Page 37 - May-June 2013

Nuclear Plant Journal, May-June 2013 NuclearPlantJournal.com 37
Fukushima
Daiichi
Status
A Nuclear Plant Journal Report.
1. Fuel Removal from the Spent
Fuel Pools
Work towards spent fuel removal is
in progress while ensuring seismic safety.
In particular, efforts are being made to
achieve the early start and completion
of Unit 4 spent fuel removal, which is
planned to be completed by the end of
2014.
Spent fuel removal at Unit 4
Thecover installation for fuel removal
is ongoing, which is to be completed by
mid-2013. In addition to the foundation
work, the steel frame construction for fuel
removal was started on January 8, 2013.
Spent fuel removal at Unit 3
Platform installation and debris
removal from the upper part of the
Reactor Building is ongoing. The steel
truss debris which had remained in the
upper part of the spent fuel pool has been
removed.
After the area surrounding the pool
is cleaned up, protection will be installed
on the spent fuel pool and debris removal
from the upper part of the operation floor
will be started. Though the fuel handling
machine mast fell into the pool during
the steel truss debris removal, it was
confirmed in an investigation on February
13, 2013 that the mast did not directly
contact the spent fuel storage rack and
the liner.
Inspection for the integrity of Unit 4
Reactor Building
The fourth regular inspection
was performed in order to confirm the
integrity of the Reactor Building and the
spent fuel pool (February 4-12, 2013).
As a result, it was confirmed that the
integrity of the building is acceptable and
the building is capable of safely storing
spent fuels. An outside expert participated
in the inspection to confirm the results of
evaluation performed so far including
seismic analysis results.
Investigation of Unit 2 Reactor
Building operation floor
The radiation released from the target
surfaces has been measured utilizing a
camera inserted from the blow-out panel
opening on February 21, 2013. The results
obtained will be provided as inputs for
developing an effective and efficient plan
for decontamination and shielding which
will be essential for the preparation for
fuel removal.
2. Fuel Debris Removal
In addition to decontamination
and shield installation being carried
out for improved accessibility to the
PCV, technology development and data
acquisition necessary to prepare for fuel
debris removal (such as investigating
and repairing the leakage location of the
PCV) are being accelerated.
Development of comprehensive
radiation dose reduction plan
Comprehensive radiation dose
reduction plan is being developed for
improving the environment of the Reactor
Building. Environment improvement
technologies to be applied under high
radiation were discussed with 6 overseas
organizations (completed on February
28, 2013).
Development of remote control
decontamination technology
The production of three types
of remote control decontamination
equipment (high-pressure water
decontamination, dry ice blast and
blast/suction) has been completed on
January 31, 2013. Demonstration test
of the equipment was performed at
Fukushima Daini Nuclear Power Station
for the purpose of identifying issues to be
resolved before putting them in operation
at Fukushima Daiichi Nuclear Power
Station from January 15 to February 28,
2013. Demonstration observation of dry
blast was held on February 15, 2013. The
results of evaluation (on-site simplified
analysis done by the plant manufacturers
and detailed analysis performed by the
JAEA) of the contaminated samples
collected in Units 1-3 Reactor Buildings
during site investigation in FY2012 have
been completed.
Removal of foreign material (such
as debris) from the first floor of Units 1
and 3
Before performing decontamination
in the Reactor Buildings, foreign
material will be removed by unmanned
machinery to secure the access route
for decontamination equipment and
investigation of the inside of the PCV.
Foreign material removal is scheduled
to be completed by September 2013 for
Unit 1 and by June 2013 for Unit 3.
Investigation of Units 1-2 Torus
The investigation of the Torus
Room in the Reactor Building basement
and the condition of the accumulated
water there, for providing inputs for the
development of equipment to investigate
the leakage locations, is ongoing in Unit
1, the Torus Room was investigated by
drilling a hole on the first floor of the
Reactor Building in February 2013. As a
result, the accumulated water level depth
was approximately 4.9m (16.07 feet),
the water temperature was approx. 23℃
and the maximum radiation dose was
(Continued on page 38)
View from the Top of Unit 4.