NEW DELHI — India is exploring the possibility of building a 65,000-ton nuclear-powered carrier as it gains confidence in its warship-making capability. The Indian navy is undertaking a detailed study on the size, type of aircraft, aircraft launch and recovery systems, and propulsion. “All options are being considered, including nuclear propulsion ... However, no final decision has been taken,” Navy Vice-Chief Adm. R.K. Dhowan says.