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| Fig. 1: The Chernobyl Nuclear Power Plant. (Source: Wikimedia Commons) - This figure dangles. - RBL |
On April 26, 1986 a major accident occurred at the Chernobyl Nuclear Power Station in Pripyat, Ukraine (see Fig. 1) when one of the station's four reactors malfunctioned and exploded. The accident released a large amount of radioactive materials into the surrounding area, resulting in the immediate evacuation of the city's residents.
The reactor that exploded at Chernobyl was known as an RBMK-1000. The explosion itself was a direct result of this specific reactor's design flaws, along with staff operation errors.
During a scheduled test of power supply, the staff at Chernobyl lowered the reactor's capacity down to an admissible low level. [1] Because of the RBMK-1000's design, the operators were unable to effectively control the reactor's work at this low capacity. The operators attempted to insert protection rods into the reactor at this low reactivity level in hopes of stopping the reactor, but instead these rods increased the reactivity, reactor power growth, and fast heating of the reactor active zone. [1] All of these factors combined resulted in the explosion.
Emergency crews immediately responded to the site of the accident, pouring sand and boron on the reactor debris. [2] The sand was intended to put out the fires caused by the accident, while the boron worked to prevent any additional nuclear reactions from occurring. In the weeks following the explosion, thousands of workers made efforts to cover the damages.
Directly after the accident, officials closed off the surrounding 18 miles within the plant. [2] Within the year, an estimated 115,000 people were evacuated from heavily contaminated areas surrounding the plant, and around 220,000 more people were evacuated in the subsequent years.
The initial coverup of the site included a temporary plan to build a concrete sarcophagus over the destroyed reactor. This took place in May of 1986, and lasted around 6 months. [2] The Sarcophagus's purpose was to help filter radiation out of the gases from the reactor, but its stability was later questioned by experts in the years following the explosion.
As a result, in 1997 Ukraine and the European Commission agreed to fund the Chernobyl Shelter Implementation to transform the sarcophagus into an arch-shaped, steel structure. [2] This structure was designed to last approximately 100 years, and proved to be an environmentally safer system in comparison to the original sarcophagus.
Only two workers died on site of the plant, but in the first four months after the accident, 28 of the 600 workers at Chernobyl were reported dead due to severe radiation. [2] Nearly 600,000 workers were required in order to cleanup the site, 200,000 of which received doses between 1 and 100 rem of radiation in the year following the accident.
Fortunately, no acute health effects occurred outside of the Soviet Union after the accident at Chernobyl. [3] The radiation doses reported outside of the Chernobyl region proved to be quite small after the accident, resulting in an extremely small probability of any person outside of this region developing a fatal radiogenic cancer over a lifetime.
As a whole, the global impact of the accident at Chernobyl is largely related to the economic cost of the incident rather than the actual levels of radiation released. The entire estimated cost of the accident was around $15 billion. Direct costs included relocations, medical care, the loss of the reactor and things alike, all of which amounted to around $6.8 billion. [3] Indirect costs like replacement of lost power, food surveillance, new construction etc, accounted for the the other part of the estimated $15 billion.
© Emma Knaus. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] V. Kortov and Yu. Ustyantsev, "Chernobyl Accident: Causes, Consequences and Problems of Radiation Measurements," Radiat. Meas. 55, 12 (2013).
[2] "Backgrounder: Chernobyl Nuclear Power Plant Accident," U.S. Nuclear Regulatory Commission, August 2018.
[3] L. R. Anspaugh, R. J. Catlin and M. Goldman, "The Global Impact of The Chernobyl Reactor Accident," Science 242, 1513 (1988).
