2017 Sino-Japanese Workshop on NPP …1995 2000 2005 2010 2015 2020 2025 2030 2035 2040 2045 2050...
Transcript of 2017 Sino-Japanese Workshop on NPP …1995 2000 2005 2010 2015 2020 2025 2030 2035 2040 2045 2050...
© Nov. 2017 ANDES
Tokai 1 Decommissioning Experience
The Association for Nuclear Decommissioning Study
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Tadamichi Satoh
Nuclear Engineering & Services Co.
Association for Nuclear Decommissioning Study
2017 Sino-Japanese Workshop on NPP Decommissioning Technology
November14, 2017 @ Atomic Energy Council 3F
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Decommissioning Projects in Japan
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Progress of Japanese Decommissioning Projects
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1995 2000 2005 2010 2015 2020 2025 2030 2035 2040 2045 2050
Tokai-1
GCR
Fugen
ATR
Hmaoka-
1,2
BWR
Tsuruga-1
BWR
Mihama-
1,2
PWR
Genkai-1
PWR
Shimane-1
BWR
Ikata-1
PWR
Fukusima
Daiichi
BWR
? ?
SF ShipmentPreparation Peripheral Reactor Building
Removable of SF
Removable of Fuel-Debirs Decommissioning
DP
DP
DP
DP
DP
DP
DP
DP
DP:Approval of Decommissioning Plan
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Shooting date:Dec 2001(before removal of outdoor piping)
Tokai-1 Decommissioning Project~The First Decommissioning Project for
Commercial Reactor in Japan ~
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SPENT FUEL CARTRIDGE COOLING POND
REACTOR BUILDING
TURBINE HALL
PIPE BRIDGE
TURBINE
GENERATORTRANSFORMER
CONDENSER
COOLING
WATER
CULVERT
BASEMENT PILEBASEMENT STRUCTURE
BASEMENT PILE
STACK
CHUTE
CHARGE MACHINE BRIDGE
REACTOR
CORE
STEAM RAISING UNIT
BIOLOGICAL SHIELD WALL
REACTOR PRESSURE VESSEL
Moderator : Graphite
Coolant : Carbon dioxide Gas
Reactor vessel : Spherical shape, 18m diameter
Steam Raising Unit : 4 Units
Turbine Generator : 83 MWe × 2 Units
Operation term :1966~1998(for 31 years operation)
Defueling and shipment :1998.5.28~2001.6.21
Tokai-1 is the first commercial NPP in Japan
Reactor Type:Gas Cooled Reactor
Capacity :166 MWe
Fuel :Metal Natural Uranium with Magnox Cladding
Tokai-1 is the sole Magnox NPP in Japan
Tokai-1 is the oldest NPP in Japan
Unit cost became higher than LWRs
Jun.1996 Formal announcement for closure
Mar.1998 Permanent Shutdown
May.1998-Mar.2001 Defueling
Jun.2001 The last shipment of Spent Fuel
Oct.2001 Submitted the notification of decommissioning plan
Dec.2001 Commenced Decommissioning work
Outline of Tokai-1
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Project Mission
Tokai-1 project has important roles for;
Demonstrating the safe and economical decommissioning of commercial NPP
Establishing key technologies for the future LWRs decommissioning in Japan (Remote dismantling techniques & Waste management strategy)
Promoting rule making and realization of waste route
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Project strategy
All facilities will be removed. After decommissioning , the
land is to be reused for future nuclear power operation
Reactor structure will be dismantled after 10-year safe-
store
Conventional components will be removed during reactor
safe-store to utilize existing human resources
Project program is divided into 3 phases because of long
term project
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Waste disposal facility will be constructed prior
to reactor dismantling
If a disposal facility is not available, safe-store
period is to be extended
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JFY2001
02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17
Safe-Storage of Reactor Area
Remove Facilities except Reactor Area
Reactor Area Dismantling
Remove SRUs
Remove Facilities
from each Building
Reactor Dismantling
BuildingsDemolition
Remove Conventional Facilities e.g. turbine
First PhaseSecond Phase
Third Phase
Original Plan for Tokai-1 Decommissioning
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First phase: 5 years
1.Isolate reactor structure for safe store by valve out and plugging.
2.Drain and cleanup spent fuel cooling pond.
3.Remove components in turbine and reactor auxiliary buildings, including
the fuel charge and discharge machines.
123
33
3
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1.Remove 4 SRUs
2.Install Radwaste Treatment System
1
Second phase:5years
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Third phase (first step): 5years
Reactor structure is to be dismantled by remote
operation manipulators.
1.Withdraw reactor inserts and take out graphite blocks
2.Dismantle RPV and Internals
3.Remove activated concrete shielding structures
1
1
2
3
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Third phase(2nd step):2 years
1. After final survey, demolish all building structures
except basements and underground structures.
2. Finally, adjust the land on ground level.
1
1
1
2
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Summary of First Phase
During the first five years of decommissioning programme,
JAPC got successful results
JAPC has managed each task as
scheduled and as budgeted
No serious trouble and accident
DIY policy enables JAPC to
accumulate practical know-how
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Item PlanActual
achievement
Manpower (man-day) 54,700 53,416
Worker dose (man-mSv) 250 297
Amount of wasteand material(ton)
10,690 10,275
First phase (2001-2005) actual result
*Total amount to be arose from whole the decommissioning project: 196,600ton(Radioactive waste:68,000 ton、Non-radioactive waste:128,700 ton)
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Some additional slides will be presented in the presentation.
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JFY
2001020304050607080910 11 12131415 16 17 18 19 20 21 22 23 24 25
Safe-Storage of Reactor Area
Remove Facilities except Reactor Area
Reactor Area Dismantling
Remove SRUs
Remove Facilities from each Building
Reactor Dismantling
Current Plan for Tokai-1 Decommissioning
Remove Conventional Facilities e.g. turbine
BuildingsDemolition
First Phase
Second Phase Third Phase
8 Years Delay
1st SRU 2nd SRU
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Sequence
2.Remove gas duct
1.Remove peripheral equipment
3.Remove SRU
Specification of SRU
Number 4 units
Material Carbon steel
Height
Diameter
24.7 m
6.3 m
Weight
750 ton/unit・Shell
250 ton/unit・Tubes
500 ton/unit
No.1,2,3,4 completed
No.1,2,3,4 completed
No.1,2 completed
[2nd Phase] SRU Dismantling Concept
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Storage
【Work Image at Work area at third floor】Remote cutting sys(Manipulator arm)
〔Primary cutting〕 〔Tier transfer〕 〔secondary cutting〕
PreparationLarge jack installationRemote cutting sys
installation
Cutting & removalPrimary cutting(Divide tiers)Secondary cutting(Cutting into pieces)
Temporal pedestal &
Jack sys installation
Jack Down
(Tiers 1-9 removal)
Temporal pedestal &
Jack sys removal
Work area at
third floor
1st SRU Dismantling Method
Large Jack
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Concept of Waste Treatment & Disposal
Tunnel or silo(50m-100m underground)
Concrete pit(10m underground)
Trench
Recycle & Disposal
27,500
(1,600)
(12,800)
(13,100)
169,000Non-Radioactive
waste*
Cont
ainer
Interim site storage
[In site storage facility]
Pack
ing
Interim site storage
[In site storage facility]
Interim site storage[In-site]
Low Level wasteDisposal facility
TreatmentVolume reduction;Metal, concrete,graphite(Including melting& burning)Decontamination;metal
TreatmentVolume reduction;Metal, concrete,Decontamination;metal
This amount is after decontamination
*Including clearance waste
Graphite
Metal
Graphite
Metal
Concrete
Metal
Concrete
Metal
Concrete
Amount (t)
[Metal] ・Recycle
[Concrete]・Gravel for landfill
Comparativelyhigh radioactivelevel(L1)
Comparativelylow radioactivelevel(L2)
Very lowRadioactive level
(L3)
Low level waste
Tunnel Silo
Cover soil
Cover soil
Waste
Type
L1
L2
L3
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Key Constraints in Japan
1. Decommissioning LLW disposal L1 waste : Regulatory standard is being developed.L2 waste : Current JNFL disposal facility is only for
operating waste.L3 waste : JAPC Tokai L3 disposal facility is under licensing
review. Each utility individually consider own L3 disposal.
2. Clearance of materialConditional release ⇒ Free releaseExcessive conservatism in verification measurement and
licensing review
3. Non-radioactive(NR) material in radiation control areaExcessive conservatism required for judgement(Required too much evidences, e.g. documents, records and
measurements)
4. Spent Fuel Paths
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Key Elements for Successful Decommissioning ~ Lessons Learned from Tokai-1 Project ~
1. Securing necessary funds- Exact cost estimation and its update- Understanding its uncertainties
2. Characterization! Characterization!!Characterization!!!- Developing radiological characterization by the
combination of calculation models and measurements- Review and analyze the results (cross-check) and update
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- On a room by room basisfocusing on materials (wastes).
•Don’t utterly trust ‘As built’ drawings•Review available documents, records and old photos•Perform interview of former or current workers•Address all the hazards (incl. non radiological one)•Focus on materials in each room,not on each components in each system
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- Database should be established which provide significant input into assess & decision on ;
•D&D techniques: decontamination processes, dismantling processes ( hands-on, semi-remote, fully remote ) and required equipment
•Radiological and industrial protection of workers, public, and environment
•Waste management, waste classification & its verification•Waste disposal and Recycling options•Cost estimations
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3. Downsizing of utilities- Early Establishment of Cold & Dark and Nuclear Island- Regarding systems and major equipment,
consider the following options:・Operable as is・Modified・Preserved for the future・New・Retired
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4. Waste Routes- Do not rush into showing ‘visible progress’ before waste routes are secured.
・Temporary space in working place ・Carrying routes ・Temporary area for waste storage & waste treatment, ・On site Interim storage facility ・Final disposal
- Maintain detailed and accurate records on the contents of waste packages
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5. Total optimization- Consider the overall optimization from Decontamination/Dismantling process to Waste treatment & conditioning / Disposal process“The next processes are our customers.”
6. Hands-on approach - Combination of low-tech and high-tech- In some cases, R&D and innovative technologies may increase Project Risks(cost)
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7. Project completion oriented management
- New and different management reflecting the need for greater emphasis on project management(different from operational phase where activities are generally routine
and well practiced by a stable work force)
- The management to be flexible and able to respond quickly to new situations
⇒ Vesting the local site management with a range of powers
(various new decommissioning activities may need closer day-to-day control or supervision)
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8. Change Culture and Mindset
・ Production oriented management VS Objectives Project completion oriented management objectives
・ Focus on functioning of systems VS Focus on management of material and radioactivity inventory (e.g. for waste minimization)
・ Reliance on permanent structures for the operating life of the facility VSIntroduction of temporary structures to assist dismantling
・ Predominant nuclear and radiological risk VS Reduction of nuclear risk, changed nature of radiological risk, significantly increased industrial risk
・ Low radiation/contamination levels relatively unimportant VS Low radiation/contamination levels important for material clearance
9. Dedicated Organization & Combination of Human Resources
- Different phases have different needs and therefore different knowledges, skills ( supply chains ) and leadership
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10. Incentive- Decommissioning is not the end, the importance of a future beyond decommissioning
11. Avoid Excessive Protection and Over-Regulation
12. Stakeholder Involvement- Communication with local community is important. It leads
to a successful decommissioning.
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Conclusions
・ Key points for the safe(安全), smooth(順利), and reasonable(合理的) decommissioning - Waste Management - Organization & Management- Culture & Mindset change
・ Non-technical factors are often more important than technological factors
・ Decommissioning is “Experience Engineering(経験工学)”Take lessons from one work (one project) to make improvement at the next.
・ International cooperation and exchange of decommissioning experience improve project efficiencies and improve safety.
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End of Presentation
Tadamichi Satoh
Secretary-General
The Association for Nuclear Decommissioning Study
Address:
401 Yoshida Bldg., Kudan-kita, chiyoda-ku,
Tokyo 102-0073 Japan
Phone: +81-3-6272-4150
Fax: +81-3-6272-4470
E-mail: [email protected]
URL: http://www.decomiken.org