1. Nuclear Power Plant Accidents Reporters: Uyangurin, Mareinne L. Suico, Monica Sharlyn L. Waresa, Daryl Mae B.

2. Chernobyl Nuclear Power Plant Accident The Chernobyl accident is the most serious accident in the history of the nuclear industry. The Chernobyl nuclear power plant is located in Ukraine, 20km south of the border with Belarus. At the time of the accident, the plant had four working reactors. The Chernobyl accident is the most serious accident in the history of the nuclear industry. The Chernobyl nuclear power plant is located in Ukraine, 20km south of the border with Belarus. At the time of the accident, the plant had four working reactors. The accident occurred on 26 April 1986 when operators of the power plant ran a test on an electric control system of one of the reactors. The accident occurred on 26 April 1986 when operators of the power plant ran a test on an electric control system of one of the reactors.

3. The accident happened because of a combination of basic engineering deficiencies in the reactor and faulty actions of the operators: the safety systems had been switched off, and the reactor was being operated under improper, unstable conditions, a situation which allowed an uncontrollable power surge to occur. The accident happened because of a combination of basic engineering deficiencies in the reactor and faulty actions of the operators: the safety systems had been switched off, and the reactor was being operated under improper, unstable conditions, a situation which allowed an uncontrollable power surge to occur. This led to a cascade of events resulting in a series of explosions and consequent fires that severely damaged the reactor building, completely destroyed the reactor, and caused the release of massive amounts of radioactive materials over a ten-day period. This led to a cascade of events resulting in a series of explosions and consequent fires that severely damaged the reactor building, completely destroyed the reactor, and caused the release of massive amounts of radioactive materials over a ten-day period.

4. The cloud from the burning reactor spread many types of radioactive materials, especially iodine-131 and caesium-137, over much of Europe. Because radioactive iodine disintegrates rapidly, it largely disappeared within the first few weeks of the accident. Radioactive caesium however is still measurable in soils and some foodstuffs in many parts of Europe. The greatest concentrations of contamination occurred over large areas of the Soviet Union surrounding the reactor in what are now the countries of Belarus, the Russian Federation and Ukraine. The cloud from the burning reactor spread many types of radioactive materials, especially iodine-131 and caesium-137, over much of Europe. Because radioactive iodine disintegrates rapidly, it largely disappeared within the first few weeks of the accident. Radioactive caesium however is still measurable in soils and some foodstuffs in many parts of Europe. The greatest concentrations of contamination occurred over large areas of the Soviet Union surrounding the reactor in what are now the countries of Belarus, the Russian Federation and Ukraine.

5. Before...

6. After...

7. After...

9. Chernobyl Human Effects

11. What caused the nuclear crisis?What caused the nuclear crisis? Problems began when Friday's massive earthquake knocked out electricity at the Fukushima No 1 power station. Back-up generators kicked in to pump coolant around the reactor cores to prevent the fuel rods from overheating. The generators worked for a short time, but were damaged by the ensuing tsunami, forcing a scramble by engineers to fit mobile battery power units. These were insufficient to cool all of the reactors properly. Problems began when Friday's massive earthquake knocked out electricity at the Fukushima No 1 power station. Back-up generators kicked in to pump coolant around the reactor cores to prevent the fuel rods from overheating. The generators worked for a short time, but were damaged by the ensuing tsunami, forcing a scramble by engineers to fit mobile battery power units. These were insufficient to cool all of the reactors properly.

12. Why did the building explode?Why did the building explode? The makeshift attempt to cool reactor 1 at the power station failed. Heat from the fuel rods in the reactor core led to a build-up of superheated water inside. The makeshift attempt to cool reactor 1 at the power station failed. Heat from the fuel rods in the reactor core led to a build-up of superheated water inside. On Saturday, engineers released water vapour – which contained radioactive caesium and iodine – from the pressure vessel as an emergency measure. Superheated water can split into hydrogen and oxygen, and it appears that hydrogen escaped during the venting procedure and exploded. On Saturday, engineers released water vapour – which contained radioactive caesium and iodine – from the pressure vessel as an emergency measure. Superheated water can split into hydrogen and oxygen, and it appears that hydrogen escaped during the venting procedure and exploded.

13. What damage was caused?What damage was caused? The blast tore the roof off the building and damaged surrounding walls. Four workers were injured. Japanese authorities told the International Atomic Energy Authority that the explosion happened outside the reactor's primary containment vessel, which appears to be intact. The blast tore the roof off the building and damaged surrounding walls. Four workers were injured. Japanese authorities told the International Atomic Energy Authority that the explosion happened outside the reactor's primary containment vessel, which appears to be intact.

14. What is the radiation risk?What is the radiation risk? Japan's Nuclear and Industrial Safety Agency (Nisa) reported higher levels of radiation around the power station over the weekend and the presence of caesium- 137 and iodine-131 in the air. These are radioactive isotopes produced in fission reactions. The isotopes were released when steam was vented from the reactor. Japan's Nuclear and Industrial Safety Agency (Nisa) reported higher levels of radiation around the power station over the weekend and the presence of caesium- 137 and iodine-131 in the air. These are radioactive isotopes produced in fission reactions. The isotopes were released when steam was vented from the reactor. Monitors around the site recorded a radiation level of 500 microSieverts per hour on Saturday afternoon, a quarter of the annual dose the general population is exposed to due to natural background radiation. The level of radiation at the power station's main gate fell on Sunday to a very low level of 3.2 microSieverts. Monitors around the site recorded a radiation level of 500 microSieverts per hour on Saturday afternoon, a quarter of the annual dose the general population is exposed to due to natural background radiation. The level of radiation at the power station's main gate fell on Sunday to a very low level of 3.2 microSieverts.

15. Have people been exposed to radiation?Have people been exposed to radiation? At least nine people have tested positive for radiation exposure near Fukushima, but a Nisa official said that number could rise to between 70 and 160. Radioactivity can cause a variety of health problems, from a reddening of the skin and increased cancer risk to fatal radiation sickness. Health officials distributed potassium iodide pills, which protect against thyroid cancers, to residents near the power station. Those unable to leave were advised to limit their exposure by staying indoors and switching off air conditioning or wearing a protective mask if outside. At least nine people have tested positive for radiation exposure near Fukushima, but a Nisa official said that number could rise to between 70 and 160. Radioactivity can cause a variety of health problems, from a reddening of the skin and increased cancer risk to fatal radiation sickness. Health officials distributed potassium iodide pills, which protect against thyroid cancers, to residents near the power station. Those unable to leave were advised to limit their exposure by staying indoors and switching off air conditioning or wearing a protective mask if outside.

16. Are the other reactors safe?Are the other reactors safe? On Sunday, engineers vented steam from reactor 3 and began pumping in sea water after its cooling system failed.Authorities said there was a risk of an explosion similar to that in reactor 1. Sea water was being readied to pump into reactor 2. On Sunday, engineers vented steam from reactor 3 and began pumping in sea water after its cooling system failed.Authorities said there was a risk of an explosion similar to that in reactor 1. Sea water was being readied to pump into reactor 2. A separate state of emergency was announced at the nearby Onagawa nuclear power station amid increased levels of radiation, but Japanese officials said this had been carried on the wind from Fukushima. A separate state of emergency was announced at the nearby Onagawa nuclear power station amid increased levels of radiation, but Japanese officials said this had been carried on the wind from Fukushima.

17. When will the power station be safe?When will the power station be safe? The strategy of pumping sea water into nuclear reactors is untested. It could take several days to bring the temperature and pressure of the reactor cores down to within safe limits. The strategy of pumping sea water into nuclear reactors is untested. It could take several days to bring the temperature and pressure of the reactor cores down to within safe limits. If the cooling fails, the reactors could overheat and cause a total meltdown of the radioactive fuel rods in the core. This would only lead to a major release of radiation if the reactor's containment vessel was breached. If the cooling fails, the reactors could overheat and cause a total meltdown of the radioactive fuel rods in the core. This would only lead to a major release of radiation if the reactor's containment vessel was breached.

18. The Japanese authorities have classified the situation as a level 4 "accident with local consequences" on the International Nuclear and Radiological Event Scale.The scale runs from zero for a deviation in normal operations to seven for a major accident. The Three Mile Island incident in 1979 was a five and Chernobyl in 1986 was a seven on the scale. The Japanese authorities have classified the situation as a level 4 "accident with local consequences" on the International Nuclear and Radiological Event Scale.The scale runs from zero for a deviation in normal operations to seven for a major accident. The Three Mile Island incident in 1979 was a five and Chernobyl in 1986 was a seven on the scale.

19. So, here are some images in the Fukushima Nuclear Power Plant…

20. Fukushima Power Plant (upper view)

21. Fukushima Power Plant parts …

22. Before …

23. After …

24. Explode !!

25. Fire !!