Document: NUREG-0800
Document ID: b172ba61-9651-45f8-ac8e-6d6e00e27060
Document Type: srp
Title: STEEL CONTAINMENT
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1006/ML100630179.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.8.2
CFR Part: 
CFR Title: 

Content:
tainments that use alternate failure criteria will be subject to detailed staff review, on a case- by-case basis. The NRC has published guidance on computer modeling of steel containments for internal pressure capacity calculations in NUREG/CR-6906. Note: In applying the analysis methodology to existing containment structures, it is permissible to use as-built material properties for the steel containment material. Sufficient material certification data must be available to establish with reasonable confidence a lower bound, a median, and an upper bound value for the important material parameters. These values must be adjusted for the design-basis accident temperature. For deterministic assessments, the lower bound values should be used. For probabilistic risk assessment, calculations of failure probability vs. pressure should consider the statistical distribution of the material properties. Containment Penetrations: The methodology described above applies to the containment structure. A complete evaluation of the internal pressure capacity must also address major containment penetrations, such as the removable 3.8.2-18 Revision 3 - May 2010 drywell head and ventlines for BWR designs, equipment hatches, personnel airlocks, and major piping penetrations. Other potential containment leak paths through mechanical and electrical penetrations should also be addressed. Special Considerations for Steel Ellipsoidal and Torispherical Heads: Under internal pressure, a potential failure mode of steel ellipsoidal and torispherical heads is buckling, resulting from a hoop compression zone in the knuckle region. This potential mode of failure needs to be evaluated, to determine if it is the limiting condition for the pressure capacity of the containment. The analysis should consider nonlinear material and geometric behavior and address the effect of initial geometric imperfections either explicitly (direct modeling) or implicitly (through the use of appropriate imperfection