Document: NRC Regulatory Guide
Document ID: fc586342-92f7-4c77-ae76-79e3674cf288
Document Type: regulatory_guide
Title: Criteria for Programmable Digital Devices in Safety-Related Systems of  Nuclear Power Plants + HISTORY –HISTORY 02/2023 – DG-1374, Proposed Revision 4 Prior to issuance of DG-1374, RG 1.152 was entitled, “Criteria for Use of Computers in Safety-Systems of Nuclear Power Plants” 06/2010 – DG-1249, Proposed Revision 3 – Revise 12/2004 – DG-1130, Proposed Revision 2 – Revise 05/1995 – DG-1039, Proposed Revision 1 03/1983 – DG-1130, Proposed Revision 2 – Revise (Rev. 4)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2301/ML23012A242.pdf
Revision Date: 2023-05
Chapter: 
Section ID: RG-1.152
CFR Part: 
CFR Title: 

Content:
lying with the requirements of regulations with respect to high functional reliability and design requirements for PDDs used in the safety-related systems of nuclear power plants. The staff takes some exceptions to the guidance in IEEE Std 7-4.3.2-2016 and provides clarifications and points of emphasis as identified below. a. Exceptions (1) Revision 2016 of IEEE Std 7-4.3.2 presents an approach that the staff considers acceptable in meeting the requirements of NRC regulations with respect to high functional reliability and design requirements for PDDs used in the safety-related systems of nuclear power plants, subject to the following specific exceptions. 1.1 As discussed in Section B of this RG, the NRC staff has not endorsed Annexes B, C, and E. However, the staff believes that these annexes contain useful information. 1.2 Revision 2016 of IEEE Std 7-4.3.2 includes examples to supplement the guidance. However, the NRC’s endorsement of IEEE Std 7-4.3.2-2016 does not constitute a determination that the examples are applicable for all licensees and applicants. A licensee or applicant should ensure that a given example is applicable to its plant-specific circumstances before implementing the guidance as described in that example. b. Clarifications (1) System Integrity 1.1 Safety-related instrumentation and control systems should be designed to operate in a predictable and repeatable manner. The term “predictable”1 generally refers to the ability to determine the output of a system at any time through known relationships among the controlled system states and required responses to those states, such that a given set of input signals will always produce the same output signals. The term “repeatable”1 generally refers to the output of a system being consistently achieved given the same input and system properties, including internal and external conditions. PDDs used in safety-related systems should have adequate system integrity such that the safety-related