It's not a big reactor: The research facility generates a fraction of the energy produced by a big commercial power reactor in industrial countries.

Still, when Laurent Kabila's rebels entered the capital this month, officials from the International Atomic Energy Agency silently held their breath, fearful that a stray mortar round might hit the containment building and cause a radioactive leak.

``We were bracing for the possibility, but luckily that was not the case," said David Kyd, a spokesman for the atomic agency in Vienna.

The university's reactor instead is more of a long-term casualty, a victim of the damage inflicted upon Zaire by former President Mobutu Sese Seko.

``We are in a regretful state as far as money is concerned," said Professor Malu wa Kalenga, 60, who has run the reactor for 34 years.

The Zairean government stopped funding the reactor nine years ago. It was shut down in 1992 after the U.S. Nuclear Regulatory Commission blocked shipment of an essential replacement part, citing the ``economic and political collapse in Zaire."

Nowadays researchers activate the reactor only at a low level when inspectors from the international atomic agency make their annual pilgrimage to count the fuel rods to ensure that no uranium has disappeared.

``They come here to make sure we are not making the bomb," said Malu, who received a master's degree from the University of California-Berkeley in 1962.

The reactor had been largely forgotten until recently, when nearby residents expressed worries that Mobutu would explode the reactor in an apocalyptic attempt to take the capital's five million residents down with him. Even the U.S. Embassy in Kinshasa was unaware of the reactor's existence until a few months ago.

Malu offered to show the reactor to several visitors this week. But he was unable to unlock the metal-framed glass doors that seal off the five-story reactor building, despite trying a handful of keys he had retrieved from his desk drawer. The visitors had to settle for peering in through the windows.

The professor, a slight man who has headed Zaire's atomic energy commission since 1965, said the reactor was a metaphor for the country now renamed the Democratic Republic of the Congo - a nation with enormous untapped human and natural resources, squandered by years of neglect.

``It is symbolic of the fact that Zaire is capable of mastering a difficult technology," said Malu. ``But we are broke. You have to emphasize: The nation is broke."

Congo wasn't always a basket case.

The University of Kinshasa, founded in 1954, was a formidable institution when Belgium gave Congo its independence in 1960.

``In the year of independence, this country was stronger economically speaking than South Africa - even Canada," said Butsana bu Niungu, 63, a physics professor who was drawn to the university's nuclear program.

Butsana said he turned down a post-doctoral fellowship at the University of Maryland in 1970 to return to Zaire, which was then undergoing an upsurge in national confidence under Mobutu's leadership.

``At that moment, I believed we had a great deal of things to do in my country," he said. ``When I see it now from a great distance, I see it was a big mistake."

Now the university is underfunded and overcrowded - almost 20,000 students are enrolled in a school designed for a third that number. The official salary for a professor is about $20 a month, which the government last paid in December. Professors survive on fees paid by parents - and by moonlighting. Butsana teaches courses at five other universities, allowing no time for research.

``When you see the reactor, it is the remains of our past ambition," he said. ``We have to start again. Everything."

The university's first reactor was built in 1959, during the Eisenhower administration's Atoms-for-Peace Program. Local legend says that Congo received the Triga I reactor as a reward for producing the uranium that went to the Manhattan Project, though officials in Vienna say the story is a myth.

There is little dispute, however, that it was the first reactor built on the continent. (There are now reactors in Ghana, Egypt, South Africa, Algeria, Libya and soon in Morocco.)

The university retired the first reactor in 1970 and replaced it with a more powerful Triga II reactor in 1972. Both reactors were designed by a California company, General Atomic.

``We built it ourselves," said Malu, pointing to a large picture of the reactor on the wall behind his desk. Another photograph has been turned to face the wall - it shows Mobutu wearing his leopard-skin hat and pressing a button to start the Triga II in 1972.

The current reactor has a capacity of one megawatt of thermal energy, and Malu said it generated up to 1,600 megawatts for a fraction of a second when it was permitted to surge or ``pulse." It is unclear what practical purpose is served by ``pulsing" the reactor, but Malu seems very proud that the reactor can generate such a strong jolt.

The reactor was primarily used for agricultural research and for creating radioisotopes for the university hospital. Agronomists irradiated corn and peanuts with the hope of altering the genetic structure of the plants and producing improved varieties. Unfortunately, it produced few meaningful results.

The government's commitment faltered over time.

The university abandoned construction of a three-story laboratory after running out of money to buy equipment. A rusting construction crane is still poised over the unfinished building, 20 years later.

The reactor itself also began to deteriorate. The reactor's electronic systems are 25 years old. Malu said the air purification system designed to prevent radioactive leaks into the atmosphere is questionable. And the fuel rods are in danger of corroding.

The international atomic agency is not worried.

``The reactor's perfectly OK, as long as no one without knowledge tries anything funny," Kyd said from Vienna. ``It can remain dormant happily and does from year to year."

Despite the university's hopes, Kyd said that the international agency had no plans to finance the reactor's repair. ``It was an interest of only a few aging scientists," Kyd said. ``For the time being, it's not a priority."

But Malu would like to restart the reactor as soon as possible, now that the country has new leadership.

He said the reactor needed only a new device that measures the core temperature - an ``instrumented fuel element." Without the device, he cannot tell if the reactor is overheating. He has been waiting for the U.S. government to lift the restriction on exporting the part, but the United States has indicated it will not consider that until there is political stability in Congo.

``I would be grateful if you can ask President Clinton to send the fuel element so I can start pulsing the reactor again. . . .," Malu told an American visitor. ``We know our job. I've been in charge of the reactor since 1963. We know what we are doing."