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Q: Where is Chernobyl?
Q: What is the main sequence of events?
Q: What is radiation?
Q: What acute effects does radiation have?
Q: What are the biological effects of exposure to radiation?
Q: Which areas were contaminated by radiation?
Q: What was the level of contamination in Belarus?

Q: Where is Chernobyl?

The Chernobyl power plant lies in northern Ukraine, near the border with Belarus. Both countries border Poland to the west and Russia to the east. The Chernobyl power plant is about 7 km from the border with Belarus, while about 100 km to the south lays Kiev, the capital of Ukraine, with a population of 3.1 million. The reactor complex, which has been inactive since 12 December 2000, stands by the river Pripyat, which joins the Dnieper at the town of Chernobyl, 12 km away.

Q: What is the main sequence of events?

26 April, 1986. The Day of Disaster

• The operating crew planned to test whether the turbines could produce sufficient energy to keep the coolant pumps running in the event of a loss of power until the emergency diesel generator was activated.
• In order to prevent the test run of the reactor being interrupted, the safety systems were deliberately switched off. For the test, the reactor had to be powered down to 25 per cent of its capacity.
• This procedure did not go according to plan: for unknown reasons, the reactor power level fell to less than 1 per cent. The power therefore had to be slowly increased.
• But 30 seconds after the start of the test, there was a sudden and unexpected power surge. The reactor’s emergency shutdown (which should have halted the chain reaction) failed.
• Within fractions of a second, the power level and temperature rose many times over. The reactor went out of control. There was a violent explosion. The 1000-tonne sealing cap on the reactor building was blown off.
• At temperatures of over 2000°C, the fuel rods melted. The graphite covering of the reactor then ignited. In the ensuing inferno, the radioactive fission products released during the core meltdown were sucked up into the atmosphere.

The Days following the explosion

• 26 April to 4 May 1986: Most of the radiation is released in the first ten days. At first, northerly and northwesterly winds predominate. At the end of April the wind switches to the south and southeast. There are frequent but local showers. This results in a very varied regional and local distribution of the radiation.
• 27 April to 5 May 1986: About 1800 helicopter flights deposit around 5000 tonnes of extinguishing materials such as sand and lead onto the burning reactor.
• 27 April 1986: The inhabitants of the Pripyat, the power plant settlement are evacuated.
• 28 April 1986, 23:00: A Danish nuclear research laboratory announces that an MCA (Maximum Credible Accident) has occurred in the Chernobyl nuclear reactor.
• 29 April 1986: The MCA at Chernobyl is first reported in German newscasts.
• Up to 5 May 1986: Over the ten days following the accident, 130 000 people are evacuated from a 30 km zone around the reactor.
• 6 May 1986: The release of radiation stops.
• 15 to 16 May 1986: New fires break out and more radiation is released.
• 23 May 1986: A Soviet government committee orders the distribution of iodine preparations. At this point, such prophylaxis is of no medical value. Radioactive iodine is only active for ten days, and will already have accumulated in the thyroid glands of the inhabitants of the contaminated territories.
• November 1986: The concrete “sarcophagus” enclosing the destroyed reactor and its molten core is completed. This shelter, or sarcophagus, was supposed to absorb the radiation and contain the remaining fuel. The sarcophagus was considered to be an interim measure. It was designed with a lifetime of only 20 to 30 years in mind. The greatest problem is a lack of stability: it was hastily constructed, and there is a risk of beams rusting.
• 1989: Three years after the nuclear accident, the Soviet government halted construction of the fifth and sixth reactor units at the Chernobyl nuclear power complex.
• 2000: After prolonged international negotiations, the entire Chernobyl Nuclear Power Station complex was closed on 12 December 2000.

Q: What is radiation?

Radiation is energy in transit in the form of high speed particles and electromagnetic waves. We encounter electro-magnetic waves every day. They make up our visible light, radio and television waves, ultra violet (UV), and microwaves with a large spectrum of energies. These examples of electromagnetic waves do not cause ionizations of atoms because they do not carry enough energy to separate molecules or remove electrons from atoms.

Radioactive Contamination
The effects of the ensuing disaster continue relentlessly, making it, in the words of the United Nations, “the greatest environmental catastrophe in the history of humanity”. Because the initial explosion was so powerful, plumes of radioactive material were thrown high into the atmosphere and carried by the wind for many miles. Over 70% of the radiation fell on Belarus. The people of Belarus have been exposed to radioactivity 90 times greater than that released by the Hiroshima bomb. The nine million people living in the affected areas of the Ukraine, Belarus and Russia have received the highest known exposure to radiation in the history of the atomic age.

3-4 million of those affected are children and the full consequences of their exposure may not be seen for another 50 years. There has already been a massive increase in the rates of cancer, blood circulation diseases and disorders of the nervous system but some of these may take years to develop. Since radiation levels in the contaminated areas are still extremely high, many children are being born with birth deformities 20 years later. The future of the men, women and children in the affected areas is now a bleak one. Having to cope with contaminated land, water and agricultural foods, a near economic collapse and a serious widespread health crisis, means the people of Belarus are in dire need of assistance.

Many radioactive elements appear to have the same composition as the natural and vital minerals that our bodies need. For example:

1. Plutonium is the most toxic substance man has ever produced, and it does not exist in nature. The body treats it as iron, due to the chemical similarity. It gets distributed by the blood system to feed growing cells. It can cause a variety of cancers and blood disorders.
2. Caesium 137 is mistaken by the body as potassium, which is needed by every living cell. It then concentrates in the muscles.
3. Iodine 131 is absorbed by the thyroid gland, which cannot determine whether it is natural or radioactive iodine. The thyroid gland makes important hormones to help the body function. Iodine 131 causes cancer and other disorders in the thyroid gland.
4. Strontium 90 – The body is fooled into accepting this element as calcium. It gets distributed throughout the bone structure and can cause leukemia and a number of cancers, along with numerous other health problems.

To follow are definitions of some other common terms:

• Ionizing radiation is radiation with enough energy so that during an interaction with an atom, it can remove tightly bound electrons from their orbits, causing the atom to become charged or ionized. Examples are gamma rays and neutrons.
• Non-ionizing radiation is radiation without enough energy to remove tightly bound electrons from their orbits around atoms. Examples are microwaves and visible light.
• Radioactivity is the spontaneous transformation of an unstable atom and often results in the emission of radiation. This process is referred to as a transformation, decay or disintegrations of an atom.
• Radioactive Material is any material that contains radioactive atoms.
  Radioactive contamination is radioactive material distributed over some area, equipment or person. It tends to be unwanted in the location where it is, and has to be cleaned up or decontaminated.

Q: What acute effects does radiation have?

People exposed to a high dose of radiation over a short period show acute effects. These are to be distinguished from so-called late effects, such as tumours or genetic mutations, which often only appear decades later.

A dose greater than 0.5 sievert (Sv) is considered to be a high dose of radiation. Above this threshold, adverse effects become apparent immediately or after a few days at most. The immune system is weakened, changes in blood count occur, and the digestive tract, lungs, other internal organs and the central nervous system are all damaged. With absorbed doses of 1 to 2 Sv and above, mortality is expected to be about 20%, according to radiation medicine specialists. Above a dose of 7 Sv the survival rate is zero.

Of the 600 power station personnel and fire-fighters that were in the vicinity of the burning reactor directly after the accident, 134 received doses of 0.7 to 13 Sv. These include the 31 people who died in the first 3 months after the accident despite intensive treatment.

The treatment of people who have been exposed to an effective dose of radiation of 10 Sv and above is very costly and has a low success rate, as was apparent after the Chernobyl accident. Since the immune system is weakened and the body no longer has a defence against infections, patients require constant treatment with antibiotics. Survival rates were not improved by the transplantation of healthy bone marrow.

Q: What are the biological effects of exposure to radiation?

The effect depends on the amount (dose), ranging from no effect (low) to death (high). For the most part, what radiation does is create ions in our cells, and these ions cause problems in the cell. The International Commission of Radiological Protection assesses radiation damage on the premise that radiation is always potentially harmful, however small dose. The radiation may interact directly with biologically significant molecules, like DNA and proteins. Radiation may also interact indirectly to cause damage, by interacting with chemicals in our bodies, such as water, and form very active chemicals like free radicals that may cause damage to the biologically significant molecules.

The damage can be fixed, or the cell may die, or it may actually affect the tissue/organ if there is enough damage. It is felt that the damage to the DNA is of the most importance, and could lead to increase risk of cancer. The damage could be to a single base pair, could cause the DNA to bind to itself or cause an actually break the DNA on one stand or more rarely, to both DNA strands. If the damage is not fixed or is fixed wrong and the cell escapes apoptosis (programmed cell death) it may be one of the several needed steps that results in the cell becoming a tumor.

Q: Which areas were contaminated by radiation?

Radiation knows no territorial boundaries. It doesn’t apply for an entry or an exit visa; it travels wherever the wind takes it. Because of variable weather conditions in the days following the accident, radiation also spread over large parts of Scandinavia, Poland and the Baltic States, as well as southern Germany, Switzerland, northern France and England. The dense clouds of radioactivity were widely dispersed over Europe, with caesium and iodine directly contaminating the lichen eaten by Lapland’s reindeer, the grass of Wales and parts of Ireland and the flora and fauna of the French and Italian Alps. But the indirect fallout travelled much farther. In spite of the control measures eventually applied, it was soon discovered that in many parts of the Third World, dangerously irradiated food was being exported from Europe.

There was outrage in July 1986 when Bangladesh discovered that a shipment of powered milk exported from Poland and used to feed infants had over 100 times the permitted level of radioactivity. To make matters worse, infants are 10 times more vulnerable to the effects of radioactivity than adults. Over the following months, similar shipments from a variety of European countries carrying different produce were found to be radioactive. It became clear that tainted produce from countries in Europe affected by the fallout were being dumped in vulnerable parts of the world where controls and safety checks were inadequate. It is conservatively estimated that about 100 million curies of radiation were released, although many scientists now believe it was closer to 250 million curies. The day after the fire was brought ‘under control’; it released 150,000 curies of radiation.

In Europe the quantity of caesium-137 deposited by Chernobyl was 400 times more than the peak levels released by all the atmospheric nuclear weapons tested up to 1963. The UN estimates that an area the size of England, Wales and Ireland combined has been contaminated. Of the curies released into the atmosphere, covering 155,000 square kilometres of land, 70 per cent fell on to the population of Belarus. Between the stricken regions of Belarus, western Russia and northern Ukraine, the UN estimates that the fallout has directly and indirectly affected up to 7 million people. The land formerly known as the ‘breadbasket of Russia’ is now poisoned with contamination from the fallout. Some 480,000 hectares of farming land, including 230,000 hectares of arable land have been withdrawn from agricultural production. The territory adjacent to the river Pripyat, once a major meat and dairy- producing area, has been turned into a depopulated radiation zone. The river is highly radioactive, and since it feeds into the river Dnieper in the Ukraine, it has caused the slit bed of the Dnieper to become radioactive. The Dnieper is now the world’s most radioactive river.

The disaster is 20 years old, but its consequences will last forever!

In addition to the reactor’s immediate surroundings – an area with a radius of about 30 km – other regions were contaminated, particularly in Belarus, Russia and Ukraine.

The contaminated territories lie in the north of Ukraine, the south and east of Belarus and in the western border area between Russia and Belarus, an area greater than that of the neighboring countries of Latvia and Lithuania combined. At the time of the accident, about 7 million people lived in the contaminated territories, including 3 million children. Rest of EU – incl Ireland.

Map showing areas of contamination as a result of the Chernobyl explosion

Q: What was the level of contamination in Belarus?

Most of the contaminated territory lies in Belarus, since up to 70 per cent of the total fallout was deposited here. Of the total area of Belarus, 22 per cent was contaminated. At the time of the accident, 2.2 million people lived in these areas, one fifth of the population of Belarus. 7.25 per cent of Ukraine’s territory was contaminated following the accident, and 0.6 per cent of the Russian Federation.