page_title: Nuclear energy policy of the United States
section_title: 1986 Chernobyl disaster
hierarchical_section_title: Nuclear energy policy of the United States / Public response to nuclear accidents / 1986 Chernobyl disaster
caption_attribution_description: Anti-nuclear rally outside the Pennsylvania State Capitol in Harrisburg, Pennsylvania.
context_page_description: The nuclear energy policy of the United States developed within two main periods, from 1954–1992 and 2005–2010. The first period saw the ongoing building of nuclear power plants, the enactment of numerous pieces of legislation such as the Energy Reorganization Act of 1974, and the implementation of countless policies which have guided the Nuclear Regulatory Commission and the Department of Energy in the regulation and growth of nuclear energy companies. This includes, but is not limited to, regulations of nuclear facilities, waste storage, decommissioning of weapons-grade materials, uranium mining, and funding for nuclear companies, along with an increase in power plant building. Both legislation and bureaucratic regulations of nuclear energy in the United States have been shaped by scientific research, private industries' wishes, and public opinion, which has shifted over time and as a result of different nuclear disasters.
  In the United States, there have been numerous legislative actions and policies implemented on a federal and state level to both regulate atomic energy and promote its expansion.
context_section_description: The 1986 disaster in Chernobyl, USSR is generally considered to be the worst nuclear disaster, to date. On 25 April 1986, during routine maintenance, the crew at Chernobyl began preparing for a test of the reactor's turbine. During the test, the site experienced a loss of their main electrical power supply  Because of this loss of power, the automatic shutdown mechanisms failed, and the reactor started to become unstable. As the Chernobyl operators tried to cool the rods by inserting them into the reactor core, a large power surge occurred. This is generally believed to be from a design flaw in the rods.
  This power surge combined with the hot fuel rods touching the water in the reactor caused "fuel fragmentation along with rapid steam production and an increase in pressure."  This led to the fuel rods to rupture, and the safety protocols for the reactor core could not withstand the damage of 3–4 of its fuel rod assemblies. The resulting pressure inside the core forced the covering plate of the reactor to dislodge itself, also "rupturing the fuel channels and jamming all the control rods, which by that time, were only half-way down."  The resulting steam from the incident caused many of the emergency cooling circuits to malfunction. This led to a large fission explosion which released radioactive materials into the atmosphere. In a period of a few seconds, a second explosion occurred which caused graphite fragments of the fuel ruptured rods to be blasted into the atmosphere, although debate still exists, some scientists believe that it was caused by "zirconium-steam reactions" 
  According to World-Nuclear.org, "Two workers died as a result of the explosions. The graphite (of which, about a quarter of the 1200 tons was estimated to have been ejected) and fuel became incandescent and started a number of fires, causing the main release of radioactivity into the environment. A total of about 14 EBq (14 x 1018 Bq) of radioactivity was released, over half of it being from biologically-inert noble gases."
  Following the explosion, hundreds of tons of water per hour were poured into the reactor to douse the fires which were releasing radioactive smoke. However, this was quickly abandoned after half a day, to prevent water from flooding units 1 and 2. For the next eight days, "Some 5000 tons of boron, dolomite, sand, clay and lead were dropped by helicopter onto the burning core in an effort to extinguish the blaze and limit the release of radioactive particles."
  Aside from the two initial deaths, officially, 28 more died in the following weeks. Soon after, 336,000 people were evacuated after the explosion and fire. Eradiated ash, dust, and smoke traveled across much of Europe including Russia, Ukraine, and Belarus. There is a heated debate over the official number of deaths, illnesses and subsequent birth defects caused by the plant's meltdown. The estimated number of deaths potentially resulting from the accident vary enormously; the World Health Organization (WHO) suggested it could reach 4,000 while a Greenpeace report puts this figure at 200,000 or more. According to WHO, by mid-2005, only about 50 deaths could be directly associated with the disaster.
caption: A 1979 anti-nuclear protest in Harrisburg, Pennsylvania after the Three Mile Island incident
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