Document: NUREG-0800
Document ID: 3ea2f0ac-4d7e-464a-b1c4-390c3970f642
Document Type: srp
Title: provides specific thermal-hydraulic criteria.  The available radioactive fission product
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0707/ML070740002.pdf
Revision Date: 2023-06
Chapter: 4
Section ID: 4.4
CFR Part: 
CFR Title: 

Content:
itional in-reactor surveillance (e.g., insertion times) may also be necessary for new designs, dimensions, and materials to demonstrate satisfactory performance. 4.2-7 Revision 3 - March 2007 vi. Fuel and burnable poison rod internal gas pressures should remain below the nominal system pressure during normal operation or other limits must be justified based on, but not limited to, the following minimum criteria. (1) No cladding liftoff during normal operation (2) No reorientation of the hydrides in the radial direction in the cladding (3) A description of any additional failures resulting from departure of nucleate boiling (DNB) caused by fuel rod overpressure during transients and postulated accidents (see Subsection II, item 1.B.vii) vii. Because unseating a fuel bundle may challenge control rod/blade insertion, an evaluation of worst-case hydraulic loads should be performed for normal operation, AOOs, and accidents. These 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. viii. Control rod reactivity and insertability must be maintained. This requires that, at a minimum, the following may need to be reviewed: (1) Changes in control rod configuration (2) Introduction of new materials (3) Changes in neutronics and mechanical lifetime (4) Changes in mechanical design (5) The ability to exclude water/coolant if water-soluble or leachable materials (e.g., B4C) are used Changes in mechanical and neutronics lifetimes need to be calculated using acceptable methods. Safety analyses must specifically account for the reduction in neutron-absorbing capabilities with time in-reactor. B. Fuel Rod Failure This subsection applies to normal operation, AOOs, and postulated accidents. Items 1.B.i through 1.B.iii below address failure mechanisms that are more limiting during normal operation; Section 4.2