Smiling Buddha (MEA designation: Pokhran-I) was the code name of India's first successful nuclear weapon test on 18 May 1974. The nuclear fission bomb was detonated in the Pokhran Test Range of the Indian Army in Rajasthan. As per the United States military intelligence, the operation was named as Happy Krishna. The Indian Ministry of External Affairs (MEA) described the test as a peaceful nuclear explosion.

The bomb was built by scientists at the Bhabha Atomic Research Centre (BARC), in assistance with the Defence Research and Development Organisation (DRDO) headed by B. D. Nag Chaudhuri under the supervision of the Atomic Energy Commission headed by Homi Sethna. A CIRUS nuclear reactor given by Canada and heavy water (used as a neutron moderator) supplied by the United States were used in the production of nuclear material for the bomb. The preparations for the test and the detonation was conducted in extreme secrecy. It was tightly controlled by prime minister Indira Gandhi with very few people outside the team of scientists being aware of the test.

The device was of the implosion-type design with a plutonium core. It had a hexagonal cross section, in diameter, and weighed . It was assembled, mounted on a hexagonal metal tripod, and was transported to the test site on rails. The test was conducted at 8.05 IST on 18 May 1974. The data on the exact nuclear yield of the test has been varied and scarce, and sources indicate that the bomb might have yielded between six and ten kilotons.

It was the first confirmed nuclear weapons test by a nation outside the five permanent members of the United Nations Security Council. The test led to the formation of the Nuclear Suppliers Group (NSG) to control nuclear proliferation. After the test, India carried out a series of nuclear tests named Pokhran-II in 1998.

Background

The origins of India's nuclear programme can be traced back to 1945 when Homi Bhabha established the Tata Institute of Fundamental Research with the aid of Tata Group. After Indian independence, the Atomic Energy Act was passed on 15 April 1948, that established the Indian Atomic Energy Commission (IAEC). India was involved in the development of the Nuclear Non-Proliferation Treaty, but ultimately did not sign it. In 1954, Department of Atomic Energy (DAE) was established which was responsible for the atomic energy development programme and was allocated a significant amount of the defence budget in the subsequent years. In 1956, the first nuclear reactor named APSARA became operational at Trombay, becoming the first operating reactor in Asia. A CIRUS reactor was given to India as a part of an understanding with Canada and the United States under the Atoms for Peace programme. India set up an indigenous programme to manufacture uranium nuclear fuel for the reactor, as opposed to importing from other countries. In 1962, India was engaged in a war with China and with China pursuing its own atomic development programme, it accelerated India's need to develop nuclear weapons. The incoming prime minister Lal Bahadur Shastri gave approval for the Subterranean Nuclear Explosion Project in 1964 under Bhabha's insistence. However, Shastri did not want to commit to a weapons test yet, and later appointed physicist Vikram Sarabhai as the head of the nuclear programme. Because of Sarabhai's non-violent Gandhian beliefs, he directed the programme towards peaceful purposes rather than military development. Meanwhile, the design work on the bomb proceeded under physicist Raja Ramanna, who continued the nuclear weapons technology research after Bhabha's death in 1966. The weapons programme was directed towards the production of plutonium rather than uranium and then in 1969, enough plutonium had been accumulated for the production of a single nuclear bomb.

Simultaneous work on the fabrication of the bomb core and implosion design was conducted by teams led by physicist V. S. Ramamurthy. The detonation system development began in April 1970 with Pranab R. Dastidar collaborating with W. D. Patwardhan at the High Energy Materials Research Laboratory (ERDL) of the Defence Research and Development Organisation (DRDO). In July, physicist B. D. Nagchaudhuri was appointed as the scientific adviser to the Defense Minister and as Director of the DRDO. The preparations were carried by civilian scientists assisted by the Indian Army. Indira Gandhi maintained tight control of all aspects of the preparations of the test, which was conducted in extreme secrecy. Besides Gandhi, only her advisers Parmeshwar Haksar and D. P. Dhar were kept informed. Dhar had protested the test, fearing that the sanctions that would follow, would affect the Indian economy. General G. G. Bewoor, Indian army chief, and Lieutenant-General T. N. Raina, the commander of Indian Western Command were the only military commanders who knew about the test.

The nuclear yield of the test has been difficult to determine with unclear data provided by Indian sources. Although politicians had given multiple numbers ranging from 2 kt to 20 kt, the official yield was initially set at 12 kt. Independent seismic data from outside and analysis of the crater features indicated a lower figure. Analysts estimate the yield at 4 to 6 kt, using conventional seismic magnitude-to-yield conversion formulas. Later, both Sethna and Iyengar conceded the official yield to be an exaggeration. Iyengar has stated that the yield was 8–10 kt, that the device was designed to yield 10 kt, and that the yield was 8 kt "exactly as predicted".

Weapon design

thumb|An [[Nuclear weapon design#Implosion-type weapon|implosion-type nuclear weapon]]

The device was of the implosion-type design with a plutonium core, similar to Fat Man, the American nuclear bomb detonated over Nagasaki in 1945. The implosion system was assembled at the TBRL of the DRDO in Chandigarh. The detonation system was developed at the HEMRL of the DRDO in Pune.

Reactions

Domestic reaction

Indian Prime Minister Indira Gandhi gained much popularity after the test, which had flagged from its heights after the 1971 war with Pakistan. The overall popularity and image of the Congress Party was enhanced and it was well received in the Indian Parliament. In 1975, Sethna, Ramanna and Nagchaudhuri were honoured with the Padma Vibhushan, India's second highest civilian award. Five other project members received the Padma Shri, India's fourth highest civilian award. India consistently maintained that this was a peaceful nuclear bomb test and that it had no intentions of militarising its nuclear programme, but according to independent monitors, this test was part of an accelerated Indian nuclear programme. In 1997 Raja Ramanna, speaking to the Press Trust of India, maintained: