When biologists began to probe the closed-off land around Chernobyl, they said they got a shock.
Chernobyl, in what is now Ukraine, became, in April 1986, the world's worst nuclear-plant disaster, far worse than Three Mile Island in Pennsylvania. Radiation sprayed from the core in powerful plumes, some of it later detected as far away as Scotland. An entire city nearby -- Pripyat, with a population of 45,000, now had a population of zero. Everyone was forced to move out, including another 90,000 people in the surrounding countryside.
Scientists expected wildlife to have been laid low too. Instead, they found plants and animals thriving. Field mice scurried about. Moose, wolves, deer, foxes and rabbits roamed wherever they wanted.
Ronald Chesser and Robert Baker of Texas Tech University studied the "dead zone" around the wrecked plant, and sent ABC News videotape they shot in 1996 as they walked around in radiation suits.
"This area is deceptively normal," said Chesser as the camera rolled. "Until you turn on the Geiger counter and spoil the mood, you really are struck by the beauty of this area."
The Missing Butterflies
But some dissenters say looks can be deceiving. Timothy Mousseau of the University of South Carolina has been studying barn swallows and other birds around Chernobyl, and he said the place is a wreck after all.
"Every study we did showed negative consequences for the ecosystem on every level," he said.
Birds' survival rates were dramatically reduced, he said. Butterflies, bumble bees, butterflies and grasshoppers were all notable by how hard it was to find them.
So Mousseau has been jousting for years with Baker and Chesser over just what Chernobyl's legacy is.
Chernobyl: Wasteland? Or Paradise?
Twenty-three years have passed since the accident. The Soviet Union has collapsed, and Chernobyl is often transliterated now as "Chornobyl." But the "exclusion zone" around the plant has been relatively untouched, almost emptied of human beings. It is vast, more than twice the size of South Carolina.
"Chernobyl is just a tremendous environmental experiment," said Chesser. "It's really sobering to see the tenacity of life."
Baker, his colleague, said he certainly would not want to give the impression that blasts of radiation are good for wildlife. Rather, he said, farming and hunting proved worse in the long run for plants and animals than the accident.
"If I were going to be a moose," he said, "I would want to live in the exclusion zone.
"They're going to live a lot longer lives, because humans are worse for them than the radiation was."
Chesser said entire villages have blended back into the environment -- so overgrown that sometimes it is hard to tell there was ever a village there. The streets of Pripyat are hard to walk in places, because vegetation has flourished and broken through the concrete.
There is an area, now known as the "Red Forest," where about 1,000 acres of pine trees were killed off by a strong, but relatively narrow, blast of radiation. Birch trees, which are more resistant, have taken their place.
"You find species doing better than when there were all these people there," he said. "That's probably true for wild boar and moose, but not for spiders or barn swallows, which aren't hunted."
So who's right? Is the exclusion zone a natural paradise, or a disaster area? There's certainly bad blood between the researchers.
"Anybody who's got an agenda is not a scientist," said Chesser.
Mary Mycio, who covered the aftermath of the accident for the Los Angeles Times and later wrote a book, "Wormwood Forest: a Natural History of Chernobyl," said she tends to side with Baker and Chesser, the Texas Tech biologists. But she said she worries that there has not been enough research on a topic that could affect the future of nuclear power in the United States, or be vital if terrorists ever managed to set off radioactive "dirty bombs."
"Because of the lack of information," she said, "you can hear a lot of different things from ideologically interested parties."
Chesser said he has been back to Chernobyl every year since 1992 and intends to keep going.
"If there's another accident, God forbid, or a dirty bomb," he said, "the public is going to turn to us and say, 'Why don't we know all these answers?'"