European Spallation Source (ESS) Pit Lids

Introduction.

The UK Atomic Energy Authority had a requirement for the manufacturing, assembly, testing, inspection and transport for shielding lids and their corresponding location frames under a ‘build to print’ contract, to be used in the European Spallation Source (ESS) in Lund, Sweden.

Objectives.

Each Pit Lid is constructed from high density reinforced concrete, encased in an 8mm welded stainless steel shell. The Pit Lids each have some variation in shape and size, with weights in the region of 15-25t. The exterior plates form a labyrinth design, that attenuates radiation. There are also 5 location frames to be constructed, from stainless steel angle bar, which also include location features. These frames are to be installed within the pit surround to form a base upon which a set of Pit Lids are placed.

The ESS will be the world’s most powerful neutron source once complete. The UK is one of 17 European countries involved and construction is expected to finish in 2025. Scientists will use the ESS essentially as a giant microscope, to study a range of materials including plastics, engines, nanotechnology and proteins.

Results.

Amber Precast supported the early technical design concept and later won the competition for the manufacture, assembly, testing, inspection and transport of the pit lids.

A fundamental aspect of manufacture was adherence to the tight tolerances required to ensure no shine path from a pit and with the use of high denisty concretes it was essential to rigidly restrain the stainless steel casings to ensure no deformation. Tolerance requirements were confirmed with large component laser scanning and with rigorous factory acceptance tests.