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Chernobyl

Background

Figure: The Chernobyl nuclear plant in Ukraine, apparently after they started to build the sarcophagus in the aftermath of the disaster. The nuclear disaster itself had happened on 26 of April 1986.

Chernobyl Accident

Figure: There is an Exclusion Zone of 30km (19 miles) radius surrounding the destroyed reactor ( which was located nearer to Pripyat than Chernobyl). Officially, nobody is allowed to live in Exclusion Zone.

Figure: Location of Chernobyl

Figure: Reactor 4, Chernobyl Nuclear Power Plant, Ukraine

The Reactor and Accident in Chernobyl-4

13

Figure: Reactor diagram.

Figure: The damaged Chernobyl unit 4 reactor building

Summary

Figure : The events are summarized in the reactor power/chronology.

Cause of Chernobyl

Flawed operating explanation

Having a mistake or weaknessIgnorant of safety requirementLack of experience and trainingInsufficient communicationOverconfident : only normal electrical test Choosing cheapness over safety

Poor Design of PlantPartial containment was bypassed and went out on the top of reactor core.Hot fuel and graphite were exposed to airCesium and radioactive Iodine

Poor Design Of Plant(Partial Containment)

Fact

The explosion at Chernobyl acted like a volcano, blowing radioactive particles far into the sky.

(a) International Spread of Radioactivity

Wind moved the plume, or cloud of radioactive particles, all around the world. Even worse, when the plume passed by several countries, it began to rain, and nuclear fallout hit the ground.

Large areas of Belarus, Ukraine, Russia and beyond were contaminated in varying degrees.

(b) Health of Plant Workers

According to Ukrainian health ministry officials, 125,000 people have died as a result of the accident, and more deaths are expected.

In the aftermath of the accident, 237 people suffered from acute radiation sickness. Most of these were fire and rescue workers trying to bring the accident under controlTwo people died in the initial steam explosion, but most deaths from the accident were attributed to radiation. 135,000 people were evacuated from the area, including 50,000 from Pripyat.Most of them received high doses of radiation, average around 100 mSv. Some 20,000 of them received about 250 mSv and a few received 500 mSv.

(c) Delayed Health Effects

Man and young boy operated for thyroid cancer after Chernobyl nuclear accident.Paralyzing fatalism

One of the most delayed effects of the radiation is the induction of cancer.For example: Solid cancers among Russian liquidators whom exposed to more than 150 mSv.

The people in the area of contamination have suffered a paralyzing fatalism.

Mutation in newly born children

The topic of the children of Chernobyl is most shocking and awful.

By year 2000, about 4000 cases of thyroid cancer had been diagnosed in exposed children. These children have to take painful procedures every day to postpone the fatal moment. Chromosome aberrations causing mutations.The increase in leukemia is even worse where there are dozens of cases of leukemia among the children.

The radioactive contamination of aquatic systems therefore became a major issue in the immediate aftermath of the accident.

(d) Residual Radioactivity In The Environment

Rivers, lakes and reservoirs

The Chernobyl nuclear power plant lies next to the Pripyat River which feeds into the Dnieper River reservoir system, one of the largest surface water systems in Europe.In the most affected areas of Ukraine, levels of radioactivity in drinking water caused concern during the weeks and months after the accident.

Groundwater

Groundwater was not badly affected by the Chernobyl accident since radionuclides with short half-lives decayed away a long time before they could affect groundwater supplies.

Longer-lived radionuclides such as radiocaesium and radiostrontium were adsorbed to surface soils before they could transfer to groundwaters.

Flora and faunaFloraAfter the disaster, four square kilometres of pine forest in the immediate vicinity of the reactor turned ginger brown and died, earning the name of the Red ForestLocal pine trees grow huge pine cones, pine needles of the needle-like leaves 10 times heavier than normal. Some fruits and vegetables also affect which causes the oddly shaped of potato, tomato and so on.

Flora and fauna(ii) FaunaRadiation has affected animals living near the site of Ukraine's Chernobyl nuclear disaster.A major effect on the livestock was mutation.The livestock was culled and buried.

Figure above: A cow that experiencing mutations. This co having a cleft lip.

Figure above: These animals suffering from a serious effect of mutation

Apartment buildings swimming pools, hospitals and other buildings were all abandoned, and everything inside the buildings were left behind, including records, papers, TVs, children's toys, and clothing, etc.

Residents were only allowed to take away a suitcase full of documents, books and clothes that were not contaminated.

Many factory and farms stopped.

The whole site was shutdown.

People were facing homelessness .

(e) Normal Life and Work

(f) CostThe accident, about US$400 Million was spent on improvements to the remaining reactors at Chernobyl, considerably enhancing their safety. The total costs including cleanup, resettlement, and compensation to victims has been estimated to be roughly US$200 Billion.In the 1986 to 1989 industrial and agricultural losses and insurance payments total about US$36 Billion spent during this period

The fire brigade of Pripyat was able to extinguish all the fire, except the graphite fire inside Reactor 4.

(a) Fighting the Fire

Eventually, the graphite fire was extinguished by using sand, boron, dolomite, clay and lead from airdrops onto the burning reactor by helicopter.The fire inside Reactor No. 4 continued to burn until 10 May 1986.

The nearby city of Pripyat was not immediately evacuated. - a government committee was formed to investigate the accident.

(b) Evacuation

The evacuation was begun a day after the explosion, as the committee faced with ample evidence of extremely high levels of radiation and a number of cases of radiation exposure.

(c) Sarcophagus

Even after the fire had been extinguished, radioactive particles were still escaping from the reactor core itself.

The Soviets devised a plan to cover the entire reactor with a shell that was to be able to exist forever. The shell was deemed the Sarcophagus.Within it, there is about 200 tons of highly radioactive material which poses an environmental hazard until it is better contained.

Chernobyl before the accident

Chernobyl at the time of the accident

Chernobyl with the Sarcophagus around Reactor Number 4

Figure above: Before, During, and After figures of the Chernobyl buildings 3 & 4.

At first, the robots are sent for the task.- robots are malfunctioned because transistors are unable to work properly in radioactive environments.

(d) Clean-up Efforts

Since this did not work, volunteers are sent for the task. -only allowed to be in the power station for 90 seconds or less-exposure to the radiation in a long period would overwhelm their nervous system and subsequently killed them.

The decontamination process took place from May until the beginning of winter, 1986. Any movable objects near the plant were buried.

About 60,000 buildings had to be washed with special chemicals, and even some roofs had to be replaced.

Special chemicals were sprayed on streets to immobilize radioactive particles.

Today, Pripyat and the surrounding area are not safe for human habitation. The radioactivity in the damaged reactor would need to be contained for 100,000 years to ensure safety.

However, the sarcophagus was designed to last for only about 30 years.

This would be a tough challenge not only for today, but for many future generations.

The Chernobyl disaster - is the worst nuclear power plant disaster in history. - resulted in a severe release of radioactivity following a massive power excursion which destroyed the reactor.

Achieving Optimum Nuclear Safety

To achieve optimum safety, nuclear plants should operate using a'defence-in-depth' approach, with multiple safety systems supplementing the natural features of the reactor core.Key aspects of the approach are:

high-quality design & construction,

equipment which prevents operational disturbances or human failures and errors developing into problems,

comprehensive monitoring and regular testing to detect equipment or operator failures,

redundant and diverse systems to control damage to the fuel and prevent significant radioactive releases,

provision to confine the effects of severe fuel damage (or any other problem) to the plant itself.

Control MeasureEnsure the design of the reactor or rods are safely design and tested before initiated uses of the design.Preparation for Emergency Responds Plans for immediate evacuation.

Hiring workers that are trained educated and discipline to their work in controlling the nuclear reactor.

Making sure that the workers are observe by their supervisor or by safety officer that are assign to ensure no unwanted event occurs.

Frequent maintenances to any broken and unusable machine or unsafe built design of the reactor.

THE END

--Thank You--