ENSC_103 Lecture 16: Case Study: Chernobyl Nuclear Disaster

Fast facts about modern Ukraine

Population (2015): 44,429,471

GDP (2015): $331.6 billion

GDP per capita (2015): $8,000

- the size of Texas

GDP per capita over time

- when the Soviet Union fell, Ukraine & Russia saw a severe economic depression

- Ukraine has not really had any recovery

Snapshot of Ukraine in 1986

- One of 15 republics of the Soviet Union

- Ruling party was Communist Party

- Political ideology was Marxism-Leninism (1 party Socialist State- communist, dictatorship of Proletariat)

- President of USSR was Mikhail Gorbachev

- Approaching end of the Cold War and dissolution of USSR in 1991

-USSR (1922-1991)

History of the Chernobyl Nuclear Power Station: Purpose for construction

Provide electricity to the Central Power Region of USSR

History of the Chernobyl Nuclear Power Station: Reason for location

- Centrally located yet near Kyiv (capital of Ukraine)

- Adequate water supply; close proximity to roads/railways

History of the Chernobyl Nuclear Power Station: Construction timeline

- 1970: Construction of plant and city of Pripyat begins

- 1977-1983: Completion of Units 1-4 reactors (unit 4 explodes)

- 1983-1986: Construction of Units 5-6 reactors (never finished)

History of the Chernobyl Nuclear Power Station: Electricity generation

- 1,000 megawatts per reactor (~16.7 mil. 60-W light bulbs)

- All four reactors produced ~10% of Ukraine's electricity

Location of Chernobyl Nuclear Power Station

- located in the City of Pripyat, where construction occurred

- drew in cool water from a cooling pond along the Pripyat River

Design of Chernobyl-type reactor (RBMK-1000)

Soviet-designed RBMK (reaktor bolshoy moshchnosty kanalny, high-power channel reactor) is a pressurized water-cooled reactor with individual fuel channels and using graphite as its moderator

- electricity moves through turbo energy at the generator

- low and high energy steam turbines spin steam -- mechanical energy

Design of Chernobyl-type reactor (RBMK-1000): Fuel rod

contains pellets of slightly-enriched Uranium-235

- can undergo fission (warms up cool water)

Design of Chernobyl-type reactor (RBMK-1000): Control rod

absorbs neutrons to control the rate of fission

Design of Chernobyl-type reactor (RBMK-1000): Graphite moderator

slows down neutrons released during fission

Floor plan of Chernobyl Nuclear Power Station

- Phase I, Chernobyl Nuclear Power Plant (Approx. +10 meters elevation)

- Unit Control Rooms w/ Personnel located right outside the Reactor building

TG = turbo generator (converts mechanical energy into electrical energy

Summary of Chernobyl accident in 1986

- Result of a flawed reactor design that was operated with inadequately trained personnel (failed tests)

- Resulting steam explosion and fires released at least 5% of the radioactive reactor core into the environment (radiation spreads throughout different locations)

Summary of Chernobyl accident: 25 April 1986

Unit 4 reactor crew begins 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; as part of this preparation, crew disables automatic shutdown mechanisms

Summary of Chernobyl accident: 26 April 1986

Test begins in the morning; extremely unstable condition by the time reactors are shut down; control rods caused a dramatic power surge as they were inserted into the reactor (as a last resort); interaction of very hot fuel with the cooling water led to fuel fragmentation along with rapid steam production and an increase in pressure; intense steam generation (turbines can't handle steam) then spread throughout the whole core causing a steam explosion

Emergency response to accident

- Helicopters were used to pour sand (to stop the fire) and boron (to quench nuclear reactions) on reactor debris

- Firefighters fought blaze at site for ~10 days

- Several weeks later, damaged unit covered in a concrete structure (or "sarcophagus") to limit radioactive emissions

Chernobyl is the most serious accident in the history of the nuclear power industry

- radiation spreads heavily to the North of where accident occurs

Radioactive gases and particles released in the accident were initially carried by the wind in westerly and northerly directions

Chernobyl accident contaminated wide areas of Belarus, Russia, and Ukraine inhabited by millions of residents

- probably due to stronger Northern winds

- cesium-137 is produced as a fission byproduct of U-235 & a marker of radioactive material after Chernobyl

Chernobyl: Evacuation following the accident

- Area within 30 kilometers (18 miles) of the plant closed off,

except for persons with official business at the plant and people involved in evaluation/clean-up

- The Soviet (and later on, Russian) government evacuated about 115,000 people from the most heavily contaminated areas in 1986, and another 220,000 people in subsequent years

-people displaced & never came back

Acute exposure and short-term health effects

- Initial radiation exposure in contaminated areas due to short- lived iodine-131; later, caesium-137 was the main hazard

- Radiation doses for first-responders on the first day were estimated to range up to 2,000,000 millirem, causing 28 deaths - six were firemen - by July 1986

- 100+ first-responders suffered from acute radiation sickness

- About 200,000 people involved in recovery and clean-up during 1986 and 1987 received above-average doses of radiation, averaging around 10,000 millirem

- However, majority of the five million residents living in contaminated areas received very small radiation doses comparable to background levels (100 millirem)

Multistage carcinogenesis

1. Initiation (genome instability as a result of accumulation)

2. Promotion

3. Malignant conversion

4. Progression

Cancer (Metastasis)

*time (age): primary variable

- defects in terminal differentiation, defects in growth control, resistance to cytotoxicity, defects in programmed cell death

- chemicals, radiation, and virus--> activation of proto oncogenes, inactivation of tumor-suppressor genes, inactivation of genomic stability genes

Chernobyl-related thyroid cancer cases in children

- Many children and adolescents in the area in 1986 drank milk contaminated with radioactive iodine, which delivered substantial doses to their thyroid glands

- To date, about 6,000 thyroid cancer cases have been detected among these children

- Ninety-nine percent of these children were successfully treated; 15 children and adolescents in the three countries died from thyroid cancer by 2005

- most cases in close proximity to Chernobyl after carried out by N. winds

*massive acceleration of thyroid cancer in a short period of time

Economic consequences

- Billions of dollars in losses, damage, etc., resulting in a major drain on budgets of the three countries involved

- Significant agricultural and forestry production losses

- Difficult to sell or export products, leading to fall in incomes

Political consequences

Accelerated the transformation from a centrally planned to

market economy in the affected countries

Psychological consequences

- Traumatic experience that left many relocated people with no employment and a belief they have no place in society

- Exaggerated sense of the danger to their health from radiation exposure and a belief in a shorter life expectancy

The Babushkas of Chernobyl

- Chernobyl Exclusion Zone (red border)

- Chernobyl Nuclear Power Station

- Zone covers approx. 1,000 sq mi

- evacuated, but snuck back in; wanted to stay in the motherland

Holly Morris (writer; film director)

The Babushkas of Chernobyl

*see lecture video