Transcript ALARA OPERATION

ALARA Programs & Occupational
Dose Trend in Wolsong NPP
Korea Hydro & Nuclear Power Co., Ltd
Wolsong Nuclear Power Plant Unit 3&4
Contents
Introduction of Wolsong NPP
 Brief History of Wolsong NPP
 Generation Capacity of Wolsong NPP
History of Korea Regulatory Law
ALARA program improvements in KHNP
 ALARA Program before 2000
 ALARA Program after 2000
 Calling ALARA Committee & Making Decision
 General Review of ALARA Program
 Cases of Improvements
Results of ALARA Program Improvements
Conclusions
Brief History of Wolsong
1975.10: Opening of Wolsong NPP
construction office
1983. 4: Commercial operation of unit #1
1997. 6: Commercial operation of unit #2
1998. 6: Commercial operation of unit #3
1999. 9: Commercial operation of unit #4
Generation Capacity of Wolsong
Generation Capacity: Total 2,778 MW
CATEGORY
Unit #1
Unit #2,3,4
CAPACITY
678MW
700MW×3
Reactor Type
CANDU (PHWR, 2-Loops)
Fuel
Natural Uranium (U-235, 0.7%)
Moderator & Coolant
Heavy Water (D 2O)
NSSS
AECL
AECL
TBN/GEN
NEI Parsons
DooSan/GE
HyunDai/DongA
HyunDai, DaeWoo
Supplier
Construction
History of Korea Regulatory Law
Korea regulatory law in radiation protection
 1958 : Establish the atomic act
 1983 : General revision based on ICRP-9(MPD, MPAD, MPC)
 1994 : Include the concept of “ALARA”
 1996 : Apply the dose limit concept (no quarterly limit)
 1998 : Apply 100mSv/5yr (50mSv/yr maximum) to effective dose
limit but 200mSv/5yr until 2002
 1999 : Require to implement “ALARA”
 2001 : Apply the concept of ALI, DAC
ALARA Prog. Improvements in KHNP
Before 2000 : Plant specific ALARA procedure
After 2000. 10 : Standard ALARA procedure
Previous (before 2000) Present (after 2000)
ALARA
Committee
Expected dose:
above 250man-mSv
ALARA
Expected dose:
Implementation
100~250man-mSv
Committee
Expected dose:
above 200man-mSv
Expected dose:
70~200man-mSv
ALARA Program before 2000
ALARA Committee
PWR
Organi
-zation
Chairman
Vice chairman
Member
Secretary
General manager
Deputy general manager
Plant senior manager
Appointed person
Radiation safety section
senior manager
Review ALARA program
- Review dose reduction plan
for work. If expected dose is
above 250man-mSv
-
Responsibility
PHWR
General manager
Deputy general manager
Plant section senior manager
QA section senior manager
Plant senior manager (sub-contractor)
Radiation safety section senior
manager
Review ALARA program
- Review dose reduction plan
for work. If expected dose is above
above 250man-mSv
-
ALARA Program before 2000
ALARA Implementation Committee
PWR
Organization
Radiation safety Section senior
manager
ALARA staff
Radiation protection sect. manager
Work planner and supervisor
-
Responsibility
Review & approve dose reduction
plan for work expected dose
100~250man-mSv
PHWR
Radiation safety section
senior manager
Radiation protection sect. manager
Maintenance section manager
Work supervisor
-
Review & approve ALARA sheet
for work expected dose
100~250man-mSv
ALARA Program after 2000
Organization of ALARA Committee
Chairman
General manager
Secretary
Rad. safety sect.
senior manager
Member
Member
Member
Member
Deputy general
manager
QA section
senior manager
All plant
senior manager
Subcontractor
senior manager
ALARA Program after 2000
Responsibility of ALARA Committee
 General reviews & approval of ALARA program
 RP Policy, Annual Target, Long-term ALARA strategy etc
 If expected dose for work is above 200 man-mSv
 Review & approve radiation protection optimization plan
 Review ALARA results after work if actual dose exceeded by 25%
more than expected dose
 Review & approve radiation safety control plan during O/H periods
 Reviews & approval of optimization plan for radiation protection
when requested by chairman
ALARA Program after 2000
Organization of ALARA Implementation Committee
Chairman
Rad. safety sect.
senior manager
Secretary
Radiation protection
section manager
Member
Member
Member
Member
Workgroup section
manager
Subcontractor
workgroup
senior manager
Radiation service
subcontractor
senior manager
A person who is
recommended by
chairman
ALARA Program after 2000
Responsibility of ALARA Implementation Commit.
 If expected dose for work is above 70~200 man-mSv
 Review & approve radiation protection optimization planning
 Review ALARA results after work if actual dose exceeded by 25%
more than expected dose
 Review & approve radiation safety control plan for following
workplace
 If airborne tritium concentration exceeds 10DAC
 If expected dose exceeds 10 man-mSv
 Review & approval of optimization plan for radiation protection
when requested by chairman
Call ALARA Commit. & Make Decision
Minimum 50% of the committee membership
must be attended
Issued meeting agenda must be agreed by twothirds of the attendee
Urgent items & imperative cases can be
decided in writing by the committee members
without the committee meeting
ALARA Documentation
Kinds of documents
Retention
periods
Radiation work plan
(Over 10 under 70 man mSv)
3 years
Doc. reviewed by ALARA Implementation committee
(Over 70 under 200 man mSv)
5 years
Doc. reviewed by ALARA committee
(Over 200 man mSv)
Plant life
time
Reviews of ALARA Program
Any Works
Expected dose
under 10 man-mSv
Expected Dose
10 ~ 70 man-mSv
Expected Dose
70 ~ 200 man-mSv
Expected Dose
over 200 man-mSv
Use general RWP
- Use RWP
- Evaluate expected dose
every work steps
Work group makes &
submits to rad. section
- expected dose sheet
- ALARA check list
Work group makes &
submits to rad. section
- expected dose sheet
- ALARA check list
Perform works
Perform works
Open ALARA
Implementation committee
Review & approve
- expected dose sheet
- ALARA check list
Open ALARA committee
Review & approve
- expected dose sheet
- ALARA check list
Perform works
Perform works
A
B
Reviews of ALARA Program
A
B
Review after works
Review after work
If actual dose exceeds
25% of expected dose
If actual dose exceeds
25% of expected dose
Open ALARA
Implementation committee
Review & discuss & apply
- dose reduction method
to hereafter works
Open ALARA committee
Review & discuss & apply
- dose reduction method
to hereafter works
Cases of Improvements
High internal exposure dose (IED) in Wolsong NPP
 Internal exposure dose of PHWR is higher than that of PWR
 Furthermore, IED reaches up to 40% of EED in the beginning
of operation
 Internal exposure is mainly caused by airborne tritium
3,000
(man-mSv)
2,500
2,000
1,500
1,000
500
0
2004
(PWR)
2004
(PHWR)
2005
(PWR)
2005
(PHWR)
Internal
0.4
396.7
0.2
412.4
External
1,211.5
1,268.4
1,114.0
1,096.1
The Comparison of Occupational Dose
Cases of Improvements
The Improvement of the Respirator using Ice Cubes
 Tritium removal media: replace vermiculate and
paper filter by ice cubes
 Year of development: 1992
 Components: canister, half face mask, rubber hose
 Ice cube mass: 670g/canister
 Tritium removal efficiency: above 95% within 2
hours
 Improvements
 The prevention of solid rad-waste generation
 The respiration became fresher and less stifling
 Easy-to-get and cost-effective tritium removal medium
Cases of Improvements
The Development of Movable Tritium Eliminator
 Application
 D2O leak from moderator and coolant system
 Spills from equipment failure
 Maintenance for the systems or facilities including tritium
 Purpose
 Preventing diffusion of airborne tritium
 Reducing internal exposure of workers
 Tritium removal mechanism
 Adsorption of airborne tritium into water
Cases of Improvements
The Other Efforts for IED Reduction
 Use of temporary ventilation fan and duct
 Use of portable air tent
 Improvement of D2O collection tools
 Development of dryer used for decontamination paper
Results of ALARA program
Diminishment of internal exposure dose
 Internal exposure dose of PHWR has been diminished
 Portion of IED have decreased to half of previous’
 Result of continuous efforts to reduce airborne tritium
4,000
(man-mSv)
4,000
3,000
3,000
2,000
2,000
1,000
1,000
0
0
1997
1998
1999
2000
2001
Internal
505
774
737
546
448
External
725
2,100
2,032
1,268
1,272
Occupational dose for Wolsong NPP1
(man-mSv)
2001
2002
2003
2004
2005
Internal
205
221
307
282
231
External
752
1,224
862
1,349
688
Occupational dose for Wolsong NNP2
Results of ALARA program
Decrease in Exposure Dose
 Annual dose has not increased (but no. of units increased)
 Average dose per person & unit have been diminished
(man-mSv)
(No of unitss)
16000
22
dose
no of units
14000
(man-Sv/unit)
3.5
(mSv/person)
dose/person
3.5
dose/unit
20
3
18
2.5
16
2
14
1.5
3
2.5
2
12000
10000
12
10
8000
8
`94 `95 `96 `97 `98 `99 `00 `01 `02 `03 `04 `05(Year)
Annual dose & no. of operating units
1
0.5
0
1.5
1
0.5
0
`85 `86 `87 `88 `89 `90 `91 `92 `93 `94 `95 `96 `97 `98 `99 `00 `01 `02 `03 `04 `05 (Year)
Annual Avg. Dose per unit & person
(ma n -mS v /u n i t )
6,000
‘ 00
‘ 01
5,000
‘ 02
‘ 03
‘ 04
4,000
‘ 05
3,000
2,000
1,000
0
K O RE A
CANAD A
IND IA
ARG E NTINA
CH INA
Annual radiation exposure dose per PHWR plant
AVE RAG E
Results of ALARA program
Diminishment of Over-exposure Workers
 No. of over-exposure workers exceeded 20mSv/year has
increased before 1990.
 There was no over-exposure workers for last 7 years
300
(Persons)
250
200
150
100
50
`77
`78
`79
`80
`81
`82
`83
`84
`85
`86
`87
`88
`89
`90
`91
`92
`93
`94
`95
`96
`97
`98
`99
`00
`01
`02
`03
`04
`05
0
(Year)
Status of over-exposure workers
Remark: 1) was happened during in-core detector motor repair work at Kori #2 NPP.
Total dose was 52.09mSv per person.
Results of ALARA program
Tendency in Exposure Dose
 Annual dose has not increased (but no. of NPP increased)
 Average dose per person & unit have been diminished
 Concentrate radiation control & ALARA activity during O/H
Dose (man-mSv)
Year
Normal
Operation
O/H
Total
Dose (man-mSv)
% of
O/H
Dose
Year
Normal
Operation
O/H
Total
% of
O/H
Dose
2000
1,811
9,583
11,394
84
2000
750
1,463
2,213
66
2001
2,181
8,571
10,752
80
2001
779
1,898
2,677
71
2002
2,671
6,644
9,315
71
2002
877
1,661
2,538
65
2003
2,756
7,532
10,288
73
2003
1,137
2,027
3,164
64
2004
2,627
10,398
13,025
80
2004
845
2,485
3,330
75
2005
2,607
9,323
11,930
78
2005
809
2,207
3,016
73
Exposure dose for all NPPs
Exposure dose for PHWR
Conclusions
Atomic law in Korea request actual ALARA
implementation
First time, management had a duty to ensure
doses were ALARA
KHNP developed the standard ALARA program
 Apply lower dose limits & organize stronger members
Successful achievement in dose reduction
 Annual total dose has not increased
 No. of over-exposure workers has been diminished until
1999 & there was no over-exposure worker till now
Thank you very much
for your attention