Document: NUREG-0800
Document ID: 915a95d4-8764-4981-952d-5a4327fad655
Document Type: srp
Title: B-4
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1515/ML15159A226.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7.1
CFR Part: 
CFR Title: 

Content:
applicant’s or licensee’s analysis should demonstrate that the number and location of sensors are adequate. Subsection 4.2 below discusses the consideration of the single failure criterion in the evaluation of this analysis. Clauses 3(4), 3(5), and 3(6) of IEEE Std 279-1971 require in part the identification of operational limits, the margin between operational limits, and the level for the onset of unsafe conditions (setpoint), and limits that require protective action (safety limit - i.e., value assumed in the safety analysis) for each variable. The applicant’s or licensee’s analysis should confirm that an adequate margin exists between operating limits and setpoints, such that a low probability exists for inadvertent actuation of the system. The applicant’s or licensee’s analysis should confirm that an adequate margin exists between setpoints and safety limits, such that the system initiates protective actions before safety limits are exceeded. RG 1.105, “Setpoints for Safety- Related Instrumentation,” and BTP 7-12 provide guidance on the establishment of instrument setpoints. The instrument performance data used in setpoint analyses should be consistent with the performance requirements established in the design basis as discussed in Clause 3(9) of IEEE Std 279-1971. BTP 7-6 provides specific guidance for determining if the timing margins for changeover from injection to recirculation mode are sufficient to allow manual initiation of the transition. Clause 3(7) of IEEE Std 279-1971 requires in part that the range of transient and steady-state conditions be identified for both the energy supply and the environment during normal, abnormal, and accident conditions under which the system must perform. This information is used in subsequent evaluations.