Document: NUREG-0800
Document ID: 7a278d84-5310-4198-b914-fa3af5a0a0ef
Document Type: srp
Title: Appendix 7-A
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0525/ML052500553.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7
CFR Part: 
CFR Title: 

Content:
functions and software for other functions such as testing should be designed to minimize the complexity of the software logic and data structures. The hardware and software used to perform automatic self-testing should be of equivalent safety classification of the tested system, unless physical, electrical, and communications independence are maintained such that no failure of the test function can inhibit the performance of the safety function. The positive aspects of self-test features should not be compromised by the additional complexity that may be added to the safety system by the self-test features. The improved ability to detect failures provided by the self-test features should outweigh the increased probability of failure associated with the self-test feature. Self-test functions should be verified during periodic functional tests. Periodic Testing Systems should provide the ability to conduct periodic testing consistent with the technical specifications and plant procedures. As required by ANSI/IEEE Std 279, Section 4.13 and Reg. Guide 1.47, if the protective action of some part of a protection system is bypassed or deliberately rendered inoperative for testing, that fact should be Appendix 7-A Rev. 4 — June 1997 BTP HICB-17-5 continuously indicated in the control room. Provisions should also be made to allow operations staff to confirm that the system has been properly returned to service. Reg. Guide 1.118 states in part that test procedures for periodic tests should not require makeshift test setups. For digital computer-based systems, makeshift test setups, including temporary modification of code or data that must be appropriately removed to restore the system to service, should be avoided. If automatic self-test features are credited with automatically performing surveillance test functions, provisions must be made to confirm the execution of the automatic tests during plant operation. The capability to periodically test and calibrate the