Common Contracts
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UNITED STATESApril 3rd, 2013
This task interface agreement (TIA) documents Region II’s position that harmonic distortion of the AC waveform on Class 1E electrical distribution buses could result in the premature reset of the degraded voltage relays at the Watts Bar Nuclear Plant (WBN), Unit 1, during a degraded voltage event. Harmonic-induced reset of the degraded voltage relays (DVRs) and associated timers during the onset of such an event would: (1) prevent the relays from actuating within the time required by technical specifications, (2) represent a condition adverse to the quality of relay operation, and (3) be subject to treatment in accordance with the requirements of 10 CFR 50, Appendix B. Concurrence of this memo by the electrical engineering branch in the Office of Nuclear Reactor Regulation (NRR) indicates their review and approval of Region II’s regulatory position.
