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Transcript of Disaster
by 50% to prepare to run a test
on a way to conserve energy.
Turbine 1 is shut off and only 1 turbine remains on in reactor 4. April 26, 1986... Staff forgets to reset a controller when they shut down the 2nd turbine, causing power to fall to 1% instead of 30%, the optimal and safe level.
This causes water to begin building in the core and the reactor became extremely unstable. April 26, 1986... The controller orders all but 6 control rods to be removed. He also foolishly shut down
safety protocols because he wanted to prevent the test from being aborted.
Since the power returned to 7% he thought the plant was stable enough to resume testing. Under a minute later... The reactor's power levels skyrocketed increasing to an extremely unstable level. At one point the reactor reached 120 times its normal max levels! The plant reaches critical point! With no turbines functioning and the plant power at a critical level, the Chernobyl reactor created enough pressure it blew off the entire top shield of the reactor releasing millions of radioactive particles including Cs-137 and I-131! Fukushima Daiichi
Nuclear Disaster Friday, March 11, 2011
At 2:46 p.m. a 9.0 magnitude earthquake strikes the Honshu Coast of Japan. Due to the quake Reactors 1, 2, and 3 shut down immediately, while 4, 5, and 6 were not in use at the time.
The emergency cooling systems are automatically turned on but are quickly manually shut off just before the arrival of the tsunami.
A 14 meter tsunami strikes the plant disabling all back-up generators and washing away all fuel tanks. Friday, March 11, 2011
After the quake, the water levels begin to fall in the fuel exposing the nuclear material. As the water level reaches the top of the fuel rods, the temperature begins to climb, and eventually the material becomes fully exposed causing major damage. The pressure inside is twice the normal levels.
The Japanese government puts out an evacuation order for all people within a 3 mile radius of the plant Saturday, March 12, 2011
The fuel rods become exposed in reactor 3 and it is decided to vent some of the pressure steam into the containment building surrounding the units of Reactor 1 and 2. With this decision comes the price of releasing some radioactive material into the air, mostly tritium and Nitrogen-16.
Fresh water begins being pumped into Reactor 1, however shortly is stopped and changed to injecting sea water.
A massive explosion occurs in Reactor 1 causing the outer containment to collapse, but no damage to the reactor itself.
The evacuation radius is extending to 20 km surrounding the plant. Sunday, March 13, 2011
The water level in the fuel of reactor 3 begin to drop drastically causing the rods to become exposed and leading to core damage.
At this time the situation in reactor 1 is a 4 which is an incident with local consequences.
Monday, March 14, 2011
The building around reactor 3 explodes but no radioactive material is released and the blast caused damage to Unit 2's water supply.
The water level in reactor 2 begins to fall and eventually reaches the top of the fuel rods causing core damage at this time.
Also a major amount of fuel in reactor 3 drops to the bottom reactor. Tuesday, March 15, 2011
A second explosion occurs in reactor 1 causing the majority of the fuel to fall to the bottom of the pressure vessel.
At this time reactor 2 is in the most severe condition, while a fire breaks out in unit 4.
Radiation levels begin to rise significantly but quickly fall luckily. At one point there were equivalent dose rates of millisieverts per hour in the area of reactor 3. Wednesday, March 16- Friday, March 18, 2011
It is believed that the water in the spent fuel pool of reactor 4 may be boiling but was reported on Thursday to have been filled with water and no rods were exposed.
Due to rising radiation levels and strange noises with in the reactor pressure suppression chambers, operations were suspended and workers had been evacuated.
Water began to be poured into reactors 5 and 6 as a precaution.
Helicopters dropped water 4 times onto the spent fuel pools of reactors 3 and 4, while water was constantly being pumped into reactor 3 later in the day on Thursday.
High radiation levels still detected 30 km away from plant, while plant levels decreased slightly possibly due to water being added
INES rating for reactors 1, 2, and 3 were raised to a 5 while reactor 4 was given a 3 due to spent fuel pool water issue. Saturday, March 19, 2011- Tuesday, March 31, 2011
Water is being continually pumped into the reactor systems and by March 20, temperatures within reactors 5 and 6 are found to be normal and are in cold shutdown.
Radiation levels are still pretty high for the average and begin to slowly drop as the month goes on.
Work is continually halted due to the presence of white smoke, most likely the steam and grey/black smoke from small fires with in the reactors.
Fresh drinking water in the Tokyo area is found to be at twice the normal legal limits and deemed unsafe for children.
Water around the plant is found to be at very high levels of radioactivity. Much of the contaminated water from the reactors is sitting around the plant making operations difficult.
Sea water radiation is found to be 1,250 times the normal levels. Researchers Simulate Fukushima Radiation Spread Fukushima Daiichi health of the workers Fukushima Daiichi Meltdown and the Effects on Groundwater Radiation & its Effects to your Body 101 - Fukushima Nuclear Plant Japan Causes and Effects of Fukushima-Daiichi Nuclear Disaster Fukushima poses long-term threat to ocean ecosystem Radiation Threats Linger Over Japan's Food Supply Three Mile Island The
Events March 28 1979 March 29 1979 Despite the repeated failure of efforts to cool the reactor, a spokesman for the Nuclear Regulatory Commission claimed that the "danger was over." March 30 1979 Governor Thornburgh issued an advisory that pregnant women and children within a five mile radius of the accident should evacuate and that people within a ten mile radius should stay indoors. Because of mechanical and human failures, the Unit 2 reactor of the Metropolitan Edison Company's plant at Three Mile Island experienced a partial meltdown. Fears that a hydrogen bubble had formed in the reactor and could potentially explode arose. March 31 1979 The rumors regarding the hydrogen bubble were put to rest, as it was discovered that there had been a miscalculation.
Cooling of the reactor continued. April 1 1979 President Jimmy Carter and Pennsylvania Governor Richard Thornburgh visited the Unit 2 control room.
Some who had evacuated began returning to their homes. April 6 1979 Control of the plant was regained.
Governor Thornburgh lifted the evacuation advisory and declared that the "crisis had passed."
Cleanup efforts would continue for years. The
Aftermath October 25 1979 The NRC recommended that Metropolitan Edison pay the maximum fine permitted by law for its violations that contributed to the accident. Numerous independent studies have concluded that the incident had no major effect on the health of the area's residents, although the issue is still debated. The only impact predicted was an increased risk for cancer, although at most only one person would probably get a fatal cancer. Following the accident, Unit 1 had its license temporarily suspended.
Despite a 3:1 vote by the citizens of three surrounding counties to have Unit 1 permanently retired, it was allowed to resume operation in 1985. During both incidents, the disasters were caused due to human and mechanical error. In Three Mile Island both types of errors were experienced when machines detected that valves were closed, but in reality the were not, and human error because they stopped machines from automatic cooling when they believed the process was complete. In Chernobyl, the workers were planning to run a test and were not following proper safety precautions. Also mechanical errors occurred because of the reactors design allowed easy break down because if one thing when wrong the entire reactor was doomed. Underwater camera surveys showed that the damage was more extensive than originally thought. In both cases, radiation was released outside fuel element cladding and also outside containment barriers. At Chernobyl, the atomic pile caught on fire due to its moderators being made of graphite blocks and was a complete disaster scenario. While at Three Mile Island, there were no fires, but some very dangerous material released including fission fragments from failed fuel element cladding. This nuclear incident was more of an accident then a complete disaster. After both events, the INES (International Nuclear Event Scale) raised both disasters to a level 7 on their scale. This means that the event had widespread health and environmental issues. Also, there was external release of a significant amount of the core. Fukushima was a disaster caused by the effects of nature, the earthquake and tsunami, which crippled the plant destroying it completely. While at Chernobyl, human mistakes and mechanical errors led to the disaster. Another major similarity between the two events was the lack of information to the public. People were not receiving proper notification from the governments and were returning to the effected areas unprotected and receiving doses of radiation. In each case due to both a lack of information and a desire to calm the public, authorities offered false reassurances. They did not tell the public correct information in hope to calm them and say they would say there was absolutely nothing wrong. This was a major downfall that prevented proper safety precautions and evacuation orders to be put in place. In both events, the major problem that caused the most damage and concern was with the failing of the cooling systems. At Three Mile Island, repeated cooling processes failed and the plant immediately began to heat up. At Fukushima there was constant loss of power causing the cooling systems to shut down. The backup generators were flooded due to the tsunami and could not provide power to the plant. In both occurrences, the reactors only reached a partial meltdown except in reactor one at Fukushima plant. The reactors were two completely different types. At Three Mile Island, it was a pressurized water reactor and at Fukushima the reactors were boiling water, however, both had complete stell casings to protect and surround the nuclear fuel. In Fukushima, the disaster was a more widespread issue with it including more than one reactor, 4 in all, and also there being more of an effect to the environment. More people were affected with evacuations and long-term effects with food and agriculture problems. Also the area around the plant was very populated causing more problems.
Chernobyl had the same problems. It was located near a populated area and on a source of water. The radioactive material spread extremely quick.
In Three Mile Island, the area is not as densely populated and there was very little environmental and health issues after the incident. The radiation was undetectable and caused very little health issues. Chernobyl Disaster: Before + After the Explosion Ghost Town of Pripyat Effects.. - 3,500 people participated
in shoveling the graphite off the roof of the reactor.
- It was crucial they took quick shifts to minimize the
exposure. Solutions put in effect... Hundreds of pilots flew over Chernobyl to try to smother the flames with a substance called Boric Acid. They hoped it could help neutralize the radiation.
Instead of dying out, the flames built up heat inside the reactor and began to melt through the concrete slabs in the base of the reactor.
If the magma melted through, it would hit the cooling water and only 1,400 kg of uranium and graphite would be necessary to cause a second explosion powerful enough to effect all of Europe. More Preventive Measures... To prevent an explosion, people drained the water from the reactor.
Thousands worked at a time to build a tunnel underneath the reactor to hold a cooling device to prevent the radioactive magma from going further into the ground. Preventive Measures (continued) All the animals, big or small, had to be killed because their fur was infected with the radioactive materials.
People called liquidators went street by street neutralizing the radioactive materials off of houses, cars, and roads. 12 Weeks after the reactor fails... Robots and machines are setup to try to isolate and envelop the 4th reactor with a huge cement structure.
The radiation made the machines unable to function properly and so people were sent in. Men on the roof of Chernobyl... The men were sent to shovel graphite from the exploded reactor off of the roof.
The men were covered in lead, wore special helmets, masks, and had double layered gloves to block as much radiation as possible.
Their job was to shovel as much rubble as they could off the roof and then run as quickly away as they could. The graphite had absorbed enough radiation to kill a man in an hour so they had to be fast. The cement casket is completed... The completed structure was supposed to be a temporary fix.
It would last 20 years before a final structure was built around it. Long-term effects Chernobyl not only effected the Ukraine but all of surrounding countries.
Thousands of people had immediate exposure but millions eventually died from the radiation.
The half life of some materials like Plutonium is 245,000 years!
Some people are still suffering from radiation poisoning today! In both events there were design flaws in the creation of the reactors. There was no instrument to help show the plant operators, when to close the pilot-operated relief valve. This was used to release excess pressure in the systems. Also in both there was no instrument to help measure the amount of water in the core. They "measured" by looking at the pressurizer above and its amount of water, but this method was deceiving to the operators. Look inside Fukushima's meltdown zone a year later Ghost town: Japan's exclusion zone Inside the Fukushima evacuation zone . Comparison of Three Nuclear Disasters:
Three Mile Island
James Martin Zones Evacuated and Closed Off 20 Years After the Explosion