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:
control rod insertion must be combined with the SSE loads, and control rod insertability must be demonstrated for that combined load. For a PWR, if combined loads on the grids remain below P(crit) as defined above, then significant deformation of the fuel assembly would not occur and con- trol rod insertion would not be interfered with by lateral displacement of the guide tubes. If combined loads on the grids exceed P(crit), then additional analysis is needed to show that deformation is not severe enough to prevent control rod insertion. For a BWR, several conditions must be met to demonstrate control blade insertability: (a) combined loads on the channel box must remain below the allowable value defined above for components other than grids; otherwise, additional abalysis is needed to show that deformation is not severe enough to prevent control blade insertion, and (b) vertical liftoff forces must not unseat the lower tieplate from the fuel support piece such that the resulting loss of lateral fuel bundle positioning could interfere with control blade insertion. 2. Safe Shutdown Earthquake Two criteria apply for the SSE: (a) fuel rod fragmentation must not occur as a result of the seismic loads,.and (b) control rod inserta- bility must be assured. The first criterion is satisfied by the criteria in Paragraph 1. The second criterion must be satisfied for SSE loads alone if no analysis for combined lodds is required by Paragraph 1. 4.2-21 Rev. 0