Outcome of the Japan Power Demonstration Reactor ... · Radioactive inventory estimation 4....

Outcome of the Japan Power Demonstration Reactor Decommissioning Project

Satoshi Yanagihara柳原敏

Research Institute of Nuclear EngineeringUniversity of Fukui

2019 Sino-Japanese Workshop on NPP Decommissioning TechnologyOctober 29-30, 2019 @ Atomic Energy Council 3F

1

JPDR拆除實地試驗的成果— 輻射調查、拆除工法與廢棄物處理

Contents

⚫Outline of the Japan Power Demonstration Reactor decommissioning project

⚫ Dismantling activities: remote / hands-on / building demolition

⚫ Project management data

⚫ Study on project planning and evaluation

⚫Outcome of the project

2

Plant Characteristics

⚫ Reactor type & power : BWR, 45/90 MWt

⚫ Facility operation period : 1963-1976

⚫ Total output power : 21,500 MWD

Objectives⚫ to gain actual experience of nuclear power plant dismantling⚫ to verify the developed techniques in actual dismantling activities⚫ to collect data on JPDR dismantling activities

Dismantling Project Overview

⚫ Project period : Dec. 1986 - Mar. 1996

⚫ Project cost : 23 billion yens (including R&D)

⚫ Waste arising : 3,770 tons (Radioactive)

⚫ Worker dose : 306 person-mSv

The JPDR Decommissioning Program

The first experience of dismantling reactor facility in Japan.

before

after

3

Brief Biography of the JPDR Decommissioning Program

1979 Oct.

1980 Mar.

1981 Apr.

1982 Jun.

1982 Dec.

1985 Dec.

1986 Jul.

1986 Dec.

1996 Mar.

2002 Oct. Approval of JPDR decommissioning completion by regulatory body

Setting Committee for JPDR（1976: cessation of operation ）

Decision of starting the JPDR decommissioning program

Start of R&D program for decommissioning

Atomic Energy Commission: Announcement on demonstration of decommissioning technology by

using JPDR

Notification of JPDR decommissionig by submitting the decommissioning plan (First stage)

Nuclear Safety Commission: Basic concept of the safety assurance on the dismantling of nuclear

reactor facilities –for JPDR Decommissioning-

Amendment of JPDR decommissioning plan( Second stage)

Start of JPDR decommissioning program

Completion of JPDR decommissioning activities

4

Management of Dismantling Activities

Basis of dismantling project

⚫ The plan of dismantling activities was made based onthe guideline issued by Nuclear Safety Commission.

⚫ The key principles of the JPDR dismantling plan are;✓safety of workers, and✓prevention of radioactive materials being released.

Organization （1986-1992）

⚫ Administrative division

⚫ Decommissioning program management division

⚫ Decommissioning operating division

⚫ Waste management division

⚫ Technology laboratory

Waste management

⚫ Classification for effective waste storage

⚫ Transport of radioactive waste to storage facility

⚫ Near surface burial in JAEA's site (extremely LLW)

⚫ Radiation control division( Dep. Health physics)⚫ Reactor control laboratory (Dep. Reactor engineering)⚫ Quality assurance committee

Support organization

5

Timeframe of Dismantling Activities

Preparatory activities

Reactor Pressure Vessel

Reactor internals

Biological shielding

Reactor building

Decontamination and final survey

Landscaping

Components around core region

1986 1987 1988 1989 1990 1991 1992 1993 1994 1995

Pipes connected to RPV

Building demolition

Dismantlement of components in auxiliary buildings

6

Research and Development for the JPDR Decommissioning

1. Systems engineering for reactor decommissioning

2. Non-intrusive measurement of radioactivity inside pipe

3. Radioactive inventory estimation

4. Dismantling techniques and systems

5. Decommissioning waste treatment, storage and disposal

6. Decontamination for reactor decommissioning

7. Radiation control

8. Remote operation technique

7

Area Classification and Applied Techniques to Dismantling Components

* shaped explosive cutting was applied to core

spray and emergency condensation system pipes in addition of these pipes

** incore monitor tube

Biological shield (III)

radioactivity : 4,000- 4Bq/g

dismantling by controlled blasting

Biological shield (IV)

radioactivity : less than 4Bq/g

dismantling by controlled blasting

Biological shield (II)

radioactivity : 40-7,000 Bq/g

dismantling by water jet cutting

Biological shield (I)

radioactivity : 40-7,000 Bq/g

dismantling by mechanical cutting

Reactor pressure vessel

radioactivity : 1.6×105 Bq/g (Max)

dismantling by arc saw

Feedwater system pipe

radioactivity : app. 2,000 Bq/g (Max)

dismantling by rotary disk knife

Water level monitoring

radioactivity : app. 2000 Bq/g (Max)

dismantling by shaped explosive (in air)

Forced circulation system pipe

radioactivity : app. 6,000 Bq/g (Max)

dismantling by rotary disk knife

Reactor internals

radioactivity : 2×108 Bq/g (Max)

dismantling by plasma arc

Control rod guide tube

radioactivity : 6,000 Bq/g (Max)

dismantling by shaped explosive (in water)

8

Schematic Diagram of Underwater Plasma Arc Cutting System

Spent Fuel Storage Pool

Water Cleanup System

Reactor Internals

Reactor Pressure Vessel

Camera

Plasma Torch

Plastic Envelop

Primary Cutting System

Control Panel

Dross Collection

System

Secondary Cutting SystemTo Ventilation

System

Cutting work of control rod

guide tube

9

Dismantling of Reactor Pressure Vessel

Work period : Sep. 1989 – Oct. 1990Component weight : 62 tonsCutting techniques : Arc saw ( underwater)Handling technique : Mast-type manipulatorWorker dose : 108 person・mSvManpower expenditure : 10,176 man・days

10

Dismantling of Inner Part of Biological Shielding

Work period : Sep. 1990 – Sep. 1992Component weight : 260 tonsDemolition techniques : Mechanical cutting ( 24.4 tons)

: Abrasive water-jet ( 29.4 tons): Controlled blasting (205.6 tons)

Handling technique : Mast-type manipulatorWorker dose : 28 person・mSvManpower expenditure : 13,573 man・days

Mechanical cutting

Abrasive water-jet

11

Dismantlement of Components using Conventional Technology

Dismantlement of components

⚫ Turbine, Piping, Pumps, Heat exchangers, etc.

⚫ Liner of spent fuel pool

Decontamination of Building

⚫ Evaluation of contamination characteristics

⚫ Removal of embedded piping in building structure

Building Demolition

⚫ Demolition（under 1m below surface)

⚫ Reuse of concrete debris

Removal of heat exchanger

Removal of pool lines (cutting)

Removal of pool lines (removal)Demolition of reactor bldg. Decontamination of floor surface 12

⚫ Facility characterization using past operation data✓Specify contaminated areas

⚫ Characterization of contamination✓Area and depth (Scoping and detailed)

⚫ Decontamination✓Surface contamination: removal of surface✓In-depth contamination: removal of penetrated

plus 5mm in depth

⚫ Confirmatory survey✓Measurement by health physics workers✓Confirmation by regulatory body

⚫ Revise of safety regulation

⚫ Demolition of building

Process for Building Demolition

Measurement of radioactivity on

building surface

Decontamination on flow

surface

13

Characterization of Building Surface Contamination

Characterization of contamination

(Depth and intensity)

Mapping of contamination

Planning of decontamination

Measurement of

Contamination

Refer of historical record

on contamination

No contamination

Contamination

Wall Floor

Sampling Points

14

Near Surface Disposal Facility for Very Low-Level Radioactive Waste

3.5m

2.5m

45m

7m

▼

Water Level

Monitoring WellCover Soil

Radioactive Waste

Low-Water-Permeability SoilRadiation Monitoring Post

GrassWaste: 1,310 tons (Bio-shield)

360 tons (Building decontamination)

Radioactivity: ～230MBq

Institutional control (30 years)

Monitoring, Surveillance, Land use control, etc.

Trench-type for waste from JPDR* (Capacity:1670 tons of concrete debris)

15

Total Waste

24,400 tons

Radiation control area

Shallow land disposal

Storage in facilityNon control area

Secondary waste24,400

tons

Radioactive Waste Arising from Dismantling Activities

Secondary waste

440 tons (1.8%)

Shallow land disposal

1,670 tons (6.8%)

Storage in facility

1,660 tons (6.8%)

Non-radioactive

20,700 tons

(84.6%)

Radioactive

3,770 tons

(15.4%)

Radiation control area

17,500 tons (71.5%)

Non control area

3,190 tons (13.0%)

16

17

Radioactive Waste Management

17Storage of 200-liter drums

Evaporation Compaction

(Melting)

Shiraishi et. al., Decommissioning Database, JAEA-Data/Code 2005-002, Jan. 2006

Thermal insulatorMetal components

Pipe & valves

Cables & conduit

Concrete

Duct

Others

Total

Breakdown of Manpower Expenditure and Worker Dose in Dismantling Activities

145,000

man-days

Supervision of dismantling

activities (20.4%)

Reactor internals (6.8%)

Pipes connected to reactor

pressure vessel (1.9%)

Reactor pressure

vessel (7.0%)

Biological shield (12.8%)

Components in reactor building (27.4%)

Demolition of

buildings (9.8%)

Decontamination &

Radiation survey (13.6%)

Manpower Expenditure

306 man-mSv

Reactor internals (23.9%)

Pipes to RPV (20.7%)Reactor pressure

vessel (35.2%)

Supervision of

dismantling work (2.6%)

Biological shield (9.3%)

Components &

Building structure (7.8%)

Decontamination &

Radiation survey (0.5%)

Worker Dose

18

Evaluation of Project Parameters (by COSMARD)

input output

Dmaf

Rado/DoseComputing Data on Project

Management & Scheduling

Unit Productivity

Factors, etc.

database

Work Packages with

Breakdown Structure &

Computing Conditions

- Activity names

- Components to be

dismantled

- Operational conditions

- Relationships with other

activities

- etc.

Data for Project

Management

- Manpower needs

- Occupational dose

- Waste generation

- Costs

- etc.

Computing of

Radioactivity & Dose

Equivalent Rate

Scheduling Data

- Bar charts

- Histograms

- Network diagrams

- etc.

Dose Equivalent

Rate at Each Area

Plant Inventory

including

Radioactivity

Setting of Work

Packages Using

Knowledge Base

Expe

COSMARD：Computer Systems for Planning and Management of Reactor Decommissioning19

Decommissioning Database

7,500

2,600

500

2,500

2,500

3,800

1,100

0 2,000 4,000 6,000 8,000

man-hours

Preparation

Power setting

Cleanup activity

Manpower Need

Unit Productivity Factors

1.12

1.08

1.66

1.79

2.21

1.11

0.60

1.27

0.00 1.00 2.00 3.00

hours/operation

Cutting preparation

Primary cutting

Cut piece transfer (large)

Cut piece transfer (small)

Secondary cutting

Cut piece packaging

Cutting (manipulator)

Machine setting(mast-type)

Machine setting(manipulator)

Removal of machine(mast-type)

Removal of machine(manipulator)

Cutting preparation(manipulator)

Mast Type Plasma Arc Cutting System

Total weight of

reactor internals: 16.6 tons

Max. radioactivity: 2×108 Bq/g

Secondary Plasma Arc

Cutting Device

Gas Supply

Cooling Water Circulation

Control Panel for

Plasma Arc

Primary Plasma

Arc Cutting Device

Carriage

Cross Travel

Carriage

Plasma Torch

Plasma Torch

Cut Piece

Cutting Capability (stainless steel)⚫Max thickness 230mm, Cutting speed 50mm/min (in air)⚫Max thickness 130mm, Cutting speed 75mm/min (underwater)

Mast-type remote handling machine

Slave arm (manipulator)

Plasma arc cutting is a thermal cutting method in which arc andplasma gas heat are produced by electrical current between arcnode and object to be cut. By-product treatment is necessary forworker safety and proper waste management.

20

Unit Productivity Factors

Dismantling & packaging activities

⚫ Hands-on dismantling : related to component type and weight

⚫ Remote dismantling : related to machine capability

⚫ Decontamination & Radiation measurement : Related to area size

⚫ Demolition of structures : related to structure weight

Preparation & cleaning activities

⚫ No specific relationship to manpower need except work conditions

21

Unit Productivity Factors of Hands-on Dismantling Activities

3.2

13.2

14.9

17.2

19.7

26.3

26.9

27.3

29.6

35.0

38.9

62.7

63.0

85.6

98.1

5.1

22.5

0.5

4.9

7.4

21.7

21.8

49.1

57.3

115.7

0.0 20.0 40.0 60.0 80.0 100.0 120.0 140.0

Transformer power supply panelPump

Wall & baseSmall machinery

Control panelHeat exchanger

Air conditionerTank

DemineralizerPiping & valve

Base hungerDuct

Cable & conduitCleaning of sludgeThermal insulation

Control blasting (outer layer)Control blasting (inner layer)

Building structureCrane

Steel wall of reactor enclosureTurbine generatorDump condenser

Turbine condenserUpper & lower part of RPV

Fuel pool liner

man-hours/ton

Facility components

Large components

Relationship between manpower expenditure and components weight

Weight of components being dismantled (tons)

Ma

np

ow

er

ne

ed

s (

ma

n-h

ou

rs)

0 50 100 150

2,000

4,000

6,000

8,000

0

：Preparation

：Dismantling & packaging

：Post-dismantling restoration

▲●■

Data Collection and Analysis

22

Construction using wall or existing pipes

Typical size (3×4m)

Covering a large component

Level 1

2

3

4

5

30～50m2 of work area

Narrow work area less than 30m2,

partially covering of work area

Large work area more than 50m2

Larger than typical size, durable or

multiple or more than single

Same criteria as above

man-hours0 20 40 60 80 100

Level 1

Level 2

Level 2

Level 2

Level 3

Level 3

Level 3

Level 4

Level 4

Level 4

Level 5

Level 5

Level 5

Level 1

Level 1

Remove of

greenhouse

Greenhouse

preparation

Cover of floor and

wall by sheet

Level 1

2

3

4

5

Leve l -5

Man-hours

(standard case)

Survey of work area

Selection of components

Carrying-in of material

Power cut

Scaffolding

Equipment preparation

Cover of floor and wall by sheet

Greenhouse preparation

Remove of greenhouse

Remove of scaffolding

Carrying-out of material

Transfer of equipment

Remove of sheet

5

7

10

10

10

16

23

24

10

10

14

14

28

0 5 10 15 20 25 30

Preparation

Cleanup

A

B

C

A B C

Unit Productivity Factors of Preparation and Post-Cleanup Activities

23

Lessons Learned: Major Consideration For Future Decommissioning Projects

Systematical Consideration For Decommissioning Project⚫ Necessity of total decommissioning plan including waste management and

technology transfer program.⚫ Planning of effective use of land or buildings after dismantling completion.

Record Keeping and Data Collection⚫ Use of any records on dismantling activities and waste management. ⚫ Analysis of project management data such as manpower expenditure,

waste arising and costs.⚫ Application and keeping of lessons learned in various aspects.

Review of Regulatory Systems for New Application or Reformation ⚫ Safety evaluation, waste management systems.⚫ Adequate inspection systems.

24

Major Outcome of JPDR Dismantling Project

⚫ Completion of nuclear reactor decommissioning safely using suitable dismantling techniques and health physics practices

⚫ Verification of the guideline on securing dismantling activities prepared by Atomic Safety Commission

⚫ Demonstration of dismantling technology and characterization

⚫ Establishment of build demolition procedures (from building surface decontamination, survey of radioactivity to demolition)

⚫ Accumulation of project data and experience on dismantlement and waste treatment/disposal.

25

Thank you for your attention.

yana511@u-fukui.ac.jp