Uranium, thorium search in Kadapa basin

By Syed Akbar
Hyderabad: After beginning the process for mining uranium in the Nagarjunasagar belt, the city-based Atomic Minerals Directorate for Exploration and Research will search for uranium and thorium reserves in the Kadapa basin including its Kurnool sub-basin.
The Kadapa basin covers a major portion of Rayalaseema area, south of the river Krishna from Srisailam and extends beyond Pennar river. The exploration covers the basin along the Kurnool-Kadapa canal and parts of Kurnool and Kadapa districts including the Rajampet, Vempalle, Mulapalli, Kanampeta and Rachakuntapalle.
The Kadapa basin is rich in mineral wealth, particularly uranium and thorium reserves. The geology of the basin dates back to 2.5 billion years
and contains minerals like diamond (Kohinoor was found here), barite, asbestos, copper, lead, limestone and Kadapa slabs. About 25 per cent of the world’s barite resources are also present in this area.
The present study of uranium and thorium reserves in Kadapa basin gains significance in view of India's plans to generate about 20,000 MWe of nuclear power by 2020. Uranium reserves in the country have been dwindling and the country is now looking forward to thorium. Availability of uranium and thorium reserves in the Kadapa basin will boost the nuclear energy plans of the country with 14 nuclear reactors and nine under construction.
If everything goes on well with the uranium reserves in the Kadapa basin, Andhra Pradesh may emerge as the largest contributor of nuclear energy sources in the country. Mining of uranium has already begun in Nalgonda district.
The study will cover about 11,000 square km area of the 44,000 sq km Kadapa-Kurnool basin in Rayalaseema. To begin with AMD will take up testing of 900 km in a test block of 15 km by 15 km and on its successful completion, the remaining area will be released for survey at an estimated cost of Rs 5 crore. Multiparametre geophysical surveys using gamma and electromagnetic waves are useful in mineral exploration and bedrock mapping studies.
“There is a possibility of encountering a number of surprises in the metallogenic evaluation of the terrain when probed at greater depth than that is usually superficially perceived,” points out RM Sinha, additional director and VP Saxena, regional director, of AMD in their recent study paper.
Though Uranium exploration began in this area in late 1950’s to search for uranium, a proper scientific survey is yet to be taken up. Thorium reserves were found at Gulcheru. Subsequent exploration in late 1980’s also throw some light on signficant uranium reserves in the area.
A decade ago, uranium mineralisation was located in the Kadapa basin near Srisailam, thereby establishing in India for the first time the presence of unconformity related uranium mineralisation — a category considered most potential world over.
Earlier studies by the AMD recognised three distinct types of uranium mineralisation, strata bound, fracture controlled (both basement granite and sediment hosted) and unconformity-related type.