Operational instruments of the Royal Observer Corps
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) was a civil defence organisation operating in 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...
between October 1925 and 31 December 1995, when the Corps' civilian volunteers were stood down. (ROC headquarters staff at RAF Bentley Priory
RAF Bentley Priory
RAF Bentley Priory was a non-flying Royal Air Force station near Stanmore in the London Borough of Harrow. It was famous as the headquarters of Fighter Command during the Battle of Britain and the Second World War. The RAF Bentley Priory site includes a Grade II* listed Officers' Mess and Italian...
stood down on 31 March 1996). Composed mainly of civilian spare-time volunteers, ROC personnel wore a Royal Air Force
Royal Air Force
The Royal Air Force is the aerial warfare service branch of the British Armed Forces. Formed on 1 April 1918, it is the oldest independent air force in the world...
(RAF) style uniform and latterly came under the administrative control of RAF Strike Command
RAF Strike Command
The Royal Air Force's Strike Command was the military formation which controlled the majority of the United Kingdom's bomber and fighter aircraft from 1968 until 2007: it was merged with Personnel and Training Command to form the single Air Command. It latterly consisted of two formations - No. 1...
and the operational control of the Home Office
Home Office
The Home Office is the United Kingdom government department responsible for immigration control, security, and order. As such it is responsible for the police, UK Border Agency, and the Security Service . It is also in charge of government policy on security-related issues such as drugs,...
. Civilian volunteers were trained and administered by a small cadre of professional full-time officers under the command of the Commandant Royal Observer Corps
Commandant Royal Observer Corps
The Commandant of the Royal Observer Corps was the Royal Air Force commander of the Royal Observer Corps. All the holders of the post were RAF officers in the rank of Air Commodore, initially retired reserve officers then Auxiliary officers and, since the end of World War II, serving officers...
; a serving RAF Air Commodore
Air Commodore
Air commodore is an air-officer rank which originated in and continues to be used by the Royal Air Force...
.
This sub article lists and describes the instruments used by the ROC in their nuclear detection and reporting role 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...
period.
Initial detection of nuclear bursts on the UK
- Atomic Weapons Detection Recognition and Estimation of YieldAtomic Weapons Detection Recognition and Estimation of YieldAtomic Weapons Detection Recognition and Estimation of Yield known by the acronym AWDREY was a desk-mounted automatic detection instrument, located at most, but not all, of the 25 Royal Observer Corps controls, across the United Kingdom, during the Cold War...
known as AWDREY was a desk mounted automatic instrument, located at controls, that detected nuclear explosions and indicated the estimated size in megatons. Operating by measuring the level of electro magnetic pulse (EMP) the instruments were tested daily by wholetime ROC officers and regularly reacted to the EMP from lightning strikes during thunderstorms. AWDREY was designed and built by the Atomic Weapons EstablishmentAtomic Weapons EstablishmentThe 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 AldermastonAldermastonAldermaston 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)KiritimatiKiritimati 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 onboard a ship). Reports following a reading on AWDREY were prefixed with the codeword "Tocsin Bang".
- The Bomb Power IndicatorBomb Power IndicatorBomb 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...
or BPI consisted of a peak overpressure gaugePressure measurementMany techniques have been developed for the measurement of pressure and vacuum. Instruments used to measure pressure are called pressure gauges or vacuum gauges....
with a dial that would register when the pressure wave from a nuclear explosion passed over the post. When related to the distance of the explosion from the post this pressure would indicate the power of the explosion. Reports following a reading on the BPI were preceded by the codeword "Tocsin".
- The Ground Zero IndicatorGround Zero IndicatorThe Ground Zero Indicator, known by the acronym GZI was a specially designed shadowgraph instrument used by the British Royal Observer Corps during the Cold War to locate the Ground Zero of any nuclear explosion.-Overview:...
, or GZI or shadowgraphShadowgraphShadowgraph is an optical method that reveals non-uniformities in transparent media like air, water, or glass. It is related to, but simpler than, the schlieren and schlieren photography methods that perform a similar function...
, consisted of four horizontally mounted cardinal compass point pinhole cameraPinhole cameraA pinhole camera is a simple camera without a lens and with a single small aperture – effectively a light-proof box with a small hole in one side. Light from a scene passes through this single point and projects an inverted image on the opposite side of the box...
s within a metal drum, each 'camera' contained a sheet of photosensitivePhotosensitivityPhotosensitivity is the amount to which an object reacts upon receiving photons, especially visible light.- Human medicine :Sensitivity of the skin to a light source can take various forms. People with particular skin types are more sensitive to sunburn...
paper on which were printed horizontal and vertical calibration lines. The flash from a nuclear explosionNuclear explosionA nuclear explosion occurs as a result of the rapid release of energy from an intentionally high-speed nuclear reaction. The driving reaction may be nuclear fission, nuclear fusion or a multistage cascading combination of the two, though to date all fusion based weapons have used a fission device...
would produce a mark on one or two of the papers within the drum. The position of the mark enabled the bearing and height of the burst to be estimated. With triangulation between neighbouring posts these readings would give an accurate height and position. The altitude of the explosion was important because a ground or near ground burst would produce radioactive fallout, whereas an air burst would produce only short distance and short lived initial radiations (but no fallout).
Static measurement of ionising radiationIonizing radiationIonizing radiation is radiation composed of particles that individually have sufficient energy to remove an electron from an atom or molecule. This ionization produces free radicals, which are atoms or molecules containing unpaired electrons...
- The Radiac Survey Meter No 2 or RSM was a 1955 meter which counted the particles produced by radioactive decayRadioactive decayRadioactive decay is the process by which an atomic nucleus of an unstable atom loses energy by emitting ionizing particles . The emission is spontaneous, in that the atom decays without any physical interaction with another particle from outside the atom...
. This meter suffered from a number of disadvantages: it required three different types of obsolete batteries, it also contained delicate valves that were liable to failure and it had to be operated from outside the protection of the post. These were favored as they had been tested on fallout in Australia after the Operation Buffalo nuclear testsBritish nuclear tests at MaralingaBritish nuclear tests at Maralinga occurred between 1955 and 1963 at the Maralinga site, part of the Woomera Prohibited Area, in South Australia. A total of seven major nuclear tests were performed, with approximate yields ranging from 1 to 27 kilotons of TNT equivalent...
, and remained in use until 1982 by commissioning a manufacturer to regularly produce special production runs of the obsolete batteries. Within the ROC the RSM was only used at post sites for three years when it was superseded in 1958 by the FSM and the RSM retained only for post attack mobile monitoring missions.
- The Fixed Survey MeterFixed Survey MeterThe Fixed Survey Meter was a specialist detection instrument used by the Royal Observer Corps during the Cold War between 1958 and 1982 to detect ionising radiation from nuclear fallout generated by a ground burst...
or FSM introduced in 1958, could be operated from within the post with a cable leading to the detector mounted externally and protected by a polycarbinate dome. The FSM used the same obsolete high voltage batteries as the RSM. In 1985 this instrument was replaced by the PDRM 82(F).
- The PDRM82 (F) was the fixed desktop version of the new Portable Dose Rate MeterCivil Defense Geiger CountersMost Civil Defense Geiger Counters and ion-chamber survey meters were issued by the governmental Civil Defense organizations in several countries from the 1950s in the midst of the Cold War in an effort to help prepare citizens for a nuclear attack...
, that were manufactured by PlesseyPlesseyThe Plessey Company plc was a British-based international electronics, defence and telecommunications company. It originated in 1917, growing and diversifying into electronics. It expanded after the second world war by acquisition of companies and formed overseas companies...
and introduced during the 1980s, gave more accurate readings and used standard 'C' cell torch batteries that lasted many times longer, up to 400 hours of operation. The compact and robust instruments were housed in sturdy orange coloured polycarbinate cases and had clear liquid crystal displays. The PDRM82 (F) had a remote sensor, mounted above ground under a polycarbinate dome and connected down a steel probe-pipe to the instrument by a coaxial cable.
Portable measurement of radiation during Mobile Monitoring missions
- The Radiac Survey Meter No 2 or RSM was a 1955 meter which counted the particles produced by radioactive decayRadioactive decayRadioactive decay is the process by which an atomic nucleus of an unstable atom loses energy by emitting ionizing particles . The emission is spontaneous, in that the atom decays without any physical interaction with another particle from outside the atom...
. Having been superseded within the ROC by the Fixed Survey Meter the RSM remained in use only for post attack mobile monitoring missions in a post attack period.
- The PDRM82 or Portable Dose Rate MeterCivil Defense Geiger CountersMost Civil Defense Geiger Counters and ion-chamber survey meters were issued by the governmental Civil Defense organizations in several countries from the 1950s in the midst of the Cold War in an effort to help prepare citizens for a nuclear attack...
was the standard portable version of the new meters, that were manufactured by PlesseyPlesseyThe Plessey Company plc was a British-based international electronics, defence and telecommunications company. It originated in 1917, growing and diversifying into electronics. It expanded after the second world war by acquisition of companies and formed overseas companies...
and introduced during the 1980s, giving more accurate readings and using standard 'C' cell torch batteries that lasted many times longer, up to 400 hours of operation. The compact and robust instruments were housed in sturdy orange coloured polycarbinate cases and had clear liquid crystal displays. The radiac sensor was self contained within the casing.
Measurement of personal absorptions
- The DosimeterDosimeterDosimeters measure an individual's or an object'sexposure to something in the environment — particularly to a hazard inflicting cumulative impact over long periods of time, or over a lifetime...
pocket meters were issued to individual observers for measuring their personal levels of radiation absorption during operations. Three different grades of dosimeter were used, depending on ambient radiation levels. The original hand wound and temperamental dosimeter charging units were replaced during the 1980s by battery operated automatic charging units.
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....
- Royal Observer Corps Monitoring PostRoyal Observer Corps Monitoring PostRoyal Observer Corps Monitoring Posts are underground structures all over the United Kingdom and Northern Ireland, constructed as a result of the Corps' nuclear reporting role and operated by volunteers during the Cold War between 1955 and 1991....
- Bomb Power IndicatorBomb Power IndicatorBomb 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...
- Ground Zero IndicatorGround Zero IndicatorThe Ground Zero Indicator, known by the acronym GZI was a specially designed shadowgraph instrument used by the British Royal Observer Corps during the Cold War to locate the Ground Zero of any nuclear explosion.-Overview:...
- Fixed Survey MeterFixed Survey MeterThe Fixed Survey Meter was a specialist detection instrument used by the Royal Observer Corps during the Cold War between 1958 and 1982 to detect ionising radiation from nuclear fallout generated by a ground burst...