Nuclear Plant Journal, September-October 2014 NuclearPlantJournal.com
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Unit 4 reactor building may be unstable
because of damage incurred from the
hydrogen explosion, and that it was
unsafe to keep the 1,500+ fuel bundles
in the spent fuel pool. TEPCO conducted
structural analysis of the Unit 4 reactor
building and, despite the fact that the
visuals are terrible due to the explosion,
we have confirmed that there is sufficient
structural integrity remaining in the
reactor building and the spent fuel pool
to withstand a large earthquake. We
also added 20% additional margin by
reinforcing the floor of the spent fuel
pool just in case. However, in order to
address the public’s concern we decided
to remove the fuels from the Unit 4
spent fuel pool. The defueling structure
was erected in November 2013, and as
of September 2014, more than 75 % of
the fuels have been transferred to the
common pool located on site. All fuels
from Unit 4 is planned to be removed by
the end of 2014.
As for Units 1, 2, and 3, much
progress has been made in investigating
inside the reactor buildings and torus
rooms utilizing various robots. For
example, robots played an instrumental
role in identifying water leakage locations
in the torus room of Unit 1 recently.
Rubble removal from the spent fuel pool
of Unit 3 is underway in preparation for
removing fuels from the spent fuel pool.
5.
Have any units at Fukushima Daini
and Kashiwazaki Kariwa nuclear power
station been approved by NRA for restart?
No.
Fukushima
Daini
and
Kashiwazaki Kariwa are totally different
stories. TEPCO has applied for the safety
review of Kashiwazaki Kariwa Units 6
and 7, the Advanced BWRs (ABWR),
to the Japanese regulator (NRA) back in
September 2013. The NRA is currently
reviewing our application to confirm
compliance with the newly established
safety standard.Wewill also have to obtain
consent from the local government prior
to restarting the units. As for Fukushima
Daini, with four BWR reactors, we are
maintaining core shutdown of the units
and do not have clear plans for the future
at this moment.
6.
Please explain the function of
emergency response center.
In 2007, the Chuetsu-Oki earthquake
struck Kashiwazaki Kariwa. Although
there was no safety significant issue at
the plant, we encountered difficulty using
the emergency response center at the site
since the entrance door got deformed and
workers could not get in.
Based on this lessons learned,
TEPCO decided to build seismic isolation
buildings to house the emergency
response center at Fukushima Daiichi,
Fukushima Daini, and Kashiwazaki
Kariwa.
This turned out to be an excellent
decision since at Fukushima Daiichi, the
seismic isolation building became the
only safe haven that people could respond
from during the accident.
We have a system called the SPDS,
the safety parameter display system, in
our emergency response centers. SPDS
provides all vital plant information for
each unit that can be displayed (but
not controlled) from the emergency
response center. The control is all at the
main control room for each unit. The
emergency director and technical staff
at the emergency response center will
provide advice to the main control room
for the shift operators to take necessary
actions in the plant during emergency
events.
Radiation monitor in front of Tatsuta train station in Naraha town on 7/11/2014.
Visit of US Ambassador to Fukushima Daiichi on 5/14/2014 (on the
refueling floor of Unit 4).
