The Chernobyl Disaster and Its Effects on Nuclear Safety

Jenna Gray
November 18, 2018

Submitted as coursework for PH240, Stanford University, Fall 2018

Background

Fig. 1: Map of Chernobyl and surrounding countries (Source: Wikimedia Commons)

On April 26th, 1986, disaster struck the Chernobyl nuclear power plant in Ukraine when a series of safety tests led to the explosion of a Soviet reactor. [1] This event was (and still remains) one of the most catastrophic nuclear accidents to ever occur. [1] The economic blow to Ukraine because of this disaster totals to about 148 billion USD. [1] Two workers were killed immediately by the explosions, and 28 more workers succumbed to side effects from the blast in the following weeks. [1] Along with the loss of workers, the radioactive material released affected not only the people in the city of Chernobyl, but also millions in the surrounding countries. Belarus and Russia, being in close proximity to Chernobyl (see Fig. 1), suffered high doses of radiation from the disaster. [1]

Cause

It began with the annual check of the long turbines that would provide power in case the main power supply went down. However, the turbine was moving too quickly, so operators disabled the automatic shutdown mechanism and proceeded with their tests. [2] When doing so, the flawed design of the control rods caused a large power surge when inserted into the reactor, causing major problems with the already unstable condition of the reactor. [2] A buildup of pressure initiated by the hot fuel and cooling water caused the 1000t cover plate to detach, which consequently jammed the control rods and ruptured fuel channels. [2] The emergency cooling circuit attempted to rectify the problem, but only furthered steam build up and caused the initial steam explosion. [2] Within a couple of seconds, a second explosion struck, spewing out hot fuel and graphite. The hot fuel projected into the environment ignited fires, which ultimately spread the radioactive materials the most. [2]

Effects on Nuclear Safety

While the operators of the facility did put the reactor in an extremely unstable state, they did not directly violate any safety rules. This lack of policy was a consequence of the Cold War isolation that Ukraine was experiencing. Before this accident, there were no international nuclear energy laws, just recommendations. [3] However, after the accident, the nuclear energy industry made revisions in order to increase safety and responsiveness to the public. The State Committee for Safety in the Atomic Energy Industry created stricter guidelines for safety inspection regulations, which includes increased operator training. They also focused on ensuring that new nuclear power stations would have properly constructed reactors to maximize stability. [3]

© Jenna Gray. 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.

References

[1] J. Smith, Chernobyl: Catastrophe and Consequences (Springer,2005), pp 5, 20, 248.

[2] R. C. Murray and G. E. Cummings, "Structural Aspects of the Chernobyl Accident," Lawrence Livermore National Laboratory, UCRL-98842, September 1988.

[3] "The Chernobyl' Accident: Social and Political Implications," U.S. Central Intelligence Agency, SOV 87-10078X, December 1987 [Sanitized 9 Dec 12].