At the Bhabha Atomic Research Center just outside Bombay, a 40-megawatt Cirus natural uranium reactor has been operating night and day almost continuously since 1960.

The Cirus reactor generates no electricity. It is used for experiments in solid state physics and reactor engineering, and to produce radioisotopes for use in medicine, agriculture and industry throughout India.

It also produced the plutonium that was reprocessed and used in India's 1974 nuclear explosion.

This latter use of the Cirus points up a fact often missed by critics who fear that the spread of atomic power stations will inevitably lead to weapons proliferation among the developing countries.

"No nation has ever misused one of its commercial nuclear reactors as the source of material for an atomic weapon," a top West German official noted. "It has always been misuse of a research facility."

The fuel burned in atomic power stations -- whether natural or slightly enriched uranium -- is not itself usable in fabricating a weapon. Though the spent fuel from power plants contains plutonium, the plutonium is not accessible until the fuel is reprocessed.

Even if a country builds a small reprocessing facility, the plutonium derived from normal operation of an atomic power station is less than ideal for use in a weapon.

"To produce plutonium for weapons," the Ford Foundation's Nuclear Energy Policy Study Group concluded, "there is little if any extra cost, and possibly an advantage, in spending $50- $100 million on a small plutonium production reactor rather than interfering with a power reactor" that can cost as much as $2 billion.

With a research reactor, an official of the International Atomic Energy Agency noted, "you can muck around as much as you wish."

In addition to India, Israel is presumed to have followed the natural uranium research reactor route -- with its Dimona reactor -- to a nuclear weapons capability.

Argentina, which has an advanced research effort supporting its natural uranium power program, would also appear to have the technological and industrial capability to build a large research reactor of this type.

None of these countries is signatories to the Nuclear Nonproliferation Treaty, and none of the research reactors in India or Israel is under safeguards.

Here at Trombey, moreover, scientists and engineers are constructing an even larger research reactor next to the Cirus that will have a 100-megawatt capacity.

Indian engineers hope to have this reactor, referred to as R-5, in operation by 1981.

Those who worry about proliferation can find little joy in the news that the reprocessing plant here at Trombey is being expanded to handle the R-5's anticipated output of unsafeguarded plutonium. CAPTION: Picture 1, India's Cirus Reactor: "You can muck around as much as you wish." Copyright (c) Indian Atomic Energy Commission; Picture 2, No safeguards: Indian engineers construct a large new research reactor. Copyright (c) Indian Atomic Energy Commission