our decontamination technologies for npss
DESCRIPTION
Our decontamination technologies for NPSs. Tadasu Yotsuyanagi Advanced Chemistry & Decontamination System Group Chemical System Design & Engineering Dept. Toshiba Corporation. Contents. Radiation exposure in BWR plants What is decontamination ? Chemical decontamination T-OZON - PowerPoint PPT PresentationTRANSCRIPT
Copyright © 2006 Toshiba Corporation. All rights reserved.
ISOE/ATC 2006 ALARA Workshop
Our decontamination technologies for NPSs
Tadasu Yotsuyanagi
Advanced Chemistry & Decontamination System GroupChemical System Design & Engineering Dept.Toshiba Corporation
October 12, 2006
ISOE/ATC 2006 ALARA Workshop
Contents
Radiation exposure in BWR plantsWhat is decontamination ?Chemical decontamination
T-OZON
Mechanical decontamination Jet Cleaning Zirconia Blast
Summary
October 12, 2006
ISOE/ATC 2006 ALARA Workshop
Reactor Water
Materials of the primary systemCorrosion Product
Fuel crud Reactor internalsｎActivation
RWCU
Insoluble activity
Crud activitySource
(CRD,LPRM etc.)
Soluble activity
Ionic activity Source
(PLR & RWCU Piping)
Radiation Exposure
Behavior of Radioactivity in Reactor Water
October 12, 2006
ISOE/ATC 2006 ALARA Workshop
Activation Reaction of Major Corrosion Product
59Co (n,γ) 60Co Half Life 5.3 y
58Ni (n,p) 58Co 70.9 d
54Fe(n,p) 54Mn 312.2 d
58Fe(n, γ) 59Fe 45.1 d
50Cr(n,γ)51Cr 27.7 d
Source of Radioactivity in Reactor Water
Oxide Film
Crud
Ion 60Co 58Co
Reactor Water
Ionic Activity Source
Material
Material
54Mn60Co
Crud Activity Source
CrudReactor Water
October 12, 2006
ISOE/ATC 2006 ALARA Workshop
Measures for Reducing Radiation Dose Rate in BWRs
Water Control
Surface Treatment
Mechanical Decon.
Chemical Decon.
Corrosion Resistant MaterialOxygen InjectionShutdown Lay-upDual Condensate polishing Sys.RWCU Capacity OptimizationFeedwater HeatersCore materialsOthers/SS & StelliteNi/Fe ControlZn InjectionUltra Low Fe ControlFuel SpringsRecirculation PipingRWCU PipingFuelOut of Core ComponentsCore ComponentsSystemEquipmentsDrywellReactor BuildingRWCU Pump
EarlyPlant
NewlyPlant
ABWR
△△ ／○△△△－／△△△－＊＊△△－△△△△△△△－
○○○○○○○○△/○/ －＊△△ ／○△ ／○－－－－＊△△ ／○△ ／○－／○
○○○○○○○○－－○○－○－－－－－○－○
○ ： Design Base△ ： Partial Application or Retrofit＊： In Consideration－： No Application
RadiationDose RateLevelReduction
ACP Reduction
ACPRemoval
Improvement of components & Systems
Optimal Shielding
Crud Generation Reduction & removal
Impurity removal
Low Cobalt Material
October 12, 2006
ISOE/ATC 2006 ALARA Workshop
Occupational Radiation Exposure in Japanese Plants
0
2
4
6
8
10
75 77 79 81 83 85 87 89 91 93 95 97 99 01
Year of Commercial Operation Start
Occ
upat
iona
l Rad
iatio
nEx
posu
re (M
an･S
v)
ＢＷＲＰＷＲＡＢＷＲ
At the 1st annual outage
October 12, 2006
ISOE/ATC 2006 ALARA Workshop
Occupational Radiation Exposure Trend of Japanese BWRs
0
5
10
15
20
25
30
70 75 80 85 90 95 00Year
Occ
up
atio
nal
Rad
iati
on E
xpos
ure
(Man･S
v/P
lan
t) Old BWR Plants
New BWR Plants
ABWRs
October 12, 2006
ISOE/ATC 2006 ALARA Workshop
1. Distance
2. Shield
3. Time
4. Removal of Source
Decontamination
What is Decontamination ?
Maintenance of high dose rate piping & equipment
October 12, 2006
ISOE/ATC 2006 ALARA Workshop
RadiationBuild-up
Material
Tight films Loose Deposits
Categories of DecontaminationRe-use
For Disposal
ChemicalDissolution of
Oxide Film
T-OZON, CORD
Electrochemical
Electro-chemical Dissolution of
material
W/O Contact
Mechanical
Removal of Deposits
Jet-Cleaning,Blast
Strong Chemical
Chemical Dissolution of material strongly
Formic Acid
October 12, 2006
ISOE/ATC 2006 ALARA Workshop
Integrity of material
FerritesChromites
Material
Oxi.
Red.Fe
Cr
Fe2+
CrO42-
Reducing Reagents
Oxidizing Reagents To be Decomposed
To RW systemIon exchanger
Optimum Temp., LV and Reagents Conc.
Resins
Principle of Chemical Decontamination
High Decontamination Factor (DF)
Minimize Secondary Waste
October 12, 2006
ISOE/ATC 2006 ALARA Workshop
TED-40
CORDTM
High DF
Reduce Waste
Minimize Waste
T-OZON
Optimum method for various needs
1980s
1990s
2000
1997First Full System Decon. (FSD)
First T-OZON for disposal
2001First T-OZON for re-use
For NPSs
History of Chemical Decontamination in TOSHIBA
October 12, 2006
ISOE/ATC 2006 ALARA Workshop
Material
Reducing reagentsReducing reagents ：： oxalic acid (COOH)oxalic acid (COOH)22 Fe2O3+(COOH)2+ 4H+ →2Fe2++3H2O+2CO2
Ferrites
Oxidizing reagentsOxidizing reagents ：： OzoneCr2O3+3O3+2H2O→2CrO4
2-+4H++3O2 Chromates
Example of decontamination conditions Reducing : 95oC, 2000 ppm oxalic acid Oxidizing : 80oC, a few ppm ozone
Reagents decomposed easilyReagents decomposed easily
Principle of T-OZON
October 12, 2006
ISOE/ATC 2006 ALARA Workshop
Results of Lab. Tests
Before
After
Ozone = 1 ppm
Mn
TED-40 CORD T-OZON
Arb
. un
it
Fe Fe
Reagents
Fe
Volume of Secondary Waste
DF > 100
Main Features of T-OZON
High DF Minimum Secondary waste volumeNo adverse impacts on material integrity
October 12, 2006
ISOE/ATC 2006 ALARA Workshop
0
10
20
30
40
50
60
70
1980～ 1985～ 1990～ 1995～ 2000～
実施
回数
（回
）
’85 ～‘ 90 ’90 ～‘ 95 ’95 ～‘ 00 ’00 ～ 05
TED-40
CORD
T-OZON
’80 ～‘ 85
Nu
mb
er o
f C
hem
ical
Dec
on
.
Experiences of Chemical Decon. in NPSs
In 13 BWRs, T-OZON applied to system decon.
October 12, 2006
ISOE/ATC 2006 ALARA Workshop
PLR piping
Before
After
DF = 10 - 20DF = 10 - 20Tank
Line Mixer
Monitor
Ion ExchangeResin Column
Heater
Main Pump
Tank
Ozone generator
Electric ReductionDevice Ozone
Decomposer
RWCU, RHR(CS)
PLR(SS)
Temporary Loop
Monitor
Heater
RPV
Injection Pump
Decon Agent Tank
R/B D/W
D/W
Tank
Line Mixer
Monitor
Ion ExchangeResin Column
Heater
Main Pump
Tank
Ozone generator
Electric ReductionDevice Ozone
Decomposer
RWCU, RHR(CS)
PLR(SS)
Temporary Loop
RWCU, RHR(CS)
PLR(SS)
Temporary Loop
Monitor
Heater
RPV
Injection Pump
Decon Agent Tank
R/B D/W
D/W
Application to System Decon. in BWR
October 12, 2006
ISOE/ATC 2006 ALARA Workshop
RadiationBuild-up
Material
Tight films Loose Deposits
Categories of DecontaminationRe-use
For Disposal
ChemicalDissolution of
Oxide Film
T-OZON, CORD
Electrochemical
Electro-chemical Dissolution of
material
W/O Contact
Mechanical
Removal of Deposits
Jet-Cleaning,Zirconia Blast
Strong Chemical
Chemical Dissolution of material strongly
Formic Acid
October 12, 2006
ISOE/ATC 2006 ALARA Workshop
Water Jet Cleaning
Spiral nozzle
GuidePump
Hose reel
FilterNozzle
Short period to get reasonable DF
October 12, 2006
ISOE/ATC 2006 ALARA Workshop
Zirconia Blast
Main Features High repetition Good Separation High DF
Duster
BlastingChamber
Nozzle
Object
Exhaust
Feeder
Cyclone separator
Dust
Abrasive
Compressor
Compressed air
0 100 200 300 400 5000.0
0.2
0.4
0.6
0.8
1.0
YTZw
J IRUw
C
C
Rat
io o
f re
usa
ble
med
ium
wei
ght
Times of repetition
Abrasive mediumZirconia :○Zircon :△Alumina :□Steel :▽
μ粒 子径／ ｍ
1 10 100 10000
10
20
30
40
50存
在割
合／
％
Diameter (um)
Fra
ctio
n (%
)
October 12, 2006
ISOE/ATC 2006 ALARA Workshop
Summary
Line-up of decontamination technologies Chemical Decontamination
We promote T-OZON application to NPPs Mechanical Decontamination
Zirconia blast has high performance for reducing wastes
Future scope T-OZON application to FSD Application to Back-End Facilities
Decommissioning Recycle Facilities
クリアランス測定装置
制御室
除染装置 廃棄物搬入口
ブラスト装置Clearance Monitor
Decon. Equipment Inlet
MCR
Zirconia Blast