What Happened at Chernobyl?
On 26 April 1986, one of the worst nuclear accidents in history occurred at the Chernobyl reactor in the Ukraine. The fourth reactor exploded in the early hours of the 26th and released radiation and particulate material, devastating a 20 mile (32 kilometer) radius and affecting to the rest of the world as well. The cause of the Chernobyl disaster was readily identified, and was deemed by some nations to be gross negligence on the part of plant operators. Thirty people died at the site of the explosion, and many more suffered illness as a result of radiation exposure. The site of the Chernobyl reactor was cordoned off, and the reactor was capped with a large concrete pad. In the twenty-first century, it became evident that the pad was not effectively sealing off the radiation and that additional steps would need to be taken to prevent additional leakage of contaminated material. The area around the Chernobyl reactor is still restricted to humans, and in the slang of the region is known
As is usually the case in any accident, a number of things combined to cause this one at Chernobyl. Unlike power reactors operating in the U.S. and other nations, the Chernobyl RBMK reactor (which is a graphite rather than a light water system) has a built-in instability that occurs at low power, which is how the reactor was operating at the time of the accident. If some of the cooling water in this reactor converts to steam, the RBMK increases in power. This in turn causes more steam to form, which causes _another_ increase in power. (In Western light water reactors, the power decreases.) The power increase feature of the RBMK caused a rupture in the cooling system and a large steam explosion occurred. This caused the cooling system to fail and the outer covering (or cladding) of the fuel elements to increase in temperature. The cladding was hot enough to react with the steam, causing hydrogen to form. The hydrogen then caused a second explosion. The release of this energy set the gra
The accident at Chernobyl occurred when a fission chain reaction was allowed to spiral out of control. Fission processes in nuclear reactors need to be very carefully controlled – if the fission becomes too vigorous, then it needs to be slowed down, usually by inserting rods made of carbon that absorb the excess neutrons and reduce the rate at which nuclear fission occurs. The reactor at Chernobyl was of a design that could, under certain circumstances, promote unstable fission chain reactions. The explosion at Chernobyl occurred during testing in which the control of the fission process was undertaken manually by power plant workers (rather than by computer). This is an inexcusable breach of safety regulations that simply would not be allowed to happen today, and one cannot blame the plant workers for what happened, who were merely acting on orders from their superiors. This mode of operation, along with the design flaws in the reactor design, resulted in a fission chain reaction that
