Jeffrey LewisThe Bomb, Dmitry. The Hydrogen Bomb.

Did India successfully test a two-stage thermonuclear device in May 1998?

There are substantial reasons for skepticism. India claimed that it detonated three devices on 11 May 1998 at Pokhran (right)—a 43-kiloton thermonuclear explosion, a 12-kiloton fission explosion and a 0.2-kiloton fission explosion. (India then claims to have conducted low yield tests on 13 May 1998.)

Seismic analyses (particularly Wallace et al) conclude the cumulative yield for the 11 May tests was only 12-kilotons. A yield that low is probably “too small to have been a full test of a thermonuclear weapon”—suggesting the test fizzled.

The US intelligence community reportedly shares this conclusion. Govenment officials told Mark Hibbs of Nucleonics Week that analysts from Livermore’s Z Division “have now concluded that the second stage of a two-stage Indian hydrogen bomb device failed to ignite as planned.” Subsequently, “senior U.S. expert” confirmed to Hibbs that this account was correct.

Indian scientists have been quick to dispute these estimates, arguing that Western scientists have made inaccurate assumptions about the geography of the Indian test site. This argument has always struck me as unconvincing, in part because of data that has been presented from the 1974 test.

A former chairman of India’s Atomic Energy Commission, PK Iyengar, has used calculations similar to those of Wallace et al to suggest that the second stage of the two-stage thermonuclear weapon failed to ignite—“the fusion core burnt only partially, perhaps less than 10 per cent.” Iyengar, however, has an axe to grind—he wants India to resume nuclear testing.

Such failures have plagued new nuclear designers before. China’s seventh nuclear test (CHICOM 7)—and second thermonuclear weapon—also fizzled, resulting in a yield estimated at the time between 15-25 KT.

Similarly, Livermore’s first attempt at “super” also failed—resulting from what Herb York called “a simple design flaw … engendered by the novelty of the technology and by our inexperience.”


Brian Barker et al, “Monitoring Nuclear Tests,” Science 281:5385 (25 September 25, 1998) 1967-68 (subscription).

Mark Hibbs,”India May Test Again Because H-Bomb Failed, U.S. Believes,” Nucleonics Week 39:48 (26 November 1998) 1.

Mark Hibbs, “Because H-Bomb Fuel Didn’t Burn, Iyengar Pleads For Second Test,” Nucleonics Week (1 June 2000) 6.

PK Iyengar, “Nuclear Nuances,” The Times of India (22 August 2000).

SK Sikka et al,”The recent Indian Nuclear Tests: A Seismic Overview,” Current Science 79:9 (10 November 2000) 1359-1366 (draft).

Gregory van der Vink et al, “False Accusations, Undetected Tests and Implications for the CTB Treaty,” Arms Control Today 28:4 (May 1998) 7-13).

Terry C. Wallace, “The May 1998 India and Pakistan Nuclear Tests,” Seismological Research Letters 69 (September 1998) 386-393 (preprint).]

Herbert York, Making Weapons, Talking Peace: A Physicist’s Odyssey from Hiroshima to Geneva (Basic Books, 1987) 78.