Leaning over the console in the control room of the Three Mile Island Unit 2 nuclear power plant, reactor operator Craig Faust scans the flashing lights. The scene is eerily reminiscent of that dark morning 4 1/2 years ago when alarms sounded and Faust declared: "Something's going wrong in the plant."

But while the control room looks much the same today as it did on March 28, 1979, the operators monitoring the instruments no longer are running a reactor generating millions of watts of electricity. They are directing an unprecedented cleanup effort mounted in the wake of the nation's worst nuclear power accident.

"They clear entries into the highly radioactive containment building, venting of radioactive gases from the containment, taking on and moving water, processing the various wastes, and all that ensures this is done legally and procedurally," said Dick Skillman, manager of reactor disassembly and defueling planning at TMI 2.

"It keeps them busy, but there is a problem in that most of these guys are on a career path which involves operating reactor plants, and not watching broken reactor plants," said Jack DeVine, technical planning director for TMI 2. "There is kind of an emotional concern a lot of them have that, 'Gee, we're going to be here forever.' "

The concern that the cleanup of TMI may last forever is shared by many critics of General Public Utilities, owner of the damaged plant.

Many supporters of nuclear power, particularly in Europe, express amazement that a crash effort was not mounted to clean up TMI, and that the damaged reactor has been permitted to remain a festering wound sapping the strength of the American nuclear industry.

"I've got to believe that in a three- or four-year time period, the kind of crash effort you are talking about would have done it," DeVine said.

But in an emotional and political climate where it was clear that GPU officials had neither fully understood nor been candid about the seriousness of the accident, any steps beyond those immediately necessary to bring the reactor under control would have been subject to lengthy public and regulatory scrutiny.

For example, the effort this year to remove the top from the reactor has been set back months by a controversy over whether the overhead crane, damaged in the 1979 accident, has been tested adequately to ensure that it will not let heavy equipment come crashing down, triggering a new crisis.

The need for tough regulatory scrutiny was brought home yesterday when a 400-pound steel beam that was being lifted into place for use as a hoist in the cleanup fell eight feet onto the service structure above the reactor. No serious damage or injuries were reported.

"But the question that people always seem to have difficulty coming to grips with is: 'How come it's 4 1/2 years and you only now are starting to disassemble the reactor?' " DeVine said. "One piece of the answer is, disassembly and defueling the reactor became our lowest priority because they were the least significant in terms of public health and safety."

So, during the first 18 months after the accident, GPU officials say they did little other than try to gain a better knowledge of what was taking place inside the crippled reactor, and bring it under better control.

"There were a number of times when we noticed something change and mobilized a lot of effort to understand it," DeVine said. "We went through a period when there was more or less a sneezing effect in the reactor, where it would build up heat and temperatures would change quickly.

"Well, the first time you are up in the control room and it has been the same for four days and all of a sudden temperatures start swinging up in the neighborhood of 20 or 30 degrees, people pay attention," he said.

But after four years, officials express confidence that the reactor--where the heat in the core today compares with that of an average home furnace rather than the inferno that existed at the peak of the accident--is well under control.

"Time has been a healer in the sense that the plant has cooled down naturally, which is a tremendous advantage, and our familiarity and confidence level and understanding" of these conditions have grown, DeVine said.

And, despite the fact that the tough tasks of removing the damaged fuel from the crippled reactor and decontaminating the containment building still lie ahead, much has been achieved already in cleaning up the mess left by the accident on the bucolic island in the Susquehanna River.

"I remember in 1979, I'd go to a Kiwanis Club and people were really concerned that we had a toxic, hazardous, radioactive waste storage problem here on the site that just couldn't be solved," DeVine said.

Officials concede that, with more than 1 million gallons of highly radioactive water sloshing about in the auxiliary building and the basement of the reactor building, there was cause for concern.

"We viewed that as the most serious hazard on this site," said DeVine. "The auxiliary building had been flooded, and the reactor building had a couple of feet of water in the basement and a continuing leakage. And that water in the reactor building was just screaming hot."

Engineers designed a system that ultimately processed all the water from the auxiliary building and the containment basement, removing 350,000 curies of radioactive cesium and 13,400 curies of strontium 90. This solid radioactive waste was sent to Energy Department facilities in Idaho and Washington state for disposal.

The processed water, which remains in storage tanks on the island, still contains more than 3,000 curies of tritium, another radioactive isotope, which cannot be separated chemically from water. Options under consideration for disposing of it range from mixing it with concrete for burial, evaporating it or discharging it into the Susquehanna.

"But that quantity of tritium is really not a consequential amount," said DeVine. "I think in terms of valid public concerns, the liquid waste problem isbehind us."

Another problem that was a source of public concern was disposal of the radioactive krypton gas that had built up in the reactor containment building following the accident, making it impossible for cleanup workers to enter the structure.

After lengthy study, the government authorized GPU to vent 46,000 curies of krypton into the atmosphere over several weeks. "The dose rate was absolutely insignificant at even the highest points," he said.

While tiny amounts of krypton continue to evolve in the containment building, the gas is vented before each entry to the building "so there is almost a continuous venting of very tiny amounts," DeVine said. "No gases of any consequence remain."