ROBERT SIEGEL, host:
We're going to focus now on the roughly 300 workers who were still at that stricken Fukushima plant. So far, at least 15 have been injured by explosions. Another 17 have suffered what the Japanese government called deposition of radioactive material to their faces, and two are missing.
NPR's Jon Hamilton says incidents at other nuclear plants show how important these workers are and how risky their jobs can be.
JON HAMILTON: Cameras have captured only a few glimpses of the workers at the Fukushima Dai-ichi plant. They're wearing white jumpsuits to keep radioactive particles away from their skin. Their faces are usually hidden behind goggles and masks or respirators.
Jim Tucker of Wayne State University says it's hard to gauge the risk these workers are facing.
Dr. JIM TUCKER (Department of Biological Sciences, Wayne State University): And there are certainly people who are putting themselves in harm's way in and around the reactors to try to minimize the adverse consequences to the population as a whole. I think this is a tremendous heroic effort on the part of these people.
HAMILTON: Tucker is a biologist who has spent years studying workers who survived the 1986 disaster at the Chernobyl nuclear power plant in the former Soviet Union. He says dozens died soon after the reactor exploded and then burned. Many more were exposed to radiation as they moved in to try to figure out what had happened.
Dr. TUCKER: The core material have flowed like lava downhill wherever it could inside this reactor building, and they didn't know where it had gone because it was much too hot to approach at first.
HAMILTON: Tucker says the workers who went in early encountered high levels of radioactivity.
Dr. TUCKER: They knew the risks. They were willing to take them. They took them on for the public good.
HAMILTON: The workers in Fukushima are facing different challenges. One is trying to figure out whether nuclear fuel is actually melting.
Mr. SAM WALKER (Historian): That's exactly what happened at Three Mile Island.
SIEGEL: Sam Walker wrote a history of the incident at Three Mile Island nuclear plant in Pennsylvania in 1979. He says the event began with tremendous confusion.
Mr. WALKER: There were a hundred alarms going off at the same time, so there was noise. But what there wasn't was any clear indication of exactly what was going on in the reactor.
HAMILTON: And like Fukushima, there were problems with the pumps that keep water flowing through the reactor.
Mr. WALKER: As the accident got worse, the reactor core pumps, which are huge - I mean, the size of a pickup truck - and they were vibrating so much that they would have self-destructed.
HAMILTON: By the time workers got things under control, about half of the reactor's core had melted. But the workers at Three Mile Island weren't exposed to much radiation. Some workers at the Fukushima plant probably have been exposed to high levels. The levels may be similar to those encountered by the Chernobyl liquidators.
Vladimir Gudkov of the University of South Carolina says if that's the case, most of the Fukushima workers may be okay.
Professor VLADIMIR GUDKOV (Department of Physics and Astronomy, University of South Carolina): I have some friends who worked as a liquidator.
SIEGEL: Gudkov is a physicist who was working at the nuclear plant in Leningrad when Chernobyl happened. He says his friends, like most of the liquidators, are still in good health.
Prof. GUDKOV: I met two of them a couple of years ago in one international conference.
HAMILTON: Gudkov says the deaths were mostly among people who were actually at the plant when it blew up. He says the Soviet government declared them heroes and honored them with monuments.
Prof. GUDKOV: Well, it was recognition for sure, but they died.
HAMILTON: The government also provided the Chernobyl liquidators who survived with a blue and red metal badge. It shows radioactive particles passing through a drop of blood.
Jon Hamilton, NPR News.