Bomb Power Indicator , also known by the acronym BPI , was an instrument built to detect nuclear explosions and measure the peak overpressure of their blast waves . It was used at the twenty five British Royal Observer Corps (ROC) controls and nearly 1,500 ROC underground monitoring posts, across the United Kingdom during the Cold War .
28-613: The instruments, operated by volunteers, measured the level of peak-overpressure at the instrument's location. Once readings had been combined with information provided by the Ground Zero Indicators it would be possible to estimate the size of the nuclear explosion in megatons . Detailed BPI information was backed up by the automatic AWDREY readings. The BPI was designed and built by the Atomic Weapons Establishment at Aldermaston . The design
56-574: A state of emergency and a transition to a war footing in the UK, and why, but these may not necessarily happen in the order listed or at all. This legislation is already pre-drafted in three stages and could be imposed by an Order in Council , without Parliament's input or approval. "Reservists" are any members of the public who serve in the armed forces and emergency services on a part-time basis. Many will hold down regular civilian jobs and be called up on
84-540: A distinctive suntrail across the papers when there was no cloud cover. Sixty seconds after any reading on the Bomb Power Indicator an observer exited the post and changed the GZI cassettes. The exposed papers were returned underground for assessment. The pre-exposed papers had a graticule grid exposed on the papers that showed degrees of bearing. The fireball from any nuclear burst within range would have burned
112-430: A hand held plastic calculator device. Normally stored below ground the drum was mounted at the start of exercises or at Transition To War on a special above ground mount set in the concrete of the entrance hatch. Concentric lugs on the mount ensured that the drum was mounted correctly even in the dark. The light sensitive photographic paper was unfixed chemically and had to be protected from daylight by being carried in
140-571: A mark on the paper. The spot size and bearing would be reported to the group control together with an indication that the spot is touching or clear of the horizon, essential for indicating an air or ground burst. Reports following readings on the GZI were prefixed with the words " Nuclear Burst " and the monitoring post's operational identifier e.g. "Nuclear Burst Shrewsbury 56 post - (time) oh six hundred - Bearing zero seven zero - spotsize zero six - touching". For realistic exercise training photographic papers with simulated burst spots were prepared by
168-549: A national emergency. For example, the Energy Act 1976 allows the Secretary of State to create regulations governing the production, distribution and use of coal , petrol , diesel , gas , biofuels and electricity in a crisis. For example, it could allow rationing, power cuts in certain areas to allow blackouts near key installations, restrictions on civilian use of cars and the like. The Broadcasting Act 1980 allows
196-480: A protective pouch strapped to the observer's chest. The cassettes were always lodged in a specific order so they could be changed in the pitch black with practice. Differing notched cutouts at the bottom of the cassettes ensured they could not be mounted at the incorrect cardinal point. Daylight inevitably darkened the unfixed papers so routine changes were made at mid day during winter operations and twice daily, at mid day and sunset, during summer months. The sun burned
224-520: A sheet of photosensitive paper mounted within a clear plastic cassette on which were printed horizontal and vertical calibration lines delineating compass bearing and elevation above the horizon. The bright flash from a nuclear explosion would burn a mark on one or two of the papers within the drum. The position of the burn spot 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
252-412: A triangulation between both neighbouring posts these type of readings would give an considered accurate height and position, which is identified by assessing the height of the explosion imprint above the horizon level that had been pre-exposed onto the paper. The GZI consisted of four horizontally mounted cardinal compass point pinhole cameras within a white enamelled metal drum, each 'camera' contained
280-456: Is a North Atlantic Treaty Organization ( NATO ) military term referring to a period of international tension during which government and society move to an open (but not necessarily declared) war footing. The period after this is considered to be war, conventional or otherwise, but the term TTW found its origins in the peak of the Cold War as a key NATO concept within the tripwire escalation of
308-557: Is sent above ground to change the photographic papers in the Ground Zero Indicator . Royal Observer Corps reports following a reading on any BPI were prefixed with the codeword "Tocsin" e.g. "Tocsin Shrewsbury 56 post - (time) oh five fifty five - pressure two point six". Ground Zero Indicator The Ground Zero Indicator , known by the acronym GZI was a specially designed shadowgraph instrument used by
SECTION 10
#1732794455747336-543: Is similar to Transition to War. The legislation that facilitates the transition to war is pre-drafted and has been in existence since the 1930s, when World War II required certain legislation to be passed to prosecute the war effectively. This mostly included the Emergency Powers (Defence) Act 1939 and the controversial Defence Regulation 18B , which allowed the detention of subversives without charge or trial. A number of these emergency regulations lasted until
364-579: The British Royal Observer Corps during the Cold War to locate the Ground Zero of any nuclear explosion. It consisted of four horizontally mounted cardinal compass point pinhole cameras within a metal drum. Flash from a nuclear explosion would produce a mark on one or multiple of the papers within the drum and its position of the mark has enabled the bearing and height of the burst to be estimated in terms of engineering. With
392-471: The DEFCON status. This could include the suspension of peacetime services, closing motorways to all but military traffic and the internment of subversives without charge or trial. The Federal Emergency Management Agency would declare this period as Increased Readiness in a move to expedite Civil Defense training, among other things in order to prepare civil authorities for a nuclear attack, and to an extent
420-566: The Exercise Division of the United Kingdom Warning and Monitoring Organisation at Cowley . Delivered sealed, the time of opening was written on the outside of the sealed envelope. Observers trained blindfolded so that they could exit the post up the vertical steel ladder and complete a GZI cassette change quickly and even in the pitch dark of a winter's night. Transition To War Transition to war (TTW)
448-657: The Northern Ireland Peace Process and the Human Rights Act 1998 passing into law, these emergency powers and the legal framework that supported them became dated and needed re-examining. The Civil Contingencies Act 2004 was introduced to provide a new enabling power to introduce emergency regulations, but it cannot be used by the Government to alter the Human Rights Act 1998 . The following table gives examples of what could happen in
476-571: The Parliament Acts or be done through an Order in Council , which is essentially a royal decree . The bills themselves would be enacted in three stages. The first stage is a covert review of what to do and what needs to be revised, done only by ministers and civil servants. The second stage is more overt and would include 24-hour manning of government departments, people being briefed of their wartime roles, testing of sirens and other communication systems, cancelling police leave and mobilising
504-479: The requisitioning of private property (including land, buildings, vehicles, ships and aircraft), preventing key workers from leaving their employment , widening the role of the armed forces and fire brigades , reorganising the National Health Service , control of transport, extra police powers , regulation of money supply and currency controls and compensation. The General Bill would be
532-420: The armed forces (including reservists). The third and final stage would be the activation of war measures, such as local councils setting up refugee centres and the like. The actual bills would effectively be enabling acts allowing for the implementation of the pre-drafted legislation. The bills' content was not divulged both on the grounds of national security and because it would be politically controversial for
560-493: 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). Once combined with the peak-overpressure readings from post Bomb Power Indicator readings the power of the burst in megatons could also be calculated by the Triangulation Team in the group control building, using
588-621: The governments to take over editorial control of the BBC , ITV , Independent Local Radio and Independent National Radio in a national emergency. The Railways Act 1976 has similar provisions with regard to the British railway system. The minister or Secretary of State can take control of the railways in the event of war, including the Channel Tunnel. Since this legislation is pre-drafted, it would be either rushed through Parliament using
SECTION 20
#1732794455747616-834: The mid-1950s, and were finally abolished with the end of rationing in 1954. However the Cold War brought the possibility of war with the Soviet Union, which would require similar legislation to allow NATO countries to defend themselves effectively. Hence pre-drafted legislation governing every aspect of life in the United Kingdom, consisting of the Emergency Powers (Defence) Bill, Defence (Machinery of Government) Regulations and other laws were devised. Other regulations included: Other existing legislation governing everyday matters already allows for special provisions in
644-496: The party in charge at that time to do so considering their draconian nature. It would also be unconstitutional, as one parliament would be effectively determining the affairs of a future one. However, they consisted of the Special Powers Bill , which allowed the police extra powers to stop, search and arrest people , restrictions on ships and aircrew, along with compensation. The second, The Readiness Bill , covered
672-410: The passing of the blast wave. The detector was connected by a steel pipe to the indicator dial below ground in the protected monitoring post. The dial was wall mounted and measured readings from 0.1 to 5 pounds per square inch peak overpressure. Readings below 0.3 pounds per square inch were noted but not reported. The baffles were normally stored below ground and only screwed onto the top of the pipe at
700-460: The start of exercises or at Transition To War . Outside of operations the BPI pipe was protected by a screw on cap and there was a drain valve at the base of the instrument to remove any excess rainwater. If the BPI registered a reading of 0.3 or higher the operator would wait ten seconds before pressing the reset button and making a report to the group control. One minute after a BPI reading an observer
728-649: The third and final stage of putting Britain on a war footing. While building on the other two, it would also provide the legal framework for regional government (national government could fail), including the powers of the regional commissioner. Along with this would be the power to take over the BBC (which already exists), control labour, the registration of births, deaths and marriages, the administration of justice (jury trials may be suspended and special courts of justice may be established, for example. Also, subversives could be arrested by police and detained without charge or trial) and compensation. When these were drafted, it
756-456: Was assumed that both the House of Commons and the House of Lords were sitting at the time of the crisis and become acts within a few hours or days, though it would be more problematic if Parliament was in recess, as it would take longer to enact the acts. The new legislation would have to be publicised and printed within two days. With the end of the Cold War in the late 1980s and early 1990s,
784-535: Was tested for performance and accuracy using real nuclear explosions at the 1957 Kiritimati (or Christmas Island) nuclear weapons tests , after being mounted on board a ship. A number of BPIs were also tested in Australia during the Operation Buffalo series of nuclear tests , with units located at various distances from ground zero . Above ground, a pair of circular plated baffles would be affected by
#746253