Top 6 Nuclear Radiation Accidents and Disasters

Top 6 Nuclear Radiation Accidents

Serious life-threatening radiation accidents are extremely rare for reasons that are apparent and compelling. Even small doses of radioactive material, when ingested, can result in illness and death. So when there are reports of a nuclear accident, the alarm bells start to ring immediately as everyone realizes the deadly implications of widespread radioactive contamination.

However, despite extensive and necessary precautions taken to protect the public, sometimes accidents have happened, some minor, some major. Below is a description of 6 accidents deemed to be the biggest and therefore most dangerous, of all time.

Fukushima Tsunami Nuclear Tragedy

Soon after the earthquake and tsunami hit Japan on March 11, 2011, there was equipment failure and release of radioactive materials at the Fukushima Nuclear Power Plant. As a result of the earthquake, the outside power supply of the plant got impaired. Initially, electricity was provided by multiple emergency diesel power generators. However, they failed due to tsunami. Then the operators of reactor shifted to emergency battery power which provided power for 8 hours for core cooling. Once exhausted with the resources, the plant operators followed emergency methods to be tracked in case of loss of cooling.

Their priority was to control the heating core, ensuring proper functioning of the fuel cladding. Thus, they had to keep the working of the fuel rods by maintaining the heat below 1200°C. To sustain the system pressure at a controllable level, they had to vent out the steam at regular intervals. However, the steam was released in a controllable manner as there were some radioactive fission matters in the released gases. Since, the radioactive gases were present in small quantities, they didn’t pose much risk to public safety and workers. Initially, the Japanese officials marked the accident on the International Nuclear Event Scale (INES) as level 4. Later, it raised the INES level to 5 and then to 7, which is the maximum.

Chernobyl Nuclear Accident

The Chernobyl power plant, outfitted with 4 nuclear reactors, was located near Pripyat in Ukraine. What happened there is considered the worst nuclear radiation accident of all time. It occurred on April 26, 1986.

On this day, normal reactor operations were suspended because an experiment was to be performed in the reactor. When the test was conducted, there was an unexpected power rise which caused an explosion and drove the reactor temperature to more than 200 degrees Celsius. This melted the fuel rods and ignited the graphite covering of the reactor, allowing a release of radiation.

A large fire ignited about 20 hours after the explosion and burned for 10 days. In all 30 people died directly during the accident, most of these being fire fighters trying to extinguish the fire. Later, a report estimated that 4000 people would die because of the accident, 270 000 people were expected to develop cancer, with 93 000 fatal. A total of 350 000 people who lived in the surrounding area were resettled. The reactor was closed but still contains radioactive material. Amazingly, there are people still living in the contaminated areas.

Thule Broken Arrow

On 21 January 1968, a USA Air Force bomber carrying four hydrogen bombs crashed into the ocean near Thule Air Base in Greenland. This resulting explosion caused extensive radioactive contamination. While three of the four bombs were accounted for, up to now, the fourth has not been found.

The incident began with the captain advising air traffic control that there was a fire on board. Within five minutes the crew realized the fire in the lower deck was out of control and the fire extinguishers were depleted. At that point the crewmen ejected and left the aircraft unmanned. The pilotless aircraft then banked sharply to the left and crashed, just west of Thule Air Base. The hydrogen bombs shattered on impact, and although they did not detonate a nuclear blast, they did disperse radioactive material over a large area. A camp was created immediately at the crash site to facilitate decontamination and clean-up. Then, in April, a Star III mini-submarine was sent to search for the lost bomb. This underwater search was, due to technical problems, eventually abandoned because of technical problems and in 2008, it was confirmed that the fourth bomb had been declared lost.

Three Mile Island Accident

The Three Mile Island nuclear generating station is located in southern Pennsylvania not far from the capital, Harrisburg. The station has 2 separate containment units known as TMI-1 and TMI-2. The accident, which captured the imagination of the country and effectively collapsing the U.S. nuclear power industry occurred on March 28, 1979, when TMI-2 suffered a catastrophic meltdown, destroying its reactor core.

This happened as a result of a combination of design related problems, equipment malfunctions and worker error. A cascading chain of events started when the feed water pumps shut down resulting in overheating of the steam generators. When this occurred the nuclear fuel itself overheated, specifically the and zirconium cladding, rupturing, followed by the fuel pellets melting, the so-called “meltdown”.

Fortunately, there were no direct injuries caused by the accident, although significant amounts of radioactive water and gas were released into the environment. The surrounding community was very lucky. Should the accident have resulted in a complete meltdown and resultant explosion as in Chernobyl, thousands of people could have been fatally poisoned. Instead, the damage was contained, the plant shut down, defueled and the radioactive waste shipped to a distant disposal site. The plant remains under careful watch to this day.

Tokaimura Nuclear Accident

Tokaimura was the third in a series of nuclear power accidents following the Chernobyl and Three Miles Island incidents.This unfortunate accident occurred at a Japanese uranium processing facility in 1999 – workers formulating nuclear fuels neglected to properly mix nitric acid and uranium oxide within an approved mixer. Rather then employed an open stainless steel container. This mistake was worsened further due to the fact that the workers wore only t-shirts and possessed no film badges to measure their exposure.

After the alarm, the plant and surroundeing area were evacuated with 350 000 people instructed to remain in their homes for at least a day. The net result of the accident was 66 people who in sume way were injured or exposed, inlcuding 3 fatalities. After some time the plant was closed and decommissioned. A public inquiry revealed the root cause and corrective measures were taken at other plants.

Goiania Accident

This was an incident which took place in central Brazil on 13 September 13, 1987 when a radiation source used for radiotherapy purposes was inadvertently uncovered at and abandoned hospital in Goiania. Among the many people who subsequently handled the material 4 died and an additional 249 individuals suffered serious radioactive contamination.

The source of the radiation was nothing more than a thimble of radioactive caesium chloride contained in a canister of steel and lead. The canister was sealed however the two men who found it, managed to open it. Being unaware of its contents and the danger they were in, they sold it to a scrap yard a few days later. Another scrap yard bought it on a week later. It was not until September 29, that the radioactivity was confirmed.

During cleanup, some houses were destroyed and top soil was removed from some sites. The clean up was made more difficult because the active material is water soluble.