Speaker
Description
The REFSANS horizontal reflectometer uses a unique system of focused neutron guides to the cold source to enable advanced reflectometry studies. These rectangular-cross-section guides are twisted and rotate through 90 degrees over a distance of 36 meters. During a recent reactor shutdown, work began on the complete replacement of this specialized guide system, which was already 20 years old.
However, the decommissioning and reinstallation process faced severe spatial and structural constraints, particularly within a transition zone known as the Kasematte. This specific room presents extraordinary logistical hurdles: it is accessible only via a single 80 cm wide entrance, completely lacks crane infrastructure, and possesses a ceiling unsuited for suspended loads. Furthermore, the handling is complicated by two adjacent beamlines with heavy shielding located just 60 cm above the floor. Navigating this environment required maneuvering vacuum vessels weighing two tones each, while maintaining a critical clearance distance between the guides of only 0.5 mm.
This presentation describes the technical solutions, handling equipment, and the procedures implemented to address these geometric and weight requirements. Additionally, the operational experiences and lessons learned from this instrument upgrade under confined conditions will be discussed.
Key Words
Neutron Guide Replacement, Twisted Neutron Guides, Space Constraints, Handling Equipment