Three Mile Island Research Paper

INTRODUCTION
Three Mile Island Nuclear Generating Station (TMI) is a civilian nuclear power plant (NPP) located on Three Mile Island in the Susquehanna River, south of Harrisburg, Pennsylvania. It has two separate units, known as TMI-1 and TMI-2. The TM-1 is a pressurized water reactor with a net generating capacity of 852 MWe while TMI-2 was also a pressurized water reactor but with slightly larger output of 906 MWe. The plant is widely known for having been the site of the most significant accident in United States commercial nuclear energy, on March 28, 1979, when TMI-2 suffered a partial meltdown. The partial meltdown resulted in the release of small amounts of radioactive gases and radioactive iodine into the environment. However,
on Wednesday, March 28, 1979, when the plant experienced a failure in the secondary, non-nuclear 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 steam generators that remove heat from the reactor core. This caused the plant 's turbine-generator and then the reactor itself to automatically shut down. Immediately, the pressure 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 it became stuck open. Instruments in the control room, however, indicated to the plant staff that the valve was closed. As a result, the plant staff was unaware that cooling water was pouring out of the stuck-open
Radioactive gases from the reactor cooling system built up in the makeup tank in the auxiliary building. Operators used a system of pipes and compressors to move the gas to waste gas decay tanks. The compressors leaked, and some radioactive gas was released to the environment. These went through high-efficiency particulate air (HEPA) filters and charcoal filters which removed most of the radionuclides, except for the noble gases, the estimated total of which was about 370 PBq (the Kemeny Commission said ‘a maximum of 480 PBq noble gases’ and NRC also quotes 1.6 PBq of krypton rlelease in July). With short half-life and being biologically inert, these did not pose a health hazard. An inter-agency analysis concluded that the accident did not raise radioactivity far enough above background levels to cause even one additional cancer death among the people in the area. The EPA found no contamination in water, soil, sediment or plant