Other IndexMountain RescueRecruitment 1957


Field Organisation
Quality Assurance
Touche Ross
WARC Project
Web Site


Call Signs
Civil Defence
Job Card System
Mountain Rescue
Recruitment 1957


Download a PDF copy of DTELS Radiac Work and Responsibilities

 DTELS Radiac work
and responsibilities
(250 Kb)

Directorate of Telecommunications

One of the lesser known aspects of communications work undertaken by the Directorate was to provide maintenance and engineering support to Radiac (Radioactivity, Detection, Indication, and Computation) users.

In February 2008, Alan Wood kindly sent me papers describing the work and responsibilities of the Radiac Section, written in 1989, at a time when DTELS was being prepared for the commercial world and the future scale of its traditional Radiac work was uncertain because of the reduction in east/west international tension.

He also included some relevant comments in his e-mails as set out below:

From Alan Wood 19/02/2008

Alan Wood for the AWDREY and e-mail comments plus documents in the download file. The contents are Crown Copyright.

page updated: 04/02/20

Atomic Weapon Detection Recognition and Estimation of Yield (AWDREY) System

The equipment known as AWDREY was designed and built at Aldermaston by the Atomic Weapon Research Establishment (AWRE) and first went into service in 1968 as an integral part of the early warning system employed by the United Kingdom Warning and Monitoring Organisation (UKWMO).

AWDREY was installed at 13 Royal Observer Corp (ROC) group control sites to provide effective warning of nuclear bursts and radioactive fallout intensities. The ROC provided the field force for UKWMO and operated a chain of monitoring posts throughout the United Kingdom.

The AWDREY systems located in England, Wales and Northern Ireland were maintained by DTELS and those in Scotland by the Scottish Office Directorate of Telecommunications.

Each system consisted of 4 units, a sensor head mounted on the roof of the bunker, a main unit with separate no-break mains supply located in equipment room, and a desk unit installed in the operations room. The electromagnetic and optical sensors were capable of detecting a nuclear burst over a minimum 100km range. Discriminatory circuits within the main unit confirmed an ‘event’ when both a nuclear electromagnetic pulse (NEMP) and optical emission signature had been detected and verified as a genuine weapon burst signal. The display desk unit generated an alarm, measured the time interval between the verified pulses and provided the ‘event’ data. An estimate of yield could then be determined using a conversion table.

On 10th July 1991, in a review of civil defence and emergency planning, the Home Secretary announced a restructuring of arrangements for the monitoring of nuclear bursts and radioactive fallout. In consequence the ROC was stood down in September 1991 and plans were made to relocate the AWDREY systems to Regional Government Headquarter (RGHQ) sites.

At this time AWDREY was upgraded with a new NEMP protected desk unit, comprising a real time clock, millisecond timer, audible alarm and integral printer. Provision was also made for the remote presentation of ‘event’ data by means of a fibre optic serial data port.

In 1992/93, following the end of the cold war and consequent reduction in international tension, the decision was made to de-commission all RGHQ sites. Arrangements were therefore made to recover the AWDREY equipment to store where it remained for many years pending disposal.

Alan Wood
19th February 2008

Site Contributers and