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

chamber small bore electrical pipes remain. The main chamber was entered from the east through
an entry porch which was originally closed by a pair of wooden doors, which were later made
more secure by the addition of crude steel doors. In the southern aisle part of the centrifuge’s (see
below)mechanism remains, comprising a large red-painted concrete block and steel work framework.
The north aisle was accessed from the west through an entry porch, the outer section of the which
was lit by 2 curved, probably perspex, roof lights and it was closed by a pair of outer wooden door
whose scar remains. Internally the passageway was sealed by a further set of wooden doors subsequently
passageway was further secured by a set of crude external steel doors with an electrical alarm
or catch. The aisle roofs are formed from concrete beams between which are curved breeze blocks.
To the west of the outer passageway are 2 small rooms of reinforced concrete, the outer and lower
room was lit by a 10 light metal framed window to the west(now removed)and on its south side is
a small 4 light window. This room is entered from the passage way through a single wooden door.
Internally is a flourescent tube light, various electrical fittings and a tiled sink splashback. This room is
separated from the room to the south by a brick partition wall laid to stretcher bond. The other room
is lit by a 5 light metal framed window on its north side and accessed by a single wooden framed
door from the passageway. Internally, are 2 toilet cubicles and a tiled splashback for a pair of sinks.
At the north end of the main chamber is the circular brick lined pit, which housed the Napier
centrifuge, to the north and south of the pit are large cut-off I section girders that supported the
centrifuge. The cahmber diameter is 30ft (9.14m(and the centrifuge arm was 8ft (2.44m). Above
the centrifuge to the west is the control room, which is accessed from a flight of concrete steps
to the east. An 18 light metal framed window overlooks the centrifuge (from the control room).
To the south of the main passageway is a self-contained rectangular reinforced concrete plant block,
20.20m (66ft 3ins)x 6.67m (21ft 11ins), height 3.85m (12ft 8ins). Originally, the building was entered
at its south end through a set of double wooden doors with a 4 light metal framed window
above and through a set of roughly central double wooden doors. The west side was originally lit
by three windows to the east two 16 light windows and between the 2 sets of doors a 12 light
window. Subsequently the second window from the north has been partially blocked and a single
door has been inserted access to which is through an added brick porch built of Fisons whites laid
to stretcher bond. This has created a self contained control room with five holes in its east wall leading
back towards the centrifuge/ main chamber. Internally there are various pipes and cable ducts
surviving. At the north end of the main plant room the large air conditioning chiller unit survives
with the main air intake from the longitudinal overhead duct within the unit air is forced through
a series of filter banks and apparently chilled through a cascade of glass sheets sprayed with water.
Signs on the side of the chiller unit state ‘Washer Spray No 1, Washer Spray No 2, Reheater’. In
the remainder of the room are 3 large machine plinths and a small machine base in the corner and
infilled cable ducting. One of the plinths adjacent to the 12 light window it appears to be secondary
and beneath the window is an inserted vent opening. In the roof are two square vent openings
within the room various fittings and cable ducts survive. Butting against the west wall is a brick built
outshot in Burwell whites, at its north end is an open transformer bay with an English bond wall to
its north within the bay are 2 rectangular concrete plant mountings on its north and south walls are
two pairs of gate brackets. To its south was the Rectifier Room, this is of brick cavity wall construction
with Fison whites laid to stretcher bond. The building was entered through a set of tall wooden
doors at its south end this side was lit by 2 upper large steel framed windows with a wooden louvred
vent above the door and windows. The south wall was lit by a single large metal framed window.
Internally there is a radiator, cable ducting and a number of cut off pipes high on the southern wall.
The early 1960s drawings suggests that the centrifuge may represent a secondary use for this laboratory.
The extensions made to the plant room in 1963 may also relate to this suggested modification.