The Chernobyl disaster on April 26, 1986 is described as one of the mostfrightening environmental disasters in the world. The plant was made up of fourgraphite reactors, which were the most modern Soviet reactors of the RBMK-type.
Two more of these reactors were still under construction at the station.
Chernobyl was an obscure town in north central Ukraine (former Soviet Union) onthe Pripyiat River near the Belarus border. Immediately its name was joined tothe Nuclear Power Plant located twenty-five kilometers upstream. The plant isactually located fifteen kilometers northwest of the city. It is not only theradioactive mess left that strikes fear. Nineteen similar stations are stillrunning, because neither the former Soviet Union nor its republics can afford toshut them down. The world first learned of this accident from Sweden, whereunusually high radiation levels were noticed at one of their own nuclearfacilities. At 1:23 am technicians at the Chernobyl Plant took some erroneousactions that will impact the course of Soviet events without exaggeration. Humanerror is what basically caused the disaster. These operators of the fourth unitslowly allowed power in the reactor to fall to low levels as part of acontrolled experiment gone wrong. The purpose of the test was to observe thedynamics of the RMBK reactor with limited power flow. Twelve hours after powerreduction was initiated, power reached 50 percent. Only one turbine was neededto take in the decreased amount of steam, so no. 2 was turned off. Power wasthen reduced to 30 percent. One of the operators made a mistake. Instead ofkeeping power at 30 percent, he forgot to reset a controller, which caused thepower to plummet to 1 percent. Now water was filling the core, and xenon (aneutron absorbing gas) built up in the reactor. The power was too low for thetest. The water added to the reactor is heated by the nuclear reaction andturned into steam to turn the turbines of the generator. The operator forced thereactor up to 7% power by removing all but 6 of the control rods. This was aviolation of procedure and the reactor was never built to operate at such lowpower. This type of reactor is very unstable when filled with water. Theoperator was not successful in getting the flow of water corrected and thereactor was getting increasingly unstable. The operator disabled emergencyshutdown procedures because a shutdown would abort the test. By 01:22 AM, whenthe operators thought they had stable conditions, they decided to start thetest. The operator blocked automatic shutdown because of a fear that a shutdownwould abort the test and they would have to repeat it. The test began and theremaining turbine was shut down. Power in the reactor began to gradually risebecause of the reduction in water flow caused by the turbine shutdown, whichlead to an increase in boiling. The operator initiated manual shut down, whichlead to a quick power increase due to the control rod design. The reactorreached 120 times its full power. All the radioactive fuel disintegrated, andpressure from all excess steam broke every one of the pressure tubes and blewthe entire top shield of the reactor. All of these factors including seriousviolations of safety operations, dangerous design flaws, and imperfect controlsystems is what led to the virtually instantaneous catastrophic increase ofthermal power which led to core meltdown. The steam explosion also destroyedpart of the building. Radioactive material was then thrown out into theatmosphere for over 10 days. Multiple fires were formed both inside and out ofthe reactor. By five o’clock the firemen had smothered the flames. In laterdays, about 5000 tons of materials were thrown into the reactor well fromhelicopters of the air force to extinguish burning graphite and suppressradiation release. The flow of different substances continued until thebeginning of June 1986. It is still not clear if the dumping of these materialsactually achieved their goal. Recent data has shown only a small part of thematerials actually got into the well. Due to the accident, the people ofChernobyl were exposed to radioactivity 100 times greater than the Hiroshimabomb. The people of the world and Northern Europe were greeted with clouds ofradioactive material being blown northward through the sky. Seventy percent ofthe radiation is estimated to have fallen on Belarus and 10 years later babiesare sill being born with no arms, no eyes, or only stumps for limbs. No one canpredict the exact number of human victims. It is estimated that over 15 millionpeople have been victimized by the disaster in some way. It has also estimatedthat ultimately the accident will claim more victims than World War II. It willcost over 60 Billion dollars to make these people healthy. Thirty-one lives werelost immediately, and more than 600,000 people were involved with the cleanup.
Many are now dead or sick. Hundreds of thousands had to abandon entire citiesand settlements within the thirty-kilometer zone of highest contamination.
Possibly as many as three million still live in contaminated areas. Ten thousandof these are still living in the city of Chernobyl today. Huge sums of many havebeen spent, and will continue to be spent to relocate settlements anddecontaminate the once rich farmlands. Chernobyl has developed as an icon forthe terror of uncontrolled nuclear power and abilities, and for Soviet deceptionand inability to provide safe conditions for workers and basic services such astransportation and health care, especially in times of greatest need. Thecatastrophe also halted a highly potential nuclear program. The impact of theChernobyl Accident on a Nuclear Energy Policy is tremendous. Some countriesstopped national nuclear energy programs. Construction of new plants in theSoviet republics were frozen. Public opinion was directed against nuclear powerplants. Some plants were even shut down, but have now been reactivated. Theaccident has also initiated an international activity in the area of nuclearsafety and nuclear emergency planning. Many countries started a development ofdecision support systems for nuclear accident cases. The way in which Sovietleaders have dealt with the situation is very unsettling. In the aftermath ofthe catastrophe several designs to encase the damaged reactor were reviewed. Theoption that was selected included the construction of a massive structure inconcrete and steel that used what remained of the reactor walls as support. Itsconstruction is considered one of the most complicated building works in theworld. In charge of building the tomb was Construction Department No. 605. Theyran into many problems while constructing the massive concrete and steel shell.
Concrete blocks for the tomb were pieced together far from the reactor itself,and the roads entering the facilities were not accommodated for such loads,which made it difficult for the drivers. Once the blocks were delivered, theworkers needed to put them in place. Each weighed several dozen tons soeventually crane operators had to perform this task. This outer protective wall,28 stories high, is placed around the perimeter and other walls connected to theUnit 3 reactor. A steel roof then completed the structure. The destroyed reactorwas entombed in a 300,000-ton concrete structure known as the”shelter” or “envelope.” In conditions of high radioactivitythe mammoth task was completed in seven months, in November 1986. The sitearound the plant had then been announced safe for about the next thirty years.
However today the sarcophagus is cracked and crumbling. Some of these cracks areas large as a garage door. Multiple sensors were placed to monitor levels ofgamma radiation, neutron flux, temperature, heat flux, as well as theconcentrations of hydrogen, carbon monoxide and water vapor in the air. Othersensors monl On the whole, there are some different points and aspects from theauthors to explain the effects of immigration on labor market. They are thedemand and supply, investment, expenditure form government, skilled immigrants,mobility and the empirical findings. Although there are both advantages anddisadvantages from immigration, most authors believed that there is no causallink between immigration and unemployment. However, it is possible that theyemphasized the benefits and gave insufficient attention to the costs ofimmigration on the labor market. In my view, government should consider moreaspects from the effect of immigration on labor market for making the policywell. Also, government should not put most responsibilities of unemployment onimmigration in order to escape the blame from high unemployment because it isnot fair to the contribution from immigration and make an unreal image ofimmigration to society.