The Smiling Buddha was the first nuclear test explosion by India on 18 May 1974 at Pokhran. It was also the first confirmed nuclear test by a nation outside the five permanent members of the United Nations Security Council having been developed and executed with no foreign help or assistance. Smiling Buddha was a crude nuclear device with a yield of not more than 8Kt.
On 7 September 1972, Prime Minister Indira Gandhi gave verbal authorization to the scientists at the Bhabha Atomic Research Centre (BARC) to manufacture the nuclear device they had designed and prepare it for a test. Throughout its development, the device was formally called the "Peaceful Nuclear Explosive", but it was usually referred to as the Smiling Buddha.
The head of the development team was Dr. Raja Ramanna. Other key personnel included Dr. P.K. Iyengar, Dr. Rajagopala Chidambaram,Dr. Nagapattinam Sambasiva Venkatesan and Dr. Waman Dattatreya Patwardhan under the supervision of Dr. Homi N. Sethna. The project employed no more than 75 scientists and engineers from 1967-1974. Keeping it small served to aid in the preservation of secrecy, according to the researcher Jeffrey Richelson.
The device used a high explosive implosion system developed at the DRDO Terminal Ballistics Research Laboratory (TBRL) in Chandigarh based on the American design from World War II.The detonation system of the implosion devices was developed at the High Energy Materials Research Laboratory (HEMRL) of DRDO at Pune. The 6 kg of plutonium came from the CIRUS reactor at BARC. The neutron initiator was a polonium-beryllium type (again like those used in early U.S. bombs of the Fat Man type) code-named "Flower." The complete core was assembled in Trombay before transportation to the test site.
The fully assembled device had a hexagonal cross section, 1.25 m in diameter and weighed 1400 kg. The device was detonated at 8.05 a.m. in a shaft 107 m under the army Pokhran test range in the Thar Desert (or Great Indian Desert), Rajasthan. Coordinates of the crater are 27.095; 71.753. Officially the yield was reported at 12 kt, though outside estimates of the yield vary from 2 kt to 20 kt.
The yield of the PNE has also remained controversial. Although occasional press reports have given ranges all the way up to 20 kt, and as low as 2 kt, the official yield was set early on at 12 kt (post Operation Shakti claims have raised it to 13 kt). Outside seismic data, and analysis of the crater features indicates a lower figure. Analysts usually estimate the yield at 4 to 6 kt using conventional seismic magnitude-to-yield conversion formulas. In recent years both Homi Sethna and P.K. Iyengar have conceded that the official yield is an exaggeration. Iyengar has variously stated that the yield was actually 8-10 kt, that the device was designed to yield 10 kt, and that the yield was 8 kt 'exactly as predicted'. Careful analysis of hard rock cratering effects establishes a tight bound around 8 kt for the yield however