Black Holt former Atomic Bomb Store: 13 individual fissile core stores within a mounded earthen bund, Coningsby, Lincolnshire

Summary

A series of 13 individual stores within a mounded earthen bund, which were used to house the fissile stores, at the former atomic bomb store at Black Holt near RAF Coningsby, dating to the 1950s.

Description

A series of 13 individual stores dating to the 1950s within a mounded earthen bund which is set beside a path which dog legs around the testing buildings (see buildings 5, 6 and 9) which were used to house the fissile stores.

PLAN: the overall plan forms an inverted S, with the storage units set along the west and south sides of the banked bund.

DESCRIPTION: each of the stores is set in a mounded bank and constructed of reinforced concrete with large single leaf steel doors. The cores themselves were stored in cylindrical or key-hole shaped holes in the ground which have since been filled in with concrete, but they are still discernible. There is a ventilation duct in the corner of the roof.

History

The built and archaeological remains of the Cold War (1946-1989) are the physical manifestation of the global division between capitalism and communism that shaped the history of the late C20. Nuclear weapons were the defining technology of the Cold War, firstly as atomic fission weapons, and later as more powerful hydrogen fusion weapons. Both types are technologically complex, expensive and dangerous products which required specialised, secure storage and handling facilities. These took the form of purpose built storage and maintenance units and special storage areas, on airfields where aircraft cleared to carry nuclear weapons were permanently stationed or might be deployed in time of war.

The evolution of nuclear bomb stores in England illustrates changing deployment strategies throughout the Cold War by the Royal Air Force and the United States Air Force - both by its Strategic Air Command deterrent forces and by its tactical forces committed to NATO. The siting of nuclear bomb stores on airfields, for example, demonstrates NATO's willingness to store nuclear weapons close to the units that would use them. Initial RAF plans to hold atomic bombs at two central stores were quickly overtaken by the need for faster response times, and small atomic bomb stores were instead provided on nine of the ten main V-bomber nuclear strike airfields. These stores were initially supported by other central stores and so were configured to hold no more than twelve bombs. In the first generation of atomic bomb stores there is a close correlation between the physical infrastructure and the bombs they were designed to house, and the relative crudity of early atomic bombs is reflected in the design and size of their stores.

The Blue Danube was the first dedicated British atomic bomb programme, as well as the colloquial name for the bombs themselves. With the increasing tensions of the late 1940s and early 1950s between the USSR and the USA, the decision was taken to instigate and develop the United Kingdom’s own atomic programme. As well as the huge technical challenges that would bring, there were also extensive logistics issues to tackle, not least because the weaponry being dealt with was both entirely unknown and very unpredictable in the early days. As part of the programme therefore, a significant expansion of existing airfields was required in the early years of the 1950s, in order to both store safely, and if required to deploy the new weaponry.

In the early days of the UK atomic programme there was a great deal of learning by trial and error as there was no precedent for handling weapons of this type or magnitude. The main central storage facilities were located at RAF Barnham in Norfolk and RAF Faldingworth in Lincolnshire. RAF Coningsby also in Lincolnshire was chosen to be one of the supplementary storage areas (SSAs) to support the central ones. The base had been used during the Second World War as a bomber station. The conversion of a site nearby to the active airfield, called Black Holt, was undertaken to create the storage facility and necessary administrative, testing and ancillary buildings to operate the storage facility and ensure the bombs were safely handled. This involved the construction of a series of mounded reinforced concrete storage facilities, each of which would house two bombs, part assembled, adjacent to one another in the steel and reinforced concrete bunkers, with a full and independent ventilation system for each one to maintain a stable environment. The bombs originally stored here were large and cumbersome, measuring 7.3m in length by 1.52m in diameter and weighing 4 tonnes. The two principal components were the plutonium core and the machined lenses of high explosive which surrounded the core and, when detonated, would cause it to implode to create critical mass. The bombs were kept in the bunkers along with the radar systems and the high explosive lenses. The fissile cores themselves were kept in mounded ‘fissile stores’ in concrete-lined circular holes in the ground. In terms of the process the part assembled bombs were brought to the site by truck, assembled in the D1 facilities prior to being stored in the D2 storage bunkers, all of which remain at Black Holt.

The buildings at Black Holt were of standard design and can be found at other storage facilities, for example near-identical structures could also be found at RAF Finningley, now Doncaster Airport, in South Yorkshire. One change which was made as the handling of the bombs became more adept, was that the storage ‘hutches’ which are present at RAF Barnham, for the fissile cores were later replaced with the concrete bunkers within mounded earthen bunds which offered greater protection from aircraft crashes or fuel leaks. Blue Danube required extensive testing and maintenance so as well as the storage facilities there are buildings dedicated to these tasks. Like the storage bunkers the buildings are constructed of reinforced concrete frames with brick and steel. They were constructed to facilitate movement of the unwieldy weaponry with large hoists and access at either end of the buildings in some cases. Further developments of the weaponry continued through the 1950s with the second generation being named ‘Red Beard, followed by Violet Club which was housed in the Blue Danube bomb casings. These were in turn replaced by the Yellow Sun Mark 1 which was the first H-bomb, which was a significant improvement on Violet Club which had been inherently unstable. Further testing facilities were therefore required for Yellow Sun, and buildings were duly constructed in 1959 as part of the expansion of the site.

Later development was required from 1960 onwards as it became clear that gravity bombs would become obsolete and that missiles would be required that could be fired from a greater distance from target. This led to ‘Blue Steel’, the second principal atomic weapons programme in the UK, and to the further adaptation and enlargement of Black Holt: the construction of 14 new storage bays adjacent to the existing ones, which were designated D3. These became storage facilities for the new megaton bombs. As the technology had advanced, the different components could be kept together, but the bombs themselves could not be kept in the same storage bays because of the risk of detonation. Therefore each of the existing bays was converted to house a single weapon. This led to a total of 24 storage bays, which corresponds with the 3 squadrons of 8 V fighters based at Coningsby. However, it does not appear that the storage was ever full to capacity and that the ability to store 24 missiles was to imply a greater strength of arms than was actually the case, an example of the use of misinformation as a tactic during the Cold War. The existing testing and other ancillary buildings on the site continued to be used and were adapted to suit the changing technology.

From the 1970s, the principal UK nuclear deterrent was via the submarine. In the 1980s Black Holt, along with other airfields, was further developed to ensure airfields could operate under full nuclear, biological or chemical conditions attack. Key airfields Europe-wide were provided with hardened accommodation. In the United Kingdom these were Wattisham, Leuchars, Leeming and Coningsby. As part of those changes one of the mounded test facilities at Black Holt was converted into an Air Defence Centre (ADC) and a further mounded facility was constructed to house the latest generation of nuclear missiles.

The site closed in the 1990s and is now in private ownership, although RAF Coningsby remains an active airfield.

Reasons for Listing

The fissile core storage huts at the former atomic bomb store at Black Holt dating to the mid-1950s, are listed at Grade II for the following principal reasons:

Architectural interest:
* as buildings which directly relate to the earliest phases of the United Kingdom's atomic bomb development programme;
* as surviving examples of mid-C20 military architecture which demonstrate the standardised design approach but nonetheless the adaptation of buildings to particular purposes.

Historic interest:
* as evidence of a critical period for the United Kingdom's defence and of the development of its early nuclear arsenal.

Group value:
* as part of a group of buildings which collectively have major historic significance.

External Links

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