1. ALARA Programs & Occupational Dose Trend in Wolsong NPP
Korea Hydro & Nuclear Power Co., Ltd
Wolsong Nuclear Power Plant Unit 3&4

2. Contents Introduction of Wolsong NPP History of Korea Regulatory Law
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

3. Brief History of Wolsong
: Opening of Wolsong NPP
construction office
: Commercial operation of unit #1
: Commercial operation of unit #2
: Commercial operation of unit #3
: Commercial operation of unit #4

4. Generation Capacity of Wolsong
Generation Capacity: Total 2,778 MW

5. 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

6. ALARA Prog. Improvements in KHNP
Before : Plant specific ALARA procedure
After : Standard ALARA procedure
Previous (before 2000)
Present (after 2000)
ALARA
Committee
Expected dose:
above 250man-mSv
above 200man-mSv
Implementation
100~250man-mSv
70~200man-mSv

7. ALARA 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
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
for work. If expected dose is above

8. ALARA 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
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

9. ALARA Program after 2000
Organization of ALARA Committee

10. 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

11. ALARA Program after 2000
Organization of ALARA Implementation Committee

12. 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

13. Call ALARA Commit. & Make Decision
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

14. ALARA Documentation Radiation work plan Retention periods 3 years
Kinds of documents
Retention 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

15. 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

16. Reviews of ALARA ProgramB
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

17. 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
The Comparison of Occupational Dose

18. 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

19. 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

20. 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

21. 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
Occupational dose for Wolsong NPP1 Occupational dose for Wolsong NNP2

22. 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
Annual dose & no. of operating units Annual Avg. Dose per unit & person

23. Annual radiation exposure dose per PHWR plant

24. 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
Status of over-exposure workers

25. Remark: 1) was happened during in-core detector motor repair work at Kori #2 NPP.
Total dose was 52.09mSv per person.

26. 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
Year
Dose (man-mSv)
% of
O/H
Dose
Normal
Operation
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
2005
2,607
9,323
11,930 78
Year
Dose (man-mSv)
% of
O/H
Dose
Normal
Operation
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

27. 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

28. Thank you very much for your attention
This a picture taken during the cherry blossom season in April.
These are briefs of KEPCO & WNPD.
Thank you, very much minister for your attention.
Thank you very much
for your attention