Document: NRC Regulatory Guide
Document ID: 49ce24c8-1a15-48b2-9e26-8c6c2f9064f7
Document Type: regulatory_guide
Title: Dedication of Commercial-Grade Digital I&C Items for Use in Nuclear power Plants
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2200/ML22003A180.pdf
Revision Date: 2023-05
Chapter: 
Section ID: RG-1.250
CFR Part: 
CFR Title: 

Content:
n. Table 4-2 in TR-106439 identifies examples of design factors that can be evaluated in assessing digital item quality. However, TR-106439 states, “The dedicator must determine which activities are appropriate for each application. In general, the choice and extent of activities undertaken to verify adequate quality, and the specific criteria applied in making the assessment, depend on the safety significance and complexity of the device.” Ultimately, this process necessitates a high level of engineering judgment and can result in variability among reviewers. To accomplish the CDR requires a survey team that includes specialists who understand the device design, programmable logic, and system in which it will be applied, in addition to QA and programmatic issues. IEC 61508 is an international, performance-based standard for the functional safety of electrical, electronics, and programmable electronic equipment that addresses standardization issues raised by the use of programmable electronic systems. IEC 61508 defines the requirements for manufacturers to follow during product development to ensure that their products will have a predictably high level of resistance to random hardware and “systematic” design failures. Nuclear industry studies conducted within the past few years that indicate the devices certified to conform to the provisions of the standard appear to provide a degree of assurance that the device can be expected to experience a low probability of failure on demand and be relatively free from design flaws leading to systematic failures. The IEC 61508 standard is composed of seven parts: (1) Part 1: General requirements (2) Part 2: Requirements for electrical/electronic/programmable electronic safety-related systems DG-1402, Page 6 (3) Part 3: Software requirements (4) Part 4: Definitions and abbreviations (5) Part 5: Examples of methods for the determination of safety integrity levels (6) Part 6: Guidelines on the application of IEC 61508-2