3 mile island

The accident began about 4 a.m. on Wednesday, March 28, ________, when the plant experienced a failure in the secondary, ___-________ section of the plant (one of two reactors on the site). Either a mechanical or electrical failure prevented the main feedwater pumps from sending water to the s________ g____________ that remove _______ from the _______ core. This caused the plant's turbine-generator and then the reactor itself to automatically ______ _______.

1979 non nuclear steam generators heat reactor shut down

As a result of the Three Mile Island accident, construction of new nuclear plants in the US was halted for ____ years after the accident.

30

Today, there are ___ reactors in use today, supplying __% of the nation's electricity, The Department of Energy __________ _________ nuclear plants as a way to _________ U.S. reliance on _________ ________, and to cut ________ _____ emissions.

99 20% supports more decrease foreign oil greenhouse gas

As a result, plant staff ____________that as long as the pressurizer water level was high, the core was properly covered with water. As alarms rang and warning lights flashed, the operators did not realize that the plant was experiencing a _________- ___- __________ accident. They took a series of actions that made conditions worse.

assumed loss of coolant

The water escaping through the stuck valve reduced primary system pressure so much that the reactor coolant pumps had to be turned off to prevent dangerous vibrations. To prevent the pressurizer from filling up completely, the staff reduced how much emergency cooling water was being pumped in to the primary system. These actions starved the reactor core of _________, causing it to ________.

coolant overheat

Within a short time, chemical reactions in the melting fuel created a large ____________ bubble in the dome of the pressure vessel, the container that holds the reactor core. Officials worried the hydrogen bubble might burn or even explode and rupture the pressure vessel.. The crisis ended when experts determined on Sunday, April 1, that the bubble could not burn or explode because of the absence of ________ in the p________ v_______. Further, by that time, the utility had succeeded in greatly reducing the size of the bubble.

hydrogen oxygen pressure vessel

As coolant flowed from the primary system through the valve, other instruments available to reactor operators provided ___________ information. There was no instrument that showed how much water covered the core.

inadequate

Without the proper water flow, the nuclear fuel overheated to the point at which the zirconium cladding (the long metal tubes that hold the nuclear fuel pellets) ruptured and the fuel pellets began to _____. It was later found that about half of the core melted during the early stages of the accident. Although TMI-2 suffered a severe core meltdown, the most dangerous kind of nuclear power accident, consequences outside the plant were ________. Unlike the Chernobyl and Fukushima accidents, TMI-2's containment building remained intact and held almost all of the accident's radioactive material.

melt minimal

Comprehensive investigations and assessments by several well respected organizations, such as Columbia University and the University of Pittsburgh, have concluded that in spite of serious damage to the reactor, the actual release had ____________ effects on the physical health of ____________ or the ____________.

negligible individuals environment

By the evening of March 28, the core appeared to be adequately cooled and the reactor appeared to be stable. But new concerns arose by the morning of Friday, March 30. A significant release of radiation from the plant's auxiliary building, performed to relieve pressure on the primary system and avoid curtailing the flow of coolant to the core, caused a great deal of confusion and consternation. In an atmosphere of growing uncertainty about the condition of the plant, the governor of Pennsylvania, Richard L. Thornburgh, announced that he was advising _________ women and _____________ age children within a ____-mile radius of the plant to leave the area.

pregnant pre-school 5

Immediately, the ________ in the primary system (the nuclear portion of the plant) began to increase. In order to control that pressure, the pilot-operated relief valve (a valve located at the top of the pressurizer) opened. The valve should have closed when the pressure fell to proper levels, but what happened to it? ___________________________. Instruments in the control room, however, indicated to the plant staff that the valve was _______. As a result, the plant staff was ____________ that cooling water was ________________ of the stuck-open valve.

pressure became stuck open closed unaware pouring out