Sample Cave Shielding for the Spectrometer SKADI at the ESS

Kurze Beschreibung

The award procedure relates to the shielding concept, design, manufacturing and installation of the sample cave shielding for the neutron scattering instrument SKADI that will be built on beam port E3 in the east hall of ESS in Lund (Sweden). The sample cave shielding protects the environment from radioactive neutron and gamma radiation. The order and thickness of the shielding elements has to reduce a maximum dose rate to 1,5 μSv/h at the exterior contact. The shielding walls should be constructed of 600 mm thick normal concrete with carbon steel rebar, the inner side of the concrete walls and top should be lined with the 50 mm thick steel plates and borepoxy plates. The access to the sample area is provided through the motorised side and roof doors.

Beschreibung der Beschaffung

The Small-K Advanced Diffractometer (SKADI) is a small-angle neutron scattering (SANS) instrument to be constructed at the European Spallation Source (ESS).
SKADI is a versatile SANS instrument, which will enable scientists to perform a wide range of investigations on topics requiring small scattering angles to access long length scales. The scientific areas targeted by SKADI include investigations of smart materials, biological and medical research, magnetic materials and materials for energy storage, as well as experiments on nanomaterials and nanocomposites or colloidal systems. These experiments promise a high potential impact on science and society. To maximise the societal applicability of these studies SKADI is designed to accommodate in-situ measurements with custom made sample environments to provide ‘real-world’ conditions. One part of the SKADI instrument is sample cave shielding. The sample cave shielding protects the environment from radioactive radiation.
During the experiments, samples are exposed to a neutron beam. For most of the experiments, the sample will be positioned in air. This setup has the advantage of fast sample change and allows an easier conversion of experiments. Those produce radioactive radiation that must be shielded. Access to the sample area is provided through the side door and roof hatch, both of which are motor operated with appropriate safety switches and interlock systems for safe access. The arrangement and the thickness of the shielding elements were preliminary calculated and simulated to provide a maximum dose rate of 1.5 μSv/h at the outer shielding surface.
The shielding walls should be constructed of 600 mm thick normal concrete with carbon steel rebar, the inner side of the concrete walls and top should be lined with the 50 mm thick steel plates depending on the shielding calculations and 5 mm Borepoxy plates as the neutron-absorbing material. This layer will absorb the neutron and will act as an activation protection for materials underneath. The steel plates are painted with primer paint only.
The concrete walls of the shielding are to be constructed modularly from prefabricated elements. The casting of the walls at the construction site is not desired. Access to the sample area is provided through the side door and roof hatch. All the doors are motor operated with appropriate safety switches and interlock systems for safe access. The roof door is opened if access from the above is required especially for handling cryostat components. This door is made of 200 mm thick steel plate and covered with 5 mm borepoxy plates from the inside. The side door is intended for access to the sample location. The door is made of 600 mm concrete and covered inside with 50 mm steel plates depending on the shielding calculations and 5 mm Bore-poxy plates as the neutron-absorbing material. The door should overlap to minimise radiation. Basically, all gaps must be covered with a chicane. The side door should also be motor-driven with corresponding position measuring systems.
Scope of work:
Scope of work for this project is the detailed design, manufacturing, delivery and installation of a turnkey sample cave for biological shielding of SKADI. This includes the following items:
1) conceptual design,
2) structure calculation and structure drawings for all relevant components,
3) calculations of the drives and design the doors,
4) shielding design with detail drawings,
5) calculations of the radiation shielding of the shielding,
6) stairs and rails,
7) manufacturing and assembly, painting (colour of painting the concrete blocks will be painted white (RAL to be defined) with plain green circle RAL6038, the steel structure in a similar manner,
8) factory acceptance tests (FAT),
9) delivery to ESS storage facility (Lund Sweden),
10) transport to ESS site,
11) installation in the instrument hall (optional),
12) site acceptance test (SAT) of the complete systems at ESS,
13) documentation.