Document: NUREG-0800
Document ID: 2dffe24e-cd37-4ffc-9c37-16faf25676b1
Document Type: srp
Title: Appendix 7-A
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0525/ML052500579.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7
CFR Part: 
CFR Title: 

Content:
en protective system may be returned to normal. In addition, timely automatic control action is required when events occur too quickly for operator intervention. Reg. Guide 1.152, "Criteria for Power, Instrumentation, and Control Portions of Safety Systems," endorses the guidance of IEEE Std 7-4.3.2, "IEEE Standard for Digital Computers in Safety Systems of Nuclear Power Appendix 7-A Rev. 4 — June 1997 BTP HICB-21-3 Generating Stations," as an acceptable method for complying with the NRC's regulations for safety systems that use digital computers. The main body of IEEE Std 7-4.3.2 does not add to the guidance of IEEE Std 603 regarding timing and performance. However, Annexes E and F, although not endorsed by Reg. Guide 1.152, contain useful guidance on certain timing and architectural requirements. Annex E E.2.2.1(k) states that timing, response time, and performance requirements must be validated and verified. E.2.2.8.2 states that sizing and timing analyses are suggested to assess the feasibility of meeting response time and performance requirements mentioned in E.2.2.1(k). Annex F F.2.3.3(b) states that sizing and timing anomalies in requirements are considered abnormal conditions. F.2.3.5(g) states that failure of code to run within timing and sizing constraints imposed by validated requirements is considered an abnormal condition. Draft Reg. Guide DG-1045, proposed revision 3 to Reg. Guide 1.105, "Instrument Setpoints for Safety Systems," endorses ISA-S67.04, Part 1, "Setpoints for Nuclear Safety-Related Instrumentation Used in Nuclear Power Plants," as an acceptable method for initially setting and maintaining instrument calibrations in nuclear reactor I&C systems in order to ensure their proper response on demand. System time delays are an important consideration in establishing instrument setpoints. In addition to the above, NUREG/CR-6082 describes data communication systems, including aspects related to system performance and timing. NUREG/CR-6083