Chernobyl Essay, Research Paper
O n April 26, 1986, a hellish white glow bejeweled a small, little-known town in central Ukraine, now notoriously recognized by the international community as Chernobyl. During the early morning hours of the twenty-sixth, operators had been running an ill-conceived experiment on reactor unit number four, during which a spike in the operating level of the core caused a catastrophic explosion. The resulting eruption of radionuclides, both from the initial explosion and from the subsequent fires, turned much of the Ukrainian countryside into a radioactive wasteland. Furthermore, prevailing winds blew radioactive clouds of particles over a large swath of Europe, irradiating many countries and endangering the overall food supply of the entire continent. Examining both short-term hazards, and long-term effects, many in the scientific community have proclaimed Chernobyl the worst environmental disaster ever (Read 66-73). It is the purpose of this paper to fully investigate every aspect of this colossal crisis. How bad was the accident? What caused it and how was it fixed? Finally, and most importantly, can humanity learn from its mistakes and prevent further such mishaps?
The Accident
Situated 65 miles north of Kiev in Ukraine next to the small town of Pripyat, the Chernobyl power station included four reactors, each with an estimated output of a thousand megawatts. Unbeknownst to the nearby residents, a dangerous experiment was conducted on reactor unit four during the early morning of April 26, 1986. Unfortunately, the Chernobyl operators breached numerous safety protocols in order to continue with their endeavor that hinted at disaster from the very beginning (Martin 16-19).
At approximately 1:23 AM on April 26, operators within the Chernobyl complex heard numerous thuds emanating from deep inside the reactor building. These ominous sounds were shortly followed by a horrifically sickening crash and an explosion which ripped through the reactor complex and buckled the meter thick concrete walls of the containment building. Emergency power units kicked on, revealing a dimly lit control room sparsely inhabited by frantic plant operators. Though nobody had a clear idea of the extent of the situation, foremost on everyone s mind was preventing a core meltdown. Numb with horror, Alexander Akimov, in command of the night reactor shift, watched as his corridors filled with dust and smoke, trapping men and machine in a furious inferno (Read 64-66).
Those looking at the complex from the outside noticed a strange ghastly white glow, as did those looking down into the empty crater where the reactor core lay completely fragmented. Sparks eerily crisscrossed the morning air as electrical systems short-circuited, while operators–realizing for the first time the severity of the accident–frantically attempted to gain control over the situation. Burst pipes allowed superheated steam to escape from many unpredictable points, scalding many workers who were attempting to fight the numerous graphite and electrical fires now raging like an uncontrollable beast throughout the building. Some of these workers stumbled about the plant, blisters covering every exposed patch of skin on their bodies, vainly trying to reach the apparent safety of the outdoors (Read 66-73).
It was determined afterward that thirty-two firefighters and plant operators had been killed in the first few days of the Chernobyl tragedy. Worse yet, debris from the shattered reactor core, coupled with the burning graphite piles, released several times the amount of radiation discharged when the United States dropped both atomic bombs on the Japanese cities of Hiroshima and Nagasaki (”The Causes of the Accident and Its Progress” 1-2). Because of the general lack of radiation monitoring equipment, the Soviet government learned the true extent of the accident only after Swedish personnel working at nuclear power plants in Sweden began to notice elevated levels of radioactivity (Martin 19).
Tragically, much of the radioactive material blown into the atmosphere was carried by the wind into the surrounding countryside, as well as distant republics. Forests surrounding Chernobyl turned a rust color as a result of high levels of radioactive contamination. However, about seventy percent of the fallout ended up contaminating the republic of Byelorussia, endangering its water and food supplies while causing an increase in the number of reported cancer cases and deaths (”Belarus”). Nearby, in the city of Kiev, the radiation level peaked at an increase of 160 to 300 times what could be expected from normal background radiation. To give some appreciation of the extent of the environmental damage caused by the release of radioactive isotopes from Chernobyl, the Swiss government banned fishing in certain lakes for nearly a year after the explosion due to high concentrations of the radioisotope Cesium-137 in aquatic life. Chernobyl also takes blame for an incredible increase in the amount of radiation absorbed by livestock and agricultural products scattered over Europe, especially within the Scandinavian countries. For instance, because of excessive levels of radiation, about seventy-five percent of the reindeer slaughtered in Sweden could not be consumed by humans (Marples 61-77).
However horrible the environmental impact of radiation may seem, it is nothing compared to the individual tragedies experienced by people who were seriously radiated. Soviet doctors described the following at a meeting in Paris on “The Medical Handling of Skin Lesions following High Level Accidental Irradiation” in 1987:
Male plant worker who received an estimated average total body dose of 9 Gy. . . He developed skin lesions from 5 days of irradiation, eventually involving 40% of the body surface area. He showed epilation of the scalp and eyelashes, but the eyebrows were not affected. Lesions were severe over both buttocks as a result of his sitting on a contaminated surface. These areas of skin developed blisters and foci of ulceration, which required covering with free skin grafts taken from the patient s flak 2 months after the accident. (Mould 69)
Many pregnant women who were exposed to radiation had abortions for fear of having offspring with serious physical defects or mental retardation. Lending some justification to these abortions, the U.S. Nuclear Regulatory Commission estimated that approximately five percent of the fetuses exposed to at least twelve rems–a measurement of the amount of ionizing radiation absorbed by body tissues (”Rem”)–from Chernobyl would be born with serious mental retardation (Marples 43-44).
Some of the mutations caused by radiation were to prove both shocking and frightening to those who lived in the most heavily contaminated zones: “To the horror of the inhabitants, a sow in Narodici gave birth to a litter of piglets without eyes. News of this spread and further freaks were discovered in the same region: a foal with eight legs, a chicken with a head shaped like a dragon s, a piglet with an eye half the size of its head, a calf with a lip like an elephant s trunk, and a goat with its hind legs three times longer than its front ones” (Read 270).
While scientists are sure that there will be many long-term deaths attributable to the exposure of people to radiation from the Chernobyl accident, many scientists are in serious disagreement as to the number of deaths and the severity of other long-term problems. Currently, scientists estimate that in the next seventy years, between 200 and 100,000 people will die because of radiation exposure to the fallout from the Chernobyl disaster. While this range is huge, most experts agree that the eventual number will finalize at about 10,000 deaths, mostly occurring because of an increase in leukemia cases in those areas most heavily radiated (Marples 52-53).
Causes of Chernobyl
The accident at Chernobyl has sparked much criticism about the safety of nuclear energy, while raising fears about nuclear power plants in the United States and other Western nations. In the decade following the disaster, images of badly scarred workers and horrifically deformed animals gradually found their way into the hands of the media (Read 270). Thus, people throughout the globe began to question whether or not an accident on the scale of Chernobyl could happen at home (Goldin 20). Central to formulating a reasonable answer to this question is an in-depth understanding of how and why the situation in central Ukraine unfolded as it did; consequently, this section is dedicated to documenting the sequence of events that contributed to the cataclysmic accident at the Chernobyl plant.
In 1949, Igor Kurchatov–already a prominent Soviet scientist–petitioned Joseph Stalin for permission to build an experimental nuclear power station using knowledge gained from captured German physicists. With permission given, the first nuclear power station in the world was commissioned on July 27, 1954, and christened Obninsk. An early design, this power station produced a mere five megawatts of electricity, not even enough to provide for the electrical needs of the actual power complex. Therefore, when American designers began working on new pressurized water reactors, the Soviet Union immediately began similar work on a new power station in hopes of implementing the practical use of atomic fission to fulfill the country s burgeoning need for electrical energy. Design and building of this new power station was problematic at best, mainly due to deficiencies in quality control. Thus, when the Soviet Union later resolved to greatly expand its use of nuclear fission, experts decided that the safest, surest reactor design would be a large modified version of the early Obninsk reactor (Read 3-15).
Construction of several new RBMK-1000 reactors commenced immediately. Roughly translated, the acronym RBMK means “reactor cooled by water and modified by graphite” (Marples 3). Basically, a RBMK reactor is a huge stack of graphite with several hundred channels drilled vertically through the carbon matrix. Some of these channels contain boron rods; boron is an excellent neutron absorber which serves as a control mechanism for the reactor. The rest of the channels contain small pipes–or pressure tubes–each of which contain thousands of enriched uranium pellets which undergo nuclear fission. Huge circulation pumps flush water through the tubes and over the uranium; this water serves as a thermal transfer medium, absorbing the heat from the nuclear fission of the uranium pellets, both to keep the core from melting and to provide steam to spin electricity producing turbines. However, as the graphite moderator is placed next to the uranium fuel elements, about five percent of the thermal energy released by the uranium is transferred to the graphite. This means that the graphite in RBMK reactors routinely functions at temperatures exceeding 700 Celsius, emitting a faint reddish glow. Unfortunately, graphite has the nasty tendency to burn at high temperatures when exposed to oxygen, so the entire core must be placed into a huge metal container where inert gases are constantly circulated (Marples 4-8).
While at first glance the RBMK may have seemed to be a safe alternative to more advanced pressurized water-cooled reactors, upon further inspection several major flaws became apparent. The British atomic Energy Authority released a list of seven reasons why RBMK reactors would not be licensed within the United Kingdom. Paramount on this list was the lack of a containment structure to provide protection in the event of a meltdown. Soviet designers felt that there was no need to provide a massive containment structure to protect against an apparently highly unlikely failure. Another major flaw of the reactor was that, in the event of an accident, it took a full eighteen seconds to lower the boron control rods into the graphite pile, an eternity in the world of nuclear reactions (Read 15).
Compounding the above design problems was the haste with which the Soviet Union built its nuclear power capacity. Because of the rapid expansion of its nuclear program, there were frequent shortages in precision parts needed in the construction of the nuclear power plants–including the Chernobyl plant. However, there was enormous pressure on those responsible for the construction of power plants to get the reactors producing electricity quickly. Thus, many components were built and improvised at the building site. Considering that piping and valve components must be assembled with extreme precision, it is unlikely that all of these make-shift components met even lenient Soviet safety standards (Read 30-31).
The RBMK was the type of reactor chosen to power the new, enormous power-producing complex situated at Chernobyl. Conceived in the late 1960s as the solution to energy shortages in the Eastern part of the Soviet Union, Chernobyl was to eventually accommodate six one-thousand megawatt RBMK reactors (Read 28-35). When the Chernobyl plant finally became operational in December 1978, several major difficulties were noticed in the operation of the huge RBMK reactors. First, the reactors tended to be highly unstable when run at low power settings. Under these circumstances, power could completely collapse within the reactor, necessitating lengthy restart procedures. Thus, when a collapse appeared imminent, operators frequently withdrew many more boron rods than was permitted by Soviet regulations, simply to give the reactor a surge of power to prevent shutdown. Second, the primitive computer used to process information and monitor reactor systems printed out incredibly complex, cryptic information, not easily understood by human operators. This would pose problems in the event of a crisis, when information must be interpreted quickly and accurately. Finally, operators at the plant had to monitor a myriad of dials and switches, making it difficult for them to understand completely what the reactor was doing at all times, crucial knowledge in the event of an accident (Read 41-42).
Besides the physical problems that hampered the RBMK reactors used at the Chernobyl plant, the mind-set of Soviet officials was such that information on past problems was withheld even from operators who could benefit from this information. To these officials, Soviet technology was infallible and the few problems that surfaced in the reactors could not possibly be due to faulty design. For instance, there was a meltdown within a reactor at a plant in Leningrad (now St. Petersburg). Although this reactor was identical to the RBMK reactors used in the Chernobyl plant, Soviet officials did not see fit to warn the Chernobyl plant of a potential problem, fearing that this information might undermine the Soviet nuclear industry (Read 39-40).
Despite the design failings of the RBMK reactors, an accident may never have occurred at Chernobyl had operators not attempted a foolishly designed experiment (”The Causes of the Accident and Its Progress”). Attempting to ascertain the length of time that inertia would keep the turbines spinning in the event that the reactors had to be shut down, operators gradually began decreasing the power output of reactor number four at 1:05 on April 25, 1986 (Martin 16-19). However, unexpected demand for power forced operators to maintain the reactor at about fifty percent power for an additional nine hours. When the experiment finally resumed at 12:28 AM, April 26, operators further reduced the power, accidentally reducing the reactor to one percent operating power. The RBMK reactor became unstable as xenon gas–a neutron absorber–formed in the core. To prevent the reactor from completely shutting down, operators withdrew virtually all of the boron control rods between 1:00 and 1:20 AM, allowing power to rise to about seven percent. Afraid that the automatic shutdown systems would SCRAM–or immediately shut down–the reactor, plant operators flipped off the emergency shutdown systems. At 1:23, steam was shunted to a previously idle turbine; at 1:23:40, power increased in the reactor as water began to flow more quickly over the fuel elements. As one Soviet expert explained, “The reactor was now running free, isolated from the outside world, its control rods out, and its safety system disconnected. . .The reactor was free to do as it wished” (Martin 17). The next events occurred very quickly as operators pressed the manual shutdown button–drastically reducing water flow over the fuel elements–to examine how long inertia would keep the turbines spinning and producing power. Had the emergency systems been connected, the loss of the electrical load would have caused the reactor to SCRAM (Martin 17). However, all automatic emergency systems were off-line, and at this low power setting shutting off the turbines caused the RBMK reactor to spike at about 100 times its full operating power (Marples 14).
Predictably, the reactor core shattered, spewing pieces of radioactive graphite and uranium throughout the destroyed reactor building and over the Ukrainian countryside. The hot graphite of the core–no longer isolated from oxygen–began to smolder, releasing tons of radioactive material, which was trapped within its carbon matrix mostly iodine-131 and cesium-137, into the atmosphere. (General Accounting Office 8).
While the faulty experiment on the day of April 26 was the precipitating causal factor in the catastrophic destruction of reactor number four at the Chernobyl complex, faulty engineering and design problems with the RBMK reactor played major contributing roles. However, the most significant contributing factor seems to have been a complacency of mind: a psychological phenomenon that seems to recur. For example, those who built the Titanic never imagined that this great ship could sink; hence, the lack of lifeboats onboard became a major factor in one of the worst tragedies of all time. In much the same way, Soviet designers never thought that their designs could fail. Thus, they did not see fit to build elaborate containment structures around their RBMK reactors. Also, test operators at Chernobyl never thought that their program could cause any real damage. For that reason, they proceeded even when problems immediately became apparent. Catastrophes such as Chernobyl are rarely caused by a single event or problem; rather, they are usually the culmination of a string of circumstances which together point to disaster.