Document: NUREG-0800
Document ID: 855b2438-2ddf-48e9-8762-e39097109e12
Document Type: srp
Title: FUEL SYSTEM DESIGN
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052340660.pdf
Revision Date: 2023-06
Chapter: 4
Section ID: 4.2
CFR Part: 
CFR Title: 

Content:
fuel system structural members should be provided. Stress limits that are obtained by methods similar to those given in Section-III of the ASME Code (Ref. 4) are acceptable. Other proposed limits must be justified. (b) The cumulative number of strain fatigue cycles on the structural members mentioned in paragraph (a) above should be significantly less than the design fatigue lifetime, which is based on appro- priate data and includes a safety factor of 2 on stress amplitude or a safety factor of 20 on the number of cycles (Ref. 5). Other proposed limits must be justified. (c) Fretting wear at contact points on the structural members mentioned in paragraph (a) above should be limited. The allowable fretting wear should be stated in the Safety Analysis Report and the stress and fatigue limits in paragraphs (a) and (b) above should presume the existence of this wear. (d) Oxidation, hydriding, and the buildup of corrosion products (crud) should be limited. Allowable oxidation, hydriding, and crud levels should be discussed in the Safety Analysis Report and.shown to be acceptable. These levels should be presumed to exist in paragraphs (a) and (b) above. The effect of crud on thermal-hydraulic considerations is reviewed as described in SRP Section 4.4. (e) Dimensional changes such as rod bowing or irradfation growth of fuel rods, control rods, and guide tubes need not be limited to 4.2-3 Rev. 2 - July 1981 set values (i.e., damage limits), but they must be included in the design analysis to establish operational tolerances. (f) Fuel and burnable poison rod internal gas pressures should remain below the nominal system pressure during normal opera- tion unless otherwise justified. (g) Worst-case hydraulic loads for normal operation should not exceed the holddown capability of the fuel assembly (either gravity or holddown springs). Hydraulic loads for this evaluation are reviewed as described in SRP Section 4.4. (h) Control rod reactivity must be maintained. This may require