Post-shot analysis has confirmed the yield of about 60 kilo tons originally estimated by the AEC, he told members of the Indian Science Writers' Association (ISWA). He, however, said the data will not be released as it contained information about the design and the material used, which is classified.

Chidambaram said the thermonuclear bomb tested consisted of a fusion-fission-fusion system of which a boosted fission device was a part without having to test it separately. He revealed that most nuclear weapon powers had gone through the traditional path of separately testing a boosted fission device.

Chidambaram said there was no basis for doubts expressed by some analysts that India's six testsat Pokhran were not sufficient for it to qualify as a nuclear weapons state, as the United States had conducted 1030 tests and China 45.

The number of tests is related to the types of devices designed and tested. The design of devices is in turn based on knowledge of physics, materials science, engineering and electronics at that point of time, he clarified. The developed countries had to redesign some of their devices and abandon the older designs, he said.

India has acquired state-of-the-art in these areas and `so each of our tests should be considered equivalent to several carried out by other nuclear weapon states'.

Chidambaram explained that sustainable development of nuclear energy required exploitation of the thorium reserves in India and reprocessing the spent fuel discharged from uranium-fuelled power reactors.

He pointed out that India could claim to be a developed country only if the per capita energy consumption went up 8-10 times and a significant amount of this energy can come onlythrough nuclear power plants.

Four nuclear power reactors are under construction, including India's first 500-mega watt reactor at Tarapur and the aim is install a reactor with a capacity of 20,000 mega watt by the year 2020. About 50 per cent of this power will come from plants designed in India, the high-profile N-expert informed the gathering.