LOKMANYA TILAK JANKALYAN SHIKSHAN SANSTHA'S

PRIYADARSHINI COLLEGE OF ENGINEERING

(Approved by A.I.C.T.E., New Delhi & Govt. Of Maharashtra, Affiliated to R.T.M. Nagpur University, Nagpur)

Priyadarshini Campus, Near CRPF, Hingna Road, Nagpur – 440 019, Maharashtra (India)

Chernobyl: The World’s Worst Nuclear

Disaster

Topic of the project: Chernobyl Nuclear Disaster.

Student Name: Aditya Dharmapal Chute.

Roll.No : 125

Subject: Environmental science.

Guide Name: Aditi Pandey mam.

Name of the Department: Robotics and Artificial Intelligence.

Subject: Environmental science.

Introduction:
The Chernobyl disaster of April 26, 1986 in Northern Ukraine is known as the worst nuclear power
plant catastrophe. Chernobyl nuclear disaster on April 26, 1986, led to the emission in the
environment of large amounts of highly toxic radioactive products that destroyed everything in the
vicinity as well as left severe unfavorable effects even to this date. This paper gives a somewhat
detailed analysis of what led to the disaster, the effects of the disaster, and the ways in which the
world dealt with nuclear accidents with examples of the lessons learnt.

1. Causes of the Disaster: The catastrophe at Chernobyl occurred due to the reactor
design failure in combination with an individual error in the course of the test. The reactor in
question was an RBMK (Reaktor Bolshoy Moshchnosti Kanalny) type, which had several
inherent structural problems that would not allow it to build up a stable state.
 Reactor Design Flaws: The RBMK reactor design was positively and negatively void
coefficient, as it meant that when water in the reactor core turned to steam the reactivity
went up rather than down. This made it unstable during the low power operations, which
 where being done during the safety test. The reactor also did not have suitable specialized
containment facilities, which posed the threat of a leakage of radioactive material in the
occurrence of an explosion.
 Operator Error: In a safety test exercise the operators shut down critical safety mechanisms
and ran the reactor at extremely low levels of power. As earlier stated, the operators were
not well trained and had a poor communication hence they could not handle the situation.
An increase in the output was the cause of the explosion which occurred in Reactor 4 and
which contaminated the air with radioactive particles.

2. Impact of the Disaster

 Explosion and Radioactive Release: The blast off ended the lives of 3,600 people and
scattered fallout equivalent to 50 million Hiroshima bombs. The clouds of the radioactive
isotopes such as iodine-131, cesium-137, strontium-90 and so on, dispersed themselves over
extensive areas in Europe.
 Evacuation of Pripyat: Pripyat town, which is situated only 3 kilometers away from the
Chernobyl plant, accommodated plant employees together with their families. Although it
was detonated early in the morning, it was only after 33hours that the authorities called for
the evacuation. By then residents’ exposure levels of radiation had already been saturated.
Altogether, most of the people from neighbouring towns and cities had been forced to flee
their homes reaching nearly 150000.

3. Long-term Environmental and Human Impact

 Radioactive Contamination Across Europe: The radioactive plume from Chernobyl spread
across much of Europe, with the highest concentrations of fallout in Belarus, Ukraine, and
Russia. Over the following days, radioactive particles were detected in countries as far away
as Sweden and the United Kingdom. Contaminated land rendered large swathes of
agricultural land unusable, and wildlife in the area experienced mutations and population
declines.
 Impact on Displaced Communities: The Chernobyl exclusion zone, covering a 30 km radius
around the plant, remains uninhabitable to this day. Tens of thousands of people were
permanently displaced, losing their homes and livelihoods. Those who were evacuated often
experienced psychological trauma and faced social stigma due to fears of radiation exposure.
 Health Consequences: The most significant long-term health effects from the disaster
include increased rates of thyroid cancer, particularly among children exposed to iodine-131.
Other cancers, genetic mutations, and birth defects have also been linked to radiation
exposure. The liquidators—workers brought in to manage the cleanup efforts—were
particularly affected, with many developing radiation-related illnesses.

4. Changes in Nuclear Safety Protocols

In response to the Chernobyl disaster, the global nuclear industry introduced major reforms in
nuclear safety and regulatory standards. Key changes include:

 International Oversight:
The International Atomic Energy Agency (IAEA) and other global organizations introduced
stricter safety standards and monitoring systems for nuclear reactors. Governments around
the world began re-evaluating their own nuclear safety protocols and reactor designs.
  Improved Reactor Design:
The RBMK reactor design, which had been widely used in the Soviet Union, was largely
discontinued after Chernobyl. Modern reactor designs now incorporate passive safety
features, meaning that reactors are designed to automatically shut down in the event of an
emergency, without human intervention.

 Emergency Preparedness:
The disaster underscored the need for better emergency preparedness and public
communication in the event of nuclear accidents. As a result, evacuation plans, disaster
response protocols, and radiation monitoring systems have been significantly improved
worldwide.

5. Ongoing Efforts to Contain Radiation

Following the disaster, immediate efforts were made to contain the radiation from Reactor 4.
This led to the construction of a temporary concrete structure known as the Sarcophagus,
which encased the destroyed reactor to prevent further radioactive release.

 New Safe Confinement (NSC):

In 2016, a more permanent solution was put in place—the New Safe Confinement (NSC).
This massive steel structure was built to cover the Sarcophagus and prevent any further
radiation leaks. The NSC is designed to last for at least 100 years, allowing for the safe
dismantling of the original reactor and ongoing decontamination efforts.

How Does It Happen? What are the Causes?

The Chernobyl disaster was a nuclear accident that occurred on April 26, 1986 at the Chernobyl
nuclear power plant in Ukraine. The accident was caused by a combination of factors, including:

 Poor reactor design

The reactor was unforgiving for operators and lacked safety

features.
 Safety measures ignored

Operators were not aware that the test could cause an explosion, and they did not follow established
procedures.

 Experiment gone wrong

Technicians shut down the reactor's power-regulating and emergency safety systems, and removed
control rods while the reactor was running at low power.

 Interaction of hot fuel and cooling water

This led to fragmentation of the fuel, rapid steam production, and pressure buildup.

The pressure caused the reactor's cover plate to detach, rupturing fuel channels and jamming the
control rods.

What radioactive elements were emitted into the environment?

 There were over 100 radioactive elements released into the atmosphere when Chernobyl’s
fourth reactor exploded.
  Most of these were short lived and decayed (reduced in

radioactivity) very quickly.

 Iodine, strontium and caesium were the most dangerous of the elements released, and have
half-lives of 8 days, 29 years, and 30 years respectively.

 The isotopes Strontium-90 and Caesium-137 are therefore still present in the area to this
day.

 While iodine is linked to thyroid cancer, Strontium can lead to leukaemia.

 Caesium is the element that travelled the farthest and lasts the longest.

 This element affects the entire body and especially can harm the liver and spleen.

How many people died as an immediate result of the accident?

The initial explosion resulted in the death of two workers. Twenty-eight of the firemen and
emergency clean-up workers died in the first three months after the explosion from Acute Radiation
Sickness and one of cardiac arrest

• The Sarcophagus

– After the disaster, a huge cement box was built around the radioactive material

– It is falling apart!

– According to a 2003 report by the Russian Atomic Energy Minister, Alexander

Rumyantsev, "the concrete shell surrounding the Chernobyl nuclear reactor is in real
danger of collapsing at any time."

– A new Sarcophagus is scheduled to be completed in 2009

C
onclusion: The Chernobyl disaster serves as a stark reminder of the potential dangers of nuclear
energy if not managed with rigorous safety standards. The disaster not only reshaped the future of
nuclear energy but also had a profound effect on environmental policy and emergency preparedness
worldwide.