From UPSC perspective, the following things are important :
Prelims level : Background Radiation
Mains level : Not Much
Central idea: The article discusses a pan-India study conducted by scientists at the Bhabha Atomic Research Centre (BARC) which found that background radiation levels in parts of Kerala are nearly three times more than what’s been assumed.
What is Background Radiation?
- Background radiation is a measure of the level of ionizing radiation present in the environment at a particular location which is not due to deliberate introduction of radiation sources.
- Background radiation originates from a variety of sources, both natural and artificial.
Nuclear Radiation and its Types
There are three main types of nuclear radiation: alpha particles, beta particles, and gamma rays.
1. Alpha particles are made up of two protons and two neutrons and are essentially helium nuclei. They have a positive charge and are relatively large and heavy, which means they can be stopped by a piece of paper or the outer layer of skin.
2. Beta particles are high-energy electrons that are emitted from the nucleus of an atom. They have a negative charge and are much smaller than alpha particles, which means they can penetrate through the skin and into the body.
3. Gamma rays are high-energy electromagnetic radiation, similar to X-rays. They are emitted from the nucleus of an atom and have no charge. They are extremely penetrating and can travel long distances through air and most materials, including the human body.
How is it measured?
- The International Atomic Energy Agency (IAEA) specifies maximum radiation exposure levels and this has also been adopted by India’s atomic energy establishment.
- Public exposure shouldn’t exceed 1 milli-Sievert every year, those who work in plants or are by virtue of their occupation shouldn’t be exposed to over 30 milli-Sievert every year.
- Generally it is measured in nanogray per second. A (nGy/s) is a decimal fraction of the SI-derived unit of ionizing radiation absorbed dose rate.
- Cosmic radiation
- Environmental radioactivity from naturally occurring radioactive materials (such as radon and radium)
- Medical X-rays,
- Fallout from nuclear weapons testing and nuclear accidents.
Factors affecting such radiation
- Natural background radiation is all around us.
- Background radiation varies from place to place and over time, depending on the amount of naturally occurring radioactive elements in soil, water and air.
- Weather conditions also affect radiation levels, as snow cover may shield these elements, and radioactive particulates can wash out of the air during rain storms.
- Cosmic radiation from the sun, our galaxy, and beyond is constantly around us and contributes to natural background radiation.
- Altitude and latitude can also influence the level of background radiation at any one site.
How threatening is it?
- All rocks and soils contain some trace amount of natural radioactivity and can sometimes be ingested or inhaled if disturbed.
- Radon is a gas that can concentrate indoors and be inhaled, along with its decay products.
- We can also ingest radioactivity from the food we eat and the water we drink.
- A number of factors determine the annual dose you and your family receive from background radiation.
- Typically, Gamma rays are a type of such radiation that can pass through matter unobstructed, and are harmless in small doses, but can be dangerous in concentrated bursts.
Findings of the BARC Study
- The study found that the average natural background levels of gamma radiation in India was 94 nGy/hr (nano Gray per hour) (or roughly 0.8 millisievert/year).
- The last study conducted in 1986 computed such radiation to be 89 nGy/hr.
- The study found that the levels in Kollam district, Kerala were 9,562 nGy/hr, or about three times more than what was assumed.
- This computes to about 70 milliGray a year, or a little more than what a worker in a nuclear plant is exposed to.
- This however does not necessarily mean that those at Kollam are being exposed to dangerous levels of radiation, as past studies have not found any higher rates of cancer or mortality.
Reasons for Higher Radiation Levels in Kerala
- The higher radiation levels in Kollam are attributed to monazite sands that are high in thorium, which is part of India’s long-term plan to sustainably produce nuclear fuel.
- Southern India has higher levels of radiation due to the presence of granite and basaltic, volcanic rock, which contains uranium deposits.