chernobyl nuclear power plant
TRANSCRIPT
What is a NUCLEAR POWER PLANT?• A nuclear power plant is
a thermal power station in which the heat source is a nuclear reactor (device to initiate and control a sustained nuclear chain reaction).
• As is typical in all conventional thermal power stations, the heat is used to generate steam which drives a steam turbine connected to a generator which produces ELECTRICITY.
CHERNOBYL POWER PLANT• a.k.a. Chornobyl Nuclear Power Station
• Chernobyl is the well-known Russian name for the site (Chornobyl is preferred by Ukraine).
• Construction of the plant at the nearby city of Pripyat, Ukraine began in 1970.
• It was the third nuclear power station in the Soviet Union of the RBMK-type and the first ever nuclear power plant on Ukrainian soil.
• consisted of four nuclear reactors of the RBMK-1000 design.
RBMKs (Chernobyl reactors) Reaktor Bolshoy Moshehnosty Kipyashiy
Russian; translated as “reactor (of) high power (of the) channel (type)”
-were high-powered reactors
-used graphite to help maintain the chain reaction and cooled the reactor cores with water.
RBMK Reactors
units 1 and 2 being constructed between 1970 and 1978, units 3 and 4 of the same design were completed in
1983. Each four types of RBMK reactors are capable of
producing 1,000 megawatts (MW) of electric power .(3.2 GW of thermal power), and the four together produced about 10% of Ukraine's electricity at the time of the accident
RBMK REACTOR FUNCTIONSPowered by slightly enriched uranium dioxide fuel pellets (U-235)Uses solid graphite to slow down neutronsFuel rods arranged cylindrically to form fuel assembly, and two fuel assemblies are stacked on top of each other and placed in individual pressure tubes (allows reactor to be refueled while running)Graphite blocks between pressure tubes act as moderators
USES of CHENOBYL NUCLEAR POWERPLANT
Nuclear Power (Generation of Electrical Power)
Nuclear Propulsion (in devices such as rockets)
Transmutation of Elements (production/creation of Plutonium/other radioactive isotopes for uses such as radiation therapy)
Research/Technology (neutron and positron radiation)
April 26,1986Disaster at the Chernobyl nuclear power plant in Ukraine was the product of a flawed Soviet reactor design coupled with serious mistakes made by the plant operators.The accident destroyed the Chernobyl 4 reactor,several workers immediately, about 30 firefighters/emergency workers from acute radiation exposure, and a smaller # from sub acute effects and several further deaths later.The reactor's power dropped suddenly, causing a potentially dangerous situation. The operators tried to compensate for the low power but the reactor went out of control - a design flaw-caused power excursion causing a steam explosion resulting in a graphite fire.The accident and the fire that followed released massive amounts of radioactive material into the environment. Emergency crews responding to the accident used helicopters to pour sand and boron on the reactor debris.
-The sand was to stop the fire and additional releases of radioactive material; the boron was to prevent additional nuclear reactions.
Acute radiation syndrome (ARS) was originally diagnosed in 237 people on-site and involved with the clean-up and it was later confirmed in 134 cases.
Officials closed off the area within 30 kilometres (18 miles) of the plant, except for persons with official business at the plant and those people evaluating and dealing with the consequences of the accident and operating the undamaged reactors.
The effects of radiation exposure fall into two main classes: deterministic effects, where the effect is certain to occur under given conditions (e.g. individuals exposed to several grays over a short period of time will definitely suffer Acute Radiation Syndrome); and stochastic effects, where the effect may or may not occur (e.g. an increase in radiation exposure may or may not induce a cancer in a particular individual but if a sufficiently large population receive a radiation exposure above a certain level, an increase in the incidence of cancer may become detectable in that population).
A few weeks after the accident, the crews (LIQUIDATORS) completely covered the damaged unit in a temporary concrete structure, called the “sarcophagus,” to limit further release of radioactive material.
Decommissioning The remaining 3 reactors continued to operate
after the accident of reactor no. 4 In 1991, reactor no. 2 suffered a major fire November 1996, reactor no. 1 was shut down Followed by reactor no. 3 (December 15, 2000) 1st stage of decommission – removal of highly
radioactive spent nuclear fuel Removal of uncontaminated equipment has begun
at reactor no. 1 and will be completed by 2020-2022
The remains of reactor no. 4 will remain radioactive for some time.
The isotope responsible for the majority of the external gamma radiation dose is Caesium-137, which has a half-life of about 30 years.
CAUSES:International Nuclear Safety Advisory Group (INSAG) investigate the causes of
the accident:
• The catastrophic accident was caused by gross violations of operating rules and regulations.
• Operators not informed by designers of dangerous conditions for reactor• Lack of knowledge of nuclear reactor physics and engineering, as well as
lack of experience and training.• Personnel disconnected a series of technical protection systems and
breached the most important operational safety provisions for conducting a technical exercise.
• Personnel had an insufficiently detailed understanding of technical procedures involved with the nuclear reactor, and knowingly ignored regulations to speed test completion.
• Thus the primary cause of the accident was the extremely improbable combination of rule infringement plus the operational routine allowed by the power station staff.
EFFECTS: 1.Direct Health Effects -Many people died in the immediate explosion from flames and intense
radiation exposure. 2. Longer Lasting Effects - The nuclear material has caused countless premature deaths due to
cancer. It has also caused many birth defects in babies.3. International Effects - The explosion not only spread nuclear material to many other parts of
the world, but nuclear power plant practices also came under scrutiny. 4. Effects on Wildlife -Many plants and animals died quickly after the explosion, but scientists
noticed that wildlife is thriving in the area of the explosion now, possibly due to the lack of human habitation.
5. Economic Effects - The explosion and its aftermath cost an estimated $200 billion.
ADVANTAGES:1. Nuclear power plants don't require a lot of space
- they have to be built on the coast, but do not need a large plot like a wind farm.
2. It doesn't contribute to carbon emissions - no CO2 is given out - it therefore does not cause global warming.
3. Nuclear power allows energy to be produced in a way which greatly reduces serious environmental pollution by carbon dioxide from conventional power plants.
4. Nuclear energy is by far the most concentrated form of energy - a lot of energy is produced from a small mass of fuel. This reduces transport costs - (although the fuel is radioactive and therefore each transport that does occur is expensive because of security implications). -It is reliable. It does not depend on the weather. We can control the output It is relatively easy to control the output
DISADVANTAGES:1. The problem of how to store the dangerous radioactive waste safely.
2. The risks of a dangerous accident or terrorist attack at the nuclear power plant the safety risks in mining and transporting the radioactive fuel.
3. The safety risks in transporting the radioactive waste.
4. The risks of theft of material, possibly for a nuclear bomb.
5. This radiation harms the cells of the body which can make humans sick or even cause death and can produce particles over a wide area.
6. Many people living near to nuclear power stations or waste storage depots are concerned about nuclear accidents and radioactive leaks. Some fear that living in these areas can damage their health, especially the health of young children.