Summary

Test buildings associated with two phases of Atomic Weapons Research Establishment (AWRE) occupation of the spit at Orford Ness.

Source: Historic England

Details

PRINCIPAL ELEMENTS
The scheduled monument includes the monumentalised, standing remains of test buildings on the Orford Ness spit associated with AWRE environmental testing of nuclear devices during two key phases of activity. Some of the structures have shingle bunds around them, which are part of their design, but there are no buried archaeological deposits associated with these structures.

The first distinct phase of AWRE activity saw the construction of highly specialised and distinctive testing buildings (Laboratories 1 to 3, and the control room to Laboratory 1), which undertook the pioneering development work for the successful production of Britain’s own nuclear capability known as Blue Danube. During the second phase of activity, from 1959, AWRE Orford Ness concentrated particularly on the development of the WE177 series of freefall bombs and the ET317 warhead for the first generation of Polaris missiles. To test these warheads distinctive and unique structures, the Vibration Test Buildings (National Trust buildings E2 and E3), latterly termed the ‘pagodas’ for their architectural distinctiveness, were constructed in late 1960. It has been suggested that these buildings were designed originally to test 'Blue Streak'. Associated with them is the control room, the magazine and hard impact facility which are contemporary and functionally inter-related.

DESCRIPTION
The AWRE phase I buildings comprise three testing laboratories (nos. 1 to 3) grouped together in the near centre of the spit, and the Control Room (National Trust building F4) for Laboratory 1. Laboratory 1 (National Trust building F3) was built by 1956 for use as the Large Vibration Laboratory. It is a massive reinforced concrete structure with a large central bay measuring 30.69m (100ft) by 9.13m (30ft) and was designed to mitigate against the effects of an accidental explosion. Its concrete walls were given extra mass by the shingle traverse placed around them, which would tend to force blast vertically rather than laterally. The roof was also relatively weak structure comprising nine steel W-shaped trusses and clad in aluminium sheeting, insulated with cork and covered in felt sheeting. The interior comprises a main bay separated into two unequal portions by a concrete dividing wall, and running along its northern side is a pit 3.18m (5ft 5in) wide and 2.74m (9ft) deep. On the dividing wall are traces of a screen mechanism to ensure that activities either side of the divide remained confidential. The larger Vibration Laboratory to the south east measures 17.32m (57ft) and the smaller Drop Test Laboratory to the north west 12.15m (40ft). Each of the bays was served by its own entrance with wooden entrance doors to either end, creating air locks measuring 10.1m (33ft) and 9.2m (30ft). Although the original specification only called for the testing of the bomb’s central section, the air locks were long enough to accommodate a fully assembled Blue Danube and its carrying trolley. Although manoeuvring such a large item through the south west entrance and into the Drop Test bay would have been extremely tight. A ledge on the top of the longitudinal walls of the central bay marks the position of a travelling crane that was used to position the bomb on the test equipment. Each of the entrance passages was later protected by crude steel doors fashioned from welded reinforcing rods, which may date to the post-AWRE era. Attached to the wall of the main bay are many small bore pipes that carried various services, including electric wires, hydraulic fluids, and carbon dioxide fire suppressant, and within the roof structure are the remains of large air conditioning ducts.

On the northern side of the south eastern entrance passage are two rooms that probably accommodated switch and monitoring equipment, and on the south side of the south west entrance passage was a staff room and toilet cubicles. Testing required the building to be temperature and humidity controlled and on the north west side of the mound is a large self-contained reinforced concrete, two bay plant room measuring 21m (69ft) by 3.89m (12ft 8in). This sits within the main shingle traverse and is insulated from it by a surrounding brick wall that acts a damp course. Air conditioning ducts from the main chamber enter this building and surviving plant within indicates that it housed air conditioning plant. On the north side of the traverse is a similar self-contained structure, surviving fittings shows that it mainly housed electrical switch gear, controls for the vibrating machines and carbon dioxide supplies for the fire suppressant system.

The operations within Laboratory 1 were considered to be so hazardous that it was provided with a detached Control Room (National Trust building F4) 130m (142yds) to its north east. This is an L-shaped reinforced concrete structure, originally with an open sided porch on its north east side that gave access to the control and monitoring room to the south west. This comprised two elements; a taller section to the north east that housed air conditioning plant, some of which survives, an entrance passage; toilet cubicles and to its southwest a large open room with a suspended floor that housed the monitoring equipment, of which a few metal cabinets survive. To protect the building from any accidental explosions in Laboratory 1 its south west side was protected by a shingle mound. In late 1963, or early 1964, the Control Room was modified to serve the new Impact Facility (National Trust building F5 - see below) that was being constructed to its north east. Alterations to the Control Room included the bricking up of the open porch and the insertion of double doors protected by a small projecting brick porch.

Laboratory 2 (National Trust building F1) was the third structure of this group to be erected, built between 1955 and 1958. Originally built to test Blue Danube casings, the Laboratory was probably modified in 1962 when a large Napier centrifuge on a brick housing was constructed. The laboratory is constructed from reinforced concrete with a large central bay 30.67m (99ft 9in) by 9.05m (29ft 9in) oriented roughly east to west. To increase the available height in the chamber, its A-frame, angle iron roof trusses are raised 0.6m (2ft) above the tops of the walls. The roof was originally clad with cork insulation board covered in aluminium sheets and protected by an outer asphalt coat. The main entrance to the central bay was from the east where a T-shaped road layout provided enough space for a vehicle and trailer to reverse into the building. The concrete entry porch was originally closed by wooden doors, but in common with the other earlier laboratories it was later secured by crude steel doors with an electrical alarm or catch. In common with Laboratory 1 the distance between the wooden doors would have probably been large enough to accommodate a fully assembled Blue Danube casing and its trolley. The building is also entered from the west through another large entrance, also with an entrance passage secured by double wooden doors, and later crude steel gates.

Internally, there are two staff amenity rooms adjacent to the west entrance. Entry from this aisle into the main chamber was through two openings in the main side wall, which would have restricted the size of items that could be taken through. At the western end of the building is a large reinforced concrete plant room, which is divided into two bays; the north bay housed a small control room and the southern, a large air conditioning plant. Surviving drawings indicate that the plant room was modified in 1963, alterations include the insertion of a single door to give access to the control room and the addition of a brick outshot to house a transformer and rectifier. At the northern end of the chamber was a Napier centrifuge, this was housed in a ground level, circular brick built feature 30ft (9.144m) in diameter, which could be entered by doorways to the east and west. The centrifuge was supported on a central base plate and above two rolled steel joists to the north and south, which have subsequently been cut off for scrap, leaving only their end sections embedded in the side walls. The centrifuge arm was 16ft (4.88m) in diameter, was capable of supporting a test piece weighing up to 1,000 lbs (453.6 kg), and was rated at 100,000 ‘g’ lb. In the south bay adjacent to the centrifuge is a large red concrete mounting block that probably held some of the control equipment for the centrifuge. A number of features and documentary sources suggest that the centrifuge is a secondary feature. In contrast to the remainder of the structure the circular feature surrounding the centrifuge was brick built rather than concrete. Entrances to either end are also large enough to accommodate a large trailer and potentially a full size Blue Danube casing. Within the main chamber the working area to the east of the centrifuge also appears disproportionately large. Within the roof structure was an internal catwalk to give access to the lighting and large central cork clad, metal air conditioning duct. Internally, along the tops of the walls are projecting ledges that supported the rails for an overhead crane. This might be used to manoeuvre test pieces within the building, and for the installation and maintenance of the centrifuge (see below). To the north and south of the main chamber are side aisles running the full length of the central chamber. These too have concrete walls but are roofed with horizontal beams with curved breeze blocks between them; above they are covered by the shingle mound. Each of the side aisles had an emergency escape exit, both also later secured by crude steel doors. At the western end of the central bay is a raised control room, accessed from a flight of concrete steps on the north wall.

Laboratory 3 (National Trust building F2) built between 1955 and 1958, was the climatic testing lab comprising two elements, the laboratory itself and the Condense Pump House to the east. Its function was to either warm or chill a weapon to simulate the variations of temperature that it might face in service. It is constructed from reinforced concrete with a barrel vaulted roof and entered from its south side through a concrete canopy, and whose southern wall was revetted with shingle. To manoeuvre the heavy test objects into position there was a hoist mounted on a beam secured to the underside of the canopy and roof of the main chamber, traces of its fittings may still be seen. Entry into the chamber was originally through double wooden doors, in common with the other earlier Laboratories security was strengthened by the addition of crude welded steel doors with may be post-AWRE features. At the top of these doors is a slot for the overhead lifting beam indicating that the doors were added while the building was operational. The interior comprises a large central chamber, 24.50m (80ft 5ins) by 6.0m (19ft 6in), and is divided into two sections. To the south was the preparation area and on its walls are the remains of electric conduits and small bore pipes for electric cabling. To the north was a rear insulated chamber 13.5m (44ft 4in) in length, which was separated from the preparation area by a cement covered expandomesh wall and a metal clad sliding door carried on an overhead rail. This slid into a corridor to the west that also gives access to a small switch room. The working area of the rear chamber measured 9.14m (30ft) by 3m (10ft) by 3m (10ft) and its floor set on four dwarf concrete walls was capable of supporting 6 tons. The temperature range that could be achieved varied between plus 60° to minus 60° centigrade, and humidity 20° on either side of the ambient, while undergoing thermal tests an object might also be subject to vibration.

Further to the west on the spit are the buildings of the second phase. The most distinctive structures built during this phase were the two Vibration Test Buildings, now commonly referred to as ‘The Pagodas’ (National Trust buildings E2 and E3). The specification for the Vibration Test Buildings included the ability to withstand the accidental detonation of 400lbs (181.4kg) of high explosives; they were designed by G W Dixon ARIBA for the UK Atomic Energy Authority and are identical. Both Vibration Test Buildings, their control room and centrifuge were constructed in 1960.

They comprise a large reinforced concrete central cell 16.47m (54ft) by 7.30m (24ft) covered by a massive reinforced concrete roof supported on sixteen reinforced concrete columns. To the south and east of the main chambers are self-contained plant rooms. The main access to the building is from the south through an entrance passage which was originally sealed by a pair of outward opening metal covered wooden doors. On its western side, adjacent to the main entrance passage is a blocked doorway that led to a small staff room and toilet. Inside the buildings on the eastern side of the passageway one set of stairs gives access down to the main test cell and another to a walkway around the top of the chamber. At the end of the passageway is a lift pit, which allowed test pieces to be lowered on to the floor of the main test cell. To assist in manoeuvring heavy objects there are a number of substantial steel eyelets screwed into the underside of the roof. A travelling crane also ran on rails mounted on a ledge beneath the windows, a loose plate on the floor recorded ‘Becker twin Lift Maximum Working Load 40 tons serial A-2647-2’.

The floor of the main cell is formed of parallel and narrowly spaced steel ‘I’ section beams for test rigs to be firmly secured to the structure. To either side are cable ducts. At the same time as being vibrated objects might also be placed in jackets to simulate extremes of heat and cold, or in a portable altitude chamber to mimic the effects of altitudinal changes. Set into the north wall are seven steel plates with vertical cruciform slots that were also used for securing tests rigs or monitoring equipment. Below these are eight pipes opening from the service passageway to the north. In the south wall are three steel plates with horizontal slots, above the plate is stencilled 1-27ft and below it 1-7.5m. The walkway around three sides of the cell was originally protected by a handrail and there is another handrail fixed to the main wall. Running around the wall is a cable conduit and attached to the wall are various pipes for carrying electrical wires, switches, junction boxes and pressure gauges. Signs on the wall above the lift pit record ‘Telephone Instrument Room’, ‘Vac Pump Running, Vac Pump Stopped’ with associated light fittings. At the north east corner of the cell is a doorway to the rear service passage running east to west along the north side of the building. To the east a flight of stairs gives access to the eastern plant room. To the west another set of stairs provides access to the northern side of the lift pit, the upper walkway and to an emergency escape passage through the north side of the traverse. To the south of the main cell are free-standing Burwell brick-built plant rooms. The main plant room is entered through two sets of double doors on its south side, internally are four machinery mounting plinths. Attached to its west wall is a metal cabinet that probably housed equipment to operate the hydraulic compressor for the internal lift. At the eastern end of the building is a store room with a blocked doorway to the south.

The Control Room (National Trust building E4) was constructed for the remote operation and monitoring of the Vibration Test Buildings. It is constructed in a simple, functional and contemporary style in Burwell white bricks that contrast with red asphalt covered lower sections of the metal framed panels of the bays. It is divided into two sections; to the west the slightly taller portion housed control and monitoring equipment, and to the east were staff facilities. The building is entered at the eastern end through an inset covered porch, which is surfaced in red and yellow flag stones arranged in a chequer board design. Entry into the Control Room was past the messengers’ room, located on the west side of the entrance and to its rear a windowless switch room. On the opposite side of the entrance was the cloak room. Along the rear wall is a ladies lavatory, cleaners’ room and a gents’ locker room and lavatory. At the eastern end of the corridor is a small tea room and to its south a large mess room. The taller western section of the building is split into two by a longitudinal east to west corridor. At its eastern end to the south is a store room and on the opposite side of the corridor a dark room. To their west and to either side were six almost identical bays, although the two in the south west corner are open to form a single large room. These rooms were used for housing control and monitoring equipment, which was supported on a raised floor, the under floor void probably accommodated air conditioning pipes and cabling. To reduce noise the upper sections of these rooms and their ceilings are lined with square pierced plaster board panels.

The centrifuge building (National Trust building E 1) lies just to the west of the Vibration Test buildings and is a rectangular concrete structure with gable ends to the north and south. It was originally entered from the west through 2 doorways which have subsequently been sealed with breeze blocks. In the southern opening a steel cage door has recently been inserted. Immediately to the north of the door opening is a small square opening to the washroom. At eaves height on the west wall are two metal ventilation grills, also on this wall are various small bore electrical pipes. The north gable is blank apart form a small square opening. The north and east sides of the building are protected by a shingle traverse supported by concrete wing walls on the north-west and south-east corners. The building is covered by a gently pitched roof supported on three RSJ girders with angle iron purlins supporting insulation boards and the pressed metal outer cladding.

The interior of the centrifuge was lit by sealed fluorescent units and heated by radiators on all walls. In the centre of the building is the circular brick-lined centrifuge pit with a diameter of c.8m and depth of c.2.5m. In the centre of the pits the central mounting plate for the centrifuge with a cable duct leading to the north east corner and a lower self contained equipment room. To the south west, north east and south east the pits’ brick wall is interrupted by a concrete section, above which may mark the position of the framework to support the centrifuge and its turning gear. To the south a set of concrete stairs provides access into the pit. It is finished in green paint, the remainder of the interior is yellow. A ledge running at eaves height along the east and west walls formerly supported an overhead travelling crane. At the north end of the building are two self contained instrumentation rooms and a door in the east wall that gave access to the emergency escape passage and the pressed metal outer cladding.

Located approximately 800m to the east of the Vibration Test Buildings, the Hard Impact Facility (National Trust building F5) was built by late 1962, in which a weapon, minus its fissile core, was propelled by a rocket powered sled against a concrete wall. It comprises a reinforced concrete wall orientated south east to north west with a battered rear to the south west; this side also has an extended tank at its base now infilled with shingle. On the top of this wall are the remains of the steel and timber superstructure which housed cameras to record the impact of the rocket sledge at the base of the wall, these remains project about 1.7m above the concrete base. On the rear wall there are also the remains of steel mountings that are probably associated with the steel and timber superstructure. At the south west end of the wall are the remains of electrical fittings and a small square bronze fitting. On the north east face of the wall are a number of spalled areas that represent where the bombs impacted on the wall. To the north east a large expanse of cast concrete slab extends away from the wall. On this slab are two electrical switch boxes and a number of metal grid covers that gave access to the cable ducts.

The last building for this phase of AWRE activity included in the scheduling is the magazine (National Trust building E5) constructed to store munitions. It was built in 1962, 400m to the north of the Vibration Test Buildings, near to Stoney Ditch. This is a reinforced concrete structure with a barrel vaulted roof and is revetted on all sides by shingle traverses. The interior comprises a main drive through entrance passage aligned roughly north to south and surfaced in a smooth concrete surface. To either end it was closed by wooden doors that were set back from ends of the passageway. These comprised a set of double doors and a single pedestrian entrance to one side. At eaves height above the passage way are a series of mounting plates that supported an overhead monorail. On the western side of the passage are two self-contained storage magazines, each of which was formerly closed by outward opening wooden doors. At the entrance to each of the rooms wooden batons on the walls indicate the presence of toeboards, separating a clean magazine area from a dirty outer area. The two bays differ slightly in size, the south bays measures 7.45m (24ft 6ins) by 4.55m (15ft), and the north bay measures 9.15m (30ft) by 7.45m (24ft 6in), both are 5.12m (16ft) high. Each was ventilated through a roof vent with a tall vertical stack projecting through the roof, and by a pair of vents leading into a rear air conditioning plant room, which was entered through a single door to the south.

EXTENT OF SCHEDULING
The scheduled monument comprises 10 separate areas of protection, restricted to the following buildings and, where present, their protective bunds: Laboratories 1 to 3, and the control room to Laboratory 1, the two vibration test buildings and their centrifuge and control room, the magazine to the north and hard impact facility to the east. Excluded are all concrete roads, paths and associated street furniture, posts and fences on Orford Beach, including modern posts and signage erected by the National Trust.

Source: Historic England

Reasons for Scheduling

Laboratories 1, 2 and 3 and the Control Room to Laboratory 1; the Vibration Test Buildings and their Centrifuge, Control Room, Magazine and Hard Impact Facility, constructed between 1954 and 1962, on Orford Beach, are scheduled for the following principal reasons:

* Rarity: the buildings on Orford Beach are rare, perhaps unique, nationally and internationally;
* Diversity: the site has a high diversity of component buildings and structures each with a bespoke design for undertaking specific testing regimes;
* Survival: the buildings and structures survive well and reflect the evolution of the experimental technologies tested here;
* Documentation: the military site at Orford Ness is well documented and researched, underpinning the assessment of national importance.

Source: Historic England

Sources

Other
Cocroft, W and Alexander, M, Atomic Weapons Research Establishment, Orford Ness, Suffolk Survey Report, October 2009, Research Department Report

Source: Historic England