ReNuclear

redefining nuclear energy in hopes of transitioning to a society run on carbon-free electricity

Nuclear Melt Downs

Identifying a Nuclear Meltdown

The meltdown of a nuclear plant is one of the greatest fears when discussing nuclear energy. From 1952-2011 there have been 33 serious incidents at nuclear plants (Rogers S., 2011). These incidents range from individual workers receiving an increased dose of radiation to the full meltdown of Chernobyl. This is a large variance, but every incident of any nature needs to be documented. Nuclear plants need to keep the fuel rods cooled by pumping cool water into the reactor. The main source of nuclear meltdowns occur when there is structural damage to the reactor and/or mechanical or electrical failures in the system. These failures can impede the process of pumping in cool water, which causes the fuel rods to heat up. This creates steam from the water that was left in the reactor, which is then catalytically broken down into oxygen and hydrogen by the zirconium coating of the fuel rods (Golte-Schroeder, 2011). This mixture of gases poses an explosion hazard, and is what lead to the explosions at chernobyl and fukushima.

Nuclear Meltdown at Three Mile Island, 1979

One example of a nuclear meltdown  was the meltdown at Three-Mile Island located near Middleton, Pennsylvania. There was a series of events that included component failures and human error. The first problem was an electrical or mechanical error that prevented the water pumps from providing cool water to the reactor. After this a small valve was opened to relieve pressure from the reactor to prevent an explosion. Once the pressure was reduced to a safe level the valve was supposed to be shut unfortunately the valve stuck open and the system showed that the valve was closed. Then there was a series of misinformation from the equipment that provided inadequate feedback on coolant levels and how much water was covering the core. This series of events started around 4 am on March 28th 1979, and the reactor was stabilized the evening of the same day. There was a major concern about the amount of nuclear radiation leaked from the meltdown. After the incident it was determined that to the surrounding population of 2 million, the population received an extra dose of 1 millirem. An x-ray provides about 6 millirem in comparison. There was no effects to the population, plant or wildlife in the area surrounding the reactor. After this meltdown a series of new U.S. NRC regulations were made to ensure better plant design and equipment, increase training requirements and emphasizing the role of operators, and various other regulations (U.S.NRC, 2014).

Impact of Nuclear Meltdowns

There have been a couple of other nuclear meltdowns other than Three Mile Island. The most famous are the Chernobyl and Fukushima meltdowns. Both of these meltdowns were significantly worse than the three mile island meltdown. The nuclear meltdown at Three Mile Island was determined to be a 5 on the International Nuclear Events Scale (INES), which goes from 1-7. Chernobyl and Fukushima were both rated at 7. After each nuclear meltdown extensive research is done  to determine the cause and what measures could have been made to prevent the situation. Since 2000, Fukushima has been the only nuclear meltdown. It was caused after a tsunami knocked out the power grid, then flooded the backup generators. This left the plant without power for its coolant pumps, which lead to three of the six reactors melting down. These meltdowns have reasonably changed public opinion to be a lot more skeptical about nuclear energy and safety measures to prevent a nuclear meltdown need to be the top priority of every nuclear plant.

Citations:

  1. Golte-Schroeder, S. (2011, December 3). The science behind how a nuclear meltdown occurs | DW | 12.03.2011. Retrieved April 26, 2018, from http://www.dw.com/en/the-science-behind-how-a-nuclear-meltdown-occurs/a-14907961
  2. Rogers, S. (2011, March 14). Nuclear power plant accidents: Listed and ranked since 1952. Retrieved April 26, 2018, from https://www.theguardian.com/news/datablog/2011/mar/14/nuclear-power-plant-accidents-list-rank
  3. United States Nuclear Regulatory Commission. (2014, December 12). Backgrounder on the Three Mile Island Accident. Retrieved April 26, 2018, from https://www.nrc.gov/reading-rm/doc-collections/fact-sheets/3mile-isle.html
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