ALARA Programs & Occupational ALARA Programs & Occupational Dose Trend in Wolsong NPPDose Trend in Wolsong NPP
Korea Hydro & Nuclear Power Co., LtdKorea Hydro & Nuclear Power Co., LtdWolsong Nuclear Power Plant Unit 3&4Wolsong Nuclear Power Plant Unit 3&4
Introduction of Introduction of Wolsong NPPWolsong NPP Brief History of Wolsong NPPBrief History of Wolsong NPP Generation Capacity of Wolsong NPPGeneration Capacity of Wolsong NPP
History of Korea Regulatory Law History of Korea Regulatory Law
ALARA program improvements in KHNPALARA program improvements in KHNP ALARA Program before 2000ALARA Program before 2000 ALARA Program after 2000ALARA Program after 2000 Calling ALARA Committee & Making DecisionCalling ALARA Committee & Making Decision General Review of ALARA ProgramGeneral Review of ALARA Program Cases of ImprovementsCases of Improvements
Results of ALARA Program ImprovementsResults of ALARA Program Improvements
ConclusionsConclusions
ContentsContents
Brief History of WolsongBrief 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 WolsongGeneration Capacity of Wolsong
Unit #1 Unit #2,3,4
678MW 700MW×3
NSSS AECL AECL
TBN/GEN NEI Parsons DooSan/GE
HyunDai/DongA HyunDai, DaeWoo
CANDU (PHWR, 2-Loops)
Natural Uranium (U-235, 0.7%)
Heavy Water (D2O)Moderator & Coolant
Fuel
Reactor Type
CATEGORY
CAPACITY
Construction
Supplier
Generation Capacity: Total 2,778 MW
History of Korea Regulatory Law 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
Previous (before 2000) Present (after 2000)
ALARA
Committee
Expected dose:
above 250man-mSv
Expected dose:
above 200man-mSv
ALARA
Implementation
Committee
Expected dose:
100~250man-mSv
Expected dose:
70~200man-mSv
ALARA Prog. Improvements in KHNPALARA Prog. Improvements in KHNP
Before 2000 : Plant specific ALARA procedure
After 2000. 10 : Standard ALARA procedure
ALARA Program before 2000ALARA Program before 2000 ALARA Committee
PWR PHWR
Organi
-zation
Chairman
Vice chairman
Member
Secretary
General manager
Deputy general manager
Plant senior manager
Appointed person
Radiation safety section
senior manager
General manager
Deputy general manager
Plant section senior manager
QA section senior manager
Plant senior manager (sub-contractor)
Radiation safety section senior
manager
Responsibility
- Review ALARA program- Review dose reduction plan
for work. If expected dose is
above 250man-mSv
- Review ALARA program- Review dose reduction plan
for work. If expected dose is above
above 250man-mSv
ALARA Program before 2000ALARA Program before 2000 ALARA Implementation Committee
PWR PHWR
Organization
Radiation safety Section senior
manager
ALARA staff
Radiation protection sect. manager
Work planner and supervisor
Radiation safety section
senior manager
Radiation protection sect. manager
Maintenance section manager
Work supervisor
Responsibility
- Review & approve dose reduction
plan for work expected dose
100~250man-mSv
- Review & approve ALARA sheet
for work expected dose
100~250man-mSv
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 2000ALARA Program after 2000
Organization 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% mor
e 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 2000ALARA Program after 2000
Responsibility of ALARA Committee
ALARA Program after 2000ALARA 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
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
ALARA Program after 2000ALARA Program after 2000
Responsibility of ALARA Implementation Commit.
Minimum 50% of the committee membership
must be attended
Issued meeting agenda must be agreed by two-
thirds of the attendee
Urgent items & imperative cases can be
decided in writing by the committee members
without the committee meeting
Call ALARA Commit.Call ALARA Commit. & Make Decision& Make Decision
ALARA DocumentationALARA Documentation
Kinds of documentsRetention periods
Radiation work plan
(Over 10 under 70 man mSv)
Doc. reviewed by ALARA Implementation committee
(Over 70 under 200 man mSv)
Doc. reviewed by ALARA committee
(Over 200 man mSv)
3 years
5 years
Plant life time
Any Works
Expected doseunder 10 man-mSv
Use general RWP
Perform works
Expected Dose10 ~ 70 man-mSv
- Use RWP- Evaluate expected dose every work steps
Perform works
Expected Dose70 ~ 200 man-mSv
Work group makes & submits to rad. section - expected dose sheet - ALARA check list
Open ALARA Implementation committeeReview & approve - expected dose sheet - ALARA check list
Perform works
A
Expected Doseover 200 man-mSv
Work group makes & submits to rad. section - expected dose sheet - ALARA check list
Open ALARA committeeReview & approve - expected dose sheet - ALARA check list
B
Perform works
Reviews of ALARA ProgramReviews of ALARA Program
A
Review after works
If actual dose exceeds 25% of expected dose
Open ALARA Implementation committee Review & discuss & apply - dose reduction method to hereafter works
B
Review after work
If actual dose exceeds 25% of expected dose
Open ALARA committee Review & discuss & apply - dose reduction method to hereafter works
Reviews of ALARA ProgramReviews of ALARA Program
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
0
500
1,000
1,500
2,000
2,500
3,000(man-mSv)
Internal 0.4 396.7 0.2 412.4
External 1,211.5 1,268.4 1,114.0 1,096.1
2004(PWR)
2004(PHWR)
2005(PWR)
2005(PHWR)
Cases of ImprovementsCases of Improvements
The Comparison of Occupational Dose
The Improvement of the Respirator using Ice Cubes Tritium removal media: replace vermiculate and pa
per 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 hour
s 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 ImprovementsCases 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 ImprovementsCases 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
Cases of ImprovementsCases of Improvements
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
0
1,000
2,000
3,000
4,000(man-mSv)
Internal 205 221 307 282 231
External 752 1,224 862 1,349 688
2001 2002 2003 2004 2005
Occupational dose for Wolsong NPP1 Occupational dose for Wolsong NNP2
0
1,000
2,000
3,000
4,000 (man-mSv)
Internal 505 774 737 546 448
External 725 2,100 2,032 1,268 1,272
1997 1998 1999 2000 2001
Results of ALARA programResults 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
Results of ALARA programResults of ALARA program
Annual dose & no. of operating units Annual Avg. Dose per unit & person
0
1,000
2,000
3,000
4,000
5,000
6,000
KOREA CANADA INDIA ARGENTINA CHINA AVERAGE
(man- mSv/unit)‘00
‘01
‘02
‘03
‘04
‘05
Annual radiation exposure dose per PHWR plant
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
Results of ALARA programResults of ALARA program
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.
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
Year
Dose (man-mSv)% ofO/H Dose
Normal Operation
O/H Total
2000 1,811 9,583 11,394 84
2001 2,181 8,571 10,752 80
2002 2,671 6,644 9,315 71
2003 2,756 7,532 10,288 73
2004 2,627 10,398 13,025 80
2005 2,607 9,323 11,930 78
Results of ALARA programResults of ALARA program
Year
Dose (man-mSv)% ofO/H Dose
Normal Operation
O/H Total
2000 750 1,463 2,213 66
2001 779 1,898 2,677 71
2002 877 1,661 2,538 65
2003 1,137 2,027 3,164 64
2004 845 2,485 3,330 75
2005 809 2,207 3,016 73
Exposure dose for all NPPs Exposure dose for PHWR
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
ConclusionsConclusions
Thank you very much Thank you very much for your attentionfor your attention
