Document: NUREG-0800
Document ID: 11a2be5f-50e6-47c7-beee-25b5049ab4bb
Document Type: srp
Title: REACTOR TRIP SYSTEM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052350474.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7.2
CFR Part: 
CFR Title: 

Content:
s required to assure that no failure of a power supply will result in maintaining power to the system such that the protective function (trip) of the RTS is 7.2-5 Rev. 2 - July 1981 negated (fail-safe de'sign). For example, loss of power to a sensor channel should cause a channel trip. Similarly, a loss of power to a logic element or actuator channel should result in a trip. Exception to this latter rule may be taken, as long as the single failure criterion is satisfied and the power sources required are designed as Class 1E power systems. The RTS logic matrices should be reviewed to determine whether redundant circuitry includes the contacts of relays or switches in mutually redundant logic ciruits. This task can be accomplished during the detailed drawing review. When violations of the single failure criterion are found, they are to be identified to the appli- cant and corrected. The staff safety evaluation report should discuss the final disposition of designs that are revised to satisfy the acceptance criterion. 3. System Testing and Inoperable Surveillance The descriptive information as supplemented by functional logic diagrams *(CP and OL) and electrical schematics (OL) are reviewed to verify that the design has the necessary provisions to permit testing of the RTS on a periodic basis when the reactor is in operation. The reviewer is guided. by the recommendations set forth in Regulatory Guide 1.22 and IEEE Std 279, paragraph 4.10, in arriving at an acceptable method of periodic testing of actuation devices (e.g., solenoids, breakers) and actuated equipment (control rods). The same guidance is used to review testability of all modules, relays, permissives, bypasses, and control devices. The descriptive information (CP and OL) and the design implementation as depicted on electrical drawings (OL) of the means proposed for auto- matically indicating, at the system level, bypassed or deliberately. inoperable RTS protection channels are reviewed to ascertain that