Document: NUREG-0800
Document ID: 76205ba0-6d0f-463f-b38b-37cc41a9b7ec
Document Type: srp
Title: COMPRESSED AIR SYSTEM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0705/ML070550044.pdf
Revision Date: 2023-06
Chapter: 9
Section ID: 9.3.1
CFR Part: 
CFR Title: 

Content:
ided into subsystems that provide control air to safety-related components and systems and subsystems that provide compressed air to nonsafety-related components and systems. For the purposes of these technical rationales, CAS portions that provide control air to safety-related components and systems are referred to as the ICAS. The technical rationale for application of these acceptance criteria to the areas of review addressed by this SRP section is discussed in the following paragraphs: 1. GDC 1 requires that safety-related SSCs be designed, fabricated, erected, and tested to quality standards commensurate with the importance of the safety functions performed. The ICAS provides compressed air or nitrogen required to actuate or control equipment that performs safety-related functions during normal operations, transients, or accidents. Generic Issue 43, “Reliability of Air Systems,” states concerns about the reliability of safety-related equipment actuated or controlled by compressed air. As indicated in NUREG-1275 and Generic Letter 88-14 as to this generic issue, (e.g., oil, particulate, water, etc.) compressed air contamination is a significant contributor to unreliability in safety-related equipment controlled or actuated by compressed air. In some plant designs, the ICAS or equipment supplied by the ICAS may be supplied under certain operating conditions from backup compressed air sources outside the scope of the ICAS. In these cases there is the potential for a contaminated compressed air source to adversely affect the reliability of the ICAS or equipment supplied by the ICAS. RG 1.68.3 recognizes this potential and RG 1.68.3, Position C.9, states the guidance that pre-operational testing should verify whether equipment designed to be supplied by the instrument and control air system is not supplied by other compressed air supplies with less restrictive air quality requirements. ANSI/ISA-S7.3-R1981 provides air quality criteria. This criteria, if followed