May 18(Today), 1974 - The day Buddha smiled

Indian Prime Minister Indira Gandhi at the Indian nuclear test site in Pokhran.

The Smiling Buddha was the first nuclear test explosion by India on May 18, 1974 at Pokhran. It was also the first confirmed nuclear test by a nation outside the permanent five members of the Security Council.

On September 7, 1972, Prime Minister Indira Gandhi gave 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 Raja Ramanna. Other key members were P.K. Iyengar, Rajagopala Chidambaram, and Nagapattinam Sambasiva Venkatesan. 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. But the Indian design was simpler and less sophisticated than the American system. 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. Officially the yield was reported at 12 kt, though outside estimates of the yield vary from 2 kt to 20 kt.

Code name:

Smiling Buddha was the code-name of the project because May 18, 1974 (the official test date) was Buddha Jayanti, a festival day in India marking the birth of Gautama Buddha.

The then-PM Indira Gandhi was not present at Pokhran so as to keep this operation confidential until the last minute. In her full cabinet, only her NSA and private secretary knew about it.

On May 18, 1974, when the blast occurred successfully, Dr Ramanna wanted to tell this news to the Prime Minister, who was miles away in Delhi. The hotline was not working, so he went to a nearby village and called her from an ordinary landline and said "Madam, Buddha has finally smiled."