Document: NUREG-0800
Document ID: d51db4b1-0b68-4e27-8107-a41ccdbd671a
Document Type: srp
Title: ASME CODE CLASS 1, 2, AND 3 COMPONENTS, COMPONENT SUPPORTS,
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070337.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.9.3
CFR Part: 
CFR Title: 

Content:
ce the "effective" stiffness of a snubber is generally greater than that for the snubber support assembly (i.e., the snubber plus clamp, transition tube extension, back-up support structure, etc.) the snubber response characteristics may be "washed out" by the added flexibility in the support structure. The combined effective stiffness of the snubber and support assembly must therefore be considered in evaluating the structural response of the system or component. Snubber spring rate should be determined independent of clearance/lost motion, activation level, or release rate. The stiffness should be based on structural and hydraulic compliance only, and should consider the effects of temperature, and the effects of temperature should be considered.50 The snubber end fitting clearance, mismatch of end fitting clearances, mismatch of activation and release rates, and lost motion must be 51 minimized and should be considered when calculating snubber reaction loads and stress which are based on a linear analysis of the system or component. This is especially important in multiple snubber applications where mismatch of end fitting clearance has a greater effect on the load sharing of these snubbers than does the mismatch of activation level or release rate. Equal load sharing of multiple snubber supports should not be assumed if mismatch in end fitting clearance exists. (3) Design Specifications The required structural and mechanical performance of snubbers is determined from the user's systemapplicant's structural analysis described in subsections II.3.b (1) and (2). The snubber Design Specification is the 52 DRAFT Rev. 2 - April 1996 3.9.3-8 instrument provided by the purchaser to the supplier to assureensure that the requirements are met. The Design Specification should contain: (i) the general functional requirements, (ii) operating environment, (iii) applicable codes and standards, (iv) materials of construction and standards for hydraulic fluids and lubricants, (v)