Document: NRC Regulatory Guide
Document ID: c361be32-682d-4496-bb9f-6e52a80b0bd9
Document Type: regulatory_guide
Title: Instrument Sensing Lines + HISTORY –HISTORY 01/2019 – DG-1352 , Proposed Revision 2 09/2016 – Periodic Review of Revision 1 – Revise 12/2008 – DG-1178 , Proposed Revision 1 Draft IC 126-5, Proposed Revision 0, published 03/1982 (Rev. 2)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1815/ML18158A303.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.151
CFR Part: 
CFR Title: 

Content:
ing lines are contributing to the degradation of safety-related instrumentation operation. In response, the NRC issued IN 2013-12 to address this operating experience with regard to instrument sensing line sloping issues caused by improper design or installation, including inadequate sensing line slope, that have occurred at U.S. nuclear power plants. The importance of applying related design and installation criteria and providing adequate oversight is emphasized in IN 2013-12. In 2014, ISA revised ANSI/ISA-67.02.01-2014. The most important changes in ANSI/ISA- 67.02.01-2014 were to identify the minimum slope requirements for instrument sensing lines. These changes addressed the issues identified and discussed in NRC’s IN 2013-12. This version of the standard also added new figures to address Regulatory Position C.2 in RG 1.151, Revision 1, with respect to containment isolation requirements for water-filled sensing lines that penetrate the containment boundary. It also added information to address Regulatory Position C.4 in RG 1.151, Revision 1, which clarified the potential impacts of noncondensable gases in sensing lines during or following depressurization, and the potential impacts of flashing reference legs. In addition, the revision corrected the technical information in some of the figures included in the 1999 version. Therefore, this revision (Revision 2) of RG 1.151 removes Regulatory Positions C.2 and C.4 that were in Revision 1. The NRC staff also reviewed ISO 2186-2007 and found that it contains additional technical information and criteria useful for the design, lay-out and installation of a pressure signal transmission DG-1352, Page 6 system, including minimum instrument sensing line diameter based on the length of long impulse sensing lines. Separately, ANSI/IEEE Std. 622-1987 (reaffirmed in 1994), “IEEE Recommended Practice for the Design and Installation of Electric Heat Tracing Systems for Nuclear Power Generating Systems” (Ref. 13) provides