Document: NUREG-0800
Document ID: b75d082b-2493-4543-981a-2ee136d737cf
Document Type: srp
Title: BTP 8-9-1
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1405/ML14057A433.pdf
Revision Date: 2023-06
Chapter: 8
Section ID: 8
CFR Part: 
CFR Title: 

Content:
). III. Restoration of preferred or Onsite AC Power Following detection of an open phase condition and alarm in the control room, plant procedures should specify operator actions to ensure the standby diesel generators are connected to the auxiliary alternating current buses if they are not automatically connected in accordance with the design basis requirements or restore the offsite power source to a functional condition. BTP 8-9-7 Draft Revision 0 – May 2014 IV. Surveillances Periodic tests, calibrations, setpoint verifications or inspections (as applicable) should be established for any new detection and alarm circuits to ensure their reliability to perform its intended design functions. 3. Considerations for Protective Devices for Alarm and Trip Functions The following guidelines provide an overview of the analyses that should be performed: a. Commercially available software packages that have been adequately verified and validated for safety related applications may be used to analyze and model open phase and unbalanced fault conditions. The software should have capabilities to perform the unbalance load flow study for a steady-state solution with opening a single phase at a time. For transformers, the effects of an embedded winding, no-load current and losses, transformer type (core and shell), and inter-phase A, B, C mutual coupling, including zero-sequence shall be included. b. Establish the capability of the major important-to-safety components to withstand unbalanced voltage/current conditions expected during various operating and loading conditions. The manufacturer provided parameters maybe acceptable if specified during the procurement process. Industry standards such as NEMA MG 1-2011 (Motors and Generators), Section 20.24, titled, “Effects of Unbalanced Voltages on the Performance of Polyphase Squirrel-Cage Induction Motors”, and IEEE Std. C37.96-2012 (Guide for AC Motor Protection), Section 5.7.2.6, “Unbalanced protection and phase