Document: NUREG-0800
Document ID: 896f0b4b-b27c-462b-aed0-872a58b455c8
Document Type: srp
Title: Revision 6 – August 2016
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1601/ML16019A327.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7
CFR Part: 
CFR Title: 

Content:
al dedication of PLC embedded, operating system software, and programming tools. 3. Purpose The purpose of this BTP is to provide guidance for NRC staff to verify conformance with the previously cited regulatory bases and standards in the design of digital computer systems using PLCs. This BTP has two objectives: • To assure that embedded and operating systems software, programming tools, and peripheral components are reviewed, and the appropriate acceptance criteria are applied. • To assure that the PLC application software (e.g., ladder-logic software) are developed using an appropriate software development process. B. BRANCH TECHNICAL POSITION 1. Introduction PLCs are often used to monitor and control industrial processes. They are typically commercial- grade computer systems that include simplified operating systems and standard service functions such as self-testing and communications. Most PLCs are configured for their specific application using a high-level language, such as ladder logic. The software for PLCs should be designed and implemented using a process that conforms to the guidance in SRP BTP 7-14. Software design and implementation for specific applications may be easier to implement for PLCs due to the use of high level languages and the fact that many service functions are already included as part of the commercial product. PLC application software can be expected to use standard functions provided by the PLC vendor. Standard functions may have considerable industrial experience. This experience may supplement other methods of evaluating the quality of the PLC software, provided the experience is commensurate with the reactor application and field trouble reports are generated, available, and reviewed. If existing industrial experience cannot be shown to be applicable to the safety system application, it is of limited use. SRP Appendix 7.0-A, “Review Process for Digital Instrumentation and Control Systems,” Subsection C.3, describes the