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Adam TimmermanMay 7, 2013

The Chernobyl Disaster

Chernobyl, located in northern modern Ukraine near the

Belarus border, is located near the former Chernobyl Nuclear

Power Plant and the city of Pripyat, where the workers of the

plant and their families lived. Construction on the plant and

Pripyat began in 1970, with the first reactor being completed in

1977. This was the third RBMK-type nuclear power plant in the

Soviet Union and the first in Ukraine. Roberta Barbalace, a

college professor, writer, editor, and environmental consultant,

retells what happened the day of the disaster and its effects.

In 1986, Unit 4 reactor experienced two explosions, and after ten

days of fires massive amounts of radiation was released into the

atmosphere (Barbalace 1999). The estimated amount of radiation

released is thought to be about 200 times greater than the

combined releases of the atomic bombing of Hiroshima and

Nagasaki, resulting in the immediate extraction of around 135,000

people in a 30 km radius (Barbalace). Another 220,000 people

were relocated from the area in the following years (World

Nuclear Association 2012).

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The location of Chernobyl is within a mild-continental

climate with warm summers and mild winters. The landscape

contains forests, ponds, reservoirs, and bogs, and there is wide

river network (“Landscape Description of Chernobyl Exclusion

Zone”). The Pripyat River and Yanov railroad station provided

easy access to the area and helped spark the building of the

plant and Pripyat (“The Pripyat city history”). Originally, the

nuclear power plant was supposed to be built only 16 miles from

Kiev, but the Ukrainian Academy of Sciences expressed concern

that it was too close to the city, though the Soviet Union at the

time prided itself on nuclear power, claiming it was the safest

of any type of power plant and creating the slogan “peaceful

atom” for it.

The reactors at the Chernobyl nuclear power plant were of

the Soviet-designed RBMK-1000 type, as described by the World

Nuclear Association. They were pressurized water-cooled reactors

and had individual fuel channels and used graphite as its

moderator (World Nuclear Association 2010). One of the most

important characteristics of the RBMK reactor is that it can

possess a 'positive void coefficient,' meaning that as production

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in the fuel channels increases, the neutrons that would have been

absorbed by the denser water now produce increased fission in the

fuel (World Nuclear Association). The World Nuclear Association

states that on 25 April, prior to a routine shutdown, Unit 4’s

crew began preparing for a test to determine how long turbines

would spin and supply power to the main circulating pumps

following a loss of main electrical power supply. Actions

preceding the test date set for April 26 included disabling the

automatic shutdown mechanisms, and by the time the operator moved

to shut down the reactor, it was already extremely unstable

(World Nuclear Association 2012).

On April 26, 1986 at 1:23 am, two explosions took place in

the Unit 4 reactor’s core after a significant power increase.

The explosion destroyed the reactor block and its adjacent

structure, and the nearby buildings were lit on fire by burning

graphite projectiles (Barbalace 1999). The fires continued for

ten days, even after boron carbide, lead, sand and clay were

dumped over the core reactor by helicopter, and it didn’t end

until the core melted, flowed into the lower part of the building

and then solidified, finally sealing off the source of where the

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radiation came from. However, this was not until 71% of the

radiation fuel from the core was left uncovered and released into

the world (Barbalace).

The Chernobyl Forum presented by the International Atomic

Energy Agency, or IAEA, chronicled the aftermath of the disaster.

Some 350,000 emergency and recovery operation workers, including

army, power plant staff, local police and fire services, were

initially involved in containing and cleaning up the accident in

1986–1987 (Kinley III 2006). At its peak, the number of workers

reached up to 600,000, and they assisted in the cleanup and

removal of about 350,000 people in the direct aftermath and later

subsequent years of the explosion.

The cloud from the reactor released numerous types of

radioactive material, especially iodine and caesium radionuclides

(Kinley III 2006). The radioactive iodine-131 released mostly

disintegrated within the first few weeks, but radioactive

caesium-137 is still measurable in many parts of Europe (Kinley

III). Figure 1 shows how far the radiation traveled across

Europe and figures 1, 2, 3, and 4 show how radiation still

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existed even after days and decades of the explosion. Farmers in

the United Kingdom to this day still are feeling the effects of

the amount of radiation released from the explosion (Macalister

and Carter 2009).

The disaster contaminated over 125,000 square miles in

Belarus, Russia, and Ukraine, and over 200,000 square miles in

Europe received levels of radioactive caesium-137 above 37 kBq

mˉ². The effects on the environment were immediate and for some

places they were long lasting. Radioactive particles settled on

trees around the site, killing around 400 hectares of pine forest

(Flanary and McGinley 2008). This zone, based off of the nature

of radiation effects, absorbed 8000-10000 doses of radiation,

causing the pine tree trunks to completely die and have its

needles turn a brick color (Barry 2012). This area is now called

the “Red Forest” because of the color of the dead forest. The

disaster also happened during the growing season for the forest,

helping to speed up and increase the damage from exposure.

Reproductive ability was hampered for around three years before

trees started to reproduce normally again.

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Agricultural areas also took a hard hit because of the

radiation exposure. Agricultural plants and plant-consuming

animals took in high doses of radionuclides. Belarus alone lost

2,640 sq. km of farmland and 1,900 sq. km of forests for human

use forever (Barbalace 1999). Cows that were exposed to the

radiation by being outside and consuming the effected quickly

absorbed the radioiodine into their milk. This led to

dangerously high levels of thyroid doses to people consuming the

milk, especially children in the areas around the disaster site

(Kinley III 2006). High levels of radioiodine-absorbed milk were

recorded around other places of Europe as well.

However, with all the hazards of radiation on the ecosystem,

local fauna have flourished in years following the disaster. The

Encyclopedia of Earth’s segment on the environmental effects of

Chernobyl points out how there have been an increase in wildlife

in the area. Without human presence in the area, the local

ecosystem has thrived as biodiversity continues to grow (Flanary

and McGinley 2008).

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Surface water and the life they support were affected too by

the disaster. Radioactive materials deposited on rivers, lakes,

and reservoirs, though most of the materials decreased rapidly

the first few weeks because of radioactive decay, were diluted,

or they were absorbed into the soil (Kinley III 2006). Fish

absorbed radioactive iodine quickly, but the levels rapidly

dropped do to the decay, but the radioactive levels in fish

reached as far as Germany and Scandinavia. Radioactive caesium-

137 still continues to enter waterways through soil run-off, but

the levels are below hazardous concerns in water systems that

aren’t “closed,” meaning lakes without an outflow site will be

contaminated with radioactive caesium-137 for decades to come

(Kinley III). Also, though groundwater was an area of concern,

most radionuclides decayed well before they could reach

groundwater sites or were absorbed by soil, making groundwater

relatively uncontaminated (Flanary and McGinley 2008).

Figuring out the effects from the Chernobyl nuclear power

plant on human health has been hard to come do because of Soviet

unreliability and their attempts to cover up the full extent of

the disaster. What is known is that two workers died as a result

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of the explosion. Of the 444 workers on site during the

explosion, only 134 of them were diagnosed with acute radiation

syndrome, and 45 - 47 of them have died to date, though some may

have died of other natural causes (Barbalace 1999). 28 of them

died in 1986 as a direct result of exposure from the disaster

(Kinley III 2006). The official Soviet death toll from the

disaster is 31, counting the 28 who died immediately after

exposure, the two who died in the explosion, and another worker

who died of coronary thrombosis (Kinley III). As for deaths and

health effects like cancer and mutations, is impossible to fully

know what was caused by the disaster and to what its extent was.

Though there have been increases in cancers and mini-satellite

mutations, the full extent of mutations and health hazards caused

by the radiation exposure happen in later generations

(Barbalace).

After Chernobyl, a new settlement was built 30 km from the

disaster site, called Slavutich. Ukraine today relies on nuclear

power for half of its total energy (World Nuclear Association

2012). A large concrete structure was quickly placed over Unit 4

so the other reactors at the site could continue operating.

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However, the last two reactors have been shut down and a new,

stronger and better confinement structure is in the process of

being built (World Nuclear Association). As for the containment

area, resettlement has started, mainly in Belarus. New road,

buildings, schools, and dwellings are presently being built for

the resettlement, with more planned in the future. Agriculture

will be able to take place in areas with low radioactive cassium-

137, and areas with high cassium-137 will be forested (World

Nuclear Association).

After the Chernobyl nuclear power plant disaster, new

strategies were put into place to make sure another disaster like

this never happens again. Reactor safety greatly increased

following the disaster, not just those in Eastern Europe. All of

the RBMK reactors still in operation have been modified to

prevent against power surges and shut down faster (World Nuclear

Association 2012). According to one German nuclear safety agency

report, another Chernobyl is virtually impossible because of the

adjustments made since the disaster. Also, multiple programs

such as the International Atomic Energy Agency and the Nuclear

Safety Assistance Coordination Centre have formed in the wake of

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Chernobyl, making sure nuclear sites are safe and secure (World

Nuclear Association).

Figure 1. The extent of nuclear radiation across Europe

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Figure 3. The amount of radiationin Ukraine 21 days after the disaster

Figure 2. RadiationLevels in Ukraine before the disaster

Figure 4. The amount of radiationin Ukraine present day.

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References

Barbalace, Roberta C. (1999) “Chernobyl Nuclear Disaster Revisited.” EnvironmentalChemistry.com. http://environmentalchemistry.com/yogi/hazmat/articles/chernobyl1.html

Barry, Michael. (2012) “The Red Forest” The Nuclear Flower. Basedoff of: Chernobyl disaster and its aftermath: Information prepared for the meeting of IAEA experts - Part 1. The compilation. August 1986. Chernobyl: the radioactive contamination of natural environments Ed. Yuri A. Izrael. Leningrad: Gidrometeoizdat, 1990. Tikhomirov F.A. Shchleglov A.I.Radiological consequences of the Kyschtyme and Chernobyl radiation accident in forest ecosystems. Ecology regions of nuclear power plants. Vol 1, 1994. 71-88 pp.http://www.nuclearflower.com/zone/zone08.html

“Chernobyl.” Chernobyl Foundation. Est. 2010. http://dev2013.chernobylfoundation.org/

Flanary, Will and Mark McGinley. (2008) “Environmental effects ofthe Chernobyl accident.” The Encyclopedia of Earth. Updated 2013. http://www.eoearth.org/article/Environmental_effects_of_the_Chernobyl_accident

Kinley III, D. (Editor) “Chernobyl’s Legacy: Health, Environmental and Socio-Economic Impacts and Recommendationsto the Governements of Belarus, the Russsian Federation, andUkraine.” The Chernobyl Forum: 2003-2005. International Atomic Energy Agency. Printed 2006. http://www.iaea.org/Publications/Booklets/Chernobyl/chernobyl.pdf

“Landscape Description of Chernobyl Exclusion Zone.” Chernobyl, Pripyat, Chernobyl NPP Exclusion Zone. Chornobyl.in.ua.

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Based off of: Davydchuk V.S., Zarudnaya R.F., Miheli S.V. etal. Landscapes of Chernobyl zone and their evaluation by condition of radionuclide migration. Kiev: Naukova dumka, 1994. 112 p.Tixomirov F. A., Scheglov A. I., Cvetnova A. B., KlyashtorinA. L. Geochemical migration of radionuclides in forest ecosystems of ChNPP radioactive zone // Pochvovedenie. 1990,№ 10. – p. 41-50.http://chornobyl.in.ua/en/chernobyl-zone-landscape.html

Macalister, Terry and Helen Carter. “Britain's farmers still restricted by Chernobyl nuclear fallout.” The Guardian. Tuesday 12 May 2009http://www.guardian.co.uk/environment/2009/may/12/farmers-restricted-chernobyl-disaster

“The Pripyat city history” Chernobyl, Pripyat, Chernobyl NPP Exclusion Zone. Chornobyl.in.ua. Based off of: Ipatiy annals (published 1908). Kiev annalistic code. In summer 6699 [1191] – in summer 6703[1195]. Nuclear Energy. Questions and answers. Issue 4. The draftersof the V.A. Krasyuk and Kachalov Metro. IzdAT 1993. p. 48.http://chornobyl.in.ua/en/the-pripyat-city-history.html

World Nuclear Association. (2010) “RMBK Reactors: Appendix to Nuclear Power Reactors” World Nuclear Association. Based offof: INSAG-7, The Chernobyl Accident: Updating of INSAG-1, A report by the International Nuclear Safety Advisory Group, International Atomic Energy Agency, Safety Series No. 75-INSAG-7, 1992, (ISBN: 9201046928). See especially: Annex I of INSAG-7, the Report by a Commission to the USSR State Committee for theSupervision of Safety in Industry and Nuclear Power (SCSSINP); and AnnexII of INSAG-7, the Report by Working Group of USSR Experts, Causes and Circumstances of the Accident at Unit 4 of the Chernobyl Nuclear Power Plant and Measures to Improve the Safety of Plants with RBMK Reactors (Moscow,

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1991)http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Appendices/RBMK-Reactors/#.UYg7gLVJOAh

World Nuclear Association. (2012) “Chernobyl Accident 1986.” World Nuclear Association. http://www.world-nuclear.org/info/Safety-and-Security/Safety-of-Plants/Chernobyl-Accident/#.UYg8RrVJOAh