A Study on Nuclear Disasters:Risks versus Benefits

Presented By

Department of Civil EngineeringSwarnandhra college of Engg.&Tech.,

Seetharampuram,Narspur   

     

 

Organization of the Presentation

Introduction to Nuclear power plants. List of dangers, connected with NPPs:

Release of radioactive particles into environment. Radioactive isotopes pollution. Water temperature increases. The threat of nuclear accidents. The threat of nuclear terrorism.

Nuclear power plants technologies that provide safety. Reactor design flaws. Mistakes and incompetence of personnel. Major incidents regarding NPPs. Conclusions Refernces

Introduction to Nuclear power plant

It was commonly to think that nuclear energy is absolutely safe until some serious incidents occurred on nuclear power plants of the USA(Three Mile Island), Japan(Kashiwaszki-Kariwa) and the most dangerous incident in the former USSR (Chernobyl). The last of them had very serious consequences. All these events changed the opinion of people about the safety of nuclear energy. However the danger of nuclear energy was not only in the nuclear accidents.

Dangers connected with nuclear power plants:

Release of radioactive particle

Radioactive isotopes

Water Temperature Increases

The Threat of Nuclear Accidents

The Threat of Nuclear Terrorism

Release of radioactive particles

Usually the radioactive particles appear from radioactive isotopes and in fission process. In most cases speaking about radioactive particles pollution, people mean gamma-radiation, which is easily determinated by a Geiger counter. At the same time there are many beta-radiators, which are badly determinated by the most of existing devices.

Radioactive isotopes Radioactive contamination is typically the

result of a spill or accident during the production or use of radionuclides (radioisotopes), an unstable nucleus which has excessive energy. However the production of those radionuclides is controlled by filters and other equipment. The biological effects of internally deposited radionuclides depend greatly on the activity and the biodistribution and removal rates of the radionuclide, which in turn depends on its chemical form.

Water temperature increase

For the NPPs just as for the thermal power stations heat release into is typical.

It is marked that the temperature of water in the area of nuclear power station is higher than without it. Because of that the balance of water evaporation is disturbed and the amount of salt in water increased. This changes can lead to extinction of some species of animals.

The treat of nuclear accidents

The most actual question appealed to NPP is the question of nuclear accidents. Thought the chances of such accident is very small the danger it carries is very serious.

Nuclear terrorism threat Another actual

question of the NPP’s safety is nuclear terrorism.

The NPP could be captured by terrorists and used like a nuclear weapon.

Nuclear power plants technologies that provide safety

The most widespread causes of the NPP accident are:Reactor design flaws.Mistakes and incompetence of personnel.

It is important to learn by your own mistakes. So the Chernobyl disaster were carefully examined and analyzed. After that new standards of safety and new technologies were adopted.

Reactor design flaws

We’ll take a Chernobyl as an example for reactor design flaws. There were several serious design flaws in the Chernobyl RBMK: The scram button that supposed to stop the reaction

accelerated it instead. the heat from the graphite, which operates at 700 degrees

Centigrade, flows from the graphite back through the pressure tubes and is taken away by the boiling water. "However, the problem with graphite at high temperatures is that if it is exposed to air, it will burn slowly.

The RBMK reactor was a large one and it could not be put in containment.

These reactors are not used nowadays and all known design flaws are removed from new reactors.

Mistakes and incompetence of personnel.

Six human errors were identified. Two permanent operating rules were violated: not

to run the reactor for any length of time at reduced power level (below 700 Megawatts-thermal), and never to have fewer than thirty control rods fully inserted into the core

If any one of these six errors had not been committed, the explosion would not have occurred.

However it’s not the fault of personnel, it’s the fault of their not sufficient training.

After Chernobyl disaster some new laws of safety were adopted.

Major incidents regarding NPPs

Chernobyl Three Mile Island Kashiwazaki-Kariwa

Reactors used •A high-power, boiling water type reactor (RBMK)

•TMI-2 reactor •BWR

The main causes of the accident

•The operators violated plant procedures and were ignorant of the safety requirements needed by the RBMK design.

•The sequence of certain events - - equipment malfunctions, design related problems and worker errors.

•Earthquake

consequences •The Ukrainian Ministry of Public Health in April 1995 said 125,000 already dead.•Economically, the consequences have been staggering: at least $300 Billion and more.

•None people died. There were no environment pollution

•None died. No environmental pollution.

Chernobyl Three Mile Island Kashiwazaki-Kariwa

Pictures

Conclusions Yes, the causes of such disasters are well

understood but there’s no certitude that government and NPP’s personnel will follow them. First of all some countries couldn’t have enough money to develop and integrate newest technologies into NPPs

Secondly the chance of human mistakes is always exists. So there always will be chance of accident like the ones we examined

Finally the thermal load based designs in civil engineering is essential.

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