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Activities
for
Dose Reduction
Hamaoka Nuclear Power Station
Chubu Electric Power Co.,Inc.
1
November 2005
1.Reactor Type
Unit No. Reactor type
Capacity
1
BWR4 Mark-I
540
2
BWR4 Mark-I
840
3
BWR5 Mark-I
improved
1100
4
BWR5 Mark-I
improved
1137
5
ABWR
MWe
1380
2
2-1. Annual Collective Dose
Unit No.2
Annual Collective Dose
Improvement Work
General maintenance
20
Start of Commercial
operation
Outage Maintenance of Unit 4
Outage Maintenance of Unit 3
Outage Maintenance of Unit 2
Outage Maintenance of Unit 1
Unit No.4
Unit No.3
Unit No.1
10
2003
2004
2001
2002
1999
2000
1997
1998
1995
1996
1994
fiscal year
1992
1993
1991
1989
1990
1987
1988
1986
1984
1985
1982
1983
1980
1981
1978
1979
1976
1977
5
1974
1975
Dose(man-Sv)
15
3
2-2. Annual Collective Dose
14
12
Hamaoka total(4 units)
Hamaoka average/unit
National average of BWRs
Dose （ man ・ Sv ）
10
8
6
4
2
0
2000
2001
2002
fiscal year
2003
2004
4
2-3.Dose in Outage Maintenance
Unit
Outage
maintenance
No.
1
15ｔｈ
’ 9 6 / 1 0 / 2 5 ’ 9 7 / 2 / 2 1
10
16ｔｈ
’98/1/5 - ’98/4/10
9
17ｔｈ
’99/3/19 - ’99/8/20
18ｔｈ
’00/9/18 - ’01/3/30
16ｔｈ
’98/6/2 - ’98/9/11
17ｔｈ
’99/10/8 - ’00/5/16
18ｔｈ
’01/6/15 - ’01/8/31
19ｔｈ
’02/7/29 - ’03/1/22
9ｔｈ
’99/1/11 - ’99/4/9
3
10ｔｈ
’00/5/8 - ’00/8/1
2
11ｔｈ
’01/9/15 - ’02/2/7
12ｔｈ
’ 0 3 / 2 / 2 0
’ 0 3 / 1 1 / 2 8
13ｔｈ
’05/1/14 - ’05/6/22
4ｔｈ
’ 9 8 / 9 / 1 0
’ 9 8 / 1 2 / 2 2
5ｔｈ
’00/1/17 - ’00/3/31
6ｔｈ
’01/5/13 - ’01/7/6
7ｔｈ
’02/9/4 - ’03/9/3
8ｔｈ
’04/9/29 - ’05/1/25
Improvement Work
General maintenance
8
Dose(man ・ Sv)
period (including test
generation period)
2
7
6
5
4
3
1
0
1u- 2u- 3u- 4u15 ｔｈ 16ｔｈ 9 ｔｈ 4ｔｈ
1u- 2u- 3u- 4u16ｔｈ 17ｔｈ 10ｔｈ 5 ｔｈ
1u- 2u- 3u- 4u17ｔｈ 18ｔｈ 11ｔｈ 6 ｔｈ
unit
1u- 2u- 3u- 4u18 ｔｈ 19 ｔｈ 12ｔｈ 7ｔｈ
1u
2u 3u- 4u13 ｔｈ 8 ｔｈ
4
1u 19th:’02/April- 5.6man-Sv
2u 20th:’04/Feb- 3.9man-Sv
As of ’05 Sept.30
5
2-4.Dose in PCV (Outage Maintenance)
Ratio of dose in PCV(%)
100
90
3u
4u
80
70
60
50
40
30
20
10
0
10th/5th
11th/6th
12th/7th
Outage Maintenance
13th/8th
6
3.Dose Reduction Countermeasures
Facility design
Reactor Water chemistry control
Shielding in D/W
Shielding lines
Flushing lines
Remote or automatic equipment
Mock –up training
Activities of dose reduction by employees
etc
7
4-1.Shielding in the D/W of Unit 3
Average dose rate in PCV
dose rate
Before
After
reduction
rate
0.095
0.069
△28%
Data at the 10th outage maintenance
unit:mSv/h
Shielded Part
8
4-2. Shielding in the D/W of Unit 3
３号機原子炉格納容器３階（放射線管理記録）
年　月　日
（ＦＬ　４５００）
180°
FPC
LPCI
MS
MS
MS
FDW
MS
FDW
PLR
ﾎﾟﾝﾌﾟ
(A)
N1-B
N2-E
N2-F
N2-D
90°
N2-G
N2-C
270°
N2-H
N2-B
N2-J
N2-A
N2-K
N1-A
PLR
ﾎﾟﾝﾌﾟ
(B)
除湿器
シャフト
スペース
LPCS
HPCS
0°
9
5.Ideas from Employees to
Achieve Dose Reduction
10
5-1.Improvement of CRD Replacement
Procedure
Shortening time for replacement
Unit No.3
RPV
ＲＰＶ
Current Procedure:
CRD is pulled out and replaced one by one
1.51man･mSv/CRD
CRD Repair room
pedestal
11
5-2.Improvement of CRD Replacement
Procedure
Unit No.3
RPV
ＲＰＶ
Improvement: Multi
CRDs are pulled out and replaced
1.26man･mSv/CRD
(-0.25man･mSv)
CRD Repair room
pedestal
12
5-3.Standardization of drawing directions
of the connected Pipes to SRVs
Unit No.3
When SRVs disassembling, the
lines connected SRVs are needed
to be removed. Drawing
directions should be determined
in advance.
13
5-4.Other Ideas for Dose Reduction
by Radiation Control Staff Members
Present
situation
Improvement
idea
Omission of
contamination
preventing sheet on
pedestal floor
Sheets cover floor to
prevent
contamination
caused by CRDs
replacement
Decontamination
by water is also
effective to
prevent
contamination
Reevaluation of
access area for CRD
Replacement
The location of
Present access area
was not the best
because there was
PLR pipe’s radiation
around area
Changing the
location of access
area
Item
Expected Effect
(man-mSv)
3.4
2.8
14
6-1. Encouragement system for dose reduction
Promoting workers’ motivation and ideas for dose
reduction by commending good practices(Since 1994).
Applicants
All employees in the Hamaoka NPS
15
6-2-1. Encouragement system for dose
reduction (example)
Transferring work of CUW powder resin from sump B
to sump A( in Maintenance of Sump B )
In inspection of storage sump B, workers were expected to be highly
exposed by CUW resin.Their dose was successfully reduced with
equipment improved by themselves.
Workers’ Idea : Taihei Electric Co,
Origination of stirring pump with 6 jets
Remodeling an ordinary water pump sold at a home center into the stirring
pump with 6 jets originated with workers
16
6-2-2. Encouragement system for dose
reduction (example)
To sump A
Workers’ Efforts
Top
Jet
Side
Front
sump B
Jet
Jet
Jet
Jet
Jet
Intake
Intake
6 Jets
Discharge device in orange was
attached to the pump
resin 2000mSv/h
Effect
Expected ４５０ man･mSv
Result 144 man･mSv
17
6-3. Encouragement system for dose reduction
(example)
Removing high radioactive sludge by Sludge Drain Separator
In replacement of drain pipes,workers were expected to be highly
exposed by high radioactive sludge remaining in the pipes.
Their dose was successfully reduced with the Sludge Drain Separator
originated by themselves.
Workers’ Idea : Chubu Plant Company
Idea : Origination of Sludge Separator
Vacuum
Drain pipe near
the ceiling
Net
Drain funnel
One part of the drain pipe running the ceiling
was cut then sludge was removed and the pipe
Sludge from the was replaced
drain pipe
Effect
Expected 270 man･mSv
18
Result 180 man･mSv
7-1.Illumination Warning Rope
Flickering diode lights call
attention to high radiation area.
19
7-2.Digital Area Monitor
20
7-3.Information Displays
at the entrance of the radiation control area
Radiation
level
Information on radiation
level and messages from
Radiation control section
is on the displays.
Message
Entrance
devise
21
8-1.Development of Radiation
Reduction
Unit 3
22
8-2.Development of Radiation
Reduction
23