Document: NUREG-0800
Document ID: 5e3dbec9-a39f-4531-9eb9-705982190066
Document Type: srp
Title: REACTOR PRESSURE VESSEL INTERNALS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1613/ML16134A059.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.9.5
CFR Part: 
CFR Title: 

Content:
failure) adversely impact the performance of safety functions (reactivity monitoring and control, core cooling, and fission product confinement). Application of GDC 4 to the reactor internals provides assurance that the effects of environmental conditions to which they are exposed over their installed life will not diminish the likelihood of performance of these safety functions under all operating conditions, including accidents. This provides assurance that failures of the reactor internals from environmental service conditions that could cause loss of capability to monitor reactivity, fuel damage from loss of reactivity control, structural damage to fuel cladding, or interference with core cooling are not likely to occur. NUREG-0609 evaluates certain postulated pipe ruptures (e.g., double-ended guillotine breaks of primary reactor coolant loop piping) that might cause asymmetric blowdown loadings on the reactor internals. SRP Section 3.6.2 provides additional guidance on 3.9.5-8 Revision 4 – March 2017 blowdown loading. GDC 4 allows such dynamic effects of postulated pipe ruptures to be excluded from the design basis when analyses accepted by the staff demonstrate that the probability of fluid system piping rupture is extremely low under conditions consistent with the design basis for the piping. Application of GDC 4 to the reactor internals provides assurance that asymmetric loading effects of postulated pipe ruptures are either accommodated in the design (with assurance of the functionality and integrity of reactor internals) or demonstrated to be extremely unlikely to occur and that overstress failures of the reactor internals that could cause loss of capability to monitor reactivity, fuel damage resulting from loss of reactivity control, structural damage to fuel cladding, or interference with core cooling are unlikely to occur. 4. GDC 10 requires that the reactor core and its coolant, control, and protection systems be designed with appropriate margin to