METROPOLIS, Ill. — With a Mayberry-meets-Disney charm, this southern Illinois town has enthusiastically claimed Superman as its favorite son.

A 15-foot bronze statue of the buff comic-book hero stands in Superman Square, just two blocks from a statue of an actress who played Lois Lane. Cartoon kitsch is festooned everywhere to create a Superman mecca that will bring in tourist dollars. Tens of thousands turn out each June for the city’s four-day Superman Celebration.

Yet months of labor turmoil now threaten to undermine the cheery tourist atmosphere in this 171-year-old Ohio River town, due to Metropolis’ dependence on uranium-related jobs as much as kryptonite.

At the sprawling Honeywell Specialty Materials plant on Metropolis’ outskirts, some 230 union workers take turns picketing at the nation’s only site for refining uranium for eventual use in nuclear power plants. The picketers have been there since the company locked out the workers last June and brought in replacements.

The strikers are warning of possible toxic releases into the community while they’re not at their jobs. They have planted dozens of small, white crosses near the highway to represent workers who have died of cancer, which they say could be linked to radiation exposure at the plant. And nearby stands a giant inflatable rat made to represent the company supplying the replacement “scabs.”

The scenes reflect tensions growing in this town of 6,500, not only among neighbors but also between the different parts of Metropolis’ economic livelihood.

The dispute “really tears a community apart. You have friend pitted against friend,” Mayor Billy McDaniel laments, noting the fraying of friendships between locked-out Honeywell workers and salaried, non-union employees still on the job. “We need that company, and we need those company men, those union workers, back in there — now.”

Despite the whimsical image Metropolis has created for the outside world, its identity as a uranium conversion site runs deeper.

The plant now run by Honeywell was built in 1949, and with a normal work force of 400, it is still the second biggest employer in town, after a riverfront casino. The average union worker’s salary of $62,000 is an enviable sum in the area.

The town branched out in the early 1970s, according to the city’s tourism officials, when a Kentuckian who moved here was floored that Metropolis had not taken advantage of its name, and began to offer ideas. The state Legislature declared the town Superman’s home in 1972.

The newspaper is now the Metropolis Planet, an homage to the fictional Daily Planet in the fictional city of Metropolis where Lane and Clark Kent sniffed out stories. Visitors shop for superhero souvenirs in the town’s shops, and the distinctive “S” is emblazoned everywhere.

Among the visitors who couldn’t resist being photographed next to the Superman statue, with chest puffed out and hands on hips in classic Superman style, was Barack Obama, who made a political appearance here years ago.

Metropolis’ troubles began last spring when efforts to negotiate a new contract broke down at the Honeywell plant. Honeywell opted not to let the union employees work without a contract, citing the lack of bargaining progress and what it called the union’s refusal to agree to provide 24 hours of notice before any strike.

Darrell Lillie, president of the United Steelworkers local, said Honeywell wants to do away with worker seniority and farm out more work to contractors. “If we accept what’s on the table right now, we’d be crushed as a union,” Lillie said.

Honeywell insists that the problem is “this union’s attitude about change,” said Peter Dalpe, a company spokesman.

As the lockout drags on, the out-of-work employees are getting by on unemployment benefits and help from the union. That has put a squeeze on Metropolis’ mom-and-pop places like Diamond Lil’s, a diner whose owner, Jerry Baird, says he has taken in $2,000 less per month since the lockout began and has forced him to lay off several of his own workers.

Many townspeople are getting increasingly anxious. The visible signs of the conflict, along with the union’s talk about possible accidents at the plant, don’t encourage visitors.

“Come on, somebody do something,” pleaded Debbie Cuttrell, 57, who caters to the tourists at her downtown Debbie’s emporium.

Jim Hambrick, proprietor of a local souvenir shop billed as “the Largest Superman Collection on the Planet,” believes most of the town backs the locked-out workers. “If you look at it in terms of Superman, you’ve got good versus evil,” he said.

Even in better times, the plant has been a source of concern. In September 2003, toxic hydrogen fluoride was released in an accident. Three months later, seepage of mildly radioactive gas sent four people to the hospital and prompted the evacuation of nearby residents.

A recent safety inspection by the Nuclear Regulatory Commission found that temporary workers may have been “coached” on job evaluations, though that agency concluded the plant was safe. “The plant would not be operating if we were not confident that it was being run in a way that protects the public and the environment. It’s as simple as that,” said Joey Ledford, an Atlanta-based spokesman for the agency.

McDaniel, the Metropolis mayor, says he has faith in the town’s resilience to weather the dispute, but he wonders how long the suffering will continue.

“The longer it goes on, the worse it will get,” he said.