On April 15, 2011, we received an instruction document entitled "Offsite
power supply security of nuclear power stations and reprocessing plants"*
from Nuclear and Industrial Safety Agency of Ministry of Economy, Trade and
Industry (NISA). Afterward, pursuant to the document, we checked the status
of implementation of measures to secure the offsite power supply and
informed NISA on May 16.
(Previously announced on April 15 and May 16, 2011)
On June 7, 2011, NISA informed us that the said report was evaluated as
valid. In addition, we also received an instruction document from NISA to
report the status of implementation of measurements to secure the offsite
power supply of Fukushima Daini Nuclear Power Station, considering the
status of the equipment restoration there and implementation of emergency
safety measurements to keep the cold shutdown of the reactors.
(Previously announced on June 7, 2011)
Afterwards, we checked the status of implementation of measures to secure
the offsite power supply of Fukushima Daini Nuclear Power Station, and
hereby announce to submit the report to NISA today.
Security of offsite power supply of Fukushima Daini Nuclear Power Station
"Offsite power supply security of nuclear power stations and reprocessing
plants (directive)" (April 15th, 2011, NISA No.3)
There was a large blackout within the service area of Tohoku Electric Power
Company due to Miyagiken-oki Earthquake on April 7, 2011.
This accident cast uncertainty about the reliability of power systems,
since it starting from a grounding fault in one part of the power systems
led to the cut of offsite power supply systems to nuclear power stations
and reprocessing facilities (collectively "nuclear power stations etc.").
Therefore, Nuclear and Industrial Safety Agency (NISA) instructs general
electricity utilities to conduct the items stated below (only 1 and 4 are
applicable to processing facilities). NISA also orders them to report the
implementation status by May 16, 2011.
1.Considering that outage in power supply due to earthquake etc. could
affect offsite power supply to nuclear power stations etc., analyze and
evaluate the reliability of power supply in your company's power systems
which could affect power supply to nuclear power stations etc, and
consider measures to improve the reliability further of power supply to
such nuclear power stations (including enforcement of on site power in
nuclear power stations etc.). As for processing facilities, consider
improving equipment within such facilities which corresponds to the
measures above concerning the reliability of power systems which supplies
power to such facilities.
2.In order to improve the reliability of power supply to each unit in your
nuclear power stations, connect all the transmission lines which are
connected to multiple power lines to each unit and enable power supply.
3.Concerning power line towers of your nuclear power stations, evaluate
seismic adequacy, stabilities of foundation against earthquakes and
depending on the result conduct necessary countermeasures such as
4.Concerning electrical facilities such as switchyards of your nuclear
power stations etc., conduct countermeasures such as installing them
indoors and making them watertight to exclude impacts on tsunami.