NUCLEAR HAZARDS, CAUSES AND EFFECTS OF NUCLEAR HAZARDS

Radiation Hazard in the environment comes from ultraviolet, visible, cosmic rays and microwave radiation which produce genetic mutations in man. The biggest hazard comes from X-rays which accounts for 95% of out radiation exposure other than cosmic rays.

Sources of Nuclear Hazards :

Various sources of Nuclear Hazards are grouped into two types

1. Natural Sources

2. Man - made ( Anthropogenic ) sources.

I) NATURAL SOURCES :

a) The very important natural source is space, which emit cosmic rays.

b) Soil, rocks, air, water, food, radioactive radon-222 etc., also contain one or more radioactive substances.

II)MAN - MADE SOURCES :

Man - made sources are nuclear power plants, X-rays, Nuclear Accidents, Nuclear Bombs, Diagnostic kits etc., where radioactive substances are used.

EFFECTS OF NUCLEAR HAZARDS :

Studies have shown that the health effects due to radiation are dependent on the level of dose.

1. Exposure of the brain and central nervous system to high doses of radiation causes delirium, convulsions and death within hours or days.

2. The use of eye is vulnerable to radiation. As its cell die, they become opaque forming cataracts that impair sight.

3. Acute radiation sickness is marked by vomiting, bleeding of the gums and in severe cases, mouth ulcers.

4. Internal bleeding and blood vessel damage may show up as red spots on the skin.

5. Nausea and vomiting often begin a few hours after the gastrointestinal tract is exposed. Infection of the intestinal wall can kill weeks afterwards.

6. Un born children are vulnerable to brain damage or mental retardation, especially if radiation occurs during formation of the central nervous system in early pregnancy.

Comments

THROTTLE GOVERNING OF STEAM TURBINES

Steam Pressure at inlet to a steam turbine is reduced by throttling process to maintain the speed of the turbine constant at part load and hence this method of governing is called "Throttle Governing". Construction : Throttle governing system consists of a centrifugal governor, a lever , an oil pump , a pilot piston , control valve , a relay piston and a throttle valve. The throttle valve is moved by a relay piston. The relay piston is actuated by pilot piston control valve. There are two piston valves covering ports in the pilot piston control valve without any overlap. These piston valves are operated by lubricating oil supplied by a gear pump at 2 to 4 bar. The oil returns to the drain from this chamber. Working : When the turbine works on full rated load, the throttle valve will remain open. When the load is decreased, the energy output of the turbine becomes in excess and the turbine shaft speed increases. Hence, governor sleeve will lift. The upward movement of the

ELECTRICAL COMPARATORS AND ITS WORKING

Electrical Comparators are used as a means of detecting and amplifying small movements of a work contacting elements. An electrical comparator consists essentially of a pick-up head or transducer for converting a displacement into a corresponding change in current and a meter or recorder connected in the circuit to indicate the electrical change, calibrated to show in terms of displacement. Generally, an amplifier is needed to provide the requisite sensitivity and to match the characteristics of different parts of the circuit. Electrical comparators can be classified according to the electrical principle used in the pick-up head. Most of the comparators use either a differential transformer, an inductance bridge, a strain gauge or a capacitor as a means of detecting movement of the gauging element. There are different types of electrical comparators. One kind called an electrolimit gauge is used to check or measure the outside diameter of a roll. The object to be checked is place

Advantages And Disadvantages Of Air Refrigeration System :

Advantages Of Air Refrigeration : 1. The refrigerant used namely air is cheap and easily available. 2. There is no danger of fire or toxic effects due to leakages. 3. The weight to ton of refrigeration ratio is less as compared to other systems. Disadvantages Of Air Refrigeration : 1. The quantity of Refrigerant used per ton of refrigeration is high as compared to other systems. 2. The COP of the system is very low. Therefore running cost is high. 3. The danger of frosting at the expander valves is more as the air contains moisture content.

Mechinopedia For Mechanical Engineers

Search This Blog