Document: NUREG-0800
Document ID: 21b37b7c-b45c-4247-b4a5-c2f28df75be4
Document Type: srp
Title: INSTRUMENTATION AND CONTROLS (Tier 1)
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070663.pdf
Revision Date: 2023-06
Chapter: 14
Section ID: 14.3.5
CFR Part: 
CFR Title: 

Content:
ing design issues: (1) General functional requirements for the system (2) Hardware and software architecture (3) Single failure criterion (4) Quality of components and modules (hardware, software, and firmware) (5) Equipment qualification (mild and harsh environments) (6) Channel integrity and channel independence (7) Classification of equipment (8) Isolation devices (electrical and data) (9) Single random failure (10) System inputs (11) Capability for sensor checks, tests and calibration (12) Channel bypasses, operating bypasses, indication of bypasses, and access to means for bypassing (13) Completion of protective action once initiated (14) Manual initiation (15) Information read-out (16) Identification Tier 1 should be reviewed for adequacy of both safety-related and non-safety-related systems of the design. The I&C design described in SSAR and Tier 1 may be to the level of control functional blocks. The block concept is useful for developing the system control interface diagrams that are needed for depicting the configuration of the I&C DRAFT Rev. 0 - April 1996 14.3.5-4 system architecture. Criteria from the SRP applicable to those systems should be used in the review. 2. For the microprocessor and digital control technology aspects of the I&C system design, applicants may provide incomplete design information in DCD Tier 2. This is because the digital computer-based I&C systems are a rapidly changing technology, and therefore it may not be appropriate for applicants to "lock in" the design for the time from design certification until the actual construction of the facility, when it could be obsolete. The staff allows the applicant to provide the processes and design acceptance criteria (DAC) by which the details of the design would be developed, designed, and evaluated. Detailed supporting information is in DCD Tier 2 Chapters 7 and 14.3. In lieu of having a completed I&C design for review, the reviewer must base the safety determination on an acceptable