BACKGROUND
RADIATION - ENVIRONMENT
News:
Background radiation high
in Kerala, but no risk, says study
What's
in the news?
●
A pan-India study by scientists at the
Bhabha Atomic Research Centre (BARC) has found that in the parts of Kerala, background
radiation levels, or that emitted from natural sources such as rocks, sand or
mountains, are nearly three times more than what’s been assumed.
Key
takeaways:
●
In Southern India, because of the presence
of granite and basaltic, volcanic rock
has higher levels of radiation from uranium deposits.
●
The higher radiation levels in Kollam are
attributed to monazite sands that are high in thorium, and this for many years,
is part of India’s long-term plan to sustainably produce nuclear fuel.
Background
radiation:
●
Background radiation is the radiation that our environment is always
exposed to.
Types
of Background Radiation:
There are two kinds of
background radiations such as
●
Natural
Radiation: These are the radiations that originate due to the
radioactive materials present on earth.
●
Cosmic
Radiation: These are the radiations that come from the sun,
stars, and other celestial bodies by penetrating our earth's atmosphere.
How
does radiation occur on Earth?
●
Radiation results from the disintegrating nucleus of an unstable
element and these can be from anywhere, including from inside our bodies to
the constituents of matter.
●
Example:
Gamma rays are a kind of radiation that can pass unobstructed through matter.
Though extremely energetic, they are harmless unless present in large
concentrated doses.
Limits
set by IAEA:
●
Around nuclear plants, gamma radiation
levels are monitored as also the average quantity of radiation that plant
workers are exposed to.
●
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.
Important
findings from the present study:
●
The present study found that average
natural background levels of gamma radiation in India was 94 nGy/hr (nano Gray
per hour) (or roughly 0.8 milli sievert/year).
●
The last such study, conducted in 1986,
computed such radiation to be 89 nGy/hr.
1 Gray is equivalent to 1 Sievert, though one unit refers to radiation
emitted and the other to biological exposure.
●
Low values (around 67 nGy/h) of absorbed
dose rate in air were recorded for mixed red and black soils of Maharashtra and
Gujarat while high values of (around 170 nGy/h) were recorded in the
west-coastal plains of Kerala containing coastal and derived deltaic alluvial
soils.