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:
a spectral analysis may be used in accordance with the guidelines of Regulatory Guide 1.60 (Ref. 41). 2. Methods Analytical methods used in performing structural response analyses should be reviewed. Justification should be supplied to show that the numerical solution techniques are appropriate. Linear and non-linear structural representations (i.e., the modeling) should also be reviewed. Experimental verification of the analytical representation of the fuel assembly components should be provided when practical. 4.2-18 Rev. 0 A sample problem of a simplified nature should be worked by the applicant and compared by the reviewer with either hand calculations or results generated by the reviewer with an independent code (Ref. 38). Although the sample problem should use a structural representation that is as close as possible to the design in question (and, therefore, would vary from one vendor to another), simplifying assumptions may be made (e.g., one might use a 3-assembly core region with continuous sinusoidal input). The sample problem should be designed to exercise various features of the code and reveal their behavior. The sample problem comparison is not, however, designed to show that one code is more conservative than another, but rather to alert the reviewer to major discrepancies so that an explanation can be sought. 3. Uncertainty Allowances The fuel assembly structural models and analytical methods are probably conservative and input parameters are also conservative. However, to ensure that the fuel assembly analysis does not introduce any non-convervatisms, two precautions should be taken: (a) If it is not explicitly evaluated, impact loads from the PWR LOCA analysis should be increased (by about 30%) to account for a pressure pulse, which is associated with steam flashing that affects only the PWR fuel assembly analysis. (b) Conservative margin should be added if any part of the analysis (PWR or BWR) exhibits pronounced sensitivity to input variations.