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Airborne
Surveys
The significance of airborne radiometric and
airborne magnetic (AM) surveys in prospecting for atomic minerals
was recognised by AMD as early as 1955 when the survey was undertaken
by hiring a Dakota aircraft with indigenously designed and fabricated
Total Count system on board. In 1972 the total count system
was replaced with in-house designed high sensitivity Airborne Gamma
Ray Spectrometer and Proton Precession Magnetometer fitted on the
hired Dakota aircraft.
The
continuous hardware
upgradation and refinement of the data acquisition, processing
and interpretation capabilities resulted in the development of
high sensitivity Notebook PC-based gamma ray spectrometer with
larger NaI (Tl) detector crystals. From 1997 till 2002, this unit,
interfaced with Cs-vapour magnetometer and Global Positioning System,
was flown by hiring Beechcraft B-200 aircraft of National Remote
Sensing Agency. The Flight line interval ranged from 500 to 2000
meters. 
In
2003 heliborne EM survey was carried out by outsourcing the operation
to NGRI (National
Geophysical Research Institute) with their instruments.
The flight line interval was 250 meters.
Calibration
pads as per IAEA standards
were constructed, at Nagpur airport for calibration of spectrometer
and calculation
of system sensitivities and stripping ratios. This is the only
facility in the entire southeast Asia. Two test strips of natural
terrain, located at Devarkonda, Nalgonda dist, Andhra Pradesh
and at Malharbodi, Bhandara dist., Maharashtra, were identified.
These are being used for the determination of height attenuation
coefficients for each of the radioelements and total gamma
radioactivity.
Digital
image processing techniques were customized to
generate images from the  airborne
geophysical (AGRS & AM) data as well as for enhancing georeference
images and integration of the derived information with other
data sets. Radioelemental and total magnetic intensity contour
maps and images are generated based on corrected and processed
data. These images are useful to study the distribution of
U, Th and K with respect to ground geology. A composite Ternary
image of K-Th-U by assigning R-G-B colours depicts better ground
geology and helps in refining geological maps particularly
in granitic terrain. The softwares used to generate outputs
are Golden Software Surfer, ERDAS Imagine, Ilwis and ENVI.
The
outputs are being utilised for atomic minerals exploration, in locating
uranium, beach and inland heavy mineral placer deposits, geological
mapping and environmental monitoring. Such surveys over Krishna-Godavari,
Cauvery and South Rewa Gondwana Basins were taken up, on contract,
for the Oil & Natural Gas Corporation in the Exploration of
hydrocarbons. Aero-radiometric surveys were also
carried out by AMD over Madras Atomic Power Plant (MAPP) at Kalpakkam
and Rajasthan Atomic Power Plant (RAPP) at Kota for monitoring
the environmental radiation.
AMD
has covered an area
of
about 5.365 lakh sq. km (till March 2004) by high sensitivity AGRS
and AM surveys. The contour maps, digital images and processed
data are available with AMD headquarters, Hyderabad. AMD dedicates
these efforts to those scientists, engineers and pilots, who while
exploring new horizons, did not return during 1962 & 1977
A catalogue
of AGRS survey data and maps prepared in
this regard are available at AMD headquarters, Hyderabad.
Remote
Sensing
The
organization has well equipped remote sensing laboratories with
opto- mechanical
instruments, digital image processing systems, scanners, printers,
plotters and expertise in processing, enhancements, Geo-referencing,
interpretation and thematic map generation.
The
remote sensing data inputs include B&W aerial photographs,
hard copies and transparencies of FCC satellite images and digital
data of various satellite sensors like IRS-WIFS, LISS-II, LISS-III,
PAN, LANDSAT-MSS, TM and SPOT-VHRR. Golden Software Surfer, ERDAS
Imagine, ILWIS and ENVI Softwares are used for the image generation
and enhancement. All the Regional Headquarters are equipped with
remote sensing laboratories.
Geographic
Information System
Spatial
database creation of atomic minerals exploration is being carried
out for data storage, retrieval, integration, analyses, thematic
map generation and target area identification. The spatial database
being created includes geological maps, lithostructural maps, AGRS & AM
contour maps and images, detailed ground uranium exploration maps,
litho-, pedo- and hydro-geochemical maps and enhanced satellite
images. The digital maps are stored in ArcView Shape file format
along with attribute data. The software used are ESRI ArcGIS
Desktop and Workstation, AutoCAD, Golden Software Surfer,
ERDAS and ENVI.
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