October 12,1998
|
|
|
|
NUCLEAR TESTS Is India's H-Bomb a Dud? New research by western scientists contest India's claims of successfully testing an H-bomb. Are they right? By Raj Chengappa
Four months down the line, the more urgent task is how to minimise the international fallout over the tests and get on with the business of managing a sputtering economy. The last thing India needs is another nuclear controversy to explode. But a report, innocuously titled "Monitoring Nuclear Tests", that appeared in the September 25 issue of Science, a reputed US journal, threatens to puncture the euphoria over India's tests and seriously damage its scientists' credibility. Based on records of 36 seismic stations across the globe, 19 researchers drawn from seven established US scientific institutions have come up with some disturbing conclusions about India's nuclear tests. The Indian scientists had claimed that the total yield of their five tests was 58 kilotonnes (one kilotonne is the explosive energy equivalent of 1,000 kt of TNT) and the yield of the H-bomb alone was 45 kt. But the Science report puts the combined yield of India's tests at a low 9-16 kt -- about one-fourth of the Indian estimate. The report also finds the yields much lower than that claimed for the two sub-kilotonne tests India conducted on May 13. In fact, most seismic recorders didn't even pick up the signals.
The implication, as Terry Wallace, professor of geophysics at the University of Arizona and one of the authors, puts it, "Conventional wisdom is that a yield of 10-15 kt would be too small to have been a full test for a thermonuclear weapon." Crudely put, India's H-bomb test may have been a fizzle. If it was any consolation to Indian scientists, the report belittles the Pakistani tests too. It pegs down the yield of the six nuclear tests conducted by Pakistan on May 28 and 30 from the claimed 60 kt to 16 kt. Although reports based on seismic waves caused by nuclear explosions are not considered conclusive evidence for yield estimates, experts say they do provide definite clues. Given the enormous force of a nuclear explosion, there are only a few reliable ways of estimating yields. The shockwaves from such an explosion travel deep underground and can be detected by special seismographs set up in any part of the globe. By measuring the velocity of the wave and its acceleration and using a logarithmic formula scientists are able to estimate yields with some confidence. That is why experts are taking serious note of the yields from the Indian tests. Says Peter Marshall, a London-based seismologist and chairman of the expert group of monitoring explosions under the Comprehensive Test Ban Treaty (CTBT): "I can't disagree with the assessment that the yields were less than what the Indian scientists stated. Our initial findings also indicate it. But it is too early to be definite." One reason: error margins could be as much as 50 per cent. But that would still put the Indian yields only at 30 kt or half the amount claimed. Others were not so cautious. In Washington DC, Christopher Paine, co-director (nuclear programme) of the Natural Resources Defence Council, charged the Indian team with making false claims, saying, "One explanation for such low yields is that while the fission (atomic) bombs worked, the thermonuclear one didn't." |
|
|
Issue Contents | Write to us | Subscriptions | Syndication BUSINESS TODAY | INDIA TODAY PLUS | COMPUTERS TODAY © Living Media India Ltd |
 |
 |
The H-bomb, quite simply, is the acme
of nuclear weapons technology. Naturally Indian scientists -- who conducted a stunning
five nuclear tests in May 1998 -- regarded the detonation of an H-bomb as their crowning
glory. It proved that they had not gone into a deep technological slumber in the 24 years
since they first exploded an atom bomb in 1974. A visibly proud Prime Minister A.B.
Vajpayee said after the tests: "We now have the capacity to make a big bomb." In
the game of blastmanship that followed in the subcontinent, India's H-bomb would put it
way ahead of Pakistan. 
