Page 238 - DCAP601_SIMULATION_AND_MODELING

Simulation and Modelling

Notes

Did u know? Markov Analysis

Markov analysis provides a means of analysing the reliability and availability of systems
whose components exhibit strong dependencies.

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Caselet Pokhran-II Revisited

n a recent interview with Karan Thapar, the former chief of the Atomic Energy
Commission, Dr Anil Kakodkar, reiterated the Principal Scientific Advisor to the
IGovernment, Dr R. Chidambaram’s stand on the success of Pokhran-II, but did not
really address any of the concerns raised about the efficacy of the thermonuclear test. Most
of the points he raised in a very general way have been dealt with before in a more
detailed technical manner.

Take, for example, the issue about the lack of a crater for the thermonuclear explosion. It
is true that if you bury such a device very deep, there will be a very small crater, or even
none at all. But no one associated with Pokhran-II has come out with a number for that
depth, though there is no secrecy needed here, as it reveals nothing about the design of the
device. In fact, for Pokhran-I, we had immediately revealed that the device was buried
107m deep.
Only K. Santhanam, former DRDO scientist, has revealed that the thermonuclear device
was buried at a depth of 130m, compared to the fission device’s 100m deep location. If
these numbers are correct, and no one has contradicted them, it is simply not credible to
say that such a small difference in the depth (only 30m) made such a huge difference in the
geology or in the crater size.

The repeated assertion that granite in the thermonuclear shaft was responsible for the
small crater is also difficult to understand. Usually, shock waves couple better to hard rock
and so the effect is expected to be larger. To muffle the explosion, one buries the device in
soft material like sand or in an empty cavity. The reverse assertion seems to be a new
advance in geology that the CTBT Organisation needs to take note of!
Puzzling Statements
Similarly, the statements on the simulations are puzzling. He brought out a new simulation
experiment, perhaps done after Dr Santhanam’s revelation. Using the borrowed data-base
of an underground nuclear explosion in Nevada, they claim to have simulated what
would have happened had the fission and fusion devices been interchanged between the
two shafts S1 and S2.

He revealed that the fission device would have shown no crater, and the fusion device a
much larger crater. This difference in the behaviour between the two sites, 1 km apart, and
at almost similar depths, 100 m and 130 m, as revealed by Dr Santhanam, is inexplicable.

Simulations can be tweaked to predict anything you want. Also, there is a huge gap
between simulating something and actually making it work in real life. Ultimately, there
is no escape from detailed experiments. The computer and the word ‘simulated’ have been
so extensively used by Dr Chidambaram and others that one wonders if there is any need
at all for testing and experimental work in a wide variety of scientific investigations!
Contd...

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