Atomic Weapons Research Establishment. Orford ... - English Heritage

passage in its ceiling are 4 very substantial eyehooks for lifting ropes. At the north end of the entrance
passage is a lift pit. 5.2m (17ft)by 4.88m (16ft)and 3.45m (11ft 4ins)deep. On its north and
south walls cut off bolts mark the former position of metal plates. In the southeast corner of the pit
is a recessed vertical channel for electrical pipes and 3 pipes possibly for hydraulic fluids The base of
the main test chamber is 1.5m(5ft) above the level of the lift pit floor and measures 9.75m (32ft)by
4.88m (16ft), the height to the to the upper walkway is (12ft) 3.67m. The base of the chamber appears
to be formed from a series of I beams, which allowed test equipment to be secured in various
places on the floor. Set into the north wall are 7 vertical, metal plates with cruciform slots, these
likewise were probably used for securing test equipment. On the east wall are 4 similar horizontal
plates, stencilled between the central plates and to the north of the northern plate are the figures
54, 60 , 66, these indicate the height above the floor surface (in inches). On the south wall are 3
horizontal metal plates with a central slot in each above the middle plate are stencilled numbers 1-
30 ft and below the plate are stencilled the numbers 1-7.5m, at 0.50m intervals. Below the bottom
plate there is a stencilled ‘C Fold’ the C is possibly earlier as it seems to be partially overpainted.
To either side of the chamber are cable ducts infilled with shingle, along the base of the north wall
are 8 pipe openings, 3 of which are sealed by bolted circular plates. Along the base of the east wall is
the remains of an air-conditioning system (not in-situ), at the southeast corner a passage leads back to
the air-conditioning plant on the east side of the building. Surrounding the test chamber is an upper
walkway which was formerly protected by a moveable handrail, whose fittings survive. Between the
walkway and the outer wall is a cable duct on the north and south walls. There is also a fixed handrail
and on the south, east and north walls along with various electrical pipes switches and junction boxes
and a single rectangular cable duct. In the north east corner is a vertical ladder that gave access to the
window level. Attached to the east wall is a large square section air-conditioning duct leading to the
plant room to the south. On the north, east and south walls of the test chamber are inserted pipes, 4
each on the north and south walls and 3 on the east which connect back to the cable ducts around
the edge of the walkway. Below these on each of the walls are pairs of circular threaded fixings.
The building’s roof is a massive concrete slab supported on 16 square columns, the under side of
the roof is 8.75m (28ft 6ins)from the floor of the chamber. On the underside of the roof and on
the walls are various screw threaded holes for eyehooks, used to position heavy test equipment.
The openings between the columns were originally filled with wooden framed windows and glazed
with perspex sheets. A ledge along the south and north walls of the main chamber carried rails for
an overhead travelling crane. At the northeast corner of the main test chamber a doorway gives
access to a service corridor running east-west along the north side of the building. For most of its
length mounted on its north wall were large cork insulated air conditioing pipes. To the west a flight
of stairs provides access to the top of the north lip of the lift pit and to the upper walkway around
the test chamber this flight of stairs also gives access to a now blocked door to the emergency exit
in the north wall. To the east a second flight of stairs gives access to the plant room attached to
the eastern side of the building, a sign on one of the switches records ‘Minerva cell DC supply isolation
relay’. On the upper west wall of the test chamber a sign records ‘telephone instrument room’
below it is a light fitting, to the south are the remains of light fittings and wooden batons for a sign.
To the south and detached from the main test chamber is an air conditioning plant of brick cavity
wall construction faced with Burwell whites laid to stretcher bond with a flat concrete roof supported
on RSJs. This building measures 11.62m (38ft 1ins)by 6.04m (19ft 10ins)and is 4m (13ft). The
block is divided into two by a brick partition wall the larger bay to the west was entered through
two pairs of wooden doors, above the eastern opening is a wooden louvred vent which connects
back to the air-conditioning plant and above the western door there is a wooden 2 light window.
Between the thetwo sets of door openings there is a large 3 light window at eaves height. Internally