Document: NUREG-0800
Document ID: 1da20040-18d5-4c75-9863-5f578a9d73a5
Document Type: srp
Title: Revision 5 - March 2007
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0705/ML070550078.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7
CFR Part: 
CFR Title: 

Content:
ance, which some licensees define as leeway given to instrument technician or calibration tolerance or setting tolerance. Setting tolerance can be based upon particular uncertainties such as reference accuracy, MT&E, and readability, but the total loop uncertainty analysis must explicitly account for each of these uncertainty terms whether or not the ST incorporates these uncertainties. ST may also be a specified value selected on the basis of engineering judgment or other consideration. However, in that situation, the as-found value must be compared with the previous as-left value. 4. Purpose The purpose of this BTP is to provide guidance for NRC staff to verify conformance with the previously cited regulatory bases and standards for instrument setpoints. This BTP has three objectives: • To verify that setpoint calculation methods are adequate to assure that protective actions are initiated before the associated plant process parameters exceed their analytical limits. • To verify that setpoint calculation methods are adequate to assure that control and monitoring setpoints are consistent with their requirements. • To confirm that the established calibration intervals and methods are consistent with safety analysis assumptions. B. BRANCH TECHNICAL POSITION 1. Introduction Instrumentation and control (I&C) safety systems control plant parameters to assure that safety limits will not be exceeded under the most severe design basis accident. Instrument setpoints and acceptable as-left and acceptable as-found bands for these I&C safety system functions are chosen so that potentially unsafe or damaging process excursions (transients) can be avoided and/or terminated before plant conditions exceed safety limits. Accident analyses establish the limits for critical process parameters. These analytical limits, as established by accident analyses, do not normally include considerations for the accuracy (uncertainty) of installed instrumentation. Additional analyses and