Cold War nuclear bomb stores and sidewinder air-to-air missile store, along with associated blast walls, at former RAF Wethersfield

Cold War nuclear bomb stores and Sidewinder air-to-air missile store at former RAF Wethersfield

This group of Cold War bomb stores, known as 'igloos', was constructed at former RAF Wethersfield for the United States Air Force. The complex consists of four bomb stores built in the 1950s (three to store nuclear weapons and one to hold nuclear triggers or capsules) and a single unit with seven cells built in the 1960s to store Sidewinder missiles, all accompanied by contemporary blast walls.

The nuclear bomb and trigger stores are earth-covered reinforced-concrete boxes, while the Sidewinder missile stores comprise earth-covered corrugated-steel barrel vaults. All structures feature reinforced-concrete headwalls, back walls, wingwalls and blast walls. The blast walls are revetted in earth at the rear. Heavy-duty steel doors provide access to all stores.

The nuclear bomb and trigger stores are arranged within a rectangular area aligned north-west to south-east, bounded by a 1950s concrete service road. Three nuclear bomb stores stand side-by-side approximately 40 metres apart on the west side, all aligned north-east to south-west. The trigger store occupies the north-east corner on a north-west to south-east axis. Detached blast walls stand on an identical alignment on the opposite side of the service road from each store. From the two northern corners of this arrangement, a 1960s concrete service road defines a smaller rectangular area aligned north-east to south-west. The Sidewinder missile store stands on the north side of this secondary area with a detached blast wall opposite on the same alignment.

Each bomb and trigger store presents a front consisting of a central headwall flanked by wingwalls, both extending above the top and sides of earthen mounds covering rectangular reinforced-concrete boxes. At the centre of each headwall are top-hung sliding double-leaf steel doors beneath a concrete hood, accessed by a concrete apron from the adjoining service road. Ventilation is provided by louvered openings in the headwall and ventilator stacks at the rear.

The Sidewinder missile store comprises a single structure with a long headwall flanked by wingwalls, extending above the top and sides of an earthen mound covering seven barrel-vaulted stores constructed from corrugated steel. Each barrel-vaulted store has a hinged double-leaf steel door beneath a concrete hood, accessed from the service road by a concrete apron. Ventilation is similarly provided by louvered openings in the headwall and ventilator stacks at the rear.

Internally, the bomb and trigger stores all have reinforced-concrete walls and ceilings with concrete slab floors. A metal hook for loading, unloading, assembly and maintenance operations is embedded in the ceiling of the three nuclear bomb stores. Although the trigger store is identical in external appearance to the three nuclear bomb stores, its internal depth is shallower and contains a small vault or safe in which nuclear triggers were stored. Two of the bomb stores were subdivided in the late 20th or early 21st century with concrete blockwork.

The interiors of the seven Sidewinder missile stores comprise corrugated-steel barrel vaults sprayed with asbestos for fireproofing and anti-condensation insulation purposes. Concrete slab floors form the base of each store. Openings in the rear walls connect to external ventilation stacks.