dose rate reduction experiences of piping replacement atfukushima daiichi unit 4 and 5atsutoshi...
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7/31/2019 Dose Rate Reduction Experiences Of Piping Replacement AtFukushima Daiichi Unit 4 and 5Atsutoshi MakihiraALALA Mini-WorkshopNov.9, 2005 Hamaoka NPS
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Dose Rate Reduction Experiencesof Piping Replacement at
Fukushima Daiichi Unit 4 and 5
Atsutoshi Makihira
ALALA Mini-WorkshopNov.9, 2005 Hamaoka NPS
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7/31/2019 Dose Rate Reduction Experiences Of Piping Replacement AtFukushima Daiichi Unit 4 and 5Atsutoshi MakihiraALALA Mini-WorkshopNov.9, 2005 Hamaoka NPS
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Removal Work Scope of Equipment and
Floor Drain Piping
4(BWR4)
Schedule
Unit
Work
Nov.22, 2002 May 21,2003
Removal:415m
Installation:556m
Reactor Building Suppression Pool Area
West East
Reactor Building Suppression Pool Area
West East
5(BWR4)Jan.20, 2003 Sep.26, 2003
Drain PipingDrain Piping
Working AreaWorking Area
Removal:446m
Installation:446m
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7/31/2019 Dose Rate Reduction Experiences Of Piping Replacement AtFukushima Daiichi Unit 4 and 5Atsutoshi MakihiraALALA Mini-WorkshopNov.9, 2005 Hamaoka NPS
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Dose Rate at Piping Before Replacement Work
Unit 4Unit 4
West
Contact (max)Contact (max)
mSv/hmSv/h
Field (max)Field (max)
mSv/hmSv/h
RHR pipingRHR piping
Work areaWork area
East East
ContactContact projectionprojection
mSv/hmSv/hFiledFiledprojectionprojection
mSv/hmSv/h
Unit 5Unit 5
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7/31/2019 Dose Rate Reduction Experiences Of Piping Replacement AtFukushima Daiichi Unit 4 and 5Atsutoshi MakihiraALALA Mini-WorkshopNov.9, 2005 Hamaoka NPS
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RHR and Drain Piping at West Part
of Suppression Pool Area
Unit 4Unit 4
West East
RHR PipingRHR Piping
Drain PipingDrain Piping
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7/31/2019 Dose Rate Reduction Experiences Of Piping Replacement AtFukushima Daiichi Unit 4 and 5Atsutoshi MakihiraALALA Mini-WorkshopNov.9, 2005 Hamaoka NPS
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(1)Filed Dose Rate and Estimated Working Time per Person-Day
(2) Estimated Working Time per Person with Annual Dose Limit
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7/31/2019 Dose Rate Reduction Experiences Of Piping Replacement AtFukushima Daiichi Unit 4 and 5Atsutoshi MakihiraALALA Mini-WorkshopNov.9, 2005 Hamaoka NPS
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7/31/2019 Dose Rate Reduction Experiences Of Piping Replacement AtFukushima Daiichi Unit 4 and 5Atsutoshi MakihiraALALA Mini-WorkshopNov.9, 2005 Hamaoka NPS
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Proposals for Improvement
2. FlushingUnit 4
High dose rate at RHR-4, RHR-41, RHR-23
because of RHR operation in shutdown Flushing RHR-4, RHR-41 by using RHR(C) pump which
circulates water in suppression pool
Flushing RHR-23 by opening MO-23 valve when RHR(C)pump running
Unit 5
High dose rate at RHR-3, RHR-7, RHR-27 because
of RHR operation in shutdown
Flushing by using RHR pumps which circulates water insuppression pool
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7/31/2019 Dose Rate Reduction Experiences Of Piping Replacement AtFukushima Daiichi Unit 4 and 5Atsutoshi MakihiraALALA Mini-WorkshopNov.9, 2005 Hamaoka NPS
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RHR-Hx(B)
PLR-5 PLR-2
MO
MO
MO
MOB
MOB
MOD
MO
MO
RHR-22 RHR-21RHR-1
MO
MO
RHR-2
MO
MO
MO
MO
MOB
RHRRHR--4141
MOB
RHR-3
RHR-3
RHR-55RHR-53
RHR-55
RHR-1RHR-21
RHR-7
PLR-1PLR-4RHR-23
RHR-41
RHR-27
RHR-23
RHRRHR--2323
RHR-53
MO
MO
MO
RHR-23
RHR-26
RHR
-24
RHR-
3
RHR
-4
RHR-6
RHR-3
RHR-53RHR-3
RHR-7RHR-8RHR-27
RHR-28
MO67MO57RHR-52
RHR-44
RHR-44
RHR-47 RHR-51
RW
RHRRHR--33
MO
MO
MO
MO
Flushing line
High Dose Pipng
MO
MO
RHR-Hx(A)
Flushing by use of RHR(C)
pumps which circulate
system water
Open VMO-20 valve when
circulate system water
2.Flushing(example)
Proposals for Improvement
Unit 4Unit 4
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7/31/2019 Dose Rate Reduction Experiences Of Piping Replacement AtFukushima Daiichi Unit 4 and 5Atsutoshi MakihiraALALA Mini-WorkshopNov.9, 2005 Hamaoka NPS
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3.Temporary ShieldingInstalling temporary shielding at high radiation piping after RHR flushing
Unit 5
Unit 4
Installing temporary shielding at projected high radiation piping during operationInstalling temporary shielding at high radiation piping after RHR flushing
RW-1C Lead
covered with SSEquipment Drain
Lead covered with
SS
RW-209
lead blanket
Installing during operation
RHR-27
lead blanket
Installing after flushing
RHR-23
lead blanket
Proposals for Improvement
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7/31/2019 Dose Rate Reduction Experiences Of Piping Replacement AtFukushima Daiichi Unit 4 and 5Atsutoshi MakihiraALALA Mini-WorkshopNov.9, 2005 Hamaoka NPS
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Reactor water drained because of RRSreplacement work
High dose rate was projected at RHR-Hx,RHR pumps, suppression pool area
Proposals for Improvement
4.Blow Down Water Treatment at Unit 4
R/B B floor suppression pool areaR/B B floor suppression pool area R/B 1R/B 1stst floorfloor RHRRHR--HxHx roomroom R/B B floorR/B B floor RHR pump areaRHR pump area
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7/31/2019 Dose Rate Reduction Experiences Of Piping Replacement AtFukushima Daiichi Unit 4 and 5Atsutoshi MakihiraALALA Mini-WorkshopNov.9, 2005 Hamaoka NPS
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Planned reactor water blow down twice
First blow down water drained tosuppression pool so as to second blowdown which contains higher activity can
be transferred to radwaste (because ofcapacity)
Removing crud deposited on RPVbottom by temporary pump and filters
Fill up RHR-44 with water before blowdown for preventing crud deposition
4.Blow Down Water Treatment at Unit 4
Proposals for Improvement
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7/31/2019 Dose Rate Reduction Experiences Of Piping Replacement AtFukushima Daiichi Unit 4 and 5Atsutoshi MakihiraALALA Mini-WorkshopNov.9, 2005 Hamaoka NPS
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5.Remote Monitoring
Dose indicator
Wireless APDWireless APD
Remote monitoring
of individual dose
TransmittanceTransmittance
Dose indicator
Individual dose can be
monitored even on cloths
Unit 5 Unit 4 &5
Proposals for Improvement
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7/31/2019 Dose Rate Reduction Experiences Of Piping Replacement AtFukushima Daiichi Unit 4 and 5Atsutoshi MakihiraALALA Mini-WorkshopNov.9, 2005 Hamaoka NPS
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RHR-27
N
EW
S
Equipment Drain
vertical
Equipment
Drain
horizontal
VerticalPiping
Horizontal Piping
CUW-19 Contact dose rate: 36.0%
RW-1C Contact dose rate: 44.4%
Field dose rate:20.0%
Results for Improvement
Equipment drain piping
Contact:66.7%
Field:88.7%
Dose Rate Reduction Effectiveness after Installing Temporary Shielding
RW-209 pipings
Contact:66.7%
Field:86.7%
Unit 4Unit 4
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