nuclear attack.

Although no official numbers have been made public, the town's weapons plant currently is said to turn out from 500 to 600 strategic nuclear weapons per year , along with twice as many smaller nuclear bombs and missile warheads. Even if the US Department of Energy shelves its plans to upgrade Pantex, output could be increased rapidly by switching from the present five-day, two-shift work schedule to round-the-clock production. More than 600 applicants are waiting for jobs at the plant, hoping the Reagan administration's talk of a major defense buildup will benefit Amarillo directly.

Fanning out from the administration building, rows of arched Quonset huts and earth-banked bunkers house probably the most controversial workforce in the US.

Pantex officials say that all prospective workers are screened to ensure that any moral doubts emerge before, not after, hiring. Paul Wagner, the Department of Energy administrator for the privately operated plant, says that two years of antinuclear protests here ''have had no adverse influence on the operation of this plant.''

But just raising questions about building nuclear arms is an important initial victory for local men and women openly campaigning for a US-Soviet freeze on manufacture and deployment of the weapons. Open dialogue, they insist, will lead to a more reasonable national defense policy, even if not to actual nuclear disarmament.

For others here, raising the question of whether it is right to expand America's nuclear arsenal gives aid and comfort to ''atheistic world communism.'' J. Allen Ford, pastor of the town's fundamentalist and rapidly growing Southwest Baptist Church, heads the campaign to get this point across. Next month his church will hold meetings in support of Amarillo's key role in nuclear defense.

Mr. Ford, who is the area's Moral Majority representative, plans to rent billboards around Amarillo to spread the message that his 1,5OO-member church feels the Pantex plant is doing God's work.

''The surest way to have a nuclear war,'' Ford says, ''is for the Soviets to perceive us as weak in weaponry or divided over using nuclear weapons.''

Another leading minister here is deeply concerned by the community's polarization. In his quiet study, lined with many of the same books on theology and ethics that crowd Reverend Ford's study, First Presbyterian Church pastor James Carroll points out a sad irony in the town's nuclear confrontation.

''The Pantex workers symbolize the tremendous strength of patriotism of this area,'' Mr. Carroll explains. ''They all sincerely feel that they are doing something which makes the country militarily strong in defense of freedom against the encroachments of the communist world.''

Yet, says Carroll, people with this love of freedom at the same time threaten freedom's cherished rights within the town.

Carroll says he's glad that local activists ''have challenged all of us to think deeply about the direction that the nuclear armaments race may be leading.''

But the sad part for Carroll is that ''with few exceptions, meaningful dialogue is not taking place.'' Instead, a Methodist minister and a local newspaper editor both lost jobs after speaking out against nuclear weapons.