Yes, Virginia, India’s H-bomb fizzled.

K Santhanam (who was director of test site preparations for India’s 1998 nuclear tests; pictured above, handing the firing keys to the range safety officer) has admitted what everyone else has known for a long time — that India’s 1998 test of a thermonuclear device was unsuccessful:

“Based upon the seismic measurements and expert opinion from world over, it is clear that the yield in the thermonuclear device test was much lower than what was claimed. I think it is well documented and that is why I assert that India should not rush into signing the CTBT,’‘ Santhanam told [the Times of India] on Wednesday.


Sources said that Santhanam had admitted that the test was a fizzle during a discussion on CTBT organised by IDSA. Karnad also participated in the seminar. He told TOI that no country has succeeded in achieving targets with only its first test of a thermonuclear device.

“Two things are clear; that India should not sign CTBT and that it needs more thermonuclear device tests,’‘ said Santhanam.

This is a subject we have covered in some detail here at Arms Control (see The Bomb, Dmitry. The Hydrogen Bomb, 10 April 2005.)

1. Yes, India’s thermonuclear device probably probably did fizzle, looking at the seismic data.

2. Some Indian scientists, including the former chairman of India’s Atomic Energy Commission PK Iyengar and now Santhanam, keep pointing out this somewhat embarrassing fact because it is part of an argument for India to resume nuclear testing.

3. India’s evident need to resume testing to complete development of a thermonuclear device is the principal reason that I opposed a “clean” NSG exemption for India (See: Will India Test Again?, 23 June 2008 ).

Here is my original post on the subject, reproduced because I am lazy and I recall the reading list was somewhat helpful:

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) (full text in the comments).

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.