Question

NONEL is used as down-the-hole initiator to

• A. avoid generation of air overpressure.
• B. provide precise delay.
• C. avoid deflagration of column charge.
• D. reduce ground vibration.

Hint:

NONEL systems are preferred for their immunity to electrical hazards, making down-the-hole initiation safer and more controlled.

Answer 1

The Correct Option is C

NONEL (Non-electric detonator) uses a plastic shock tube system to transmit an initiation signal through a low-energy shock wave. As a down-the-hole initiator, its main purpose is to safely initiate the primer without igniting the main explosive column prematurely.
If the primer accidentally ignites the column charge before proper confinement, deflagration may occur—an uncontrolled burning instead of a proper detonation. NONEL prevents this because:
1. It is immune to stray electrical currents.
2. It eliminates risks caused by static electricity, radio frequency, and electrical leakage.
3. It provides safe, controlled transfer of the initiation impulse only when required.
Thus, NONEL's chief purpose in this context is to prevent early ignition or deflagration of the column charge during priming.