Document: NUREG-0800
Document ID: c3be7591-d074-48a8-bb9c-4dcdfccd0ddf
Document Type: srp
Title: Draft Revision 6 – August 2015
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1515/ML15159A959.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7
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CFR Title: 

Content:
38). Periodic tests include surveillance tests. A self-test is a test or series of tests performed by a device upon itself. Self-tests include on- line continuous self-diagnostics, equipment-initiated self-diagnostics, and operator-initiated self- diagnostics. Surveillance tests are conducted specifically to confirm compliance with technical specification surveillance requirements. A watchdog timer is a form of interval timer that is used to detect a possible malfunction (IEEE Std C37.1-1994, “IEEE Standard Definition, Specification, and Analysis of Systems Used for Supervisory Control, Data Acquisition, and Automatic Control”). BTP 7-17-4 Draft Revision 6 – August 2015 4. Purpose The purpose of this BTP is to provide guidance for NRC staff to verify that the previously cited regulatory basis and standards are met by an applicant or licensee's submittal. The objectives of this BTP are to confirm that: • The safety system (including self-test) is designed for in-service testability commensurate with the safety functions to be performed through all modes of plant operation. • The positive aspects of self-test features are not compromised by the additional complexity that may be added to the safety system by the self-test features. • Hardware and software design support the required periodic testing. • Failure modes assumed to be detectable by the single-failure analysis are in fact detectable. Failures may be detectable by observing operational characteristics as well as other methods. B. BRANCH TECHNICAL POSITION 1. Introduction Surveillance testing taken together with automatic self-testing should provide a mechanism for detecting all detectable failures. Digital computer-based instrumentation and control (I&C) systems are more prone to different kinds of failures than traditional analog systems are. Self-testing and watchdog timers should reduce the time to detect and identify failures. Computer self-testing is most effective at detecting random