''Argentina is so close to developing a nuclear bomb,'' says an engineer in the country's atomic energy program, ''that we can have a bomb ready for use in less than a year.''
A knowledgeable observer of the Argentine program adds: ''The Argentines are going like gangbusters in their atomic program. It is one of the few success stories in Argentina.''
Moreover, a Western intelligence report says that Argentina's nuclear program includes a ''secret plan'' to divert a ton of enriched uranium from under the noses of international inspectors and use it to make nuclear fuel elements.
The plan, it is said, focuses on the acquisition of enriched uranium and heavy water by the Argentines for use in facilities at the Bariloche Atomic Center in the mountains of southern Argentina. Some 1,000 well-trained researchers work there.
If these estimates of Argentina's atomic capabilities are correct, Argentina could be the next nation to join the nuclear club - that increasingly less exclusive group of nations that possess the atomic bomb.
(But whether it wants to build the bomb is a less clear. Several international experts - including the head of Argentina's nuclear power program Adm. Carlos Castro Madero - discount reports that the country will develop a bomb.)
What such a step would mean for Argentina and for South America is easy to imagine. It would obviously give Argentina massive new clout in disputes like those with Britain over the Falkland Islands and with Chile over the Beagle Channel at the southern tip of South America.
Moreover, it would give Spanish-speaking Argentina a decided edge over Portuguese-speaking Brazil, its rival for hemispheric hegemony.
For Argentina, a nation beset by political instability and one of the world's most chaotic economies, a successful nuclear program would remove some of the onus of failure that surrounds so many other things in the country.
But the possibility that Argentina will soon develop the ability to build nuclear weapons frightens many in Western circles.
''This ability in the hands of a nation with such political instability,'' says one Western diplomat here, ''is tantamount to giving a gun to an unstable child. The whole issue is frought with danger to the world.''
Washington worries that, if Argentina builds the bomb, it would seriously alter uffeajump,9p6WAYWAYufmrk,88l
the strategic balance in the South Atlantic. The strategic consequences are far-reaching.
Ironically, however, despite longtime United States efforts to limit the number of nations with potential to build the bomb, the Reagan administration two months ago allowed the sale to Argentina of 143 tons of ''heavy'' water, used in some types of nuclear reactors.
For the administration, there were good political reasons for the decision. Following slippage in Argentine-US relations after the Falklands war, the US sought ways to improve ties with Argentina.
But the administration took the step despite Argentina's refusal to open its own atomic facilities to international inspection.
The administration did not seek the concurrence of the Nuclear Regulatory Commission, as is generally done. Some NRC officials said they would have raised objections to the sale if they had been asked.
The heavy water is owned by West Germany, not the US. But the US approval of the $100 million sale was required because the water was originallyUS-produced.
Earlier administrations resisted such sales. The Carter administration pressured both West Germany and Canada not to sell Argentina a heavy water nuclear plant unless Argentina agreed to place all its facilities under international safeguards. Switzerland, however, agreed to the sale of a nuclear plant and to help in its construction.
But Argentina has had a difficult time getting either enriched uranium or heavy water for its nuclear facilities. Recently, the Soviet Union has begun providing enriched uranium for Argentine research reactors. Argentina has said it will seek supplies and fuels for its atomic program wherever they are available.
With the most advanced nuclear program in Latin America and one of the most advanced in the third world, Argentina insists on its right to develop as it chooses in the atomic field. It has not signed the nuclear Non-Proliferation Treaty, under which nations agree not to build nuclear arms. Nor has Argentina ratified the Treaty of Tlatelolco, which set up Latin America as a nuclear-free zone.