1. Introduction of the Decontamination Method Which Uses Blasting
ISOE/ATC 2006/10/12
ALARA SYMPOSIUM
Introduction of the Decontamination Method Which Uses Blasting
Oct./12/2006
IN　YUZAWA　JAPAN　　

2. Contents 1. Outline Decontamination
2. History of Mitsubishi decontamination technologies
3. Decontamination using blasting
4. Cavitations jet (CJ) decontamination
5. CJ + blast decontamination
6. Revolving flow polishing method
7. Summary

3. 1. Outline Decontamination
The purpose of decontamination
Cost
Configuration of an object
（structure, physical amount）
function of subject
Schedule （Time required）
Loss in quantity of radioactive waste
The amount of secondary wastes
Exposed reduction of a worker
Area space DF
Determination of the decontaminating method 1

4. 2. History of Mitsubishi decontamination technologies

5. 3. Decontamination using blasting
facility which lifts
Accumulator Drier
The control panel of a whole system
Compressor
Cooler
Blaster
Drier
Air pressure power control panel
Filter
Drum
Drum with radiation shield
Outdoors
Blower
Blast tank
Blast equipment
(primary cyclones separator )
Hose balancer
Hose balancer
Hose balancer
2次ｻｲｸﾛﾝｾﾊﾟﾚｰﾀ
Bag filter dust sampler
ﾌﾞﾗｽﾄ材収
Supply of air
(Vacuumed pressure)
Recovery blower
R/V
platform for shields
Decontamination equipment
R/V outlet shield plug
Vacume blast gun
R/V outlet nozzle neck
Blaster （Blast circulation system） 3

6. 3. Decontamination using blasting
Functional examination situation
Pipe（nozzle neck mockup）
AIR Cylinder for forcing nozzle
　研削した跡
Guide roller
Nozzle （ Vacuumed blast gun） 4

7. 3. Decontamination using blasting
main specifications
１． Decontamination equipment
（１） Decontamination system：Dryness type vacuumed blast
（３） Guide system ：Trapezoid screw sending type nozzle rotation
（４）Weight：About６００kgf／set
2．Utilities
（１）Used power supply：ＡＣ２００Ｖ
（２） Used air supply：Station service air ０.６MPa 5

8. 3. Decontamination using blasting
Features of various blasting materials
alumina
Aℓ2O3
Glass
SO2
Boric
Iron
SUS
Particle
Cut Wire DF
large
small
middle
Remaining effects
Cost
Damage 6

9. 3. Decontamination using blasting
Particle diameter of the blast materials　：
　Usual　φ0.1～2mm
Blast pressure　：　Usuaｌ　l5～6kg/cm2
Blast Angle　：　Usual　45°≦
The configuration before and after activity of blast material (stainless steel grid)
Case of　projection factory test to steel materials
Before（×２００）
After 1-time use（ × ２００） 7

10. 3. Decontamination using blasting
The check of the soundness of target material
When the amount of grinding is large
　⇒　Reduction in thickness　
Loss of a resisting pressure function　
　　　8.1～8.7μm/2times，13.3～15.1μm/3 times
When the amount of grinding is locally large
　⇒　SCC，Fatigue occurs　　　
Influence on the plant by remaining
（Remainder of recovery， Remainder of Pierced）
　　　They are 10cc remains at the blast of about 300ℓ　 8

11. 4. Cavitations jet (CJ) decontamination
It compares with high-pressure water washing in mind,
and is a high physical impulsive force efficiently
　　⇒　Compact equipment
With no pollution expansion of dust generating etc.
into air because of underwater washing
With no influence which it has on lining in washing time
of a decontamination level
Fundamentally, with no secondary waste by decontamination
Contraction
Cavitation
bubbles
Liquid 9

12. 4. Cavitations jet (CJ) decontamination
Track record ①
Spent fuel pit surface of wall and fuel rack cell inside
Object
Purpose
Before
After DF
Note
Pit
surface
Pollution
removal
22000 cpm
700～1200 cpm
18～30
ＣＪ＋
washing
fuel rack
cell inside
Dose
rate
reduction
5.9 mSv/h
0.9 mSv/h
6.6
Underwater
Measureme-nt data
Track record②
The part which has clad adhesion by contact to the fuel for a fuel extraction facility
ＤＦ ２．１～１３．５（総平均８．８） 10

13. 4. Cavitations jet (CJ) decontamination
The application example to fuel extraction equipment
Before
(Those with blackish brown clad)
After
(With no adhesion remains of clad) 11

14. 4. Cavitations jet (CJ) decontamination
Enforcement example：
　Fuel transfer pit
　　　　　Outline specification
High-pressure pump：16MPa－18L/min
　　(Hand-pushed conveyance type)
Nozzle：10MPa－4.4 L/min
Required utility：The power supply for pumps
　220V－23A，Water for washing about4ｍ3
High-pressure pump
Pure water for work
Operation floor
Cavity
Ｃ／Ｖ
Ａ／Ｂ
About 6m
Lifting frame
Nearly drain Floor
surface washing
Transfer pipe
Track frame 2m
Drain part washing 長靴
Nozzle 12

15. 5. CJ + blast decontamination ［Finishing patent application］
The polish grain mixed in the cj grinding-removes adhered clad
The decontamination effect higher than what added the decontamination effect of CJ and a blast simply
◎Influence examination to in service equipment and apparatus
・In a system application test, it affection-evaluates with a mock-up
The faculty of a facility is not affected even if it executes for 30
minutes
◎The faculty of a facility is not affected even if it executes 13

16. 5. CJ + blast decontaminationP PI
High-pressure pump feed line
crane
High-pressure pump
22MPa,15 ℓ
/min
Nozzle feed device
To air filter
Filter housing
Air purge line
Surplus water return line
control panel
Water recovery line
Water drain line
フィルター
Container
Circulation pump
Mono flex pump ( )
Manometer
Blast grain
suction nozzle
strainer ＣＪ +
stream
Blast grain SG
insert plate
When collecting
Blast grains
Turn table
return line
Frame
To floor drain 14

17. 5. CJ + blast decontamination
Applicability test with actual machine
Object ： SG insert plate
After
Before 15

18. 5. CJ + blast decontamination
The decontamination result in a system
application test
Notes : ( ) inside value is the dose rate to extracted
Object
Before
After
Decontamination time
D.F.
Ｂ-ＳＧ
ＨＯＴ
40mSv/h
(14.97mSv/h)
0.7mSv/h
(0.09mSv/h)
60 min.
166
Ｄ-ＳＧ
ＣＯＬＤ
25mSv/h
(9.96mSv/h)
0.63mSv/h
90 min.
111 16

19. 6. Revolving flow polishing method ［Finishing patent application］
　〈Aim〉
　 Inside contamination of long piping which has a crookedness part is decontaminated
　 A revolution style is given to a flow Blast grain Blast grain
In the conventional blasting, it checks that the piping crookedness part round which an Blast grain does not spread can also be decontaminated efficiently. 17

20. 6. Revolving flow polishing method
The outline of the gas revolution flow grinding method
Principle of generating revolving flow
Distances the revolving flow can reach
Q1: Air to be used for revolving flow
Q2: Air to be used for suppressing revolving flow
Q3: Air to be used with abrasive
Speed of abrasion　 δ (μ　m/min) μ δ
Abrasive
Fluidics
Insertion type
Revolving flow type
Distance from nozzle outlet L (m)
Insert the sliding nozzle from tube end and make it move.
Butt tube ends
Tube to be decontaminationed
Tube to be decontaminationed
Characteristic between speed of abrasion and distance (Long tube)
Range of decontamination is small
Sliding nozzle
Range of decontamination is small
Fixed nozzle 18

21. 6. Revolving flow polishing method
Element examination
Speed of abrasion　
Speed of abrasion　
Average speed in piping
Flux ratio
Relation between grinding speed and the average flow velocity in piping
Relation between grinding speed and a flux ratio
Since the flux which induces revolution speed is Q1, if a flux ratio becomes large, degree centrifugal force will become weaker and grinding speed will become small.
If the average speed in piping is made quick, grinding speed will increase 19

22. 6. Revolving flow polishing method
System application examination
Heart exchanger tube
① Supply air former Pressure： 0.5MPa
② amount of grinding airstreams
ａ．For revolution style generating（Q1）：1200NL/min
ｂ．For revolution style control（Q2）：400 NL/min
ｃ．For grinding material supply（Q3）：180NL/min
③ Blast material： 200μm　Alumina grain
④ Decontamination time ： 40分 SG
Suction plug
管 板 ＊A ＊D
＊B ＊C
Seal plug
Seal plug ＊F ＊G
Steam generator
Channel head
A：For blast material supply
B：For revolution style generating
C：For revolution style control
D：For hopper pressurization
E：For vibration
F：For discharge part seals
G：For inhalation part seals
Oil pressure pump
Oil pressure pump ＊E
Preliminary
recovery line
Hopper
Recovery line
Supply line
Fluidics
Vacuum cleaner
Discharge side
（Hot side）
Inhalation side
（Cold side）
Separator
Steam generator heat-exchangers tube inside decontamination equipment System composition figure 20

23. 7. Summary The needs for decontamination 【Former is also from now on】
Reduction of the amount of secondary generation wastes
Improvement in the speed of decontamination speed
Cost reduction
Radiation exposure reduction
The spirit of ALARA has been, and will be respected in our efforts forever. 21