Safety
Safety Research
Research forfor thethe Disposal
Disposal ofof Radioactive
RadioactiveWaste
Waste Generated
Generated byby Decommissioning
Decommissioning
oｆoｆ Nuclear
Nuclear PowerPower Facilities
Facilities
Kenkichi ISHIGURE
Japan Radioisotope Association

1 Decommissioning of nuclear power facilities andpreparations in Japan・ introduction
・ regulation
・ R&D
2 Waste generated from decommissioning
・ disposal
・ clearance and recycle
3 Future tasks
1

What
What isis Decommissioning
Decommissioning ??
•Decommissioning- Administrative and technical actions
taken to allow nuclear facilities
to release from regulatory controls･ Safety ensuring and consideration on
environmental impact required･ Economical factors including cost issue
important2

Options
Options ofof Decommissioning
Decommissioning• USA (NRC)
1) SAFSTOR（Safe Storage）
2) DECON （Immediate Dismantling）
3) ENTOM（Safety Enclosure）
・ Usually dismantled after SAFSTOR• IAEAA wide range of options from immediate dismantling to in-situ
burial including intermediate onese.g. Delayed dismantling(dismantled after safe storage for a certain period)• JAPAN
Standard process（for commercial plants）: partly modified after
decision in 1985, used for estimation of decommissioning cost・Strict definition on decommissioning is not so important.
It is applied flexibly depending on the plant situations.

3Decommissioning
DecommissioningStatus
Statusofof NPPNPPinin Major
MajorCountries
Countries
the numbers of unit, counted based on the different criteria from different sourcesCountry

Under
Safe Storage

Under
Dismantlement

CompletedUSA

10211UK

10*10France720

Germany292Japan221* Under the preparation for safe storage· There are ca. 120 plants permanently shutdown in the world (OECD/NEA)· USA and Germany are advanced in taking dismantling option
DECON in USA has been quiet down
· France is now active to move up decommissioning.
· UK was planning the long term safe storage (for 65-96 years), but changed to takethe earlier dismantling4

Decommissioning
Decommissioning ofof NPP
NPP inin JapanJapan
１．Japan Power Demonstration Reactor（BWR 12.5MWe） Operation 1963 - 1976
Decommissioning（R&D） - Dismantling 1986 - 1996
2. Tokai-1（GCR 166MWe）
Decommissioning

3. Fugen （ATR 165MWe）
Decommissioning

4. Hamaoka-1(BWR 540 MWe)
Hamaoka-2(BWR 840 MWe)
Decommissioning
5. Tsuruga-1（BWR 357MWe）

Operation 1966 - 1998
- ”Notification of Reactor Dismantling” submitted,
decommissioning started in 2001
- The first phase completed in 2006
- ” Decommissioning Plan” approved in 2006
Operation 1979 - 2003
- Removal of spent fuels started from 2003
- “Decommissioning Plan” approved in 2008
Operation 1976 - 2009
Operation 1978 – 2009
・”Decommissioning Plan” approved in 2009
Operation 1970 – 2016（planned）

56Standard Process for Decommissioning of Commercial NPPReutilization of site

Treatment and disposalof waste

Dismantling

System Decontamination

Removal of spent fuel

Permanent shutdown

Decommissioning

Safe Storage
about 5 to 10 yeas

Operation

Reuse of site

in ca. 30 years
Source: Report from Nuclear Energy Subcommittee, Advisory committee for Natural Resources andEnergy, January 1997

Features- Decommissioning phase after removal of the spent fuels
燃料搬出後 廃止措置段階- Safe storage : 5-10 years
安全貯蔵 ５－１０年- Completion period : around 30 years
to be used with flexibility depending on plant situations and usually for cost estimation

7Outline of dismantling process ーFugen Case
① period for removal of spent fuels② period for dismantling areas around nuclear reactor

turbineturbinReactor coolant
systemfuel handling
And exchangesystems③ Period for dismantling reactor area

④ Period for demolition of buildings

Reactor area

Typical
Typical Radio-nuclides
Radio-nuclides Remaining
Remaining
after
after Reactor
Reactor Shutdown
Shutdown
former STA “Decommissioning of Nuclear Facilities”

nuclidedecay pattern

half life

locus containing radio- nuclide
pressure vessel biological shielding coolant
core internalconcrete

Tβ12.3y〇〇〇

C - 14β5730 y〇〇----

Mn - 54γ312 d〇--------Co - 60β,γ5.27 y〇〇〇Ni - 63β

100 y〇〇〇

Nb - 94β,γ20,300y〇

----

----

Cs - 134β,γ2.06 y----〇〇Sb - 125β,γ2.73y

〇

----

----

Eu - 152β,γ13.5 y----〇----Eu - 154

β,γ8.59 y----〇----Ensuring
Ensuring Safety
Safety onon NPPNPP Decommissioning
Decommissioning
1 Characteristics of Decommissioning
・Plants being in the static condition after permanent shutdown
no possibility of the occurrence of abnormal events inducedby sudden transient changes such as of reactivity, pressure,temperature etc,
・ Fuels removed and decontamination applied at an early stage.
radio-activities contained much reduced・ Some decommissioning works very similar to repair works of plant.
experience accumulated to ensure safety
2 Safety
・Safety assessment on hypothetical accident : Radiation exposures tothe public near the plant is about 25％ of radiation exposures fromthe natural origin on the assumption of missing reactor container andreactor buildings as barriers against spread of radioactivities.
When they are maintained properly, the exposures much reduced
・ The safety level on decommissioning is very high.

Preparations
Preparations forfor NPP
NPP Decommissioning
Decommissioning
inin Japan
Japan
Preparations in various aspects required for implementing NPP
decommissioning safely and smoothly.
1. Regulatory Framework:- Development of legal procedures for decommissioning
2. Technology Development :- JPDR dismantling demonstration project- Technical verification test by Nuclear Power Engineering Corporation(NUPEC)
in 1982～2003
2. Waste Management :- Development of regulation on radioactive waste disposal- Development of repositories corresponding to radioactivity levels- Establishment of clearance system
4. Securing Funds :- Establishment of provision account system for decommissioning
in 1990 and 2000
- Reserve fund based on the standard process of decommissioning

Japan has made steady progress toward the decommissioning oflarge scale commercial NNP.

11

New
NewRegulation
Regulationon
onDecommissioning
Decommissioning
Continuation of Construction and Operation Permit
Decommissioning Phase

In-service

Transfer, Decontamination, Disposal
Dismantling and other actions

Approval criteria

Regulation based on decommissioning plan(compliance obligation with the plan)

Decommissioning completion
confirmation application

Approval

Application ofDecommissioning plan

Shutdown
Process/method for “dismantling andother actions”
Treatment/disposal of radioactive waste
Safety assessment etc.

Dismantling/ Decontamination
with change of facility use

Confirmation
Confirmation
criteria

Regulation on facility
Regulation on disposal and transfer outsidesite
Safety regulation
Regulation on physical protection[Point]1. “Decommissioning regulation” is applied to reactor facilities even in the case of partial decommissioning.
2. Facility/safety regulations are concretely provided as ministerial decree to maintain a reasonable
regulation level corresponding to decommissioning progress“Nuclear Reactor Regulation Law” partly amended and enforced in 2005
12

Technologies
Technologies Required
Required ｆｏｒｆｏｒ Ｄｅｃｏｍｍｉｓｓｉｏｎｉｎｇ
Ｄｅｃｏｍｍｉｓｓｉｏｎｉｎｇ〇Elemental Technologies
1 inventory evaluation
2 decontamination
3 dismantling
4 remote handling
5 waste processing
and management
6 radiological characterization(radiation measurement)from view point of waste management

evaluation of waste amountvolume reduction
sortingmanagement
measurement〇System Engineering・ Selection and combination of technical options (optimization)
important・ preparation (planning) of vital importanceTechnology
TechnologyDevelopment
Development byby NUPEC
NUPEC
Laser cutting

Blast ﾌﾞﾗｽﾄ除染
decontamination

Ultrasoniccleaning

払出し
OutletMeasurement ofclearance level

Electrolytic
decontamination

Inlet
受入れ

Measurement ofdistribution ofradioactive
contamination

Strong chemical
decontamination

Establish the system to remotely treat the radioactive metal by thecombination of decontamination and measurement of radioactivity.

Waste Treatment System
Grip of steel plate and graphite block14

Dismantling
Dismantling Technology
Technology〇 Dismantling of core internals and reactor pressure vessel□ radioactivity levels very high□ use of remote control systems〇Available technology□ thermal cutting : PAC, EDM, gas cutting etc.
□ mechanical cutting : AWJ, DWS, handsaw etc.
cutting under water or in air〇One-piece removal as an alternative□ Trojan: one piece removal of R.P.V. including C.I.
□ Cont. Yankee etc.: one piece removal of R.P.V. without C.I.
□ Ranch. Sec.: cutting all
Achievable with the use of existing technologies
Achieving efficiently and economically is a technical problem
to solve
collection of dross, reuse of abrasives and treatment of aerosol
key issues

One-Piece
One-PieceRemoval
RemovalandandTransportation
TransportationofofTrojan
TrojanRVPRVP

Removal andshipping out

Transporting on river using
barge
PVP : Reactor Vessel Package
Transporting to disposal site
after landing

18

Examples
Examples ofof Lessons
Lessons Learned
Learned〇Dismantling of core- internals --- few operational experiences
・ better to start dismantling the parts with the lower activity levels
・ serviceable to use multi- purpose remote systems
・ important to investigate the characteristics of materials
suspended in water〇Optimization by selection and combination of cutting techniquesof vital importanceno established principle, requiring the accumulation of experiences〇Countermeasures for hazardous materials
preparative survey important with asbestos, lead, PCB etc.
〇 Preservation of information
・ important with not only documents but also human memory
・ site history information required for site characterization

Preservation
PreservationofofInformation
InformationandandRecords
Records〇Data required
・ data related to design, construction, and repair work・ data related to operation, shutdown and subsequent works
・ data during decommissioning〇Purpose・ decommissioning plan : makeup, modification and actual operation
・ waste management : especially confirmation related to clearanceand N.R. criteria〇Present situations
・regulation considering safety during operation of NPP :ex. construction permit and its modification
operational records: “Nuclear Reactor Regulation Law” art. 34,
METI ordinance art. 7
decommissioning not considered〇Future Tasks
・ collection of employees` memory on their retirement and leaving
・ extraction of important information on such as impurities containedin materials, compositions of natural compounds used etc.
・ sorting of information and records required
・ how to preserve necessary data considering easiness of access importantWasteWaste Generated
Generated fromfrom Decommissioning
Decommissioning(Estimated）(Estimated）
Unit: 10,000tonＢＷＲ（1,100MW）

ＰＷＲ（1,100NW）

ＧＣＲ（170MW）

0.008
0.085
1.2

0.02
0.17
0.40

0.16
0.85
0.81

計

1.3

0.6

1.8

not necessary to be treated asradioactive( below clearance level)＋non radioactive

52.4

48.9

17.4Category of Radioactivity Level
Low Level

L1L2
L3

radioactivity relatively high Ｌ1 sub-surface disposal
relatively low Ｌ2 concrete pit disposal
extremely low Ｌ3 trench disposal

Generation of Radioactive Waste (Estimate): Fugen

Generation
GenerationofofWaste
Waste*This generation is estimated based on current plan,with possible review depending on future progress.

Generation (ton)

Level
Level
1
● Level 2● Level 3●08 09 10 11 1213 1415 16 17 18

19 20 21 22• Radioactive waste
mostly of very low level(corresponding to level 3)• Concrete
the main part of waste
generated at the final
phase of decommissioning

23 24 25 26 27 28

Fiscal Year
12,000 ton/year

Generation of Waste under Clearance Level (Estimate): Fugen

Generation (ton)• Metal waste at the earlier
stage of decommissioning*This generation is estimatedbased on current plan, with possible review
depending on future progress.

MetalNon-Metal

08 09 10 11 12 13 14 15 16• Other non-radioactive waste
306,500ton

17 18 19 20 21 22 23 24 25 26 27 28

Fiscal Year22Waste
Waste Generated
Generated during
during Decommissioning
Decommissioning
1.

A large volume of waste generated intensively
for a relatively short period

2. Waste mostly with no need to be treated as radioactive( below clearance level) and non-radioactive waste
most are concrete and metals
3. A relatively large amount of metal waste generated at theearly stage of dismantling and a huge amount of concrete
waste at the final phase.
4. Recycle of waste extremely important
concrete and metals

23

Establishment
Establishment ofof Clearance
Clearance Systems
Systems〇Regulatory Framework
・ “Nuclear Reactor Regulation Law” partly amended andenforced in 2005・ METI ordinance regarding the approval of measurements
and evaluation methods for the concentration of radioactivematerials
・Guide line ( NISA documents)〇 Application
・ target materials : solid materials (metals and concrete)
generated from decommissioning of
nuclear reactor facilities
・ clearance levels : IAEA Safety Guide RS-G-1・7 adopted
・ confirmation : commitment of the government at two stages

dismantlingorremoval
large components

measurement /judgment
building, all-in-one design equipment

RecordThe use of the Japan Nuclear Energy SafetyOrganization as an implementation body

[Reuse/recycle use]

• Custody, management and shipment

measurement /judgment

Dismantlementormodification

modification
small components, concrete
structures, etc.

and judgment result (Note. 2 )ormeasurement /judgment

2[Appropriate disposal] (Note 3 )establishment of criterionof measurement andjudgment method

dismantling•custody and management･•Measurement /judgment ofclearance level verification object• government confirmation of measurement

private standard

government approval of measurement /judgment method (Note.1)• establishment of measurement/judgment method• confirmation object selection• pre-evaluation

Flow of Clearance Level Confirmation(Note) 1. Government approval of measurement and judgment method (review content upon approval)
Establishment method of radioactive nuclide selection for evaluation object and composition ratio, setting and measuring method of
measurement condition corresponding to characteristic of object, evaluation method of measurement result, method of temporary storage ofobject completed measurement and judgment, confirmation of record, creating quality assurance, and others.
2. Government confirmation of measurement and judgment result
The record concerning the measurement and the judgment made on the basis of the method of obtained approval is confirmed (usingextraction measurements, if necessary). Moreover, the state can conduct at an appropriate opportunity the confirmation of implementation
status of quality assurance activity concerning a series of measurements and judgments for the objects selected by reevaluation.
3. It is requested that owners should hold and record the first shipping location upon disposal and reproduction use of clearance objects until thesystem is established..

25Ｔｅｎｔａｔｉｖｅ Ｐｏｌｉｃｙ ｏｎ Ｒｅｃｙｃｌe ｏｆ Ｗａｓｔｅ
クリアランス対象物の当面の再利用方針
below Clearance Level
NPP

metal

Recycle in Nuclear
and Electric Power Facilities
reuse

Shielding blocks
Reinforcing
iron rods

Reception table

Cast material, iron rods etc

Recycle as Cast Materials of Metals below Clearance
Level in Tokai Power Plant

benches

reception table

Shieldingblocks（for ＫＥＫ)

1000×500×200ｍｍ
ca. ７００kg

Use
Use ofof Blocks
Blocks inin J-PARK
J-PARK Experimental
Experimental Facility
Facility

Picture 2. Zoom-in from the opposite
side of dotted-line circle

Picture1. Overview

Picture3. Zoom-in from different
angle of full-line circle

28

FutureFutureTasks
Tasks
1 Development of system engineering・ to make decommissioning more efficient and economical by optimal
selection and combination of elemental technologies
・with the need of development of data base2 Rationalization of reactor core dismantling・ more accumulation of operational experiences required, acquiring
lessons learned
3 International sharing of lessons learned important
4 Investigation on site release criteria
consistency with those for the other facilities needed
5 Securing waste disposal sites corresponding to L1. L2 and Ｌ3 levels
6 Making steady progress with the clearance system and the releaseof “non-radioactive” (NR) waste
・rationalization of confirmation process on clearance level・ establishment of definite procedure to make judgment on NR criteria
・establishment of recycling business with processing manufacturers
available

Summary
1. Japan has made steady preparations in regulation, technology development, andwaste management toward the decommissioning of large NPP.
It is required to put all the lessons learned from Fugen and Tokai NPP topractical use in decommissioning of LWR .
2. The safety level of the plant during decommissioning is very high.
It is possible to complete the decommissioning very safely using the existing
technologies developed and applied so far.
3. There are so many types of elemental technologies developed.
It is a technical problem how to select and combine them for achieving
decommissioning efficiently and economically.
4. A large amount of waste is generated for a relatively short period
during decommissioning.
mostly non radioactive waste and waste that need not to be treated as radioactive.
5. Clearance system was already introduced in Japan and some materials were alreadyrecycled and, for the moment, reused in the nuclear community.
It is important for the clearance system to stay steadily in the society, getting more
understanding and confidence.

30