Document: NUREG-0800
Document ID: 00a272ef-67f0-4667-9a5b-6f9c9490ef5b
Document Type: srp
Title: CONTROL SYSTEMS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1602/ML16020A095.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7.7
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Content:
r design considerations that should be emphasized in the review of the control systems are identified below. • Design bases - The review should confirm that the control systems include the necessary features for manual and automatic control of process variables within prescribed normal operating limits. • Safety classification - The review should confirm that the plant accident analysis in Chapter 15 of the SAR does not rely on the operability of any control system function to assure safety. • Effects of control system operation upon accidents - The review should confirm that the safety analysis includes consideration of the effects of both control system action and inaction in assessing the transient response of the plant for accidents and anticipated operational occurrences. • Effects of control system failures - The review should confirm that the failure of any control system component or any auxiliary supporting system for control systems does not cause plant conditions more severe than those described in the analysis of anticipated operational occurrences in Chapter 15 of the SAR. This evaluation should ensure that failure modes that can be associated with digital systems such as software design errors and random hardware failures, as well as the methods used to account for these failure modes, are addressed and documented. (The evaluation of multiple independent failures is not intended.) • Effects of control system failures caused by accidents - The review should confirm that the consequential effects of anticipated operational occurrences and accidents do not lead to control system failures that would result in consequences more severe than those described in the analysis in Chapter 15 of the SAR. • Environmental control system - The review should confirm that I&C systems include environmental control as necessary to protect equipment from environmental extremes. This would include, for example, heat tracing of safety instruments and instrument