Document: NUREG-0800
Document ID: 42e7682f-df25-4a6a-94f4-7d44ea029702
Document Type: srp
Title: STEAM SYSTEM PIPING FAILURES INSIDE AND OUTSIDE OF CONTAINMENT
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070677.pdf
Revision Date: 2023-06
Chapter: 15
Section ID: 15.1.5
CFR Part: 
CFR Title: 

Content:
med value should be justified. h. For postulated pipe failure in nonseismically qualified portions of the main steam line (outside containment and downstream of the main steam isolation valves, MSIVs) due 38 to a seismically initiated event, only safety grade equipment should be assumed operative to mitigate the consequences of the break. 15.1.5-7 DRAFT Rev. 3 - April 1996 i. For postulated instantaneous pipe failures in seismically qualified portions of the main steam line (inside containment and upstream of the MSIVs), only safety grade equipment should be assumed operative. If, in addition, a single malfunction or failure of an active component is postulated, credit may be taken for the use of a backup nonsafety-grade component to mitigate the consequences of the break. j. During the initial 10 minutes of the transient, should credit for operator action be required (i.e.e.g., reactor coolant pump RCP trip), an assessment for the limiting 39 consequence must be performed in order to account for operator delay and/or error. Technical Rationale40 The technical rationale for application of these acceptance criteria to reviewing analyses of transients initiated by steam system piping failures is discussed in the following paragraphs:41 1. Compliance with GDC 17 requires (in part) that onsite and offsite electrical power systems be provided to ensure the functioning of structures, systems, and components important to safety. The safety function for each power system (assuming the other system is not functioning) shall be to provide sufficient capacity and capability to ensure that (a) the specified acceptable fuel design limits and the design conditions of the reactor coolant pressure boundary are not exceeded as a result of anticipated operational occurrences and (b) the core is cooled and containment integrity and other vital functions are maintained. GDC 17 is applicable to this section because it requires that the loss of offsite power be considered — not as a