Document: NUREG-0800
Document ID: 7bd74f6c-471d-40b1-9659-6a5e00c5f169
Document Type: srp
Title: MAINTENANCE RULE
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1409/ML14099A044.pdf
Revision Date: 2023-06
Chapter: 17
Section ID: 17.6
CFR Part: 
CFR Title: 

Content:
ing function, and includes those SSCs required to support the explicitly used SSCs even though they are not called out in the EOP. For example, all SSCs associated with an instrument loop supporting a control room instrument that is specifically called out in the EOP are considered explicitly used. “Implied” use means those SSCs not specifically called out in the EOP, but are understood to be essential for successful completion of the associated mitigating EOP step, although they may not directly address or mitigate the event. For SSCs whose failure could prevent safety-related SSCs from fulfilling their safety-related functions, the applicant should describe how the process considers system interdependencies, including failure modes and effects of nonsafety-related SSCs (e.g., support systems) that could directly affect safety-related functions. For SSCs whose failure could cause scrams or unwanted engineered safeguard feature actuations and those whose failure caused a reactor 17.6-6 Revision 2 – July 2014 SCRAM or actuation of safety-related systems, the applicant should describe the process for identifying and using relevant utility- specific and industry-wide operating experience. Note: NRC Generic Letter 2007-001 describes underground power cable failures that may cause plant transients. If at the time of the COL application, the Commission has approved the applicant’s program for implementing 10 CFR 50.69 for its new reactor plant, the requirements of 10 CFR 50.69 may be followed instead of those of 10 CFR 50.65 for risk- informed safety classification (RISC)-3 and RISC-4 SSCs in the scope of the MR except for the purposes of 10 CFR 50.65(a)(4). In this case, the applicant should describe its process for identifying RISC-3 SSCs among those in MR scope under 10 CFR 50.65(b)(1) and RISC-4 SSCs among those in MR scope under 10 CFR 50.65(b)(2). The applicant should also describe its process for treatment under 10 CFR 50.69 of those RISC-3 and RISC-4 SSCs