Monument record ORF 159 - Laboratory 2 Centrifuge, circa 1957

2007: Field survey of the Atomic Weapons Research Establishment by Historic England (S1).
Structure F1: Laboratory 2 comprises a large open central chamber oriented roughly east to west with covered aisles to its north and south,a plant room to the west and is revetted in shingle. It is covered by a steel framed roof consisting of 9 trusses (including the gables), giving 8 bays. The last but one bays at either end are cross braced. The two gable trusses are angle iron A-frames the remainder of the trusses comprise steel channels and angle iron with queen posts. The trusses are raised 0.6m (2ft) above the concrete superstructure on steel columns. The roof was clad with pressed aluminium sheeting insulated with cork sheet and protected by a outer layer of roof felt. Internally, the building was lit by florescent tubes (missing) and a secondary emergency lighting circuit. At nearly eaves height on either side of the chamber there is a projecting ledge which supported rails for an overhead travelling crane. Running longitudinally down the building is a square sectioned air-conditioning duct formerly insulated with cork with a catwalk to its west. On the walls to either side of the main 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.

SCHEDULED ANCIENT MONUMENT (S2).