Pune blasts: Old ammonium nitrate may have reduced intensity

The crude bombs that exploded on Pune's Jangli Maharaj Road on Wednesday contained a creamy emulsion gel believed to be commercial ammonium nitrate and had clock timers to trigger the detonators. The intensity of the explosions was, however, not high as the bombs did not contain a powerful booster explosive like RDX and the ammonium nitrate was possibly old, forensic sources said on Thursday.

Investigators had found from the two unexploded bombs that were defused that they were built into a boat-shaped wooden case, a method of bomb-making seen in blasts elsewhere in the country. The case is designed to direct the force of explosion in one direction to inflict damage.

"This makes the blast cause an impact in a specific direction. Ball bearings were placed to cause injuries. But the circuit has only caused the detonators to explode and so all the main charges at all the places have not exploded," said an expert from the CRPF's Institute of IED Management in Talegaon which investigators consulted.

The damage, however, was largely contained as the ammonium nitrate is suspected to have been from old stock. Commercial ammonium nitrate has a shelf-life of three months and is further known to lose its capabilities in humid weather, other forensic experts said.

The bombs were unique in their use of three detonators — similar bombs used in the past depended on two. "The circuit shows an expert mind as two power supplies have been used. This was to ensure that if one source of energy falters, a standby source can be used," said an officer. "But so far, terror groups have not gone beyond using two detonators. This one had three."

The three detonators did not explode in none of the four blasts, investigators are questioning why the detonators were connected "in series" to power sources— another cause that may have contributed to the ammonium nitrate just burning and not exploding.

... contd.

ALSO READ

Not bound by EWS quota, these schools still fill it

German Bakery back in business, silently

Apex court rejects petition, traders to continue stir

NDA vice-principal resigns, says nothing to do with row