World's Worst Disasters

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Bhopal gas tragedy

Worlds worst disasters

A.Swamy Naidu (141fa08113)

Bhopal gas tragedy

TheBhopal disaster, also referred to as theBhopal gas tragedy, was a gas leak incident in India, considered worlds worst industrial disaster .

It occurred on the night of 23 December 1984 at the Union Carbide India Limited (UCIL)pesticide plant inBhopal, Madhya Pradesh. Over 500,000 people were exposed tomethyl isocyanate (MIC)gas and other chemicals. The highly toxic substance made its way into and around theshanty townslocated near the plant .


Union Carbide Corporation

Plant Production Process

Methylamine (1) reacts withphosgene (2) producingmethyl isocyanate (3) which reacts with1-naphthol(4) to yieldcarbaryl(5)

The Bhopal UCIL facility housed three underground 15000 gallon liquid MIC storage tanks: E610, E611, and E619 .

During the night of 2-3 December 1984, water entered in tank E610 contain 42 tons of MIC .

The resulting exothermic reaction increased the temperature inside the tank to over 200c (32 F) and raised the pressure .

About 30 metric tons of methyl isocyanate (MIC) escaped from the tank into atmosphere of Bhopal in 45 to 60 minutes .

The Accident

Factors leading to the gas leakStoring MIC in large tanks and filling beyond recommended levels .

Poor maintenance . Failure of several safety systems .

Safety systems being switched off to save money including the MIC tank refrigeration system which could not have mitigated the disaster severity .

Plant location close to a densely populated area .

Undersized safety devices the dependence on manual operations .

Among the 500,000 people exposed to the gas, 20,000 have died till date and 120,000 continue to suffer devastating health effects as a result of their exposure.

Effects on Human HealthRespiratory Disorders Irritation to the lungs, causing coughing and/or shortness of breathing. Higher exposure caused build up of fluids (pulmonary enema). Caused Asthma.Cancer Hazard Caused mutation (genetic changes). It caused cancer.Reproductive Hazard Association between exposure to Methyl Isocyanate and miscarriages. It may damage the growing fetus.May also affect fertility in men and women.Traces of many toxins were found in the Brest Milk of mothers and were in turn transmitted to the recipient babies.

Chernobyl Disaster April 26, 1986

The Chernobyl disaster was a nuclear reactor accident in the Chernobyl Nuclear Power Plant in the Ukraine, which used to be a part of the Soviet Union.

It is considered to be the worst nuclear power plant disaster in history and the only level 7 instance on the International Nuclear Event Scale. Introduction

What is nuclear power?

The energy produced by splitting atoms in a nuclear reactor.

Why is it dangerous?

Nuclear power technology produces materials that are active in emitting radiation and are therefore called radioactive. We are all exposed daily to a little radiation but too much or in mass quantities can destroy cells, cause organs to shut down or after long and continuous exposure cause cancer.

As the reaction occurs, the uranium fuel becomes hot .

The water pumped through the core in pressure tubes removes the heat from the fuel .

The water is then boiled into steam .

The steam turns the turbines .

The water is then cooled .

Then the process repeats .

Reactor Plant Scenario

Saturday, April 26, 1986:

Reactor #4 was undergoing a test to test the backup power supply in case of a power loss. The power fell too low, allowing the concentration of xenon-135 to rise.

The workers continued the test, and in order to control the rising levels of xenon-135, the control rods were pulled out.

What happened ?

The experiment involved shutting down the coolant pumps, which caused the coolant to rapidly heat up and boil.

Pockets of steam formed in the coolant lines. When the coolant expanded in this particular design, the power level went up.

All control rods were ordered to be inserted. As the rods were inserted, they became deformed and stuck. The reaction could not be stopped.

The rods melted and the steam pressure caused an explosion, which blew a hole in the roof. A graphite fire also resulted from the explosion.

What happened ?


The Chernobyl reactor after explosion

203 people were hospitalized immediately. 31 of them eventually died. Most of these people were workers in the plant or local firefighters. NW winds from the Black Sea carried the radiation for miles in the following days. Scandinavian detectors picked up on the abundance of radiation, but the Soviet government denied everything.

Immediate Impact

Effects Several critical effects of the explosinDirect killing of 31 peopleMore than 200,000 indirectly dead caused by the radiation (tumors and different organ disorders).160,000 km2 of contamination.400,000 people evacuated.

Effects of radiation

Thyroid cancer

BLUE :- 2046 Years oldRED :- ChildrenYellow :- Adults over the age of 46Thyroid cases graph

Fallout levels were very high right around explosion and affected all wildlife.

Red Forest- was a forest right by the plant was named this because plants had a red hue after the explosion. These trees also died from the amount of radiation they received.

Environmental effects

Between 300,000 to 600,000 people were brought in to clean-up.Crops were destroyed, livestock was killed, everywhere there was radiation. Over 235 billion dollars has been spent to clean up the disaster.Belarus lost 1/5 of its farming lands(700 million dollars a year loss.)350 industries were lost due to the disaster.

Economical effects