Document: NUREG-0800
Document ID: 4a1b6190-0ab9-4f40-b882-2069d09c8f97
Document Type: srp
Title: -
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1602/ML16029A367.pdf
Revision Date: 2023-06
Chapter: 5
Section ID: 5.4.2.1
CFR Part: 
CFR Title: 

Content:
Draft Revision 4 – April 2016 manufactured, and tested to ASME Class 1 criteria, although the staff-required classification is ASME Class 2.)* 3. The crevice between the tubesheet and the inserted tube will be limited because the tube will be expanded to the full depth of insertion of the tube in the tubesheet. The tube expansion and subsequent positive contact pressure between the tube and the tubesheet will preclude any buildup of impurities from forming in the crevice region and will reduce the probability of crevice boiling. The tube-to-tubesheet welds comply with ASME Class 1 criteria. The feedwater inlet design, including the feedring, uses materials and design features that resist degradation from flow-accelerated corrosion, water hammer, and thermal stratification. (The tube support plates will be manufactured from ferritic or martensitic stainless steel material, which laboratory tests have shown to be corrosion resistant to the operating environment.)* (The tube support plates will be designed and manufactured with noncircular holes (e.g., a quatrefoil-shaped hole) that only come in close contact with the tube at a limited number of locations around the tube’s circumference. The noncircular hole design promotes high-velocity flow along the tube, sweeping impurities away from the support plate locations.)* (The tube support structure manufacture will use a lattice grid design. This design (1) eliminates the narrow annular gap at the tube supports because the support may contact the tube at only four lines on the tube circumference and (2) provides almost complete washing of the tube surface with steam generator water.)* (The U-bend region of short-radius tubes will be stress-relieved after bending to reduce the residual stresses in this portion of the tube.)* 4. The fracture toughness of the ferritic materials is acceptable because it conforms with 10 CFR 50.55a, Appendix G to the ASME Code, and Appendix G to 10 CFR Part 50. 5. The welding of the