Three Mile Island nuclear accident: March 28, 1979

Accident occurs at Three Mile Island nuclear power plant near Harrisburg, Pennsylvania.
4:35 | 03/20/19

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Transcript for Three Mile Island nuclear accident: March 28, 1979
For many years there has been a vigorous debate in this country about the safety. Of the nation's 72 nuclear energy power plants. I debate is likely to be intensified because of what happened early this morning at a nuclear power plant in Pennsylvania. Facts. Market with an accident at the Three Mile Island nuclear power plant which is located on an island in the Susquehanna River ten miles from Harrisburg. A cooling pump broke down and the plant did just what was supposed to do so that's all well. But not before some radioactivity had a strict we have two reports first between a Greg. It happened at the number 2 generator about 4 o'clock this morning something caused the secondary cooling system to fail. It shut off the reactor but heat and pressure built up and some radioactive steam escaped into the building housing the reactor. And eventually out into the plant and the air. What you would it lives across the river. I heard today yet very. Live noise. That it sounded like get. A year gauge relation. Staying. And a but that there when that was it was dark but you could see from the lace over there that there was geyser of steam that was. Racing up in the air. Mike in askew was working inside the anything didn't hear it. Prosecutors turbine trip and that she comes and then Nelson waved off. Workers were evacuated the plant was completely shut down a crew from the Nuclear Regulatory Commission rushed from Washington and sped around all day testing for radiation. Workers in their cars were checked and re checked for radiation some was found. Late today in Washington the NRC said quote there's a hell of a lot of radiation in the reactor building. Adding that radiation had penetrated the four foot thick walls of that building and was detected as far as one mile away. Officials of metropolitan Edison conceded some workers may have been contaminated but they insisted this was not a serious accident. This had only 110 the amount of radiation needed for a general alarm escaped. Why did then was a general alarm sounded and not until three hours later. Company officials said just to be safe but state officials were upset that they weren't told of the accident earlier. If there is a situation where. There was a perception of an emergency and they passed maneuvers he management agency council were not notified we intend to find that out that would be extremely disturbing. We will make a thorough investigation. Officials say they still don't know what caused the malfunction that triggered the general alarm they said the only thing that sickness does this. That there will be an investigation and that this nuclear power plant won't reopen until they're sure it's safe. Bettina Gregory ABC news Three Mile Island near Harrisburg and something. This is Roger Pedersen. Most people have little knowledge of what goes on at a nuclear plant and couldn't care less until something goes wrong. Like most nuclear facilities the water at Three Mile Island as a pressurized water reactor. What that means is simply water under pressure is heated as it circulates through uranium filled fuel rods. I water and turning eats another water system turning it into steam to run turbines that generate electricity. Here's what nuclear experts believe happened in this system. The pomp that circulates water through the steam generator in the turbines apparently failed. With a pump out water couldn't circulate. Pressure built up until a relief bell blue on the turbines that's where the radiation was released into the atmosphere but well below any danger level. With that system down there was no way to draw a heat out of the cooling water that circulates through the reactor itself. Again pressure built up until another relief valve was triggered this time sending highly radioactive steam throughout the containment building. The loss of pressure in the cooling system automatically shut the reactor down. Inside the containment building the radiation is reportedly being measured at from fifty rank pins per hour at the base to 4000 reckons per hour at the top. Anything above 600 is considered deadly. Some of that radiation is leaking out through the walls. A high levels inside the building indicate damage to the fuel rods in the core. And that deadly radiation will have to be cleaned up before any repairs can be made. Roger Peterson ABC news.

This transcript has been automatically generated and may not be 100% accurate.

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