Document: NUREG-0800
Document ID: f4b8f0c1-9a14-46be-88c9-a6cb74d64dff
Document Type: srp
Title: Rev. 4 — June 1997
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0525/ML052500499.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7
CFR Part: 
CFR Title: 

Content:
ecovery actions. During either partial or full system initialization or shutdown after a loss of power, control output to the protection system actuators should fail to a predefined, preferred failure state. System restart upon restoration of power should not automatically transfer the actuators out of the predefined failure state. Changes to the state of plant equipment from the predefined state following restart and reinitialization (other than changes in response to valid protection system signals) should be under the control of the operator in accordance with appropriate plant procedures. 11. Section 5.6 — Independence This section requires in part independence between (1) redundant portions of a safety system, (2) safety systems and the effects of design basis events, and (3) safety systems and other systems. Three aspects of independence should be addressed in each case: • Physical independence. • Electrical independence. • Communications independence. Guidance for evaluation of physical and electrical independence is provided in Reg. Guide 1.75, "Physical Independence of Electrical Systems," which endorses IEEE Std 384, "IEEE Standard Criteria for Rev. 4 — June 1997 SRP 7.1-C-9 Independence of Class 1E Equipment and Circuits." The applicant/licensee should confirm that the safety system design precludes the use of components that are common to redundant portions of the safety system, such as common switches for actuation, reset, mode, or test; common sensing lines; or any other features which could compromise the independence of redundant portions of the safety system. Physical independence is attained by physical separation and physical barriers. Electrical independence should include the utilization of separate power sources. (The EELB and Plant Systems Branch (SPLB) review power source requirements. HICB reviewers should coordinate with these branch requirements to confirm that I&C safety system power sources are adequate.) Transmission of