Document: NRC Regulatory Guide
Document ID: c458fb43-5ee6-4e14-a33d-808ec974115a
Document Type: regulatory_guide
Title: Instrument Lines Penetrating Primary Reactor Containment + HISTORY - HISTORY 09/2009 – DG-1225 , Proposed Revision 1 Prior to the issuance of Revision 1, RG 1.11 was entitled "Instrument Lines Penetrating Primary Reactor Containment (Rev. 1)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0909/ML090970530.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.11
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CFR Title: 

Content:
l guidance document. In some cases, applicants or licensees may propose an alternative or use a previously established acceptable alternative method for meeting the intent of specified portions of the NRC’s regulations. Otherwise, the methods described in this guide will be used in evaluating implementation of the applicable regulations for license applications, license amendment applications, and amendment requests. REGULATORY ANALYSIS Statement of the Problem GDC 55 and 56 require, in part, that each line that penetrates the primary reactor containment and that is part of the reactor coolant pressure boundary or connects directly to the containment atmosphere has at least one locked, closed isolation valve or one automatic isolation valve inside containment, and at least one locked, closed isolation valve or one automatic isolation valve outside containment (a simple check valve may not be used as the automatic isolation valve outside containment) “unless it can be demonstrated that the containment isolation methods for a specific class of lines, such as instrument lines, are acceptable on some other defined basis.” Regulatory Guide 1.141 describes the methods that the NRC staff considers acceptable for use in meeting the intent of the GDC and endorses, in large part, the provisions of ANSI N271-1976. That industry standard provides limited guidance for instrument lines and, in fact, defers in large part to Safety Guide 11 (Regulatory Guide 1.11) for guidance on the other defined basis for acceptable instrument line isolation methods. DG-1225, Page 6 Objective The objective of this regulatory action is to update the NRC guidance on acceptable methods for the isolation of instrument lines that penetrate the primary containments of light-water-cooled reactors. Alternative Approaches The NRC staff considered the following alternative approaches: Do not revise Regulatory Guide 1.11. Revise Regulatory Guide 1.11. Alternative 1: Do Not Revise Regulatory Guide 1.11