Chernobyl DisasterPresenter:Sheikh Jalal Sajid

Background

• Happened on April 26, 1986 at 1:23a.m.• Has been called the biggest socio-economic

catastrophe in peacetime history• 50% of the area of Ukraine is in some way

contaminated• Over 200,000 people had to be evacuated

and resettled• 1.7 million people were directly affected by

the disaster

FIGURE: LOCATION OF CHERNOBYL

Contents

•How it happened• Immediate crisis management• Impact of disaster:• Socially• Evironmentally• Economically

Accident in Reactor-IVReactor crew preparing for a test to determine how long turbines would spin and supply power following a loss of main electrical power supply

Plants known to be very unstable at low power settings.

Disabling of automatic shutdown mechanisms, preceded the attempted test early on 26 April.

As flow of coolant water diminished, power output increased.

When the operator moved to shut down the reactor from its unstable condition arising from previous errors, a peculiarity of the design caused a dramatic power surge.

The fuel elements ruptured and the resultant explosive force of steam lifted off the cover plate of the reactor

Releasing fission products to the atmosphere

Second explosion threw out fragments of burning fuel and graphite from the core and allowed air to rush in

Causing the graphite moderator to burst into flames.

Over 1200 tons of Graphite - burned for 9 days, causing the main release of radioactivity into the environment.

A total of about 14 EBq (1018 Bq) of radioactivity was released, half of it being biologically-inert noble gases.

Summary

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

The fire inside Reactor No. 4 continued to burn until 10 May 1986.

Eventually, the graphite fire was extinguished by using sand, boron, dolomite, clay and lead from airdrops onto the burning reactor by helicopter.

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

accident.

The evacuation was begun a day after the explosion, asthe committee faced with ample evidence of extremelyhigh levels of radiation and a number of cases of radiationexposure.

iii. 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: The Chernobyl nuclear plant apparently after they started to build the sarcophagus in the aftermath of the disaster.

• At first, robots were sent for this task.• But their transistors did not work in that radioactive

environment.• Then volunteers were sent for the task.• But they were allowed to stay for 90 seconds or less in

the reactor otherwise their nervous system could break down.• The decontamination took place from the beginning May

till the end of Winter 1986.• Every movable objects around the plant were burried.

iv. Cleanup Efforts

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.

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 ministryofficials, 125,000 people were reported dead

as a result of the accident.

In the aftermath of the accident, 237 peoplesuffered from acute radiation sickness. Mostof these were fire and rescue workers tryingTo bring the accident under control

Two people died in the initial steamexplosion, but most deaths from theaccident were attributed to radiation.

135,000 people were evacuated from thearea, including 50,000 from Pripyat.

(c) Delayed Health Effects

One of the most delayed effects of the radiation is the induction of Cancer especially amongst those Russian liquidators who were exposed to more than 150 mSv.

The people in the area of contamination have suffered a

paralyzing fatalism.

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 thePripyat River which feeds into the Dnieper River reservoirsystem, one of the largest surface water systems inEurope.

Flora and fauna(i)Flora• After the disaster, four sq. km of pine forest in the

immediate vicinity of the reactor turned ginger brown and died, earning the name of the “Red Forest”

• Local pine trees grew huge pine cones, with needle-like leaves 10 times heavier than normal.

• Some fruits and vegetables also turned oddly shaped eg; potato, tomato etc.

(ii) Fauna• Radiation 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.

(f) Cost

And about US$400 Million was spent on improvements to the remaining reactors in Ukraine 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 estimating US$36 Billion were spent during this period

• 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.

Any Questions??