radiometric surveying- final.pptx

7/29/2019 Radiometric Surveying- Final.pptx

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Surveying for the acquisition of radioactive

minerals, using their radioactive properties of

radiation emission.

Radiometric Surveying



Characteristics:•Shallow method.

•Success rate depends upon rock

exposure (99% gamma radiations areattenuated by 35-40 cm of soil)

•Survey planning is the same as gravity

and magnetic method.

Radiometric Surveying



Air-borne Radiometric Surveying




•These are done before pursuing a groundradiometric survey.

• Scintillation counters or gamma-ray detectors are

mounted on an aircraft flying 80m above theground.

• Flight lines are spaced 1-5 km apart forreconnaissance surveys and 250 - 5000 m fordetailed surveys.



Radiometric Airborne Surveying




•The helicopter flies at speeds of 50 m/s (90knots), recording a sample every 30-60 m alongthe flight path.

•

These anomalies are later used for ground follow-up surveys .



Ground Radiometric Surveying




• Once an anomaly is identified using airborne

methods, a hand-held or jeep mounted

scintillometer or GM counter is used for detail

surveys.• The most common procedure is to walk over the

terrain while listening to the counts on

earphones or watching the dial of the counter.

• Ground radiometric surveys are most effective

where rock exposures are available.




Radiometric ground surveying



• This spectrum has peaks corresponding to the

presence of potassium, thorium and uranium. The

heights of the peaks relate to the number of

gamma rays recorded (in counts per second), and

the horizontal axis relates to the energy of the

gamma rays (high energy at left and low energy at

right).



Exploratory drilling

• Once an anomaly has been deciphered with

a fair level of confidence, it is explored by

drilling.

• The borehole samples are then studied in

the lab to determine the ore mineralogy.



Applications of Radioactive

method




method• Exploration of radioactive minerals.

• Exploration of petroleum.

• Delineating Faults and Fractures: Radon leakage.

• Geological mapping.

• Useful in Agriculture: in mapping different soiltypes.




method• Monitoring the natural radioactivity at reactor

sites.

•

Identification of radioactive industrial waste.

• Assessment of slope stability (which are oftenassociated with fractures and groundwater flow) .

• Contamination in soil from leakage from nuclearreactors.



Advantages of Radioactive

method

• Only method by which radioactive mineral

exploration can be done accurately.

• Easy method.

• Has a lot of applications apart from

exploration of radioactive minerals



Disadvantages of Radioactive

method

• Shallow method.

• Cannot be applied for anomalies below 35-

40 cm of soil.

• Does not tell us the specifications of

anomaly.



QUESTIONS

radiometric surveying- final.pptx

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