ADVANCEMENT OF FUNDAMENTAL TECHNOLOGIES FOR RETRIEVAL OF FUEL DEBRISREMOTE CONTROLLED LASER CUTTING AND DUST GATHERINGPROJECT OF DECOMMISSIONING AND CONTAMINATED WATERMANAGEMENT IN THE FY2017 SUPPLEMENTARY BUDGETPERFORMANCE REPORT
2019/07

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REF ND-2613150428-PRZ-023789-EN

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CONTENT OF THE PRESENTATION

1. Background / Objective of Research
2. Project Outcomes
3. Application to Fukushima site

ONET Technologies CN subsidized project « Advancement ofFundamental Technologies for Retrieval of Fuel Debris Remote Controlled laser cutting and dust gathering » March 19th, 20192

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1. BACKGROUND & OBJECTIVES(REMINDER)

Fundamental Technologies for Fuel Debris Cutting
Reasons why this research is necessary•••

Development of cutting and collection technologies on fuel debris with the Fukushima Dai-ichi damaged reactors
environment
Several cutting technologies developed depending on cutting configuration with TRL 3/6 to be developed further
for site deployment (TRL5/7 foreseen at the end of the project)
Management of secondary outlets, needing these outlets to be measured and collected

Use of the research results• Advanced cutting technologies with combined collection technologies for the different
configurations expected to be found on site
• Extend secondary outlets knowledge for collection and treatment purpose• Alpha emitters behavior for dispersion and release control
TRL 1

TRL 2

TRL 3

TRL 4

Research – Proof of concept
Research/Concept

Functional blocs/Functions

TRL 5

TRL 6

TRL 7

Development of the system
Subsystems

Prototype of the system

TRL 8

TRL 9

Qualification & deployment

International TRL scale
used for the studies

Operational system

ONET Technologies CN subsidized project « Advancement ofFundamental Technologies for Retrieval of Fuel Debris Remote Controlled laser cutting and dust gathering » March 19th, 20193

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1. BACKGROUND & OBJECTIVES(REMINDER)
Exhaust / DF

Environment

Objective N°°1
Develop Fundamental Cutting
Technologies for fuel debris
Advancement of laser cutting technologies
development for fuel debris cutting in severe
conditions
ELC-W / NELC-A / NELC-W

Aerosols dispersion

Collection

Deployment

Cutting

Objective N°°2
Develop collection technologies forfuel debris
From the results achieved in FY2017, continue
the development of collection technologies inair.
Development of the spray scrubbing technology
application for aerosols collection.

ONET Technologies CN subsidized project « Advancement ofFundamental Technologies for Retrieval of Fuel Debris Remote Controlled laser cutting and dust gathering » March 19th, 20194

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1. BACKGROUND & OBJECTIVESOBJECTIVE OF RESEARCH (REMINDER)

Strategy for cutting fuel debris and collecting dust and fumes

Environment assumptions - In-air conditions
•
•
•
•
•
•

Fuel debris in air with dripping water
Accessibility to fuel debris through robotics means (out of scope)
Massive debris emerging from water
Fuel debris inside CRD and mixed with structure
Utilities outside pedestal including HVAC (treatment out of scope)
Waste management of fuel debris as solid waste (out of scope)

Environment assumptions - Underwater conditions
•
•
•
•
•
•

Fuel debris underwater
Accessibility to fuel debris through robotics (out of scope)
Massive debris inside water and smaller debris inside water
Utilities outside pedestal including HVAC (treatment out of scope)
Waste management of fuel debris as solid waste (out of scope)Contaminated water treatment (out of scope)

ONET Technologies CN subsidized project « Advancement ofFundamental Technologies for Retrieval of Fuel Debris Remote Controlled laser cutting and dust gathering » March 19th, 20195

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1. BACKGROUND & OBJECTIVESOBJECTIVE OF RESEARCH (REMINDER)

Strategy for cutting

Acronyms:••

ELC-A: Emerging Laser Cutting in Air
NELC-A: Non Emerging Laser cutting in Air•

ELC-W: Emerging Laser Cutting under
Water
NELC-W: Non Emerging Laser Cutting
under Water•

ONET Technologies CN subsidized project « Advancement ofFundamental Technologies for Retrieval of Fuel Debris Remote Controlled laser cutting and dust gathering » March 19th, 20196

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2. PROJECT OUTCOMES

2. Project Outcomes
1. Laser cutting development
2. Dust and Fumes Collection in air development
Final outcomes of the technologies
3. Spray Scrubbing Development
Final outcomes on spray scrubbing
4. Dust & Fumes data acquisition
Final outcomes on dust & fumes

ONET Technologies CN subsidized project « Advancement ofFundamental Technologies for Retrieval of Fuel Debris Remote Controlled laser cutting and dust gathering » March 19th, 20197

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2. PROJECT ITEMS OUTCOMESLASER CUTTING DEVELOPMENT

ELC-W Development
Principle of the ELC-W cutting head: Dry cavity concept
for cutting under water••••

Laser beam propagates in air to avoid water absorption
Dry cavity coaxial to the laser beam
Molten material ejected by the assist gas airflow
Water nozzle implementation for better stability andhomogeneity

Cutting head

Laser beam

Water curtainDrycavitySampleFY2017 Progress:• Mechanical design corrections made to the ELC-W head model (beam centering, shutter operation,cylindrical airflow uniformity optimization)• Characterization campaigns of the dry zone without laser and without kerf to optimize the parameters
low water flow, low thickness of the water curtain and high air flow

Cylindrical air jet
Regular shape stable &homogeneous dry cavity

Optimized parameters

FY2018 progress:• Tolerance assessment tests underwater (stand-off, tilt, position – with/without water curtain,
35/560 cm H2O)•
Good results on ZrO2 30 mm thick samples : 5 to 20 mm stand-off , 20°tilt, different
positions•No water curtain nozzle with the new airflow parameters• Industrial design and manufacturing the first operational cutting head
ONET Technologies CN subsidized project « Advancement ofFundamental Technologies for Retrieval of Fuel Debris Remote Controlled laser cutting and dust gathering » March 19th, 20198

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2. PROJECT ITEMS OUTCOMESLASER CUTTING DEVELOPMENT

ELC-W Development
Specifications of the manufactured ELC-W cutting headSpecified by the CEA, designed based on CEA prototype, made by anindustrial laser head manufacturer• Operational prototype: 60 cm long, 15 cm diameter, 20kg
without umbilical cable, no electronic components, water proof• Simplified nozzle architecture : no water curtain• Robust and efficient shutter (stop bubbles for video
observation)• Safety functions integrated: open and close shutter sensors,
temperature sensors & thermoswitch• Design for 16 kW• Easy umbilical connection
Pre-design of umbilical and utility unit
• Architecture done and safety functions defined• Umbilical possibilities defined
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2. PROJECT ITEMS OUTCOMESLASER CUTTING DEVELOPMENT

ELC-W Development
Tests results – Performances @8 kW
ZrO2 :••

100 mm cut under 560 cm of H2O: the same cutting performances as in AIR
For every tested thickness under 35 or 560 cm of H2O the same maximum performances
as in air had been reachedZrO2 sample

10 cm

Stainless steel:• Only 40 mm cut under 560 cm of H2O instead of 100 mm in Air
Zirconium alloy :• 30 mm cut under 560 cm of H2OONET Technologies CN subsidized project « Advancement ofFundamental Technologies for Retrieval of Fuel Debris Remote Controlled laser cutting and dust gathering » March 19th, 201910

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2. PROJECT ITEMS OUTCOMESLASER CUTTING DEVELOPMENT

NELC-A Development
Laser
beam
40 mm @ 10 cm/min

Flat jet nozzle

Kerf

Principle:• Assist gas air jet inclined to eject the molten material
form the kerf
• Kerf’s depth reaches 40 mm in nominal conditions

FY2017 progress:• Flat jet nozzle implementation compact design validation• Process robustness validation (stand-off, tilt, starting point, cutting speed): very satisfactory
results obtained

FY2018 progress:• Design, manufacturing and tests of a mechanicalmodule added to the ELC-A industrial head for non
emerging cuts (NELC-A)• Study of the monitoring of the process

ELC-A Head

NELC-A
Add-onELC-A industrial head

Flat jet nozzle

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2. PROJECT ITEMS OUTCOMESLASER CUTTING DEVELOPMENT

Cutting process monitoring
Device features:••

Remote observation of the laser cutting process
Small diameter fits inside the assist gas nozzle•

No intrusiveness : the same cutting performances as
without the borescope 40 mm depth @10 cm/min
2 operation modes•

Borescope

NELC-A
moduleRanging Mode Operation:••

Distance measurement between cutting head and work piece
Measurement accuracy ~ ±2 mm

Assist gas nozzle

ELC-A
cuttinghead

CameraDepth Gauge Mode Operation••

Depth measurement between of the kerf
Measurement accuracy ~ ±2 mm

Real-time visualization of the distance between the
cutting head and the bottom of the kerf
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2. PROJECT ITEMS OUTCOMES

2. Project Outcomes
1. Laser cutting development
2. Dust and Fumes Collection in air development
Final outcomes of the technologies
3. Spray Scrubbing Development
Final outcomes on spray scrubbing
4. Dust & Fumes data acquisition
Final outcomes on dust & fumes

ONET Technologies CN subsidized project « Advancement ofFundamental Technologies for Retrieval of Fuel Debris Remote Controlled laser cutting and dust gathering » March 19th, 201913

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2. PROJECT ITEMS OUTCOMES
DUST & FUMES COLLECTION IN AIR DEVELOPMENT

Dust and fumes collection in air development – Overview (1/2)
Reminder: secondary outlets produced by laser cutting:Laser cutting on fuel debris will produce:• The fuel debris block that will be later
recovered and treated as waste• Chips, dross and dust that are settled
in nearby area and that will need to be
recovered and treated as solid waste• Gas, fumes and aerosols that are
dispersed, if not collected, in the PCV

Why do we focus on aerosols collection?
As secondary outlets of the laser cutting operations, they represent the most challenging matter:• From a safety point of view (risk of inhalable particles dispersion in case of loss of depression inside the PCV)
• From an operational point of view (necessity of a local collection)
Nevertheless, local collection cannot prevent the collection of some of the bigger particles that are produced
such as chips, dross and dust: these particles must be also be treated by the collection system
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2. PROJECT ITEMS OUTCOMES
DUST & FUMES COLLECTION IN AIR DEVELOPMENT

Dust and fumes collection in air development – Overview (2/2)
Axis of development from FY2016•••

One collection head for each in-air configuration:
ELC-A and NELC-A
One first level of capture for the collected dust
and chips
One collection line to transport the aerosols, dust
and chips to their filtration points

Cutting headCollection heads

Fuel debrisFirst level of capture

Collection line: hoses, pipes
and filtering devices

Filtration
systemLimit of the development

Progress FY2016 – FY2017
FY2016: Feasibility, first approachof in-air collection

FY2017: Specifications and design, manufacturing andtests of the first NELC-A and ELC-A collection heads
embedded on the cutting head and cyclonic filter

Designed only for tests
Study of influential
parameters
Very good
performances inaerosols collection

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2. PROJECT ITEMS OUTCOMES
DUST & FUMES COLLECTION IN AIR DEVELOPMENT

Collection devices developments – NELC-A and ELC-A collection heads FY2018
Objectives of the FY2018: Collection head embedded on the cutting heads, optimization of the dimensions
in order to ease operations on site, aerosols collection efficiency unaltered compared to FY2017
Phases of development: Design, numerical simulations, manufacturing of prototypes, tests to measure theperformances

DESIGNNUMERICAL SIMULATIONMANUFACTURINGPERFOMANCE TESTSONET Technologies CN subsidized project « Advancement ofFundamental Technologies for Retrieval of Fuel Debris Remote Controlled laser cutting and dust gathering » March 19th, 201916

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2. PROJECT ITEMS OUTCOMES
DUST & FUMES COLLECTION IN AIR DEVELOPMENT

Collection devices developments – Filtration and transportation line
Objectives of the FY2018: Study and realization of a particles transportation line in which air is blown
instead of being sucked and of a new first level of capture
Sedimentation filter: It aims to be placed in the transportation line close to the cutting point and to stop
biggest particles. It is designed to work in every orientation
Inflow, air loaded with fumes,
particles and aerosols

Particles whose diameter issuperior to 50 µm fall into therecipient surrounding the filter

Aerosols and particles whose
diameter is inferior to 50 µm
transported to a later collection
point

Drawing of the collection loop used for the tests

Tests with new transportation line: Transportation tests have been realized with the new transportation
line. Positive results obtained but interfaces with the collection heads need to be improved andcomplementary tests need to be performed
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2. PROJECT ITEMS OUTCOMES
DUST & FUMES COLLECTION IN AIR DEVELOPMENT

Collection performance tests – Overview•

The tests are performed in the
DELIA facility (Saclay) on cast fused
Zirconia blocks•

Secondary outlets produced by laser cutting:

Extraction andsampling line

Laser cutting on fused cast Zirconia block will produce:•

Fused cast Zirconia block
after a cutting operation

Airborne aerosols: they are released in air and may present a safety
problem for workers and environment on site if not properly
collected•

Chips: the main part of the melted mass will stay stuck on theblock, some of them will fall from it•

Dross and dust: they are settled in nearby area of the cutting point

ONET Technologies CN subsidized project « Advancement ofFundamental Technologies for Retrieval of Fuel Debris Remote Controlled laser cutting and dust gathering » March 19th, 2019

Chips

Dross and dust

18

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2. PROJECT ITEMS OUTCOMES
DUST & FUMES COLLECTION IN AIR DEVELOPMENT

Collection efficiencies – Results for NELC-A configurations•

Results for closed and open NELC-A configuration with cutting conditions
The results are to be taken as order of magnitude

Configuration

Aerosols
collection
efficiency

Integrated
aerosols collectedmass (g)Integrated
aerosols dispersed
mass (g)Chips, dross anddust mass
recovered (g)NELC-A –Configuration 1

> 98%

15

0,3

11

NELC-A –Configuration 2

> 96%

11

0,4

11
View of the NELC-A collection head
mounted on the cutting head inside DELIA

Aerosols mass thathas to be treated bya filtration system

Aerosols mass
released that mustbe treated by HEPA
filtration

Recovered in
cyclonic filter, massfraction that will betreated as waste

View of the block after 2 cuts (NELC-A
configuration)
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2. PROJECT ITEMS OUTCOMES
DUST & FUMES COLLECTION IN AIR DEVELOPMENT

Collection efficiencies – Results for ELC-A configurations•

Results for ELC-A configurations with cutting conditions
The results are to be taken as order of magnitude

Configuration

Aerosols
Collection
efficiency

Integrated
aerosols collectedmass (g)Integrated
aerosols dispersed
mass (g)Chips, dross anddust mass
recovered (g)ELC-A Configuration 1

> 99%

4

0.001

41

ELC-A Configuration 2

> 99%

10

0.006

22

ELC-A Configuration 3

> 99%

24

0.02

32

Tests implementation in DELIA

View of the block after 4 cuts (ELC-A
configuration)
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2. PROJECT ITEMS OUTCOMES
DUST & FUMES COLLECTION IN AIR DEVELOPMENT

Projection of aerosols release – (Tentative/Order of magnitude) (1/2)•

Fuel debris laser cutting:Releasedaerosols•

E

1 kg cut block in NELC-A:
Configuration

A

B

C

D

E

NELC-A– Closed

Approx 1Kg +adhering chips

B < 200 g

~15 g

~20 g

~0.4 gNELC-A– OpenApprox 1Kg +adhering chips

B < 200 g

~15 g

~15 g

~0.5 g0.4 – 0.5 g ofreleased aerosols~1230 g of retrievable solid waste• Cut block with adhering chips• Chips, dross and dust that fall
• Chips, dross and dust collected incollection system• Aerosols collected and transported
to a filtering point

A

Released aerosols are inferior
to 0.03 %tw of cut andretrieved fuel debris

115 mm
40 mm

B

40 mm
C
D

Retrievable and treatable as solid
waste

Theoritical block of fuel debris:• V = 184 cm3• W = 993.6 g (density = 5.4 g/cm3)• 270 mm of cut• Vkerf = 43 cm3• Wkerf = 233 g

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2. PROJECT ITEMS OUTCOMES
DUST & FUMES COLLECTION IN AIR DEVELOPMENT

Projection of aerosols release – (Tentative/Order of magnitude) (2/2)•

Fuel debris laser cutting:Releasedaerosols• Cut block with adhering chips• Chips, dross and dust that fall
• Chips, dross and dust collected incollection system• Aerosols collected and transported
to a filtering point

•

E

A
B
C
D

Retrievable and treatable as solid
waste

1 kg cut block in ELC-A:

Configuration

A

B

C

D

E

ELC-A –
Configuration 1

Approx. 1 kg +adhering chips

B < 26 g~25 g~2.5 g~6.10-4 g

ELC-A –
Configuration 2

Approx. 1 kg +adhering chips

B < 35 g

~14 g

~6 g

~4.10-3 g

ELC-A –
Configuration 3

Approx. 1 kg +adhering chips

B < 24 g

~20 g

~15 g

~12.10-3 g< 0.02 g ofreleased aerosols~1050 g of retrieved waste
Released aerosols are inferior to
0.001%tw of cut and retrieved fueldebris

50 mm
50 mm

Theoritical rod full of fuel debris:• V = 187.5 cm3• W = 1012.15 g (density = 5.4 g/cm3)• 50 mm of cut• Vkerf = 10 cm3
Wkerf = 54 g

ONET Technologies CN subsidized project « Advancement ofFundamental Technologies for Retrieval of Fuel Debris Remote Controlled laser cutting and dust gathering » March 19th, 2019

75 mm

22

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2. PROJECT ITEMS OUTCOMES

2. Project Outcomes
1. Laser cutting development
2. Dust and Fumes Collection in air development
Final outcomes of the technologies
3. Spray Scrubbing Development
Final outcomes on spray scrubbing
4. Dust & Fumes data acquisition
Final outcomes on dust & fumes

ONET Technologies CN subsidized project « Advancement ofFundamental Technologies for Retrieval of Fuel Debris Remote Controlled laser cutting and dust gathering » March 19th, 201923

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2. PROJECT ITEMS OUTCOMESSPRAY SCRUBBING DEVELOPMENT

Progress from FY2016 to end of FY2018
Approaches with experiments with fuel debris simulants
Aerosol initial production
Cutting tools (laser, other)
Materials (ex, in vessel
debris, others)

Airborne aerosols versus cutting
configurations
Air
Underwater
Pool scrubbing

Airborne aerosol: Size, morphology, composition

Assessmentof initialaerosolsource term

FY2017/2018

FY2016/2017
Experimental and modelling approaches
Contribution
to theassessment ofcontamination
release in caseof loss ofcontainment

Mitigation means
Negative pressure
Aerosol collection system
Spray scrubbing
Filtration

FY2017/2018

Aerosol Transport- Agglomeration- Deposition

FY2017/2018

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2. PROJECT ITEMS OUTCOMESSPRAY SCRUBBING DEVELOPMENT

Underwater collection• The main tasks for the development of underwater collection system in FY2018 are:•Development and validation of pool scrubbing model to predict airborne aerosol releasefraction during underwater cutting at different depths•••

Design and specification of spray droplets characteristics with regards to 1F site conditions toachieve the best aerosol collection efficiency•••

CFD simulations of aerosol collection
Tests with single spray in TOSQAN facility including pool scrubbing phenomena

Enhancement and validation of CFD model of aerosol collection by single spray••

Laser cutting tests in DELIA facility
Pool scrubbing tests in TOSQAN facility with simulated aerosol

Model validation based on TOSQAN spray test

Aerosol collection efficiency assessment by preliminary numerical simulations in 1F site

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2. PROJECT ITEMS OUTCOMESSPRAY SCRUBBING DEVELOPMENT

Underwater collection – Experimental – Numerical approach
ANALYTICALSEMI ANALYTICAL

CFD numerical simulations
1F SITE••••

Spray & pool scrubbing efficiencies
Assessment of airborne aerosol release fraction
Analytical data base for model validation
Possibility to simulate other aerosol source terms
emitted by different cutting tools

Validated toolfor 1F site
calculations

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2. PROJECT ITEMS OUTCOMESSPRAY SCRUBBING DEVELOPMENT

Underwater collection – Validation of spray modelling with TOSQAN spray tests
Gas velocity t=400s
TOSQAN vessel

Particle mass fraction t=100s

Particle mass fraction t=400s

Single spray(200 µm)

Single nozzle is used in TOSQAN
4 sprays for the whole volume

Single spray
4 sprays (extrapolation)Goodagreement
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2. PROJECT ITEMS OUTCOMESSPRAY SCRUBBING DEVELOPMENT
Different scenarios of aerosol emission within TOSQAN spray tests with single nozzle
Spraying during continuous aerosol emission
Aerosol concentrationin TOSQAN

Aerosol concentration
decrease

Aerosol concentrationin TOSQAN at t=1500s
1500

∗

.

Formula determined experimentally,
0.0014 = λ, removal rate

Equilibrium is reached between aerosol emission andaerosol collection by spray

Discontinuous aerosol emissions
•
•
•
•
•

Decontamination Factor determination for various
aerosol source terms
Underwater scenario is reproduced (pool scrubbing)
Data base has been acquired to assess different
strategies of mitigationTOSQAN experiments have feed a database to improveand validate numerical tool
Simulation of 1F site conditions can be then achieved

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2. PROJECT ITEMS OUTCOMESSPRAY SCRUBBING DEVELOPMENT

Single spray modelling in the geometry of 1F pedestal
Preliminary spray simulations for single sprayNozzleGas velocity

Conditions of the simulation
Water level = 3 m
Spray injection level = 1.6 m from the water
Spray droplet mean size : 200 microns
Aerosol (Ex-vessel) mean size ∼ 200 nm
Tgas = Tspray = 20 °C

Water
Norm. vapour concentration

Norm. particle concentration

Simplified pedestal geometry
for over water area

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2. PROJECT ITEMS OUTCOMESSPRAY SCRUBBING DEVELOPMENT

Full spray modelling in the geometry of 1F pedestal
Spray simulations for a full spray (with same conditions)
Full spray (enlarged single spray)

Norm. particle concentration

Gas velocity

Enlargement of the spray area for sweeping
the whole section of the pedestal⇒ Better particle collection due to thegreater area swept by the spray but
particle entrainment weekly efficient⇒ Need of implementing several single
sprays rather than an enlarged spray

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2. PROJECT ITEMS OUTCOMESSPRAY SCRUBBING DEVELOPMENT

Thermal-hydraulics influence modelling in the geometry of 1F pedestal
Gas temperature influence (Tgas = 303K and 323K)
Gas temperature (Tgas = 323 K)Time = 10sTime = 100 s

Norm. water gas concentration (Tgas = 323 K)Time = 10sTime = 100 s

Different gas temperatures taken into accountwith different vapour concentrations⇒ Better particle collection when the gas
temperature increases⇒ Capability to take into account ventilation
conditions, obstruction and more realistic
or changing conditions of 1F site

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2. PROJECT ITEMS OUTCOMESSPRAY SCRUBBING DEVELOPMENT

Synthesis• Pool scrubbing efficiency analytical model was developed and validated based on laser
cutting tests performed on DELIA facility for underwater conditions• Spray design and specifications for best aerosol collection efficiency were determined• Spray scrubbing CFD model was developed and validated based on analytical TOSQAN tests• Both experimental and numerical approaches provide the capability to achieve relevant
predictions of spray system mitigation mean for various cutting strategies

Porcheron et al. OECD PreADES
meeting, Paris, January 25-29, 2019

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2. PROJECT ITEMS OUTCOMES

2. Project Outcomes
1. Laser cutting development
2. Dust and Fumes Collection in air development
Final outcomes of the technologies
3. Spray Scrubbing Development
Final outcomes on spray scrubbing
4. Dust & Fumes data acquisition
Final outcomes on dust & fumes

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2. PROJECT ITEMS OUTCOMES
DUST & FUMES DATA ACQUISITION

Summary of experimental approach (1/2)•

Aerosol measurement during laser cutting of simulant
fuel debris. In air/In water•

In-vessel and Ex-vessel (MCCI) fuel debris
compositions have been simulated• UO2 replaced by HfO2 (thermal ppties)• Pu replaced by Ce• FPs : Natural isotopes (except Ru)••

Aerosols collected by Filters
Collection + size distribution by 13stage impactors

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2. PROJECT ITEMS OUTCOMES
DUST & FUMES DATA ACQUISITION

Summary of experimental approach (2/2)
MCCI

in air underwater

In vessel In vesselin airunderwater

6g
1.3 g
Dross
Solid particles in
0.25 g0.9-1.4 g
water
Solution in water
0.35 g~1 g
Aerosols
0.8 g 0.6 – 3 g
9g
3-8 g
Total
7g
1-4 g
10 g
5-10 gFrom composition and isotopic inventory,
Aerosol masses are converted to radioactivity
MCCI MCCI
VF-04 in VF-04
For 1 m of cut
in air underwaterair
underwater
1011

Dross
Solid particles inwater
Solution in water
Aerosols
3.1010Total
1011

3.1011
3.109

0.8-1.5.109

4.10102.1010 - 8.1010 1010
0.6-1.2 1011
3.10111-2.1010
1-2. 1010
2-4.1010

100,0000%
10,0000%

MCCI sample
laser- cut in air

1,0000%0,1000%0,0100%0,0010%0,0001%
Al
Mg
Hf
B
Zr
Cr
Fe
Ni
Ca
Sn
Ce
Cs
La
Mo
Nd
Pd
Pr
Sm
Sr
Te
Y
Ba

MCCI

Detected mass (arb. Unit)

For 1 m of cut

5
4
3

Ba
Cs
Hf (U)

Ce
Pd
Zr

2
1
0

0,030,060,090,160,270,390,620,951,602,383,986,569,90
Aerodynamic diameter (µm)

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2. PROJECT ITEMS OUTCOMES
DUST & FUMES DATA ACQUISITION

Outcomes

Objectives

Modeling of Aerosols Release•••

Comparisons with chemical thermodynamic calculations

50% Ex-vessel block cut in air– Determination of fraction of volatilized elements from a mass of 45%
40%
fuel debris simulant
35%– Determination of a calculation methodology approaching the30%
measured aerosol compositions
25%
20%
Aerosols are modeled as gaseous fraction from initial
15%
10%
composition of the block5%– GEMINI thermodynamic code0%
– NUCLEA database
Fe
Ni
Cr
Sn
B Zr+Hf– equivalent temperature (2800 – 2900 K) corresponding to laser
heating
2800 K 2900 K Measurement– A quantity of air or water/steam is considered in equilibriumwith molten debris (quantity fit on experimental data)

Quite good agreement with experiment on major elements inaerosols.
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2. PROJECT ITEMS OUTCOMES
DUST & FUMES DATA ACQUISITION

Modeling of Aerosols Release••

Use of the validated modeling methodology to othercompositions
Transposition to reactor cases

Outcomes– Estimation of aerosol releases for various fuel debris
compositions and configurations• There is not only 1 “in-vessel” and 1 “MCCI” fueldebris composition !
1,E+00• Role of Uranium– Replacement of U by Hf in simulant block (done for testing
cutting ability not aerosol generation) leads to reduction ofaerosol formation by more than 1 order of magnitude(MCCI composition) or a factor of 4 (in vessel composition).
– Uranium becomes larger element in aerosols.
– Need for tests with uranium (also for mechanical cutting)to confirm these theoretical results.

1,E-02
1,E-04
1,E-06
U

Ni

Sn

Zr
Al
(+Hf)

Hafnium modelled by Zr

BaSr

With uranium

ONET Technologies CN subsidized project « Advancement ofFundamental Technologies for Retrieval of Fuel Debris Remote Controlled laser cutting and dust gathering » March 19th, 201937

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2. PROJECT ITEMS OUTCOMES
DUST & FUMES DATA ACQUISITION

Modeling of Aerosols Release– ~10 times less vaporization in neutral gas than in air(mainly due to steel oxide vaporization in air)– Barium and strontium release more in neutral atmospherecompared to air.

• Other fuel debris compositions– For instance, releases from 3 different composition of MCCI
corresponding to 3 layers of melt in lower head
– Heavy steel (with U) releases more U and lesslanthanides than other compositions– The more oxidic fuel is mixed with concrete, the less themass of released aerosols, but the larger the mass of
released uranium.

1,E+03Mass of released vapor (1/10 000)• Effect of air vs. neutral gas used for laser cutting:

1,E+02

1,E+01

1,E+00

1,E-01
Te

B

Ba

Cr
Argon

Fe

Sn

La

Ni

Sr Zr+Hf

in air

ONET Technologies CN subsidized project « Advancement ofFundamental Technologies for Retrieval of Fuel Debris Remote Controlled laser cutting and dust gathering » March 19th, 201938

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2. PROJECT ITEMS OUTCOMES
DUST & FUMES DATA ACQUISITION

Final outcomes on dust & fumes
A unique set of data on aerosol characteristics have been acquired within these projects• Size distribution : low median diameter• Composition of released aerosols different from fuel debris composition• Larger particles (> 1µm; low mass fraction): rich in (U ,Pu, Zr)O2• Fractal morphology of smaller particles (chain-like agglomeration of nanoparticles)• Composition can be inferred from released vapors calculated at 2800-3000 K(taking into account atmosphere, + water if necessary)• Capacity to predict different various fuel debris compositions• Uranium computed to be badly reproduced by simulant.
• Need for data with prototypic material containing depleted uranium

ONET Technologies CN subsidized project « Advancement ofFundamental Technologies for Retrieval of Fuel Debris Remote Controlled laser cutting and dust gathering » March 19th, 201939

Final outcomes on dust & fumes

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A unique set of data on aerosol characteristics have beenacquired within these projects•

Size distribution : low median diameter•

Composition of released aerosols different from fueldebris composition•

Larger particles (> 1µm; low mass fraction):rich in (U ,Pu, Zr)O2•

Fractal morphology of smaller particles (chainlike agglomeration of nanoparticles)•

Composition can be inferred from released
vapors calculated at 2800-3000 K (taking into
account atmosphere, + water if necessary)•
Capacity to predict different various
fuel debris compositions•

Uranium computed to be badly reproduced bysimulant.
•
Need for data with prototypic material
containing depleted uranium

ONET Technologies CN subsidized project « Advancement ofFundamental Technologies for Retrieval of Fuel Debris Remote Controlled laser cutting and dust gathering » March 19th, 201940

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3. APPLICATIONTO FUKUSHIMA SITE
Cutting scenarios in air – ELC-A and NELC-A•

Assumptions (under confirmation with IRID):
•
•
•
•
•
•

NELC-A
Non immerged materialHigh humidity (about 100%)Tight environment, confined space
High radioactivity level①
Massive blocks laying on walls and floor (fuel Debris)Internal structures at various elevation inside RPV/PCV (CRD housings, gratings, beams, pipes…)②•

Solutions to be developed:••••

Define cutting implementation procedure to remove small blocks
Propose suitable equipment to handle the cutting tools and the embedded collection system
Define the most appropriate technologies (ELC or NELC) for each potential situation
Design very robust solutions able to face the severe conditions (high radioactivity, poor accessibility,
humidity, …)

ONET Technologies CN subsidized project « Advancement ofFundamental Technologies for Retrieval of Fuel Debris Remote Controlled laser cutting and dust gathering » March 19th, 201941

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3. APPLICATIONTO FUKUSHIMA SITE
Cutting scenarios in air – ELC-A (1/2)
Cutting technologies
NELC-A
ELC-A

①
②
Local
collection

Aerosol mitigation
Cutting technology ELC-A
associated with local collection as
aerosols mitigation means

ELC-A technology could be used in air for the cutting and retrieval of the following items••••

CRD & CRD housings
Melted objects solidified on CRD
Platform structures, gratings, beams,… on which fuel debris has solidified…

ONET Technologies CN subsidized project « Advancement ofFundamental Technologies for Retrieval of Fuel Debris Remote Controlled laser cutting and dust gathering » March 19th, 201942

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3. APPLICATIONTO FUKUSHIMA SITE
Cutting scenarios in air – ELC-A (2/2)
With the ELC-A cutting head mounted on one arm and a handling device mounted on a second, it
is possible to cut and retrieve different from the totom NELC-Aof the reactor

①
②

ELC-A

Local
collection
The ELC-A cutting head can be used to cut the CRD housings in air for example
It can also be used to cut and retrieve pieces of structures, gratings, etc.
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3. APPLICATIONTO FUKUSHIMA SITE
Cutting scenarios in air – NELC-A (1/2)
Cutting technologies

NELC-A①②

Local
collection

Aerosol mitigation
Cutting technology ELC-A
associated with local collection as
aerosols mitigation means

NELC-A technology could be used in air for the cutting and retrieval of the molten material(fuel debris) at the bottom of the PCVONET Technologies CN subsidized project « Advancement ofFundamental Technologies for Retrieval of Fuel Debris Remote Controlled laser cutting and dust gathering » March 19th, 201944

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3. APPLICATIONTO FUKUSHIMA SITE
Cutting scenarios in air – NELC-A (2/2)
With the NELC-A cutting head mounted on one arm and a handling device mounted on a second,
it is possible to cut and retrieve different items at the bottomof PCV
NELC-A

①
②

ELC-A

Local
collection
Solid fuel debris melted onto the floor and not covered by water

ONET Technologies CN subsidized project « Advancement ofFundamental Technologies for Retrieval of Fuel Debris Remote Controlled laser cutting and dust gathering » March 19th, 201945

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3. APPLICATIONTO FUKUSHIMA SITE
Cutting scenarios in air – Dust retrieval for ELC-A and NELC-A
Waste retrieval for in-air cutting

Exhaustin PCV

HEPA
filterBarrelPipes and hoses
for thetransportation
before filtteringof the fuel debris
dust

Filtration device (for instance,① cyclonic filter) with collection
barrel + remotely handlable HEPA filter: collection of chips,
dross and dust. HEPA filter and barrel to be retrieved②
andtreated as solid waste when needed.
Platform to be entered in the same time as the carrier andtelescopic arm are implemented into the PCVAnother solution can be to place a fan and the filteringsystem in a specific room at the vicinity of the PCV

ELC-A

Local
collection

As an order a magnitude, 300 g of fuel debris in the barrel will represent a dose rate of 50
mSv/h at 1 m distance. The critical mass would be about 10 kg
Pieces cut to be retrieved by a specific arm able to carry solid wastes and place them in
specific barrels for treatment

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3. APPLICATIONTO FUKUSHIMA SITE
Cutting scenarios underwater – ELC-W and NELC-W•

Assumptions:
Same as in air conditions with the following additional constraints:• Fully immerged material (under few centimeters or several meters)• Poor visibility•

NELC-A

Solutions to be developed:••••

Define cutting implementation procedure to remove small blocks
Propose suitable equipment to handle the cutting (without collection system – impossible under water)
Design very robust solutions able to face the severe conditions (high radioactivity, poor accessibility,
humidity, …)
Propose suitable equipment to implement the spray scrubbing system and manage the interfaces suchas:
- Installation equipment for lifting, assembling or anchorage- Supporting : fixed to the walls, floating on the water or attached to existing steal structures- Piping : flexible or rigid, quantities , dimensions, …

ONET Technologies CN subsidized project « Advancement ofFundamental Technologies for Retrieval of Fuel Debris Remote Controlled laser cutting and dust gathering » March 19th, 201947

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3. APPLICATIONTO FUKUSHIMA SITE
Cutting scenarios underwater – ELC-W and NELC-W
Cutting technologies

ELC-W

Spray
and poolscrubbing②

Aerosol mitigation

ELC-W and NELC-W technology could be used for the cutting and retrieval of the molten material (fuel debris)that are situated underwater. The aerosol mitigation mean would spray scrubbing
ONET Technologies CN subsidized project « Advancement ofFundamental Technologies for Retrieval of Fuel Debris Remote Controlled laser cutting and dust gathering » March 19th, 201948

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3. APPLICATIONTO FUKUSHIMA SITE
Cutting scenarios underwater – ELC-W and NELC-W
With ELC-W and NELC-W technologies, it can be possible to integration the spray scrubbing system to the mechanical arm that bears thetools. In this configuration, the reached area by the spray scrubbing can be large enough to cover all
the aerosols scattering
NELC-A

①
②

ELC-W

Spray
and pool scrubbing

On the pictures above, one mechanical arm is bearing the ELC-W cutting head that can cut element suchplatforms, gratings, bars, etc. The spraying system is mounted onto the mechanical arm and stays above thewater level
ONET Technologies CN subsidized project « Advancement ofFundamental Technologies for Retrieval of Fuel Debris Remote Controlled laser cutting and dust gathering » March 19th, 201949

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3. APPLICATIONTO FUKUSHIMA SITE
Cutting scenarios underwater – ELC-W and NELC-W
NELC-A①②
Solid fuel debris cut on the floor
The spray scrubbing system is mounted onto the telescopic arm. 14 spraying nozzles
could cover a large surface under which the cuts are realized (it represents
approximatively a 5 m3/h waterflow)
NELC-W

Sprayand pool scrubbing
Entry of the system into the PCVONET Technologies CN subsidized project « Advancement ofFundamental Technologies for Retrieval of Fuel Debris Remote Controlled laser cutting and dust gathering » March 19th, 201950

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3. APPLICATIONTO FUKUSHIMA SITE
Cutting scenarios underwater – Other solution for spray scrubbing implementation
NELC-A①
Entry and implementation of one
moduleNELC-W②

Sprayand pool scrubbing
In case it is possible to drill modules onto the pedestal’s walls, the spray scrubbing
system could be implemented as it is shown on the pictures (8 modules of 3 spraying
nozzles each will cover the entire surface of the pedestal)
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CONCLUSION

Conclusion•

This project has achieved significant results in laser cutting development, dust and fumes knowledge
and aerosols mitigation•

Fuel debris retrieval will need complementary tools to overcome the various conditions andsituations to be faced : laser can be considered as one robust system for site application even if
challenges still exist (NELC-W).

•

The collection technologies have proven their efficiency, tests on more realistic material along withdesign improvement are now necessary to confirm full applicability•

Spray scrubbing is considered as a key technology for inhibiting aerial diffusion of the dust and could
be applied to other cutting techniques

ONET Technologies CN subsidized project « Advancement ofFundamental Technologies for Retrieval of Fuel Debris Remote Controlled laser cutting and dust gathering » March 19th, 201952