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Radiological Work Management Aspects influencing
Dose Reduction at the Ignalina NPP during Outages and
coming Decommissioning
Radiation Protection Centre
Kalvariju 153, LT-08221 Vilnius
Lithuania
http://www.rsc.lt
Gintautas KLEVINSKAS, MSc.
Head of Subdivision of Supervision and
Control
4th EC/IAEA/ISOE WORKSHOP
on OCCUPATIONAL EXPOSURE MANAGEMENT AT NPPs
Lyon, France, 24-26 March, 2004
Outline
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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 2002-2003 during Outages
Occupational Exposure Results
Decommissioning of Ignalina NPP – Issues of
Concern
Application of ALARA Principle during the
Decommissioning
Conclusions
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General Information – Ignalina NPP
Two non-upgradeable
nuclear reactors of
RBMK-1500 (LWGR) series
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• Natural cooler - Lake Druksiai
Located in north-eastern
part of Lithuania, 160 km
distance from Vilnius
2 Units
Unit 1: 31 /12/ 1983
Unit 2: 15 /08/ 1987
• Designed thermal output -4200 MW
• Designed electrical output 1500
MW (actual - 700-1250 MW)
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Number of workers ~ 4500
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Fundamental Parameters of the
RBMK – 1500 Reactor
Coolant
Water (Steam-Water Mixture)
Heat Cycle Configuration
Core Dimensions
Single Circuit
height 7 m
diameter 11.8 m
Number of Channels
Fuel
Initial Fuel Enrichment for 235U, %
fuel
1661
control and shutdown system
235
reflector – cooling
156
Uranium Dioxide
2.0 (2.4, 2.6 with Erbium)
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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
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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)
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Sources of high dose rates at INPP
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Main sources of ionizing radiation at the INPP
contributing to high dose rates during outages:
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Reactor
Corrosion products in ,,blind” areas
of the circuit
Radioactive substances in steam
and water
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Requirements for Occupational Radiation
Protection in Nuclear Facilities – Radiation
Protection Programme
The radiation protection programme addresses following issues:
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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.
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Works mostly contributing to the annual
collective dose
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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;
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Use of a Structured
Approach
Recognition of Problem where Exposure
Optimization is needed
ALARA PROCEDURE
Final Decision
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ALARA Programme at the Ignalina NPP
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ALARA programme:
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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
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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 Discussion on Optimization
Measures for Specific Tasks
Selection and Analysis of Options
Respect to Dose Reduction Factors
Evaluation and
Feedback
with
Approval of Measures, Allocation of Necessary
Resources
Implementation of Measures,
Cost-Benefit Analysis
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26493
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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26493
EXAMPLE OF DOSE MAPS USED FOR DOSE PLANNING AT
IGNALINA NPP
(DOSE MAP OF LEFT LOOP OF PRIMARY CIRCUIT)
Box 409/1
Downcomer:
0.3-0.85 mSv/h
Box 409/1
Connections PH-SH:
0.01-0.05 Sv/h
Box 409/1 mark 10.0
Pressure pipes:
0.3-0.5 mSv/h
Box 409/1 mark 10.0
Pipes PH-GDH:
0.5-1 mSv/h
Box 208/1 mark 6.0
ECCS T-joints:
0.7-5 mSv/h
Welded joints to GDH:
2.2-3.6 mSv/h
Box 117/1-7
Service foot-plates:
0.15-0.31 mSv/h
Nearby valves Du800:
0.08-0.13 mSv/h
Drainages of Du800:
0.02-0.14 Sv/h
Box 506/1
Between the DS:
1-4.5 mSv/h
Box 506/1
Downcomers,
horizontal parts:
1.2-2 mSv/h
Box 506/1
Downcomers about
plugs:
0.8-1 mSv/h
Box 506/1
Drum Separator
Connection
(500 cor.):
1.5 Sv/h
Main Circulation
Pumps
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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
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Head of WS Department.
26493
EXAMPLE OF CONTENTS OF THE WORK PERMIT USED AT
IGNALINA NPP
(PART: RADIATION PROTECTION MEASURES)
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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)
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Room No.
Gamma dose rate, mSv/h
Decontamination
factor
Before
decontamination
After
decontamination
117/1-7
1-400
0.6-1.2
1.7-330
409/2
50-400
2-2.3
25-170
1.5-100
0.2-1.1
75-90
213;
215
214/1,2;
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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
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Room No.
Room 506/2,
blind pipes
Gamma dose rate, mSv/h
near
the
Room 208/1, near the the
joints 6,8 of headers of the
emergency cooling system
Without radiation
shielding
With radiation
shielding
5.0-2000
5.0-45
8.0-400
8.0-70
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Radiological Work Management Approaches for
Exposure Reduction during Outages
Training of Personnel
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ALARA questions are included in personnel training programmes
Educational book on radiation protection is introduced since
2002 (Russian translation), since 2004 (Lithuanian translation)
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Self - assessment procedures
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Regular training and instructions, advanced training is performed
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Training on mock-ups before the beginning of jobs
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Positive experience and involvement of individual awareness
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Occupational Exposure Results during the Outages at
Ignalina NPP in 2003
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Outages:
Unit 1: 12/07/03-21/10/03
 Unit 2: 05/04/01-01/06/03 (unplanned 0106/11/03)
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Planned doses:
7.59 manSv (plant personnel)
 2.57 manSv (contractors)
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Actual doses:
6.66 manSv (plant personnel)
 1.88 manSv (contractors)
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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
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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
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items of TELETECTOR, 2 items of FH40 G with detector FHT 752).
Evolution of Occupational Exposure at INPP,
man mSv/Unit, 1984-2003
12000
10000
8000
6000
4000
2000
0
1984 1985
1986 1987
1988 1989
1990 1991
1992 1993
1994 1995
1996 1997
Year
1998 1999
2000 2001
2002
INPP Workers
INPP Workers and Contractors
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Planned Decommissioning Activities and ALARA
Approach
Nuclear Safety Agreement in 1994 - 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. 2002 – 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
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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
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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
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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).
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Conclusions
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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.
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Acknowledgement
I would like to thank the IAEA for the
financial support provided for
participation in this Workshop
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