Document: NUREG-0800
Document ID: 965060de-8238-4868-a4c8-9a07c3e8cf13
Document Type: srp
Title: Diversity and
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1515/ML15159A199.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7.9
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acceptance criteria, and review process. For simple modifications, such as incorporating a single digital function into an otherwise analog I&C system, the diversity and defense in depth analysis may be very simple. Extensive and detailed analyses may be required for modifications that replace each of the reactor protection and control systems with digital I&C systems. 3.4 Review of Software Life-Cycle Process Planning The staff’s conclusion regarding the quality and reliability of digital computer systems is based on confirmation of the following points: Appendix 7.0-A-12 Draft Revision 6 – August 2015 i. Plant and overall I&C system requirements are correctly decomposed into the digital I&C system requirements for each digital I&C system under review. Critical hardware and software characteristics are identified. ii. A development process is specified and documented such that implementation of the process gives a high degree of confidence that the functional requirements are or will be or are implemented in the computer system. The life-cycle process plan describes a coordinated engineering process in which design outputs at each planned stage of the design process are verified to implement the input requirements of the stage. iii. The specified process and products, including design outputs, are designed to be inspected at staged checkpoints. iv. The installed system functions as designed. Validation and integration tests, acceptance tests and onsite preoperational, and startup functional tests demonstrate that the identified critical hardware and software characteristics are verified. As discussed above, the staff’s determination of the qualification of digital I&C systems and components is based in part on confirmation that the software for the systems is developed using a disciplined engineering process. Typically, this process is described in a set of software life-cycle process development planning documents that define the process requirements and