Remote sensing for flow induced vibrations in the PARR-1 core assembly

Reactor core vibrations of the Pakistan Research Reactor-1 (PARR-1) have been investigated using remote technique and mechanical accelerometers. The signals taken from the reactor core grid plate and at the support structure have been compared to find out the damping. For remote sensing technique, a 1 mW He-Ne laser has been used to detect the vibration signal reflected from the mirror fixed at the dummy fuel assembly on a grid plate. In comparison with the vibrations at the core and at the support structure, it was observed that the vibrations were damped by a factor of 38%.