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Dose reduction actions in Tsuruga-2 NPP

Hiroshi WADA, Yuuichi HAMANAKA, Masayuki FUKUDA

Tomomi YOSHINAGA, Eiji SANEHIRA,Masahiro YANO,Yasuo UNI, Kazushige HAYASHI

Fumitoshi NAKAO

The Japan Atomic Power Company

NUCLEAR PLANT SERVICE ENGINEERING Co.,Ltd.

2008 ISOE International ALARA Symposium

The following materials may contain JAPC’s proprietary and confidential information; and all or any part of these materials or informationcontained herein may NOT be used for any purposes other than originally intended or may NOT be reproduced, disclosed, transferred, distributed orin any manner transmitted in any tangible, electronic or any other form to any third party without prior written consent thereto by JAPC.

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Contents

Outline of JAPC Transition of dose in Tsuruga-2

NPP Dose reduction actions so far Action to large-scale work Situation of countermeasure for

reducing radiation exposure Electric personnel dosimeter Conclusion

2008 ISOE International ALARA Symposium

The following materials may contain JAPC’s proprietary and confidential information; and all or any part of these materials or informationcontained herein may NOT be used for any purposes other than originally intended or may NOT be reproduced, disclosed, transferred, distributed orin any manner transmitted in any tangible, electronic or any other form to any third party without prior written consent thereto by JAPC.

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Outline of JAPC’s NPP

Tsuruga-1 (BWR)

357 MW

Tokai II (BWR)1,100 MWe

Tsuruga-3 and 4 (PWR) (Currently planed)

JAPC Total 2,617 MWe

Tsuruga-2 (PWR)

1160 MW Tokai (GCR) (Decomi. phase)

2008 ISOE International ALARA Symposium

The following materials may contain JAPC’s proprietary and confidential information; and all or any part of these materials or informationcontained herein may NOT be used for any purposes other than originally intended or may NOT be reproduced, disclosed, transferred, distributed orin any manner transmitted in any tangible, electronic or any other form to any third party without prior written consent thereto by JAPC.

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Outline of Tsuruga-2 NPP

2008 ISOE International ALARA Symposium

△ △ △ △ △

△

▲

Nuclear reactor

Reactor containment

To turbine

From condensor

△

Ｒ

Steam generator

(SG)

pressurizer

MCP Cold leg

The following materials may contain JAPC’s proprietary and confidential information; and all or any part of these materials or informationcontained herein may NOT be used for any purposes other than originally intended or may NOT be reproduced, disclosed, transferred, distributed orin any manner transmitted in any tangible, electronic or any other form to any third party without prior written consent thereto by JAPC.

•Entering into the reactor containment is limited in operation condition.

•Many equipments containing radioactivity are opened every periodical outage for inspection or maintenance.

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Transition of dose in Tsuruga-2

0.74 0.76 0.60 0.62 0.49 0.49 0.45 0.44 0.580.29

0.66 0.630.94

0.760.92

0.96

0.22 0.29 0.220.51 0.26

0.39

0.41

3.27

0.59

2.63

1.020.06 0.04

0.270.66

0.15

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

#1 #2 #3 #4 #5 #6 #7 #8 #9 #10 #11 #12 #13 #14 #15 #16Periodical Outage

Col

lect

ive

dose

man

-Sv

（）

Improvement workPeriodical inspection

MCP branch pipe repair work(0.46)Hot leg outer surface inspectionwork(0.29),etc.

Modification of primary coolant temperature measuring system (0.28)Primary coolant pump current transformer vane replacement (0.22), etc.

Plugging of SG heat transfer tube (0.80)Anti- SCC activities for SG tube sheet(0.69)CVCS pipe repair work(0.39) etc.

SG nozzle repair work (0.99)Activities associated with SG nozzle repair (0.41)Boron injection piping, etc. repair (0.41)SG shoot peening (0.33) etc.

2008 ISOE International ALARA Symposium

The following materials may contain JAPC’s proprietary and confidential information; and all or any part of these materials or informationcontained herein may NOT be used for any purposes other than originally intended or may NOT be reproduced, disclosed, transferred, distributed orin any manner transmitted in any tangible, electronic or any other form to any third party without prior written consent thereto by JAPC.

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Dose reduction action so far (1/4)

• Design and Construction phase

• Commercial operation phase

• Action to hardware and software

• Recent action

2008 ISOE International ALARA Symposium

The following materials may contain JAPC’s proprietary and confidential information; and all or any part of these materials or informationcontained herein may NOT be used for any purposes other than originally intended or may NOT be reproduced, disclosed, transferred, distributed orin any manner transmitted in any tangible, electronic or any other form to any third party without prior written consent thereto by JAPC.

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Dose reduction action so far (2/4)

•Action in design and Construction phase

Action to hardwareMeasures Details

Permanent shield Primary piping

Automation

Stud bolt tensionerSteam generator (SG) heat transfar tubeeddy current examination robotAutomatic UT handling system

Improvement ofwork efficiency

SG manhole cover handling system

Remote control Filter replacement system

2008 ISOE International ALARA Symposium

The following materials may contain JAPC’s proprietary and confidential information; and all or any part of these materials or informationcontained herein may NOT be used for any purposes other than originally intended or may NOT be reproduced, disclosed, transferred, distributed orin any manner transmitted in any tangible, electronic or any other form to any third party without prior written consent thereto by JAPC.

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Dose reduction action so far (3/4)

•Action in operation phase(1/2)

Action to hardwareMeasures Details

Permanent shield Residual heat removal system, etc.

Temporary shield Primary system and piping

Improvement ofwork efficiency

Adoption of new type nozzle coverAdoption of seal plate

Chemical decon.Reactor coolant recirculation pumpinternal

Radiation sourceremoval

Highly radioactive pipe

Radiation sourcedecay

SG manhole inner cover (Rotation parts)

2008 ISOE International ALARA Symposium

The following materials may contain JAPC’s proprietary and confidential information; and all or any part of these materials or informationcontained herein may NOT be used for any purposes other than originally intended or may NOT be reproduced, disclosed, transferred, distributed orin any manner transmitted in any tangible, electronic or any other form to any third party without prior written consent thereto by JAPC.

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Dose reduction action so far (4/4)

•Action in operation phase(2/2)

Action to hardware

Measures Details

Water chemistrycontrol

High Li operationAdoption of fine mesh filterReactor water diversion and purification at RCPstartupTwo-step pollution

Action to software

Mockup traning SG nozzle cover attachment and replacement

Awareness-buildingmeasure

Indication, participation in morningceremonies, call out, introduction of case oftroubles, etc.

2008 ISOE International ALARA Symposium

The following materials may contain JAPC’s proprietary and confidential information; and all or any part of these materials or informationcontained herein may NOT be used for any purposes other than originally intended or may NOT be reproduced, disclosed, transferred, distributed orin any manner transmitted in any tangible, electronic or any other form to any third party without prior written consent thereto by JAPC.

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Recent action to hardware

0

20

40

60

80

100

#1 #2 #3 #4 #5 #6 #7 #8 #9 #10 #11 #12 #13 #14 #15 #16

Periodical outage

SG HOTSG COLD

Radiation source decays due tolong period outage for periodicalinspection associated with lekagefrom SG heat exchanger

Start of zincinjection

Dos

e eq

uiva

lent

rat

e (m

Sv/

h)

2008 ISOE International ALARA Symposium

The following materials may contain JAPC’s proprietary and confidential information; and all or any part of these materials or informationcontained herein may NOT be used for any purposes other than originally intended or may NOT be reproduced, disclosed, transferred, distributed orin any manner transmitted in any tangible, electronic or any other form to any third party without prior written consent thereto by JAPC.

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Recent action to software

2008 ISOE International ALARA Symposium

JAPC ContractorRP MaintenanceMaintenance RP

Work plan

Design

Prediction,

Assessment

Rad. work plan

Shielding,Decon.

Check,Review

Cost plan

Review of work contents and radiation dose

Validitycheck /review

Work Plan Annual dose

Disapproval

Work control Radiation controlApproval Work Start

Possibility of planned dose significant exceedance

The following materials may contain JAPC’s proprietary and confidential information; and all or any part of these materials or informationcontained herein may NOT be used for any purposes other than originally intended or may NOT be reproduced, disclosed, transferred, distributed orin any manner transmitted in any tangible, electronic or any other form to any third party without prior written consent thereto by JAPC.

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Steam (to turbine)

From condenser

From reactorto reactor

SCC at nozzle welds

SG

2008 ISOE International ALARA SymposiumAction to large-scale work (1/5)

(SG nozzle stub weld mending)

MCP*(High dose

rate)

SG lower shell(High dose

rate)

* MCP: Main Coolant PipeThe following materials may contain JAPC’s proprietary and confidential information; and all or any part of these materials or informationcontained herein may NOT be used for any purposes other than originally intended or may NOT be reproduced, disclosed, transferred, distributed orin any manner transmitted in any tangible, electronic or any other form to any third party without prior written consent thereto by JAPC.

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SG lower shell

(High dose rate)MCP*

(High dose rate)

Elbow replacement

SG coolant inlet nozzleNozzle

stub

Cutting

Cutting

Contaminated

* MCP: Main Coolant Pipe

Contaminated

Contaminated

2008 ISOE International ALARA SymposiumAction to large-scale work (2/5)

(Work plan)

The following materials may contain JAPC’s proprietary and confidential information; and all or any part of these materials or informationcontained herein may NOT be used for any purposes other than originally intended or may NOT be reproduced, disclosed, transferred, distributed orin any manner transmitted in any tangible, electronic or any other form to any third party without prior written consent thereto by JAPC.

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2008 ISOE International ALARA Symposium

Action to large-scale work (3/5)

(Planned dose)

1600 man-mSv

(planned)

ShieldingDecontaminationAutomatic and remote equipmentMock-up training

The following materials may contain JAPC’s proprietary and confidential information; and all or any part of these materials or informationcontained herein may NOT be used for any purposes other than originally intended or may NOT be reproduced, disclosed, transferred, distributed orin any manner transmitted in any tangible, electronic or any other form to any third party without prior written consent thereto by JAPC.

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2008 ISOE International ALARA Symposium

Action to large-scale work (4/5)(action plan based on 1100 man-mSv)

Cutting off elbow

MCP

Shielding(additional)

Decontamination (additional)

Shielding(additional)

24 mSv/h

6 mSv/h 4.7 mSv/h

3.7 mSv/h 2.8 mSv/h 1.5 mSv/h

The following materials may contain JAPC’s proprietary and confidential information; and all or any part of these materials or informationcontained herein may NOT be used for any purposes other than originally intended or may NOT be reproduced, disclosed, transferred, distributed orin any manner transmitted in any tangible, electronic or any other form to any third party without prior written consent thereto by JAPC.

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2008 ISOE International ALARA Symposium

Action to large-scale work (5/5)

(Reexamined plan )1600 man-mS

v (planned)

1100 man-mSv

(approved)

Additional shieldingAdditional decontamination

ShieldingDecontaminationAutomatic and remote equipmentMock-up training

Dose for additional dose reduction ～ 20 man-mSv

The following materials may contain JAPC’s proprietary and confidential information; and all or any part of these materials or informationcontained herein may NOT be used for any purposes other than originally intended or may NOT be reproduced, disclosed, transferred, distributed orin any manner transmitted in any tangible, electronic or any other form to any third party without prior written consent thereto by JAPC.

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Situation of countermeasure for reducing radiation

exposure

2008 ISOE International ALARA Symposium

Situation of installation of shield

The following materials may contain JAPC’s proprietary and confidential information; and all or any part of these materials or informationcontained herein may NOT be used for any purposes other than originally intended or may NOT be reproduced, disclosed, transferred, distributed orin any manner transmitted in any tangible, electronic or any other form to any third party without prior written consent thereto by JAPC.

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Situation of installation of shield （ 1/3）

• screen-type shield • Screen-type shield for watchmenDecontaminatio

n of MCP and SG nozzle inner surface

Screen-type shieldShiel

d

2008 ISOE International ALARA Symposium

The following materials may contain JAPC’s proprietary and confidential information; and all or any part of these materials or informationcontained herein may NOT be used for any purposes other than originally intended or may NOT be reproduced, disclosed, transferred, distributed orin any manner transmitted in any tangible, electronic or any other form to any third party without prior written consent thereto by JAPC.

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Situation of installation of shield （ 2/3）

• Shielding for MCP Nozzle inside

• Shielding for SG nozzle inside

・ Shield for MCP nozzle inside Shield for SG nozzle inside

2008 ISOE International ALARA Symposium

The following materials may contain JAPC’s proprietary and confidential information; and all or any part of these materials or informationcontained herein may NOT be used for any purposes other than originally intended or may NOT be reproduced, disclosed, transferred, distributed orin any manner transmitted in any tangible, electronic or any other form to any third party without prior written consent thereto by JAPC.

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Situation of installation of shield （ 3/3）・ Shield for RHR/SIS piping

Cold-leg, Charge, Boric acid injection, Accumulator injection piping

RHR piping

2008 ISOE International ALARA Symposium

The following materials may contain JAPC’s proprietary and confidential information; and all or any part of these materials or informationcontained herein may NOT be used for any purposes other than originally intended or may NOT be reproduced, disclosed, transferred, distributed orin any manner transmitted in any tangible, electronic or any other form to any third party without prior written consent thereto by JAPC.

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2008 ISOE International ALARA Symposium

Result of dose rate reduction

Cutting off elbow

MCP

24 mSv/h

6 → - mSv/h 4.7 → 9.0 mSv/h

3.7 → 6.0 mSv/h 2.8 → 1.6 mSv/h 1.5 → 0.9 mSv/h

Shielding(additional)

Shielding(additional)

The following materials may contain JAPC’s proprietary and confidential information; and all or any part of these materials or informationcontained herein may NOT be used for any purposes other than originally intended or may NOT be reproduced, disclosed, transferred, distributed orin any manner transmitted in any tangible, electronic or any other form to any third party without prior written consent thereto by JAPC.

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Situation of training by using mock-up

Installation of cutting machineInstallation of beveling machine

2008 ISOE International ALARA Symposium

The following materials may contain JAPC’s proprietary and confidential information; and all or any part of these materials or informationcontained herein may NOT be used for any purposes other than originally intended or may NOT be reproduced, disclosed, transferred, distributed orin any manner transmitted in any tangible, electronic or any other form to any third party without prior written consent thereto by JAPC.

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Wireless monitoring unit of the E.P.D

Enable working without relying on the alarm

2008 ISOE International ALARA Symposium

Detail will be shown in another presentation of JAPC.

The following materials may contain JAPC’s proprietary and confidential information; and all or any part of these materials or informationcontained herein may NOT be used for any purposes other than originally intended or may NOT be reproduced, disclosed, transferred, distributed orin any manner transmitted in any tangible, electronic or any other form to any third party without prior written consent thereto by JAPC.

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Result

2008 ISOE International ALARA Symposium

～1100

～990

The following materials may contain JAPC’s proprietary and confidential information; and all or any part of these materials or informationcontained herein may NOT be used for any purposes other than originally intended or may NOT be reproduced, disclosed, transferred, distributed orin any manner transmitted in any tangible, electronic or any other form to any third party without prior written consent thereto by JAPC.

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Conclusion (1/2)

2008 ISOE International ALARA Symposium

Effective shielding and decontamination based on technical evaluation Strictly mock-up training in works Maintenance section is very cooperative for the matter which radiological protection section recommends in JAPC and MHI.

The following materials may contain JAPC’s proprietary and confidential information; and all or any part of these materials or informationcontained herein may NOT be used for any purposes other than originally intended or may NOT be reproduced, disclosed, transferred, distributed orin any manner transmitted in any tangible, electronic or any other form to any third party without prior written consent thereto by JAPC.

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Conclusion (2/2)

2008 ISOE International ALARA Symposium

Positive inflection of the machinery automation and remoteness

Carrying out the radiation survey finely and limit an entrance to work area strictly

System which cooperated from a plan stage of the construction has begun to be seen.The following materials may contain JAPC’s proprietary and confidential information; and all or any part of these materials or information

contained herein may NOT be used for any purposes other than originally intended or may NOT be reproduced, disclosed, transferred, distributed orin any manner transmitted in any tangible, electronic or any other form to any third party without prior written consent thereto by JAPC.