The systems have been in continuous operation since they were installed but thankfully, they have never been needed. The new systems being installed across the fleet, incorporate the latest Sonardyne Wideband technology which provides a superior acoustic link.

BNFL originally commissioned Sonardyne to design an acoustic system that would enable a sunken ship to be relocated from a safe distance and for the condition of its radioactive cargo to be monitored before any salvage attempt is made.

Sonardyne supplied each ship with four custom engineered acoustic transponder modems interfaced to two Data Acquisition Units (DAUs). The transponders were located on the fore, aft and port and starboard superstructure of each ship so that there would be a clear acoustic transmission path to the surface from at least one transponder regardless of the ship’s final resting position.

Each DAU has internal pitch, roll and depth sensors and is also connected to radiation and hatch cover sensors in each hold. The data provided by the sensors is transmitted acoustically and provides a clear picture of the condition of the ship before it is approached.

The Pacific Sandpiper was the first vessel to be equipped with the Sonardyne system in August 1985 and it has just become the latest to be upgraded. The original equipment has now been replaced with the latest Wideband technology which provides faster and more robust acoustic communications. It also includes new, easy to use operating software that enables the crew to test the system before each voyage and to monitor it while at sea.

Commenting on the refurbishment programme, Ian MacDonald, project head for Sonardyne said, 'We are delighted with the performance and reliability of the first generation of equipment supplied to BNFL. The transponders have remained fully operational despite being exposed to the elements on deck for over two decades. By upgrading to Wideband, the Sonardyne systems will provide many more years of dependable service for our customer, International Nuclear Services Ltd.'