Document: NUREG-0800
Document ID: 123b0c6f-59c2-4a34-9ab3-623e0eb04db3
Document Type: srp
Title: B-9
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:
Draft Revision 6 – August 2015 4.8. Derivation of System Inputs (IEEE Std 279-1971, Clause 4.8) A protection system that requires loss of flow protection would, for example, normally derive its signal from flow sensors. A design might use an indirect parameter such as a pressure signal or pump speed. However, the applicant/licensee should verify that any indirect parameter is a valid representation of the desired direct parameter for all events. Even a directly measured variable should be reviewed and its response to postulated events compared with the credit taken for the parameter in the events for which it provides protection. For both direct and indirect parameters, the applicant or licensee should verify that the characteristics (e.g., range, accuracy, resolution, response time) of the instruments that produce the protection system inputs are consistent with the analysis provided in Chapter 15 of the SAR. 4.9. Capability for Sensor Checks (IEEE Std 279-1971, Clause 4.9) The most common method used to verify the availability of the input sensors is by cross checking between redundant channels that have available readout. When only two channels of readout are provided, the applicant or licensee should state the basis used to ensure that an operator will not take incorrect action when the two channel readouts differ. The applicant/licensee should state the method to be used for checking the operational availability of non-indicating sensors. 4.10. Capability for Test and Calibration (IEEE Std 279-1971, Clause 4.10) Guidance on periodic testing of the protection system is provided in RG 1.22, “Periodic Testing of Protection System Actuation Functions,” and in RG 1.118, “Periodic Testing of Electric Power and Protection Systems,” which endorses IEEE Std 338, “Standard Criteria for the Periodic Surveillance Testing of Nuclear Power Generating Station Safety Systems.” The extent of test and calibration capability provided bears heavily on whether the