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:
No loss of coolable geometry due to (1) fuel pellet and cladding fragmentation and dispersal and (2) fuel rod ballooning. D. FISSION PRODUCT INVENTORY The total fission-product gap fraction available for release following any RIA would include the steady-state gap inventory (present prior to the event) plus any fission gas released during the event. The steady-state gap inventory would be consistent with the Non-LOCA gap fractions cited in RG 1.183 (Table 3) and RG 1.195 (Table 2) and would be dependent on operating power history. Whereas fission gas release (into the rod plenum) during normal operation is governed by diffusion, pellet fracturing and grain boundary separation are the primary mechanisms for fission gas release during the transient. Based upon measured fission gas release from several RIA test programs, the staff developed the following correlation between gas release and maximum fuel enthalpy increase: Transient FGR = [(0.2286*ΔH) – 7.1419] Where: FGR = Fission gas release, % (must be > 0) ΔH = Increase in fuel enthalpy, Δcal/g The transient release from each axial node which experiences the power pulse may be calculated separately and combined to yield the total transient FGR for a particular fuel rod. The combined steady-state gap inventory and transient FGR from every fuel rod predicted to experience cladding failure (all failure mechanisms) should be used in the dose assessment. Additional guidance is available within RG 1.183 and 1.195. 4.2-35 Revision 3 - March 2007 FIGURE B-1: PWR PCMI Fuel Cladding Failure Criteria 0 25 50 75 100 125 150 175 200 0 0.04 0.08 0.12 0.16 0.2 Oxide/Wall Thickness Fuel Enthalpy Rise (cal/g) Cladding Failure (0.04, 150) (0.20, 60) (0.08, 75) 4.2-36 Revision 3 - March 2007 FIGURE B-2: BWR PCMI Fuel Cladding Failure Criteria Figure B-2 Note: The empirical database supporting the BWR fuel cladding failure criteria consists of NSRR tests conducted from initial test temperatures ranging from 20 to 85 EC. Due to