Baseline Design for Braidwood Victor Guarino Group Leader - Mechanical Engineer Argonne National Laboratory High Energy Physics division Victor Guarino Mechanical Support Group High Energy Physics - ANL

BaselineWork Accomplished Written 50 page detailed design report. Defined detector Parameters Identified and evaluated industry standards for designing and fabricating Acrylic structures. Defined detector Assembly procedures. Performed detector Structural Analysis Performed structural analysis for detector Support Structure Defined and costed required Facilities and worked on site location. Technology Transfer trip with Reynolds Polymer Technology. Victor Guarino HEP-ANL

Detector Parameters Three Volumes Inner volume 0.1% Gadolinium – 3.8m Dia. Middle Volume – no Gadolinium – 4.8m Dia. Outer Volume – Mineral oil without scint. or Gadolinium – 6.5m Dia. Victor Guarino HEP-ANL

Detector Design Outer steel sphere will be constructed in two halves joined with a flange to permit access if needed to PMTs. 6 vertical and 3 horizontal straps will support each inner sphere. All spheres will be simultaneously filled to reduce forces on internal support structure. Victor Guarino HEP-ANL

Designing With Acrylic Laminated Glass Scratch resistant High strength and stiffness Very brittle Low impact strength Acrylic Soft and scratches easily Potential to yellow in UV light Higher impact strength than glass Polycarbonate Cast Acrylic is the material of choice Commonly used for large structures Only material allowed in PVHO Stronger than Polycarbonate and does not have the brittleness of glass Victor Guarino HEP-ANL

Designing With Acrylic Fracture Mechanics Acrylic structures can fail at stresses lower than yield in a brittle manner due to unstable crack propagation. Design to a leak before failure criteria. Design stress of ~507psi is calculated on textbook values of fracture toughness. ASME PVHO -1,2 standards provide additional guidelines for maximum crack size and inspection. Cracks may develop during service due to chemical attack, thermal gradients, and fatigue. This may be a significant problem with pseudocumene. Victor Guarino HEP-ANL

Detector Assembly Inner acrylic sphere will be completely assembled off-site. Half spheres of middle acrylic sphere will be assembled off-site. Top half of middle sphere will be attached to inner sphere and then this assembly attached to bottom half sphere. Top half of outer steel sphere will be attached to middle sphere and then this assembly attached to bottom half sphere. Victor Guarino HEP-ANL

Detector Assembly Victor Guarino HEP-ANL

Detector Assembly Victor Guarino HEP-ANL

Detector Assembly Victor Guarino HEP-ANL

Detector Assembly Acrylic joints are a potential problem SNO had many problems Shrinkage during bonding caused deformation and internal stresses – potential source of future crazing. Thinner walls (8-12mm) should minimize this problem. Bonded joints need to be polished on the inside and outside. This is not possible on all of the joints. What is the optical quality of joints not polished on the inside? A possible 2” wide band not polished on the inside on the equator of the middle sphere. Victor Guarino HEP-ANL

Detector Structural Analysis Three Loading Scenarios examined Empty and being moved During filling process Full and being moved. Calculations performed: Sphere thicknesses based on supporting the entire weight of the liquid. Internal support structure of spheres supporting only the weight of the spheres. External support structure of detector to minimize deflections and induced stresses in spheres. Victor Guarino HEP-ANL

Detector Structural Analysis Sphere thicknesses: Inner Acrylic Sphere 10mm Middle Acrylic Sphere 14mm Outer steel sphere 6mm 6 vertical and 3 horizontal straps will be used to locate inner spheres No straps on the bottom of the sphere because it is felt that the sphere self weight is enough to insure that they do not float. Victor Guarino HEP-ANL

Detector Structural Analysis Victor Guarino HEP-ANL

Detector Support Structure Victor Guarino HEP-ANL

Facilities Near/Far Detector Buildings: $300k for surface building 300 tons overhead crane 40’ x 60’ travel and 550’ lift capacity At the far detector site there will be office space in a trailer. Utilities, lighting, Heat in each building $300k for surface building $1.4M for crane ~$15k for trailer for office space Victor Guarino HEP-ANL

Braidwood Near Detector Site Victor Guarino HEP-ANL

Comments from trip to Reynolds Polymer 800 psi design stress for acrylic Based on year tests done by Navy No crazing found in flexural loaded samples with 810 psi tensile stresses Bonds are design at 85% of this value Standard bond requires access to both sides of joint. Making two separate hemispheres allows full access Special well joint then needed for assembling full sphere 2” wide area of poor transparency Inner sphere could avoid this by having large enough chimney for person access (>18” ID ) Chimney design requires carefully designed ring to reduce stress concentrations Curved Acrylic pieces less than 1” thick are formed from stock cast sheet sizes. Surface flaws are repairable. Standard design guarantee from Reynolds is 10 years We must conduct tests to check compatibility of scintillator solution Grand Sasso rejected Acrylic after identifying chemical compatibility problems Maximum piece size for the detector is a trade off between shipping costs and on-site bonding effort. Need to sample acrylic for background radiation. Reynolds can provide samples of bonded joints to test light transmission. Victor Guarino HEP-ANL

Conclusion We need to begin immediately the pseudocumene/acrylic compatibility. Preliminary Baseline Design has been completed. Trip to Reynolds confirmed basic design/assembly of acrylic spheres. More R&D is needed on acrylic sphere construction/bonding and cost estimating. Outer steel sphere construction/geometry needs additional thought. Detailed design and the development of an R&D plan will be completed in the near term. Victor Guarino HEP-ANL