1. Radiological Work Management Aspects influencing Dose Reduction at the Ignalina NPP during Outages and coming Decommissioning
Radiation Protection Centre
Kalvariju 153, LT Vilnius
Lithuania
Gintautas KLEVINSKAS, MSc.
Head of Subdivision of Supervision and Control
4th EC/IAEA/ISOE WORKSHOP
on OCCUPATIONAL EXPOSURE MANAGEMENT AT NPPs
Lyon, France, March, 2004

2. Outline
Introduction
ALARA Programme at the Ignalina NPP – a Use of the Structured Approach
Radiological Work Management Aspects Influencing Dose Reduction During Outages
Challenges and Improvements in Radiation Protection in during Outages
Occupational Exposure Results
Decommissioning of Ignalina NPP – Issues of Concern
Application of ALARA Principle during the Decommissioning
Conclusions

3. General Information – Ignalina NPP
Two non-upgradeable nuclear reactors of
RBMK-1500 (LWGR) series
Located in north-eastern part of Lithuania, 160 km distance from Vilnius
2 Units
Unit 1: 31 /12/ 1983
Unit 2: 15 /08/ 1987
Number of workers ~ 4500
Natural cooler - Lake Druksiai
Designed thermal output MW
Designed electrical output 1500 MW (actual MW)

4. Fundamental Parameters of the RBMK – 1500 Reactor
Coolant Water (Steam-Water Mixture)
Heat Cycle Configuration Single Circuit
Core Dimensions height 7 m
diameter 11.8 m
Number of Channels fuel
control and shutdown system 235
reflector – cooling
Fuel Uranium Dioxide
Initial Fuel Enrichment for 235U, % 2.0 (2.4, 2.6 with Erbium)

5. Ignalina NPP – Unique Features
Identical to BWR Type, but:
Each nuclear assembly bank located in a separately cooled fuel channel (pressure tube)
Nuclear fuel assemblies are changed without shutting down the reactor
For improvement of neutron characteristics, large amount of graphite is needed

6. Ignalina NPP – Unique Features
Identical to BWR Type, however:
Occupational exposure results are probably the highest if comparing with reactors of other types
Main ,,contributors” to the annual collective dose are the annual outages of the units.
Good and effective radiological work management programmes during the outages are needed (as a part of the radiation protection programme)

7. Sources of high dose rates at INPP
Main sources of ionizing radiation at the INPP contributing to high dose rates during outages:
Reactor
Corrosion products in ,,blind” areas of the circuit
Radioactive substances in steam and water

8. Requirements for Occupational Radiation Protection in Nuclear Facilities – Radiation Protection Programme
The radiation protection programme addresses following issues:
classification of working areas and access control;
local rules, measures of supervision of safety at work and order of organization of work;
procedures of monitoring of workplaces and individual monitoring of workers;
individual protective equipment and procedures for their application;
main premises, control systems for assurance of radiation protection;
requiremenets for management of radioactive waste;
radiation protection measures applied during the accident;
application of optimization principle (ALARA) and measures on exposure reduction;
health surveillance of workers;
training of workers and their instructions.

9. Works mostly contributing to the annual collective dose
Replacement of reactor fuel (technological) channels;
  Maintenance of primary system pipes Du-300 (d=300 mm);
  Maintenance of primary system pipes Du-800 (d=800 mm);
  Control of metal;
  Replacement of spherical valves used for measuring of outlet water flow (SHADR-32M) and replacement of removable parts of regulation valves;
   Repair of pipes of the main circulation circuit, reactor emergency cooling system, blow-off and cooling system of the reactor;
   Insulation works;

10. Use of a Structured Approach
Recognition of Problem where Exposure Optimization is needed
ALARA PROCEDURE
Final Decision

11. ALARA Programme at the Ignalina NPP
Work organization;
Training of personnel;
Improvement of working environment;
Improvement of technological processes;
Implementation of quality assurance programme;
Improvement of safety culture;
Evaluation of influence of ,,human factor”
Implemented by ALARA Group

12. Evaluation and Feedback
The ALARA Procedure
Analysis and Evaluation of the Exposure Results from Previous Years
Establishment of List of Works during which the Exposure Reduction is needed
Evaluation and Feedback
Evaluation and Discussion on Optimization Measures for Specific Tasks
Selection and Analysis of Options with Respect to Dose Reduction Factors
Approval of Measures, Allocation of Necessary Resources
Implementation of Measures,
Cost-Benefit Analysis
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13. Dose Planning (dose distribution maps, annual ,,dose budget”)
Radiological Work Management Approaches for Exposure Reduction during Outages
Work Planning and Organization
Description of Works
Dose Planning (dose distribution maps, annual ,,dose budget”)
Description of specific operations
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14. EXAMPLE OF DOSE MAPS USED FOR DOSE PLANNING AT IGNALINA NPP
(DOSE MAP OF LEFT LOOP OF PRIMARY CIRCUIT)
Box 506/1
Between the DS:
1-4.5 mSv/h
Downcomers, horizontal parts:
1.2-2 mSv/h
Downcomers about plugs:
0.8-1 mSv/h
Drum Separator Connection
(500 cor.):
1.5 Sv/h
Main Circulation Pumps
Box 409/1 mark 10.0
Pressure pipes:
mSv/h
Box 208/1 mark 6.0
ECCS T-joints:
0.7-5 mSv/h
Welded joints to GDH:
mSv/h
Box 117/1-7
Service foot-plates:
mSv/h
Nearby valves Du800:
mSv/h
Drainages of Du800:
Sv/h
Pipes PH-GDH:
0.5-1 mSv/h
Box 409/1
Connections PH-SH:
Sv/h
Downcomer:
mSv/h

15. Work Permits Preliminary measurements of: Dose rates
Radiological Work Management Approaches for Exposure Reduction during Outages
Work Permits
Preliminary measurements of:
Dose rates
Surface contamination levels
Air contamination levels  
Preparation of workplaces by operational workers;
  Estimation and appointment of individual protective equipment;
 Instructions to team workers before the beginning of works;
  Issuance and approval of work permits by the Shift Head of WS Department.
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16. EXAMPLE OF CONTENTS OF THE WORK PERMIT USED AT IGNALINA NPP
(PART: RADIATION PROTECTION MEASURES)

17. Decontamination of Systems
Radiological Work Management Approaches for Exposure Reduction during Outages
Decontamination of Systems
Gives very positive results in exposure reduction (main forced circulation circuit, outage of Unit 2 in 2003)
Room No.
Gamma dose rate, mSv/h
Deconta-
mination factor
Before decontamination
After decontamination
117/1-7
1-400
409/2
50-400
2-2.3
25-170
213; 214/1,2; 215
75-90

18. Without radiation shielding With radiation shielding
Radiological Work Management Approaches for Exposure Reduction during Outages
Installation of Temporary Radiation Shielding
Led blankets used
Approach: averted dose should be higher than received during installation
Room No.
Gamma dose rate, mSv/h
Without radiation shielding
With radiation shielding
Room 506/2, near the blind pipes
5.0-45
Room 208/1, near the the joints 6,8 of headers of the emergency cooling system
8.0-70

19. Radiological Work Management Approaches for Exposure Reduction during Outages
Training of Personnel
ALARA questions are included in personnel training programmes
Educational book on radiation protection is introduced since 2002 (Russian translation), since 2004 (Lithuanian translation)
Self - assessment procedures
Regular training and instructions, advanced training is performed
Training on mock-ups before the beginning of jobs
Positive experience and involvement of individual awareness

20. Unit 2: 05/04/01-01/06/03 (unplanned 01-06/11/03) Planned doses:
Occupational Exposure Results during the Outages at Ignalina NPP in 2003
Outages:
Unit 1: 12/07/03-21/10/03
Unit 2: 05/04/01-01/06/03 (unplanned 01-06/11/03)
Planned doses:
7.59 manSv (plant personnel)
2.57 manSv (contractors)
Actual doses:
6.66 manSv (plant personnel)
1.88 manSv (contractors)

21. Main Exposure Optimization Measures implemented During Outages in 2002-2003
Replacement of fuel (technological) channels
Installation and training on mock-up
Purchase of equipment and putting into operation of non cable connection
Installation of equipment for removal of filing
Preparation and implementation of additional equipment for replacement of fuel channels
Maintenance of pipes Du-300, Du-800
Training of personnel on replacement of welded seams on the mock-up
Purchase of equipment and training of welders on welding of pipes with equipment VAS 120
Purchase of equipment for cutting and replacement of parts of pipes Du-800
Training of personnel on repairement technology of pipes Du-300 on the mock-up
Application of automatic welding for pipes Du-300
Replacement of spherical valves used for measuring of outlet water flow (SHADR-32M) and replacement of removable parts of regulation valves
Training of personnel on repair technology on the mock-up

22. Achievements in Radiation Protection in 2002-2003
new whole body counter "ACCUSCAN 2260-G2KG " was putted into operation (in 2003 – 2659 of personnel was monitored) ;
new system for training of personnel in the field of radiation protection has been introduced: educational book ,,Radiation Protection” is issued. New programmes for training and checking of knowledges of personnel have been applied
replacement of equipment for measurement of radioactive contamination at the exits from controlled area (RZB-04 have been replaced to RTM-860, PPM-1, PMW-3e)
set of dosimetric equipment is renewed (50 items of RAD-62-, 4 items of TELETECTOR, 2 items of FH40 G with detector FHT 752).

23. Evolution of Occupational Exposure at INPP,
man mSv/Unit,

24. Planned Decommissioning Activities and ALARA Approach
Nuclear Safety Agreement in Closure of the Ignalina NPP at the time of so-called ,,gap closure”
Closure of Unit 1 in 2005, Unit 2 – probably in 2009
Nov – Immediate Dismantling Strategy for Unit 1
Dismantling will continue at least 30 years
Can be treated as extended outage
Predicted total collective dose : ~ 35 manSv
Need for advance preparation, which is already started
The draft of the Final Decommissioning Plan is prepared (appr. 500 pages)
Radiation Protection Programme is included

25. Interfaces with ALARA Commitment during Decommissioning
The compliance with the ALARA policy objectives for the plant personnel basically relies on 2 key issues:
on careful engineering, technical, administrative preparations of the activities to be carried out
on monitoring of their implementation in the controlled area and implementation of corrective actions in case of individual and collective dose exceed the ALARA objectives

26. Interfaces with ALARA Commitment during Decommissioning
PREPARATORY ACTIVITIES
Keeping the personnel exposure in accordance with ALARA principle during decommissioning will require:
Authorization of works in the controlled area by work permits;
Establishing the dose maps in the to be accessed areas;
Carrying out computer simulations of the activities to be performed in the controlled area.;
Implementation of countermeasures to reduce the background: decontamination, installation of temporary shielding, use of remotely operated equipment, additional ventilation capacities, additional confinement zones, etc.;
Careful review of the lessons to be learned from previous similar activities already carried out either at INPP or at other NPPs and, when relevant, adaptation or optimization of the operation procedures;
Checklists of the equipment to be consigned (isolated).

27. Conclusions
A set of procedures, forming of the radiation protection program, was created and is effectively implemented at INPP. Good radiological work management procedures applied during the outages give successful results in reduction of occupational exposure.
Keeping the personnel exposure in accordance with ALARA principle during the decommissioning of Ignalina NPP will require careful engineering, technical, administrative preparations of the activities to be carried out. Positive experience gained in optimization of protection during the normal operation of the Ignalina NPP will be taken into account.

28. Acknowledgement
I would like to thank the IAEA for the financial support provided for participation in this Workshop