Atomic Weapons Detection Recognition and Estimation of Yield
Encyclopedia
Royal Observer Corps
The Royal Observer Corps was a civil defence organisation operating in the United Kingdom between 29 October 1925 and 31 December 1995, when the Corps' civilian volunteers were stood down....
(ROC) controls, across the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
, during the Cold War
Cold War
The Cold War was the continuing state from roughly 1946 to 1991 of political conflict, military tension, proxy wars, and economic competition between the Communist World—primarily the Soviet Union and its satellite states and allies—and the powers of the Western world, primarily the United States...
. The instruments would have detected any nuclear explosions and indicated the estimated size in megatons.
With the display unit mounted in a 3 foot (0.9144 m) steel cabinet, the system operated by measuring the level of Electromagnetic pulse
Electromagnetic pulse
An electromagnetic pulse is a burst of electromagnetic radiation. The abrupt pulse of electromagnetic radiation usually results from certain types of high energy explosions, especially a nuclear explosion, or from a suddenly fluctuating magnetic field...
(EMP) generated by any nuclear explosion. The instruments were in operation 24/7/365 between 1955 and 1992 and tested daily by full-time ROC officers.
AWDREY regularly reacted to the EMP from lightning strikes during thunderstorms. Additional AWDREY instruments were also installed at most of the Regional Government Heaquarters
Regional Seat of Government
Regional Seats of Government or RSGs were the best known aspect of Britain's Civil Defence preparations against Nuclear War. In fact, however, naming conventions changed over the years as strategies in Whitehall changed....
(RGHQs) and at UKRAOC at RAF High Wycombe
RAF High Wycombe
RAF High Wycombe is a Royal Air Force station, situated in the village of Walters Ash, near High Wycombe in Buckinghamshire, England. Its purpose is to serve the needs of the RAF Air Command, situated on the site. It is also the headquarters of the European Air Group...
Operations
AWDREY was designed, built and maintained by the Atomic Weapons EstablishmentAtomic Weapons Establishment
The Atomic Weapons Establishment is responsible for the design, manufacture and support of warheads for the United Kingdom's nuclear deterrent. AWE plc is responsible for the day-to-day operations of AWE...
at Aldermaston
Aldermaston
Aldermaston is a rural village, civil parish and electoral ward in Berkshire, South-East England. In the 2001 United Kingdom Census, the parish had a population of 927. The village is on the southern edge of the River Kennet flood plain, near the Hampshire county boundary...
and tested for performance and accuracy on real nuclear explosions at the 1957 Kiritimati (or Christmas Island)
Kiritimati
Kiritimati or Christmas Island is a Pacific Ocean raised coral atoll in the northern Line Islands, and part of the Republic of Kiribati....
nuclear bomb test (after being mounted on board a ship). Although a single AWDREY unit could not differentiate between the EMP from a nuclear explosion and a lightning strike, the units were installed sufficiently far apart that a lightning strike would not simultaneously register on two adjacent AWDREYs.
The first two primary responsibilities of the United Kingdom Warning and Monitoring Organisation
United Kingdom Warning and Monitoring Organisation
The United Kingdom Warning and Monitoring Organisation was a British civilian organisation operating between 1957 and 1992 to provide the authorities with data about nuclear explosions and forecasts of likely fallout profiles across the country in the event of war.The UKWMO was established and...
(UKWMO), for whom the ROC provided the field force were:
- Warning the public of any air attack. (see Four-minute warning )
- Providing confirmation of nuclear strike on the UK.
AWDREY was the principal method by which the UKWMO would achieve its second responsibility. Simultaneous responses on two or more AWDREY units would identify the explosion as a nuclear strike.
ROC post bomb detection instruments (see Bomb Power Indicator
Bomb Power Indicator
Bomb Power Indicator known by the acronym BPI was a detection instrument, located at the twenty five British Royal Observer Corps controls and nearly 1,000 ROC underground monitoring posts, across the United Kingdom, during the Cold War that would have detected any nuclear explosions and measured...
) operated by recording the pressure of the blast wave from any nearby nuclear explosion. Any ultra-high-altitude nuclear explosion, designed to knock out the UK's communications and electronic equipment would not produce a detectable blast wave, and the AWDREY system was therefore the only method of identifying these bursts.
Installation
The AWDREY installation consisted of three separate elements: the sensor, the detection unit and the display cabinet. The sensor was mounted on the roof of the building under a polycarbonatePolycarbonate
PolycarbonatePhysical PropertiesDensity 1.20–1.22 g/cm3Abbe number 34.0Refractive index 1.584–1.586FlammabilityV0-V2Limiting oxygen index25–27%Water absorption – Equilibrium0.16–0.35%Water absorption – over 24 hours0.1%...
protective cover. The detection unit was installed in a special room that was enclosed inside a Faraday cage
Faraday cage
A Faraday cage or Faraday shield is an enclosure formed by conducting material or by a mesh of such material. Such an enclosure blocks out external static and non-static electric fields...
; in the case of the Royal Observer Corps controls, this was the "Radio Room" that already protected the sensitive radio equipment from the effects of EMP.
The display unit (shown in the photograph above) could be mounted anywhere in the building – at ROC controls this was usually on the balcony adjacent to the Triangulation Team. The three elements of the installation were connected by EMP-shielded and heavy duty cabling.
During the early phase of operations, a spare observer was required to stand next to the display unit and monitor it constantly to identify initial responses. Once a nuclear strike on the UK had been confirmed by the Director UKWMO (or his deputy), readings from AWDREY were ignored during subsequent nuclear bursts within the attack, and the readings from ROC posts became the main method of detecting and identifying any subsequent near ground bursts.
Codeword
Royal Observer Corps reports following a reading on AWDREY were prefixed with the codeword "TOCSIN BANG". The message would also include the three letter group identifier, followed by the time and yield reading from the AWDREY printout. Eg "TOCSIN BANG – CAR – 11.06 (hours) – 3 megatons" (with CAR relating to Carlisle control).See also
- Royal Observer CorpsRoyal Observer CorpsThe Royal Observer Corps was a civil defence organisation operating in the United Kingdom between 29 October 1925 and 31 December 1995, when the Corps' civilian volunteers were stood down....
- Operational instruments of the Royal Observer CorpsOperational instruments of the Royal Observer CorpsThe Royal Observer Corps was a civil defence organisation operating in the United Kingdom between October 1925 and 31 December 1995, when the Corps' civilian volunteers were stood down....
- United Kingdom Warning and Monitoring OrganisationUnited Kingdom Warning and Monitoring OrganisationThe United Kingdom Warning and Monitoring Organisation was a British civilian organisation operating between 1957 and 1992 to provide the authorities with data about nuclear explosions and forecasts of likely fallout profiles across the country in the event of war.The UKWMO was established and...