Actions concerning the vulnerabilities of power supply design

Issued on July 16, 2013

Summary

A transformer’s single phase linked to the transmission system was interrupted (opened) at a U.S. nuclear power station, but the protective relay failed to detect this. In view of this, a proposal has been made for domestic power stations to check the ways of detecting single phase interruption and to work out action plans as necessary.


Status of Implementation by Utilities (as of March 2014)

Utilities are identifying cases in which protective relays failed to detect single phase interruption at plants, and are also conducting training for operators to enable early actions. This has been or is being incorporated into related manuals. Utilities will obtain overseas information to work out necessary actions as appropriate.