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Surveys show no radioactivity at Pokhran, says BARC

The Bhabha Atomic Research Centre says no radioactivity was released from the five nuclear tests conducted last month at the Pokhran range in Rajasthan.

BARC, in its latest report on nuclear tests, said extensive radioactive surveys, both ground-based and air-borne, were carried out before and after the events, and in all the cases no increase in radiation levels was observed.

The yield of the thermonuclear device was chosen so that the seismic damage to surrounding villages (the nearest one was five km away) was minimal, the report on preliminary results of the tests, said. The depths of emplacements were fixed so that the explosions were contained with no radioactive venting, the report said, adding that "we were guided here by our past experience at Pok-1, backed by computer simulations of past shot phenomenology of these events".

Close-in array accelerementers and geophones spanned distances up to four km from surface ground zeroes, while the stand-alone stations were deployed between one km and 10 km. The report also gave details of vertical ground acceleration and velocity profiles at various distances from surface ground zero of tests one and two conducted on May 11.

The report said test two resulted in a crater while test one produced a sand mound, and ''this was as expected from our pre-shot rock mechanics computer simulations, as also from depth considerations and different geology of the two shafts (test one was in harder rock and buries deeper)''.

Fortyfive national seismological observatories gave body waves between five and 5.4 magnitude and for these body wave magnitudes, the yield of May 11 explosions is bracketed in the range of 40 to 70 kiloton.

However, the report said the International Data Centre at Arlington, USA, had classified India's nuclear explosions as an earthquake of 4.7 at a depth of 56 km, and this misclassification is due to the complexity of the source.

After the announcement of the tests, IDC has revised the magnitude to five with zero depth, the report said.

Meanwhile, the Anubam Virodhi Andolan, in a statement, said that ''there are already signs of radiation sickness in the villages around Pokhran range after the nuclear tests last month."

UNI

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