PROJECT OF DECOMMISSIONING AND CONTAMINATED WATER MANAGEMENT (DEVELOPMENT
OF TECHNOLOGIES FOR SCALING UP RETRIEVAL OF FUEL DEBRIS AND INTERNAL STRUCTURES)

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR
FUEL DEBRISPERFORMANCE REPORT FOR FY2018 SUPPLEMENTARYBUDGET(2022/01)

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

CONTENT OF THE PRESENTATION

1. Background and purpose of the project
2. Items of work
3. Schedule of the project – Overview
4. Final outcomes
1. Item #1 – Dust properties
2. Item #2 – Dust collection systems
1. Spray scrubbing development
2. Local collection
3. Dust extraction system

3. Item #3 – Application on site2

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

1. BACKGROUND & PURPOSE
Development of Dust Collection System for Fuel Debris Processing
Reasons why this research is needed
•
•
•
•
•

Prior to fuel debris retrieval, fuel debris processing is needed. Different fuel debris processing methods will lead todifferent retrieval strategies
In order to retrieve fuel debris after it has been processed, it is necessary to collect as much data as possible concerning
the final shape of the fuel debris (blocks, slags, dust, etc.)
It is also mandatory to collect data concerning the airborne particles that are generated during the fuel debris
processing for every processing tools (dust, aerosols)
Finally, the mechanical behaviour towards the fuel debris and the Fukushima Daiichi situation must be assessed
Following this data collection, it is possible to determine strategies to recover the fuel debris while implementing
solutions in order to mitigate all the risks that have identified (safety management, mitigation of aerosols release, etc.)
and to improve the operability of the systems (implementation, maintenance, etc.)

Project goal•

The goal of the project is to support the development of dust collection technologies contributing to thedecommissioning of Fukushima Daiichi NPS of Tokyo Electric Power Company

Duration of the project•

April 2019 – May 2021 (2 years)

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DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

2. ITEMS OF WORK
Development for Dust Collection of Fuel Debris System
Dust collection strategies
Considerations for the development of dust and aerosols collection systems are based on the following statements:• During fuel debris processing, several mechanisms are involved to propagate
dust generated :1. Dust deposition
2. Dust transport by air flows
3. Dust resuspension due to air flows

2

2

1

1

2
3

1
Fuel debris processing

2
3
1• These mechanisms are dependent of the processing method and theprocessed material, most influent parameters being:
The processing method (core boring, laser, grinder, etc.): eachprocessing methods will generate different dust and aerosols
characteristics
The fuel debris type and composition: previous showed that aerosols
characteristics also depend on the characteristics of processedmaterial
The air flows generated by the processing method: airflows transport
aerosols. Therefore, this parameter must be considered for the
implementation of systems• Development of collection systems must be adapted to these constraints

Dust transfer

Air Flows4

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

2. ITEMS OF WORK
Development for Dust Collection of Fuel Debris System
Dust collection strategies – Strategies for spray scrubbing and for local collection
1

Local spray: the area close to the cutting point is the target. This system
could allow a good efficiency rate while minimizing the water
consumption

2

3

Multi spray – Global spray: a large area is covered. This systemallows to collect the aerosols that have not been collected by othercollection systems and that are not already deposited

Local collection: the collection device is implemented so it can collect the
dust that is generated by the fuel debris processing. Dust and aerosols arerecovered in the different filtering devices in adapted waste cans
The study of applicability on site of these strategies focus on:
1.

Numerical simulations: calculations of deposition and collection ofparticles fractions for different scenario cases

2.

Implementation of spraying system and evaluation of the operability onsite (implementation of the system, water consumption)

3.

Implementation of local dust collection in air and evaluation of theoperability on site (implementation of the system, lifetime,
maintenance)

Fuel debris processing

4.

Safety analysis

Dust transfer

Output data: Assessment of the operability on site

Air Flows5

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

2. ITEMS OF WORK
Development for Dust Collection of Fuel Debris System
Generalities – FY2019/2020 subsidy project
Following the previous achievements, the objectives of the subsidy project for FY2019/2020 is to focus on dust collection systems. In this frame,
3 main items have been identified:1.

Data collection on dust and aerosols:
Data collection on dust generated during fuel debris processing operations. Fuel debris processing can either considered with mechanicaltools (grinder, saw) or with thermal tools (plasma torch, laser cutting).
Data collected will be used as input data for the development of dust and aerosols collection devices (especially for the spray scrubbing
strategies and for the filtration system of local collection in air)2.

Development of dust and aerosols collection strategies
1.

Development of aerosols and dust collection by spray scrubbing techniques
Spray scrubbing techniques must be adapted to the configurations on site and to the fuel debris processing tool that will be used. Different strategies are
considered: global application or local application of spray scrubbing.
Performances of systems are assessed both with experimentations and with numerical simulations

2.

Development of local extraction devices for dust and aerosols collection
Local collection devices are especially designed to be tested with laser cutting techniques. Also, collection devices are connected to the dust extraction system:
the goal is to be able to recover the dust that has been collected. Also, the filtration device is meant to be implemented in-situ: therefore development seeks thefiltration efficiency and the best solutions to make the system able to work entirely remotely inside the Primary Containment Vessel (PCV)

3.

Study of application on site and scenario assessment
1.

Implementation of devices
Studies on the implementation of the systems on site and their use. Focus is also made on the operability of the system (maintainability, safety analysis,
efficiency, etc.)

2.

Numerical simulations
Starting from data acquired during the tests, numerical simulations are performed with pedestal modelization in order to procure first assessment of aerosolsand dust collection efficiency in real case scenario

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DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

2. ITEMS OF WORK
Project Methodology
This section explains the methodology and the relationships between the different items of work:

Input data from past projects, status reports, publications, etc.
Fuel debris simulant manufacturing

Tests with laser cutting
and dust collection in air

Test for different mechanicalprocessing tools in air

Data collected:•
Aerosols collection efficiency•
Transportation and filtration of particles
efficiency (dust and aerosols)•
Operability of collection devices

Proposal of the best strategies fordust collection and site
applicability

Data collected:•
Aerosols characterization (mass concentration, size
distribution)•
Characteristics of fuel debris after cutting (assessment ofamount of dust, blocks, slags, etc.)•
First approach of mechanical behaviour of the processing
tools

Spray scrubbing tests in
TOSQAN facility withsimulated aerosols
Spray scrubbing tests in
DELIA facility with laser
cutting and with andwithout dust collection
devices in air

Input data for spray scrubbing
development (local and global strategy)

Numerical simulations for sprayscrubbing efficiency for various
conditions

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DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

3. SCHEDULE OF THE PROJECT
Overview of project schedule – FY2019
APR.

MAY

JUN.

JUL.

AUG.

SEP.

OCT.

NOV.

DEC.

JAN.

FEB.

MAR.

Preparation of R&D program

ITEM 1 – DATA COLLECTION ON DUST EMISSION WITH DIFFERENT FUEL DEBRIS PROCESSING METHODS
Choice of FD simulants
Fuel Debris simulants manufacturing (MCCI and In-vessel simulants) – 6 batches in total
Manufacturing report

Test program & facility
preparation – Disc saw
Essential tests + report of the tests

Improvement of facility (instrumentation) for complete disc saw tests

Test program & preparationof tests – Core boring

Design of equipment and supply for core-boring tests
Preparation of DELIA facility for laser cuttingwith N2ITEM 2 – COLLECTION OF AEROSOLS BY SPRAY SCRUBBING TECHNIC
Test program definition
Design, supply of equipment and modification of TOSQAN facility for the realization of the tests – Single spray and multi nozzles spray
CFD calculations – Tests of configurations through numerical simulations
Preparation of tests for spray scrubbing with laser cutting (testprogram + supply of equipment)

Tests – Laser cutting withspray scrubbing

Tests report

ITEM 3 – LOCAL COLLECTION AND EXTRACTION OF DUST AND AEROSOLSDefinition of local collection
system & essential tests
Improvement of design of collection systems & preparation of tests
Tests & analysis of results

Study & supply of transportation and filtration equipment
Essential tests with and without laser cutting & analysis of results
Study of applicability of solutions on site88

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

3. SCHEDULE OF THE PROJECT
Overview of project schedule – FY2020*
APR.

MAY

JUN.

JUL.

AUG.

SEP.

OCT.

NOV.

DEC.

JAN.

FEB.

MAR.

Update of
Research
Plan

ITEM 1 – DATA COLLECTION ON DUST EMISSION WITH DIFFERENT FUEL DEBRIS PROCESSING METHODS
Preparation of core-boring tests
Improvement of facility (instrumentation) forcomplete disc saw tests

Core-boring tests on FD simulants & analysis ofresults
Cutting tests with grinder on FD simulants
Analysis of results
Preparation of DELIA facility for laser cutting with N2
Laser cutting tests with N2

ITEM 2 – COLLECTION OF AEROSOLS BY SPRAY SCRUBBING TECHNIC
Design, supply of equipment and modification of TOSQAN
facility for the realization of the tests – Single spray and multinozzles spray
Spray scrubbing tests in TOSQAN facility
Study for the implementation of local spray during laser cutting
Laser cutting tests with sprayscrubbing
Study of the applicability of the system on site & expected performances (tentative)

ITEM 3 – LOCAL COLLECTION AND EXTRACTION OF DUST AND AEROSOLS
Design and procurements of local collection devices
Laser cutting tests with representative materials
Improvement, design of extraction prototype and expansion of system to mechanical FD processing tools
Tests
Final study of applicability of solutions on site

* Due to Covid-19 situation, delays occured on the project. Official termination date of project: 31 May 2021 (final report on 18/5/2021)
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DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #1 – DUST PROPERTIES

1010DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #1 - DUST PROPERTIES
1. ITEM #1 – DUST PROPERTIES
Objectives
1.
2.

Gather dust properties for several processing methods (thermal / mechanical) to have data for collection systemdevelopment*
Basic comparison of dust emission between several processing methods* Complementary from IRID/JAEA CLADS project

Tasks implemented in the frame of item 1[1] Fuel debris simulants manufacturing[2] Data collection on dust and fumes for mechanical tools (and plasma torch)
1: Tests with manual reciprocating saw and grinder in TRANSAT test bench
2: Test with automatized disc saw (grinder) in CAPIMIF test bench
3: Tests with plasma torch on CAPIMIF test bench
4: Tests with core boring tool in DELIA facility[3] Data collection on dust and fumes for laser cutting (including tests with N2)
1: Tests on stainless steel
2: Tests on Ex-vessel fuel debris simulant
3: Tests on In-Vessel fuel debris simulant
4: Conclusions[4] Data collection on dust and fumes for various cutting tools and conditions
11
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DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #1 - DUST PROPERTIES[1] – Fuel debris simulants manufacturing
Objective: Manufacturing of representative fuel debris samples
Two compositions of fuel debris have been considered for the manufacturing of fuel debris
simulant.
In-vessel composition has been determined from the average of Fukushima Daiichi unit 2
lower head debris composition
Ex-vessel composition has been determined in order to simulate a debris from interaction
between the molten core and the concrete in the sump of Fukushima Daiichi unit 1.

Mixed oxide-metal in-vessel (1F2)
fuel debris simulant (based on 1F2
average BSAF compositions)
Oxidic MCCI 1F1 simulant (based on
1F1 Robb and al. calculations withlarger concrete content

Fuel debris simulants for in-vessel and ex-vessel
compositions are provided to support thedevelopments of technologies studied in the frameof the “Dust collection of fuel debris system”
project

The fission product prototypes included (proportions typical of 10 years after accident) except Ru (for health regulation issue) are:• Raw materials (natural isotopic composition) for Nd, Mo, Cs, Ba, La, Pd, Pm, Sr, Y, Te• Powders: HfO2, Zr, ZrO2, CeO2 (FP + Pu surrogate), SnO2, B4C for both compositions) and SiO2, FeOx, Al2O3, Cr2O3 and CaO for the ex-vessel
composition
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DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #1 - DUST PROPERTIES[1] – Fuel debris simulants manufacturing
Loads
In-Vessel fuel debris simulant blocks
wt%

Ex-Vessel fuel debris simulant blocks
wt%

HfO2

30.2%

CsOH.H20

0.08%

Zr

37.9%

BaO

0.05%

ZrO2

19.8%

La2O3

0.035%

CeO2

0.2%

PdO

0.033%

SnO2

1.0%

Pr2O3

0.033%

B 4C

1.1%

Sm2O3

0.016%

Stainless steel 304L*

9.3%

SrO

0.024%

Nd2O3

0.12%

Y 2O 30.016%

MoO2

0.09%

TeO2

0.015%

wt%

HfO2
Zr
ZrO2
CeO2
SnO2
B 4C
Stainless Steel 304L*
Cr203
Fe
FeO
SiO2
Al2O3
CaO

20.5%
0.6%
11.7%
0.2%
0.2%
0.2%
5.6%
0.6%
2.9%
5.0%
30.6%
7.6%
6.2%

wt%

Fe2O3
Nd2O3
MoO2
CsOH.H2O
BaO
La2O3
PdO
Pr2O3
Sm2O3
SrO
Y 2O 3
TeO2

7.8%
0.09%
0.09%
0.06%
0.039%
0.027%
0.026%
0.027%
0.019%
0.019%
0.011%
0.012%

Preparing VF-06 in vessel load*304 L steel rods: 0.017 wt% C, 0.44% Si, 1.5 % Mn, 0.039% P, 0.027% S, 18.5% Cr, 8.07%
Ni, 0.5% Cu, 0.08% N, 0.13% Co, 0.37% Mo

Preparing VF-10 ex-vessel load

13

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #1 - DUST PROPERTIES[1] – Fuel debris simulants manufacturing
Manufacturing process1.

Selection of raw materials

In-Vessel fuel debris simulant blocks

2.

Set up of melting furnace

The total mass of in-vessel fuel debris simulant blocks produced is 35 kg.
Various shapes have been obtained (4 melting procedures)
Ex-Vessel fuel debris simulant blocks

Crucible is filled with pellets and raw materials
before melting

3.

Melting operation

Metal phase

The total mass of ex-vessel fuel debris simulant blocks is 38 kg (including
blocks of denser solidified metal) (4 melting procedures)
Apparent density for the different fuel debris simulants:•
In-vessel block: ~4.7 g.cm-3•
Ex-vessel oxidic block: ~2.6 g.cm-3•
Ex-vessel metallic layer : ~5.8 g.cm-3

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DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #1 - DUST PROPERTIES[2] – Data collection on dust and fumes
1 – Tests with manual reciprocating saw and manual grinder in TRANSAT test bench
TRANSAT facility and instrumentation:

437 mmRotameter
OpticalParticleCounter

800 mm

604 mmHEPA
FilterfilterTHE

FanFluoropor
Membranemembranefilter FSLW
filterTRANSAT is a small glove box (250L). This facility is instrumented
with an optical particle counter (GRIMM, size range 0,25 µm –30 µm)
Cutting tests with a reciprocating saw and a grinder are
performed manually inside the glovebox in order to obtain
information about aerosols generation due to fuel debris
simulant cutting with these two cutting tools.

598 mmTest procedure and cutting parameters:
Operations are realized manually (no automation of devices).
Therefore, cutting strenght has not been monitored and canhave variations due to the operator.
Reciprocating saw

Picture of manual grinder in TRANSAT gloebox (left) and example ofreciprocating saw

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DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #1 - DUST PROPERTIES[2] – Data collection on dust and fumes
1 – Tests with manual reciprocating saw and manual grinder in TRANSAT test bench

105
104
103
102
101
100
10-1
10-2

Reciprocating SAW / In-vessel
2

4

6

8

10

12

14

16

Channels (µm)
0.3
0.4
0.5
106
0.65
105
0.8
1
4
10
1.6
103
2
3
2
10
4
101
5
7.5
0
10
10
15
10-1
Reciprocating SAW / Ex-vessel
20
-2
10

18

0

5

20

10

Time (min)Channels (µm)
0.3
0.4
106
0.5
0.65 105
0.8
104
1
1.6
103
2
102
3
4
101
5
7.5
100
10
10-1
15
20
-2
15

20

Concentration for In-Vessel (#/L) cut by Grinder

106

Concentration for Ex-Vessel (#/L) cut by Saw

Concentration for In-Vessel (#/L) cut by Saw

Results obtained concern the numerical concentrations of particles emitted for every size in the range [0,25µm;10µm] for the two cutting
processes and for in-vessel and ex-vessel simulants:

10

Channels (µm)
0.3
0.4
0.5
0.65
0.8
1
1.6
2
3
4
5
7.5
10
15
20

GRINDER / In-vessel
0

2

4

6

8

10

12

14

16

18

20

Time (min)Time (min)1616DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #1 - DUST PROPERTIES[2] – Data collection on dust and fumes
1 – Tests with manual reciprocating saw and manual grinder in TRANSAT test bench
Relative particle concentration according to the size:
3,0

3,0

2,0

dN/NdlnD (-)

dN/NdlnD (-)

Ex-Vessel
In-Vessel 2,5Zircone

Saw

2,5

1,5

2,0

1,5

1,0

1,0

0,5

0,5

0,0
0,1

1

10

Optical Diameter (µm)

Grinder

0,0
0,1

1

10

Optical Diameter (µm)

Main conclusions of the tests:• Concerning the number of emitted particles:– With the same simulant (in-vessel), the grinder emits more particles, for every size;– With the same processing tool (reciprocating saw), more particles are emitted with Ex-vessel fuel debris simulants• Concerning the particles concentration according to the size range:– The reciprocating saw and the grinder both produce high concentrations of very thin particles

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DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #1 - DUST PROPERTIES[2] – Data collection on dust and fumes
2 – Tests with automatized disc saw (grinder) on CAPIMIF test bench
2.1 – CAPIMIF test bench and instrumentation:
CAPIMIF is an airtight facility. It is composed of a test bench that can be instrumented in order to monitor aerosols characteristics during cutting
operations. Monitoring concerns aerosol concentration in mass and numbers, electrical charges distribution, morphologies and physical andchemical analysis on some samples.
Also, particles mass concentrations are integrated with HEPA filter and particles morphologies are studied thanks to TEM and EDS vizualisation
Pegasor

ELPI+
DLPI

Fuel debris simulant

Data acquisition and instrumentation:• Particle size distribution: integrated measurementwith DLPI+ (30 nm to 10 µm)• Particle size distribution: temporal measurementwith ELPI+ (6 nm to 10 µm)• Particles electrical charges: measurement with ELPI+• Particle mass and number concentrations:
measurement with Pegasor PPS sensor• Particle morphology is realized with TEM
visualization• Particle composition is obtained by EDS based on
TEM imageCutting strength is monitored and constant through a cutting test thanks to the automatic grinder. Aerosols production has been monitored forvarious cutting strengths, cutting speeds and for different materials (fuel debris simulants)

18
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DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #1 - DUST PROPERTIES[2] – Data collection on dust and fumes
2 – Tests with automatized disc saw (grinder) on CAPIMIF test bench
2.2 – Example of data collection on one specific experiment :a – Calculation of Kairbone ratio:•••

Mass concentration is monitored during the 6 consecutive cuts (numbered from 1 to 6 in the figure below)
Fuel debris sample has been weighted before and after the cuts: therefore, it is possible to determine the mass it has lost during the
cutting
Kairborne represents the ratio between the mass of aerosols that has been emitted in comparison of the total mass that has been removed
from the fuel debris simulant sample
Measurement of material
mass loss during cutting
n°6 on the Fuel Debris
sampleMassmaterial_loss = 31.2 g

1

2

3

4

5

Kairborne=
0.0023

6
Start ofcutting

Mass concentration for a sequence of 6 cuts

Stop of cutting

Measurement of mass concentration integrated throughthe cutting time with measured airflow
Massairborne_particle = 73 mg

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DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #1 - DUST PROPERTIES[2] – Data collection on dust and fumes
2 – Tests with automatized disc saw (grinder) on CAPIMIF test bench
2.2 – Example of data collection on one specific experiment :b – Particles size distribution in mass and number:
The graph below shows the distribution in mass and numbers according to the aerodynamic diameters of the particles. Data have beenobtained during the 6 cuts of fuel debris simulant VF12.
The most important for the contribution in mass comes from the big particles. However, small particles are more important in number,especially for the particles with an aerodynamical diameter between 0.2 µm and 0.3 µm: this size is the critical one from the containment pointof view (lowest point of efficiency of HEPA filter)

Critical particle sizes for confinement issues, lowcontribution in mass while highest one inparticles number

View of impactor plates

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DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #1 - DUST PROPERTIES[2] – Data collection on dust and fumes
2 – Tests with automatized disc saw (grinder) on CAPIMIF test bench
2.2 – Example of data collection on one specific experiment :c – Electrical charges:
The median aerodynamic diameter for the VF12 fuel debris simulant is 11.6 µm (top left figure). The cumulated mass shows that 90% of thetotal mass comes from particles with an aerodynamic diameter superior to 3 µm (bottom left figure).
Distribution of electrical charges is given on the right figure. Electrical charges have been measured thanks to ELPI+. Results show significant
electrical charges with particles larger than 5 µm having positive electrical charge and particles smaller than 0.5 µm having negative electricalcharge.

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DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #1 - DUST PROPERTIES[2] – Data collection on dust and fumes
2 – Tests with automatized disc saw (grinder) on CAPIMIF test bench
2.2 – Example of data collection on one specific experiment :c – Electrical charges:

Particles charge are induced by mechanical frictions (No such significant charges observed for particles generated by laser cutting)More investigations are needed in order to evaluate the consequences of the electrical charge for dust transportation, deposition andfiltration
Real fuel debris are expected to generate particles with high electrical charges due to radioactive content

Figure on the left shows the cumulative mass of observed particles depending theirdiameter

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DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #1 - DUST PROPERTIES[2] – Data collection on dust and fumes
2 – Tests with automatized disc saw (grinder) on CAPIMIF test bench
2.2 – Example of data collection on one specific experiment :d – TEM and EDS vizualisations:
Particle visualization by TEM&EDS with physico-chemical analysis shows various morphologies and heterogeneous composition by particles.
Various morphologies including aggregated particles with fractal patterns similar to the ones emitted during laser cutting are observed. This
result was not expected for particle generation with a mechanical tool. In terms of composition, results underline heteregeneity for submicronic
particles. This tendency seems different compared to the one observed for laser cutting (a homogenous composition was globally observed).
Aggregates ofvery fine particles(fractal like forlaser cutting)
1 µm

Zr

Fe

Cr

Cu is mainly
coming from TEM
grids and fromstainless steel

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DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #1 - DUST PROPERTIES[2] – Data collection on dust and fumes
2 – Tests with automatized disc saw (grinder) on CAPIMIF test bench
2.2 – Example of data collection on one specific experiment :e – Particles size distribution for a different cutting strenght:
Tests have been realized with different cutting strengths in order to observe the influence of this parameter in the particles emission. The figure
below shows two cutting tests: each cutting test consists in 6 cuts, with 100N as cutting strength. Tests have been realized on fuel debris
simulant VF12.

Results:• Tests show a variability of the particles size distribution for the same material. Also, variability in terms of massconcentration has been observed.
• Kairbone was calculated and has a 30% variation: Kairborne is between 0.0023 and 0.0035• This variability both for the particles size distribution and mass concentration can be explained by the heterogeneity of the material.
Therefore, it is difficult to conclude whether the force applied on the cutting tool has an influence or not. Tests must be conducted on
homogeneous cast fused Zirconia blocks.

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DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #1 - DUST PROPERTIES[2] – Data collection on dust and fumes
3 – Tests with plasma torch on CAPIMIF benchExperimental set-up:
The plasma torch is implemented in front of the instrumented ventilation pipe for particle aspiration and measurement



Plasma torch (Power 180W)



Ventilation pipe for particle
suction and measurement25

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #1 - DUST PROPERTIES[2] – Data collection on dust and fumes
3 – Tests with plasma torch on CAPIMIF bench
Tests with Ex-vessel simulant – Particle morphology and composition by MET &EDS
Particle morphologies are quite varied: they can be angular, spherical or fractal. A particle with polydispersed size has been observed based on
MET analysis, from 50 nm to more than 5 µm.

26

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #1 - DUST PROPERTIES[2] – Data collection on dust and fumes
3 – Tests with plasma torch on CAPIMIF bench
Tests with In-vessel simulant – Particle morphology and composition by MET &EDS
The same tendency has been observed for In-vessel fuel debris simulant regarding particle morphology and particle size. Individual particles ofCesium and Zirconium have been observed. Particles of Cs and Zr have been identified.

CS

Zr

27

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #1 - DUST PROPERTIES[2] – Data collection on dust and fumes
4 – Tests with core boring tool in DELIA facility
Core boring tool in DELIA facility:
DELIA facility is an airtight vessel with a chimney connected to an instrumented aerosols sampling ine
PegasorAerosols
instrumentation at
the exhaust

Chimney

DELIA vessel

DLPI
For particle size distribution, integrated measurement with DLPI+ (30 nm to 10 µm)
For particle mass and number concentration (Pegasor PPS sensor)

Methodology applied:• The cutting parameters are monitored and constant during all the cutting• Different parameters that can have an influence on aerosols generation have been tested: tests cutting on cast fused Zirconia blocks,
cutting on in-vessel and ex-vessel simulant blocks, influence of spray scrubbing• Data monitored: cutting strength, cutting speed, water flow for spray scrubbing, air injection for air circulation in the vessel• Data acquired: number and mass concentrations, particles size distribution, data for the study of the applicability on site of the core
boring tool28

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #1 - DUST PROPERTIES[2] – Data collection on dust and fumes
4 – Tests with core boring tool in DELIA facility

Core boring test on a cast fused Zirconia
block. The core boring produces a very thinpowderCore boring of in-vessel fuel debris simulant. The core boring produces, among others, dust and asolid block. The solid block is not automatically removed from the core boring toolCore boring test of ex-vessel fuel debris simulant.
Bore coring appears to be difficult, even
impossible, when the tool cuts into melted andcompact metal cluster. Also, cutting tool is quickly
damaged and needs to be changed frequently

Core boring test on exvessel
fueldebrissimulant with spraying
system on

29

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #1 - DUST PROPERTIES[2] – Data collection on dust and fumes
4 – Tests with core boring tool in DELIA facility
Results:

Evolution of the concentration number of particles (left) and converted in mass (right) during the core boring of Ex-vessel fuel debris
simulant 11A:

Particle size distribution of the particles: airborne particles sampled in the sampling line of DELIA facility (left) vs particles found at thevicinity of the core boring after the test (right):

30

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #1 - DUST PROPERTIES[3] – Data collection on dust and fumes for laser cutting
Objectives of the tests:
The tests aim at establishing comparisons between secondary emissions generated by air and N2 gas during laser cutting
tets.
Progress/Methodology of the tests:• Laser cutting tests in air are realized following the usual laser cutting protocol• For the laser cutting tests using N2 instead of air:•For every laser cutting operation, aerosol generation is monitored and characterized in terms of:




•

DELIA vessel is vented with nitrogen until O2 concentration reaches 1% (which is more accurately representative of the 1F
conditions)
Laser cutting starts with N2 as assist gas
Mass and number concentration (Pegasor sensor)
Particle size distribution (DLPI)
Particle morphology and composition (MET & EDS)

Tests are realized with stainless steel (316L) plates and in-vessel and ex-vessel fuel debris simulants for bothconditions:

Dry condition
Humidity conditions (generated thanks to spraying system) – HR=100%31

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #1 - DUST PROPERTIES[3] – Data collection on dust and fumes for laser cutting
1 – Tests on stainless steel
Laser cutting tests have been realized on a stainless steel plate (316L, 40 mm thickness) successively in air and with N2 in dry conditions. Figures
below show the results of these tests.
Slag shapes depending on the cutting configuration

Air cutting
Nitrogen cutting

Air cutting
Nitrogen cutting

Adherent slag are lessspread for N2 cutting• The figure below shows the particle size distributions for laser cutting of stainless steel plate (316 L, thickness = 40 mm) for the cutting in air
dry conditions
Air – Dry condition• A decrease of particle mass concentration with nitrogen in dry conditions for stainlesssteel compared to air condition has been observed• Decrease of particle size for N2 cutting compared to air cutting has been observed32

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #1 - DUST PROPERTIES[3] – Data collection on dust and fumes for laser cutting
1 – Tests on stainless steel
Particle morphology and composition by MET &EDS
AIR – Dry condition

N2 – Dry condition

N2 + Humidity condition

Oxidation
Oxidation

N2 influence on morphology & compositionMorphology is still fractal with about the same dimension (Df close to 1.8)
Decrease of primary particle size is observed (which is consistent with the decrease of aerodynamic diameter measured thanks to the
DLPI)
33
Oxidation is underlined for air and N2 with humidity tests

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #1 - DUST PROPERTIES[3] – Data collection on dust and fumes for laser cutting
2 – Tests on Ex-vessel fuel debris simulant
Laser cutting tests have been performed on the same sample of ex-vessel fueldebris simulant in dry conditions with air and then with nitrogen.
 Sample thickness is similar for air and N2 cuttings

Visually, no clear difference between air and N2 cuttings on slag structure
A slight influence on particle number concentration is observed but no significant differences for particle mass concentration
No significant difference between nitrogen/air for ex-vessel simulant in terms of particle size, particle morphology & composition andparticle number & mass concentrations is observed

34

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #1 - DUST PROPERTIES[3] – Data collection on dust and fumes for laser cutting
3 – Tests on In-vessel fuel debris simulant
Laser cutting tests have been performed on the same sample of in-vessel fuel debris simulant in dry conditions with air and then with nitrogen.
In-vessel simulant is expected to provide more influence with N2 gas due to its lesser oxidation than ex-vessel simulant
 Sample thickness is similar for air and N2 cuttings

Visually, no clear difference between air and N2 cuttings on slag structure••

For dry conditions, N2 cutting induces a decrease of particle mass and number generation compared to air cutting
A slight influence of Nitrogen on particle size distribution for dry conditions is observed35

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #1 - DUST PROPERTIES[3] – Data collection on dust and fumes for laser cutting
3 – Tests on In-vessel fuel debris simulant
Particle morphology and composition by MET &EDS and particle size by DLPIAIR – Dry condition

N2 – Dry condition

36

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #1 - DUST PROPERTIES[3] – Data collection on dust and fumes for laser cutting
3 – Tests on In-vessel fuel debris simulant
Particle morphology and composition by MET &EDS and particle size by DLPIN2 + Humidity condition

Fe

O

Fe

Hf

No nitriding reactions were characterized with EDS. Oxidation reaction are amplified for N2 + humidity cutting37

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #1 - DUST PROPERTIES[3] – Data collection on dust and fumes for laser cutting
4 – Conclusions

Influence of N2 used as assisted and surrounding gas during laser cutting – 1F site conditions
 Stainless steel: Strong reduction of particle generation (mass&number) by factors between 6 and 8 depending on dry or wet
conditions
 Wet conditions induce an increase of particle mass concentration and a slight increase of particle size Ex-vessel simulant:
 No significant effect of N2 for dry conditions. The content in O2 in Ex-vessel simulant is important enough sooxidation is not enhanced by the addition of oxygen provided by water No conclusion for wet conditions
 In-vessel simulant: Reduction of particle generation (mass&number) in dry conditions for nitrogen For nitrogen and wet conditions, important increase of particle generation (mass&number) compared to N2 dry
condition. No significant evolution of particle size with humidity. The oxygen content of the in-vessel simulant
being low, additional O2 due to humidity leads to strengthen oxidation reactions which increases aerosol
generation
 Complementary analysis of particle composition by X-ray photo-electron spectroscopy (XPS) would help us to
improve the understanding of the results obtained with nitrogen for humidity conditions.
38DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #1 - DUST PROPERTIES[4] – Data collection on dust and fumes for various cutting tools & conditions
During FY2019 and FY2020, various tests have been performed with different cutting tools in various
conditions leading to develop a database for airborne particle generation.
Cutting conditions investigated- Tool (laser, mechanical, thermal)- Fuel debris simulants (in and ex-vessel), stainless steel- 1F site conditions (those that can be simulated)- Humidity rate
- Rain/spray- Underwater- Air atmosphere- Nitrogen atmosphere

FY2019 & FY2020 trials*FY201739

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #1 - DUST PROPERTIES[4] – Data collection on dust and fumes for various cutting tools & conditions
Structure of analytical table for particle generation
Items for operating
conditions of tests

Operating conditions

Cutting conditions

Test bench name / location
Cutting tool type
Ambient conditions (dry, air, nitrogen, rain)
Ventilation flow rate
Other

Morphology

Fuel debris simulant ormaterials specifications

In-vessel, Ex-vessel, zirconia, stainless-steel
Dimensions
Composition, density, hardnessSize aerodynamic mass median diameter (Dg) Aerodynamic number median diameter (Dn)Geometric standard deviation (g)Cutting tool
specifications

Disk diameter
Rotation speed, pressure force
ELC* or NELC**, Laser power, wave length, laser beam
diameterElectrical charges

Metrology for particles
characterization

DLPI, ELPIHEPA filter
PegasorTEM & EDS

Mass / number concentration

Cutting performances /cutting issues

Cutting speed
Kerf thickness and depth
Tool blocking or damage

Airborne fraction coefficient
Mass emission rate

* ELC: Emerging Laser Cutting** NELC: Non-Emerging Laser Cutting

Particles data

Main composition

40

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #1 - DUST PROPERTIES[4] – Data collection on dust and fumes for various cutting tools & conditions• The objective is to evaluate radioactive airborne release particles for safety assessment management during fuel debris
cutting with various tools.
• The complexity of this work is linked to the following points:• Difficulty of comparison of experimental results obtained with various aerosols metrology measuring various
physical magnitudes (particle size distribution in mass, in number, aerodynamic, electrical mobility, …)• Experimental uncertainties• Heterogeneity of fuel debris simulant giving a dispersion of experimental values• Repeatability of the cutting tool implementation or user effects• Well knowledge of safety assessment expectations from nuclear safety authorities
IRSN has developed the “BADIMIS” database used by French Nuclear
Authorities (ASN) capitalizing dust resuspension results for accidental
scenarios (see next slide). (May be used for further data collection
work.)FY2019&FY2020 results regarding particle generation are synthetizedin analytical table.

41

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #2 – DUST COLLECTION SYSTEMS42

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS
2. DUST COLLECTION SYSTEMS
Objectives•

Study, test and design suitable solutions in order to mitigate the aerosols release during fuel debris processing using
spraying systems, including mechanical fuel debris processing tools, with local and global spraying strategies•

Design and test a first prototype for local collection of dust and aerosols in air for laser cutting and its expansion tomechanical tools

Tasks implemented in the frame of item 2[1] Dust dispersion mitigation by spray scrubbing
1: Numerical simulations
2: Tests in TOSQAN facility with simulated aerosols
3: Assessment of spray efficiency for laser cutting[2] Advancement of local collection during laser cutting
1. Improvement of local collection device
2. Collection efficiency and operability tests
3. Local collection and spray scrubbing with laser cutting[3] Numerical simulations (CFD) in PCV geometry[4] Operability tests[5] Dust extraction system development

43

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS
2. DUST COLLECTION SYSTEMS
Overview of the work achieved – Spray scrubbing & Local collection
Spray scrubbing strategy development
Numerical simulations:First assessment of collection efficiency withdroplets characteristics

Local collection of dust (laser cutting)p.45

Tests in TOSQAN with simulated aerosols- Simulation of fuel debris processing withmechanical tools and laser cutting- Tests with local and global sprays strategies

Dust extraction system

Preliminary tests
To work on coating and minimize deposition ofmolten material
Numerical simulations:
To improve aeraulics of collection heads with laser

Design of dust extraction system
With definition of elements

p.53-54

p.46-50

Spray scrubbing tests with laser cutting- Laser cutting of fuel debris simulant- With global and local spray strategies

p.66-69

Preliminary tests
Cyclonic filter, flexible hoses, self-cleaning HEPA
filter
p.70-72

Efficiency and operability tests
To prove that collection efficiency is high withrepresentative materials
p.55-57

p.51-52

Laser cutting tests with local collection and filtrationequipment
p.73-75

Local collection and spray scrubbing duringlaser cutting tests
Laser cutting tests with local collection and sprayscrubbing strategies implemented together
p.58-59

Extrapolation of results for on site conditions

Operability tests of local collection
Operability tests
To assess the feasibility of implementation on site
p.65

Numerical simulations in order to assess efficiency ofboth strategies in PCV
p.60-6444

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS[1] – Dust dispersion mitigation by spray scrubbing
1 – Numerical simulations• Objective: The objective of this task was to determine the most promising local spray characteristics to be implemented (droplets size, mass
flow rate, position and orientation of the spraying nozzle)• Input data: Aerosols characteristics gathered thanks to previous experiments, tools characteristics (airflows for the laser cutting for instance)
Example of numerical modeling results: view ofdroplets concentration in TOSQAN facility for laser
cutting

Example of numerical modeling: Laser cutting
NELC-A* configuration implemented in TOSQAN
facility to forecast the spray scrubbing efficiency
for different spraying characteristics• Results of the study:• First assessment for aerosols collection efficiency with a local spray system for various tools (grinder, reciprocating saw, laser)
These characteristics for the sprays have been used for the tests in TOSQAN facility and in DELIA facility*: NELC-A stands for Non Emerging Laser Cutting in Air

45

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS[1] – Dust dispersion mitigation by spray scrubbing
2 – Tests in TOSQAN facility with simulated aerosols
2.1 – Overview of the tests• Objectives:• Improvement of dust mitigation by spray systems coupling local and global sprays• Assessment of collection efficiencies for various particle generation (mechanical tools and laser)• Study of scenarios of local and global sprays activation for reducing water consumption• Methodology:• Powders are used in order to simulate the aerosols generated during the fuel debris processing. They have been selected to be
representative of each cutting tool that has been studied• Sensibility of droplets size for global spray have been studied• Time evolution of particle concentration in the vessel is monitored to evaluate the collection efficiency during various scenarios of
cutting simulation

The tests aimed to assess mitigation efficiency of spray scrubbing strategy for different scenarios, for various cutting tools
and for various global spray characteristics
Efficiency of spray scrubbing systems will be evaluated within following physical magnitudes: Particle removal rate () Decontamination factor (DF) - DF=(C0-Ct=1800s)/C0
 Initial and chosen time particle number concentration (C0 and Ct=1800s)
46

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS[1] – Dust dispersion mitigation by spray scrubbing
2 – Tests in TOSQAN facility with simulated aerosols
2.2 – Overview of the tests
The picture below describes TOSQAN facility. The global spray device is situated at the top. With global spray, all the surface of the vessel iscovered with the droplets. Between 5 and 9 spray nozzles can be used depending on the test parameters.
The local spray is situated closer to the injection point. Other characteristics are given on the picture.

Global spray

Local spray

5 to 9 spray nozzles can be used with different
characteristics in terms of droplet size and in terms ofwater flow:• Large droplet size
• Small droplet size

One single nozzle is used:• Large droplet size

Characteristics of powders injected to simulate the aerosols:• For laser cutting: 0.4 µm (single mode distribution)• For wheel grinder: 0.5 µm - 5 µm (bimodal size distribution)
47

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS[1] – Dust dispersion mitigation by spray scrubbing
2 – Tests in TOSQAN facility with simulated aerosols
2.3 – Simulation of laser cutting with global spray (big droplets) and local spray
Test scenario consists in 3 phases for the laser cutting operation. Large droplets size is used for the global spray.
• (1) Particle injection + Local spray on (= cutting operation starts with only local spray on)• (2) Particle injection + Local/Global sprays (= cutting operation with both strategies of spray scrubbing on)• (3) Particle injection stopped + Local/Global sprays (= cutting operation is stopped but sprays are still on to collect the remaining particles)
The graphic below shows the evolution of concentration in number of particles inside TOSQAN vessel:
Laser cutting simulation

(1)

(2)
(3)
Removal rate = 2.2.10-3 s-1

DF=(C0-Ct=1800s)/C0=0.91
48

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS[1] – Dust dispersion mitigation by spray scrubbing
2 – Tests in TOSQAN facility with simulated aerosols
2.4 – Simulation of laser cutting with global spray (small droplets) and local spray
Test scenario consists in 3 phases for the laser cutting operation. Small droplets size is used for the global spray.
• (1) Particle injection + Local spray on (= processing operation starts with only local spray on)• (2) Particle injection only (= processing operation with spraying systems off) showing an increase of particle concentration• (3) Particle injection stopped + Global sprays (= cutting operation is stopped and global spray is started again)
The graphic below shows the evolution of concentration in number of particles inside TOSQAN vessel:
Laser simulation
No sprays

Local spray inj.

1

DF=(C0-Ct=1800s)/C0=0.93

2

3

49

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS[1] – Dust dispersion mitigation by spray scrubbing
2 – Tests in TOSQAN facility with simulated aerosols
2.5 – Conclusions on local/global spray scrubbing efficiencies•

During particle generation (cutting phase), local spray is very efficient to mitigate aerosol dispersion and to confine
particles in the lower part of the vessel which decrease the mean airborne particle concentration in the vessel•

Global spray activation in addition to local spray during the cutting phase does not bring a significant improvement oncollection efficiency•

Influence of global sprays is similar for particles generation representative of laser and mechanical cuttings with higher
efficiency obtained for highest water mass flow rates•

The mitigation strategy could be based on the activation of the Local spray during cutting phase and on the activationof the Global spray at the end of the cutting phase to clean the gas volume above the local spray area•

The use of fine droplets for global spray out of the cutting phase (no gas injection inducing airflow in the vessel) allows
to save drastically water for mitigation systems by spray•

Even if sprays systems do not reach efficiency close to 100%, they reduce strongly the dispersion of aerosols comparedto the case of simple sedimentation.

50

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS[1] – Dust dispersion mitigation by spray scrubbing
3 – Assessment of spray efficiency for laser cutting• Two sets of tests have been realized in DELIA facility: first set of tests in October 2019,the second set of tests in November 2020
• Objectives of the tests were to assess the efficiency of spray scrubbing strategy withlaser cutting:• First set of tests: tests of two different spraying nozzles and different spraying configurationsin DELIA facility (number of nozzles, from 1 to 12 spraying nozzles used in the same time).
Assessment of collection efficiency on cast fused Zirconia blocks, fuel debris simulants andstainless steel for different laser cutting configurations (in air emerging cut and nonemerging cut, underwater)• Second set of tests: tests of local spraying strategy on cast fused Zirconia blocks and fueldebris simulants

1

Two different spraying nozzle used during the first set of tests. The
one on the picture in the right has a larger spraying cone

2

3

4

View of DELIA facility. The bottom figure shows the implementation of
the laser cutting head and the 12 spraying nozzles (4 ramps of 3
nozzles). It is possible to use 1 to 12 spraying nozzles

51

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS[1] – Dust dispersion mitigation by spray scrubbing
3 – Assessment of spray efficiency for laser cutting
Efficiency of spraying systems are determined by comparing the airborne particles concentrations in the aerosols analysis line (same cutting isrealized successively with and without spray).
Results:
Implementation of devices:

Comparison of aerodynamical without spray (left) and with spray (right): spray tends toincrease the mean diameter of generated particles

Global spraying system (left) vs local spraying
system (right).

For every configuration tested, results show a decrease of airborne particles release: depending whether concentrations are measured in massor in number, the decrease is between 25% to 70%. Spraying system is more efficient with larger particles. Also, it has an influence on the
aerodynamical diameter of the particles: the median diameter increases, which is beneficial for filtering systems. Results are similar whatever
the spray strategy (number of nozzles, local or global strategy).
52

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS[2] – Advancement of local collection during laser cutting
1 – Improvement of local collection devices
Objective: Collect particles as close as possible of the cutting point while lowering the deposition of molten material inside the collection heads
in order to improve their lifetime on site and while ensuring that the aerosols collection efficiency is not altered (ratio above 90% of collected
airborne particles in the range [0.01µm; 1 µm]).
Note: The efficiency of local collection devices were already proven in the previous project. The current project aims at developing first
operational prototypes
Laser head

Aerosols, dust and moltenmaterial projections

ELC-A* collection head
Illustration for an application on site of laser cutting in air

Illustration: cutting an element (with or without fuel debris) creates
not only aerosols but also molten material projections

Progress during the project:
Start with
prototypes of
FY2018Work for the improvement ofsystems:- Essential tests for theincrease of collection
heads lifetime andgeometry optimization- Aeraulic studies*: ELC-A stands for Emerging Laser Cutting in Air

Tests in DELIA facility inorder to assess airborne
particles collection
efficiency on
representative materialWork on applicability:- Tests with robotic arm- Studies of remote
operations,maintainability,
operability, safety, etc.
53

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS[2] – Advancement of local collection during laser cutting
1 – Improvement of local collection devices
Essential tests to improve lifetime of collection heads:• Essential tests have been realized on simplified collection devices. Different materials have been tested in order to lower the molten material
deposition. Results proved to be efficient for the duration of the tests that have been held.

Work on aeraulics• It is important to work on aeraulics in order to ensure that there is no point of retention. Also, it is important to ensure that airborne particles
are sucked into the exhaust. Essentials tests helped with the design.
Design and manufacturing of prototypes• Design is based following essential tests and simulation work
• Design integrates the following functions:• Capability to be mounted remotely on the same laser cutting head
• Be fitted with mechanical interface for the robotic arm• Be able to be adapted to different shapes to be cut
54DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS[2] – Advancement of local collection during laser cutting
2 – Collection efficiency and operability tests
Collection tests in DELIA facility with laser cutting on representative material:
Previous work prove the collection system to be very efficient (over 90% of very thin airborne particles generated by laser cutting collected).
Therefore, the goal was to measure the collection efficiency with representative material for the two laser cutting configurations (emerging andnon-emerging).
Collection efficiency tests are realized in DELIA facility. The measurements concern the airborne particles concentrations, in number and in mass:
more precisely, measurements are realized in the collection line (measurement of particles collected) and in the extraction and sampling line
(measurement of airborne particles that are dispersed).

Reminder: NELC-A = Non-Emerging Laser Cutting in Air, ELC-A = Emerging Laser Cutting in Air

55

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS[2] – Advancement of local collection during laser cutting
2 – Collection efficiency and operability tests
Methodology of collection efficiency measurement:
Means of measurements:• Concentration number: Pegasor in therange [0.01 µm – 3 µm]• Mass measured on filters in the range[0.01 µm – 10 µm]

Airborne particles are monitored in 3 locations in order to measure the fractions that are :1. Collected by the collection head (ELC-A or NELC-A depending on the configuration tested),
2. Sucked into DELIA’s extraction line (that represents the fraction of dispersed aerosols) and3. Inside DELIA’s vessel (that represents the “ambiant” particles)

The collection efficiency is determined by the ratio:𝐄𝐟𝐟𝐢𝐜𝐢𝐞𝐧𝐜𝐲 = 𝟏 −Collection
Extraction
Ambiant

𝑨𝒆𝒓𝒐𝒔𝒐𝒍𝒔 𝑪𝒐𝒏𝒄𝒆𝒏𝒕𝒓𝒂𝒕𝒊𝒐𝒏𝑬𝒙𝒕𝒓𝒂𝒄𝒕𝒊𝒐𝒏
𝑨𝒆𝒓𝒐𝒔𝒐𝒍𝒔 𝑪𝒐𝒏𝒄𝒆𝒏𝒕𝒓𝒂𝒕𝒊𝒐𝒏 𝑪𝒐𝒍𝒍𝒆𝒄𝒕𝒊𝒐𝒏

56

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4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS[2] – Advancement of local collection during laser cutting
2 – Collection efficiency and operability tests• ELC-A configuration:
Tests have been performed to assess collection efficiencies when cutting a tube, a tube filled with cast fused Zirconia block, a tube with a tube
inside. Tests with collection head alone and collection associated to spraying system have been realized.

All configurations gave high collection efficiency rates (above ≈ 93% when considering number concentrations and around 85% when
considering mass concentrations). Coating of collection head proved to be efficient during these tests (few deposition that is easy to remove).
• NELC-A configuration:
Tests have been realized with fuel debris simulants and cast fused Zirconia blocks to be representative of material at the bottom of thepedestal.

57

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4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS[2] – Advancement of local collection during laser cutting
3 – Local collection and spray scrubbing with laser cutting
Tests have been performed to assess collection efficiencies when cutting a tube, a tube filled with cast fused Zirconia block, a tube with a tube
inside for ELC-configuration. Tests with collection head alone and collection associated to spraying system have been realized.
For NELC-A configuration, tests have been realized on cast fused Zirconia blocks, cast fused Zirconia blocks implemented in such a way that they
formed “stairs” geometry and on two surfaces of a same block of fuel debris simulant (one plane surface, one uneven surface).
The goal of the tests is to measure the efficiency of the collection system with representative geometries.
Cutting/Local collection
configuration

ELC-A

NELC-ASpecimen test

Zirconia
block

Stainless steel pipe

Zirconia block“stairs”

Simulant VF10 –Plane surface

Simulant VF10 –Uneven surface

Spray scrubbing (local spray – 1
nozzle)Spray off

Spray
off

Spray
on

Spray
off

Spray
on

Spray
off

Spray
on

Spray
off

Spray
on

Spray
off

Spray
on

Average number concentration
efficiency of collection line

97%

95%

96.5%

90.5%

92.5%

85%

-

87%

88%

73.5%

-

Average mass concentration
efficiency of the collection line

96.5%

84%

85%

81%

82.5%

63%

-

81%

83%

54.5%

-

Zirconia block• Efficiency rate is high. Mass concentration efficiency is a bit lower for tests on tubes than for cast fused Zirconia blocks  due to the nonflat surface of the tubes as opposed to zirconia blocks.
• Spraying systems has a positive impact on the aerosols collection:• It induces a slight increase of collection efficiency in the collection line
• Both concentration number of aerosols collected and dispersed (extraction) are lowered58

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS[2] – Advancement of local collection during laser cutting
3 – Local collection and spray scrubbing with laser cutting
Lifetime assessment: NELC-A collection head
During the collection efficiency tests with the collection head NELC-A, first assessment of lifetime could have been realized.
70 cuts have been carried out with the NELC-A collection head on different samples (cast fused zirconia, fuel debris Ex-vessel or In-Vessel)
70 cuts ≈ 10 m cutting length
Deposits have been observed on the head during the cutting of fuel debris simulant samples but have been mostly washed out thanks to the useof sprayConclusions••••

Collection efficiency rates due to the collection heads remain high on representative materials
Collection efficiency in NELC-A configuration is dependent on the distance between the collection head and the material that is cut
Collection heads are more efficient on very thin particles, a little less with bigger particles (over a few microns)
Sprays have a slight impact on the collection efficiencies rates of the NELC-A and ELC-A collection heads but they lower the aerosol
concentration in the extraction line as well as in DELIA’s vessel ambiance. Spray collects about 30% of airborne particles generated
 Spray scrubbing system collect aerosols, for one part before the collection heads, and also in the vessel: the fraction of dispersed aerosols
is lowered• Spray system is more efficient on bigger particles compared to the thin ones
Collection heads and spraying systems are complementary: the association of the two systems improve the collection efficiency rates andlower the total quantity of airborne particles that go to the different systems (collection, extraction)

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4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS[3] – Extrapolation of results – Numerical simulations (CFD) in PCV
1 – Strategies for aerosols collection and dispersion in PCV global geometry
Objective:
The main objective of CFD calculations in the PCV* geometry is to evaluate strategies of spray systems implementation
during and between cutting phases. CFD calculations can help for the design and implementation of the best strategies foraerosol removal.
Methodology:• Different scenarios of spray activation (local and global) allowing to limit and reduce the aerosol dispersion andaccumulation in PCV are simulated as in the experimental approach with TOSQAN tests. Input data for the
calculations come from the results of experiments of dust and fume characterization. Output data is the particle massconcentration in the PCV.
•

Results of the different calculations are compared. Therefore it is possible to assess the efficiency of each strategy andoptimize the solution to be implemented on site. These scenarios are simulated by CFD code and compared between
them in order to optimize the collection and the contamination release•

Different options are considered for these scenario depending on their collection efficiency primarily, but also on
their complementarity: Local collection
 Local spray collection
 Global spray collection
 Each of them may be activated on demand* PCV = Primary Vessel Containment60

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS[3] – Extrapolation of results – Numerical simulations (CFD) in PCV
2 – Modelling description
The two figures present the geometry that has been modelled (pedestal with CRD and clutter) and the characteristics of the dust
collection devices: this scenario considers fuel debris processing at the bottom of the pedestal with laser cutting in NELC-A
configuration.
 3 dust collection systems are implemented: local extraction (= collection head), local spray and global spray.
• Complete geometry of pedestal with CRD and clutter• Deposit on the ground more representative of melt fuel debris pile

NELC configuration for
consideration in this scenario:
fuel debris is processed with laser
cutting and NELC-A collection
head is implemented

1 spray bar with 8 nozzles and large
angle: it represents a global spray
configuration, covering of large
area at the bottom of the pedestal•

2 local spray nozzles with small angle are implemented close to theNELC-A collection head61

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4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS[3] – Extrapolation of results – Numerical simulations (CFD) in PCV
3 – Scenarios description

The scenario consists in alterning the phases of cutting and non-cutting:•During the first phase, laser cutting produces aerosols. Part of these aerosols are collected (by the local extraction or by the sprays), and thenon-collected aerosols will accumulate in the PCV•
During the second phase, the concentration of accumulated aerosols will decrease by collection (spray and extraction)

C0

For this scenario, a cutting time of 10 min isconsidered and the non cutting time has to beevaluated depending of the concentration time
evolution or Decontamination Factor (DF)

DF=(C0-Ct)/C0

The challenge is to optimize the phases of the
scenario in order to limit the aerosol accumulation in
the PCV and to stay always below a threshold todefine62

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4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS[3] – Extrapolation of results – Numerical simulations (CFD) in PCV
4 – Calculation results & interpretation

The figure below shows the fraction of particles that is collected by the local extraction (=NELC-A collection head, in blue), the fraction that iscollected by the spray scrubbing systems (in green), the fraction of particles that are deposited and the fraction of aerosols that remains noncollected (thus dispersed, in yellow), for two PSD from two cutting devices (Laser and Core Boring)
Laser – Ex-vessel

Localcollection

 Best extraction efficiency for smallest particles.
Local extraction is more efficient with small particles

Core boring – Ex-vessel

Localcollection

 Best spray efficiency for biggest particles
Spray scrubbing is more efficient with bigger particles

It may be noticed that the non collected fraction is overvalued because the particle
collection by the wall liquid film is not implemented in the model63

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS[3] – Extrapolation of results – Numerical simulations (CFD) in PCV
5 – Conclusion & prospects
 The scenario studied here highlights the very good efficiency of the coupling of collection means(extraction, local and global spray) according to the experimental data acquired on DELIA and TOSQAN
facilities
 Whatever the size distribution of emitted particles by the cutting devices, the collection means are
efficient and only a few amount of particles are not collected thanks to the addition of the mitigationmeans
 This scenario highlights also the difficulty to collect small particles (0.1 µm) regardless of the cutting
device or the mitigation means used because it is inherent to this particle size due to their low
collection efficiency by droplets Even with efficient collection devices, a fraction of small particles will inevitably accumulate inside the
PCV and will need to be removed / treated To improve the removal of small particles, it can be benefic to increase the extraction volume flowrate This can be done with a local extraction device or by using the global extraction and ventilation
system of the PCV64

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS[4] – Operability tests of local collection system
Presentation of the tests
Tests have been realized in a specific cell with a remote controlled arm in order to assess the operability of the collection
system. Cutting tests have been realized on materials representative of inner parts of the PCV (gratings, tubes, beams).

These tests prove that the prototypes of collection devices are capable of working in real cutting conditions (geometrical).

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DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS[5] – Dust extraction system
1 – Design of the dust extraction system• Development of a system able to transportand filter particles emitted during laser
cutting operations and collected by thecollection head. Its extension to mechanicaltools is also assessed.
• This design needs to take into account onsite conditions and constraint functions asradioactivity, criticality, humidity, remotely
operated, fire risk,…

CUTTING HEAD

COLLECTIONHEADSPRELIMINARY
FILTRATIONFINE
FILTRATION

Collection line: hoses, pipes andfiltering devices

FUEL DEBRISCHALLENGES FOR DUST EXTRACTION SYSTEMPRELIMINARY FILTRATION(SEPERATION SIZE 10 µm)

TRANSPORT OF PARTICLES(DUST AND AEROSOLS)






Retention of chips
Deposition
Pressure loss
Incandescentparticles
Flexibility







Separation size
Dust collection by aremote controlled arm
Pressure loss
Volume size
Constraints ofimplementation

Clogging
Side waste (used filter
media)
Dust and filter media
collection by a remotecontrolled arm
Resistance to radiation

Scope of thedevelopment

Limit of thedevelopment

EXTERNAL PROJECTFINE FILTRATIONVACUUMPUMP

VACUUM PUMP

FINAL FILTRATIONBEFORE EXHAUST

MaintenanceResistance toradiation
Constraints ofimplementation

To be studied outof the frame ofdust collection
development
project

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4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS[5] – Dust extraction system
1 – Design of the dust extraction system

VACUUM PUMP
COLLECTION HEADSFLEXIBLE HOSEPRELIMINARY

 FINE FILTRATIONFILTRATIONREF.

PRESENTATION OF MAIN EQUIPMENT

LIST OF DATA COLLECTED DURING FY2020

The collection head, placed near the cutting area, collects the particles
produced during fuel debris processing operations.

-Collection efficiency with or without spray-scrubbing-

Operability and lifetimeA flexible stainless steel hose is used to transport the particles while
maintaining the levels of mobility of the remotely operated arm.

-

Pressure drop and transportation efficiency-

Resistance to incandescent particles



The cyclonic filter (preliminary filtration) protects the pulse-jet filter andthe vacuum pump from incandescent particles and collects the drossand chips.

-

Pressure drop and filtration efficiency-

Mass collected during laser cutting operations



The fine filtration system composed of stainless steel cartridges and aself-cleaning device using compressed air.

-Self-cleaning efficiency in laboratory conditions-

Filtration efficiency, self-cleaning efficiency and mass filtered during laser cutting
operations

The vacuum pump creates a negative pressure inside the line in order totransport the particles collected.

-

Transportation efficiency

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4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS[5] – Dust extraction system
1 – Design of the dust extraction system
CHALLENGES FOR FLEXIBLE HOSESFLEXIBLE HOSES

 Retention of chips
 Deposition
 Pressure loss Incandescent particles
 Flexibility

Flexible hoses are needed to keep the degrees of mobility of the remotely operated arm.
Studies and tests have been carried out in order to find a flexible capable of meeting the challenges
imposed by on-site and operating conditions.

PRELIMINARY
FILTRATIONFLEXIBLE
HOSES

FINE
FILTRATIONVACUUM
PUMP

Two important parameters to meet the challenges:
 Air velocity inside: need to be superior to particles sedimentation rate. It induces the flow rate
and the inside diameter of hoses
 Composition of the flexible hoses: structure (smooth interior or not) and material.
CHALLENGES FOR PRELIMINARY
FILTRATIONPRELIMINARY FILTRATION: THE CYCLONIC FILTER
The cyclonic filter has been designed in order to reach the best trade-off between
segregation rate, pressure drop and dimensions.

 Separation size
 Dust collection by a remotecontrolled arm
 Pressure loss Volume size Constraints of implementation

The main role of this device is to protect the rest of the line from incandescentparticles and to collect the dross and chips in order to slow down the fine filtration
system clogging.

PRELIMINARY
FILTRATIONFINE
FILTRATIONVACUUMPUMP

FLEXIBLE
HOSES

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4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS[5] – Dust extraction system
1 – Design of the dust extraction system
CHALLENGES FOR FINE FILTRATIONFINE FILTRATION : CHOICE OF THE TECHNOLOGIES Clogging
 Side waste (used filter media)
 Dust and filter media collection by aremote controlled arm
 Resistance to radiation

Different technologies and designs have been under study for the filtration of thinnest
particles. For each technology, input data about laser cutting (characteristics of dust andaerosols), expected efficiencies and on-site constraints were taken into account. It has been
decided to manufacture a self-cleaning metallic filter prototype for the tests.

FINE
PRELIMINARY
FILTRATION FILTRATIONVACUUMPUMP

FLEXIBLE
HOSES

INSTRUMENTATION USED FOR TESTS IN ONET TECHNOLOGIES PREMISES AND IN DELIA VESSELOBJECTIVES
Study of the transport efficiency
Data collection on preliminary filtration
Data collection on fine filtration (filtration
efficiency, clogging, self-cleaning efficiency)
Data collection to extrapolate for the on-site
systemTYPE OF MEASUREMENTS-

Measurement of masses of particles injected at the entrance of the line and the ones that are collected inside thecyclonic filter’s can & visual observation of potential damages due to incandescent particles on flexible hoses-

Pressure drop-

Mass of particles collected inside the cyclonic filter’s can-

Mass concentrations of aerosols upstream and downstream of the filter & aerosols size distribution according to
the aerodynamic diameter-

Pressure drop-

Temperature and humidity in the room and inside pipes with and without the spray scrubbing69

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4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS[5] – Dust extraction system
2 – Preliminary tests
2.1 CHARACTERIZATION OF TRANSPORTATION WITH THE DUST EXTRACTION SYSTEM
Tests were held in Onet Technologies premises. The dust extraction system has been implemented in order to be representative of aconfiguration on site.
The tests aimed to determine the characteristics of the dust
extraction system (pressure drop) and verify the capability of thesystem to recover dust and chips in representative conditions.



Dust extraction system set-up to
represent the bending of the line dueto the remotely operated armCollection head with a kerf and laser head mock-up to inject dust andchips with an airflow rate representative of the one occurring duringlaser cutting operation

Transportation efficiency tests have been done with alumina powder (), titanium and iron () granules and chips of zirconia coming fromprevious laser cuts (). The transportation tests concern the first part of the dust extraction system from the collection head to the cyclonic filter
in which particles are recovered (in orange in the figure of the right, flexible hoses are made in stainless steel). The transportation efficiency goesfrom 95 % to 100 % depending on the particles.
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4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS[5] – Dust extraction system
2 – Preliminary tests
2.2 PRELIMINARY TESTS OF FILTRATION DEVICES – CYCLONIC FILTER
Cyclonic filter has been designed in order to reach the best trade-off between segregation rate, pressure drop and overall dimensions. Its mainrole is to protect the rest of the line from incandescent particles, collect dross and chips that have entered the dust extraction system during
cutting operations and filter smaller particles in order to slow down the clogging of the fine filtration system.
Preliminary tests have been realized in order to qualify the cyclonic filter and establish its performances in lab conditions.

Example of mass concentration measurements before and after the cyclonic filter with polydispersed aerosols with different mean aerodynamical diameters (3.1 µm and 4.7µm)

Conclusions of the qualification tests in lab facilities:• The pressure drop of the cyclonic filter is around 750 Pa for a 200 m3.h-1 airflow• In these conditions, tests results are that more than 99% (in mass) of particles with an aerodynamic diameter greater than 2 µm are collected71DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS[5] – Dust extraction system
2 – Preliminary tests
2.3 PRELIMINARY TESTS OF FILTRATION DEVICES – SELF-CLEANING METALLIC HEPA FILTER
The fine filtration level is a HEPA filter composed of a vessel containing stainless steel cartridges (filtering media) and self-cleaning device.
In order to optimize the design of the filter, preliminary tests have been conducted in lab facility
on samples. These samples were different stainless steel grid that can compose the cartridge.

The vessel cancontain one ormoremetallic
cartridges

Drawing of prototype

Two compositions of cartridges (number of layers and type of mesh) have been determined to
be promising following these tests (Configuration 1 with 2 layers of very thin mesh andConfiguration 2 with 1 layer of ME mesh and 1 very thin mesh)

The self-cleaning filter has also been qualified on a specific test bench with a calibrated powder to be representative of aerosols produced
during laser cutting operations.
72DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS[5] – Dust extraction system
3 – Test of the dust extraction system with core boring
Test conditions
Two tests were done in order to carry out preliminary tests on the dust extraction system in the presence of core boring operation (same as theone used in [2]-4). The set-up is presented below. For the first one, the flexible stainless steel hose was fixed to the core drill near the cutter andthe air flow rate of the line was adjusted to 200 m3.h-1 to extract the dust. For the second trial, no extraction was in operation.
The cut were done on cast fused zirconia blocks and the core drill had the following settings: cutter diameter 52 mm (diamond core for dry coring),
cutting speed 900 rpm, micropercussion on (improved dust evacuation), lowering control cylinder pressure 1 bar

Results
The cast fused Zirconia block is almost clean after thetrial with extraction (on the left), which is not the casewithout extraction (on the right).

View of particles collected by thecyclonic filter during the core boring
operation.

Complementary trials would be needed in order to calculate aratio between the particles produced and the particles collected.
However these first results are promising for a use of the dust
extraction system with mechanical cutting.

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4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS[5] – Dust extraction system
4 – Test of the dust extraction system with laser cutting
TESTS OF DUST EXTRACTION SYSTEM WITH LASER CUTTING IN DELIA FACILITY

The tests aimed to verify the performances of the dust extraction system with laser cutting: the performance of the self-cleaning HEPA filter, theresistance to incandescent particles of the flexible hose, the mass of particles collected.
In order to do so, collection system is implemented to the laser cutting head: dust and aerosols are collected into the collection line. Number
and mass concentrations of aerosols are monitored inside the collection line so it is possible to quantify the particles that enter the collection
system. Monitoring is realized before and after the self-cleaning filter: number and mass concentrations in order to verify the filtering
performance and the evolution of the pressure drop. It is therefore possible to monitor the evolution of the pressure drop with the evolution ofaerosols concentration.
MAIN RESULTS OF THE TESTS• Flexible hoses are resistant to incandescent particles.
• For both tested cartridges, filtering efficiency of pulse jet filter is above 99.99%.
• The cartridge Configuration 2 has a slower increase of the aeraulic resistance and so a longer life time. The self-cleaning cycles give also a
better regeneration for this cartridge.
• Due to the layer of filter medium, which has a coarser mesh size, theduration of the depth filtration is increased and the adhesion surfaces forthe particles and therefore the adhesion forces are reduced. This result is
consistent with tests in lab facility on filter media samples.
• Nevertheless, self-cleaning of the cartridge, for laser cutting, needs to be
optimized.

Configuration 1

Configuration 2

Mass of zirconia aerosols filtered
to reach 50 mbar for the first time

About 1.89 g

About 2.0 g

ΔP after 1st cleaning

46.6 mbar

25 mbarΔP after 2nd cleaning

48 mbar

38 mbar74

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4. FINAL OUTCOMESITEM #2 - DUST COLLECTION SYSTEMS[5] – Dust extraction system
5 – Conclusions
MASS BALANCE FOR A ONE-METER CUT
Cutting conditions:• Laser head power: 7.5 kW• Air flow rate on the transportation and filtration line: 200 m³.h-1(*): Mass estimated from the accumulated mass of 1 cartridge with a flow rate of 16.7 m³.h-1
and transposed for a flow rate of 200 m³.h-1 (12 cartridges)

Zirconia

In-Vessel VF05

Average cutting depth

35/40 mm

50 mm

Mass of particles collectedby the cyclonic filter

77.6 g60.1 gMass of particles filteredby the fine filtration*

8.3 g

18.9 gConclusions• The dust extraction system prove to be efficient for particles transportation (particles generated by laser cutting)• The flexible stainless steel hose chosen is resistant to incandescent particles and easy to handle• The cyclonic filter enables to have higher filtration efficiency with lower pressure drop, compared to previous ones, while
having a reasonable size and weight to be handling by a remotely operated arm.
• The self-cleaning filter has a good filtration efficiency. The lifetime of the cartridge has been increased by a new combinationof stainless steel grid. Further studies and tests are expected in order to:• Improve the self-cleaning performances with laser cutting. Several options could be studied to do so in the future.
• Validate the functioning of the complete filtration line when high rates of humidity are involved.

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4. FINAL OUTCOMESITEM #3 – APPLICATION ON SITE

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4. FINAL OUTCOMESITEM #3 – APPLICATION ON SITE
3. APPLICATION ON SITE
Objectives•

Assess the applicability of the system under development

Tasks implemented in the frame of item 3[1] Study on applicability
1: Overview of the global system
2: Dust collection head
3: Filtration system (tentative)
4: Filtration system (tentative) implementation
5: Spraying system
6: Cutting scenarios and maintenance operations[2] Safety analysis assessment
1: General safety analysis
2: Safety analysis applied to the dust extraction system with laser

77

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4. FINAL OUTCOMESITEM #3 – APPLICATION ON SITE
[1] – Study on applicability
1 – Overview of the global system
The global laser cutting system is divided in four
different parts :Spraying system equipment• The laser head
• The dust collection head:o A Collection head for Emerging Laser Cutting in
Air (ELC-A)

o A Collection head for
Cutting in Air (NELC-A)

Non Emerging Laser• The filtration system including:o A cyclonic prefiltration
Filtration system equipmento A fine filter (Pulsejet filter)

Flexibleo A vacuum pump

Laser cutting head

• The spraying system including:

Dust collection heado A global systemo A local system

Spraying system equipment(global spray)

Spray nozzles(local spray)78

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4. FINAL OUTCOMESITEM #3 – APPLICATION ON SITE
[1] – Study on applicability
2 – Irradiation performance of the laser cutting system components
The system is developed to be highly resilient to irradiation. The summary of irradiating performances for each material is presented in thetable on the right.

All components that should be in high ambient dose rate
have a performance higher than 107 Gy except for seals
and electronic components.
The degradation of seals could leads to minor leak in thesystem after 106 Gy. Considering the low pressure in thesystem and the probability to replace the component
including seals before to reach 106 Gy, the risk is very low
and without consequences.
For electronic components, the countermeasure is to put
them away from the high ambient dose rate (outside thePrimary Containment Vessel) and to facilitate thereplacement of equipment.

Material

Components

Lifetime (Gy)

Wire

Pulsejet108

PUR (polyurethane)

Flexible hose107-108

Motor

Turbine

5 x107

Fiberglass

Stainless steel flexible hose (seals)

107

Connectors

Pulsejet

107

Seals

Pulsejet, cyclonic filter,..

106 - 107

Electronic components

Turbine and control pannel andsensor102 - 103

Source : « Résistance aux rayonnements ionisants des matériaux » and « Compilation ofradiation damage test data », CERN

In case of failure, replacement of each component is easy and quick done by the robotic arm.

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4. FINAL OUTCOMESITEM #3 – APPLICATION ON SITE
[1] – Study on applicability
3 – Dust collection headCollection heads are designed to be easily and quickly set up on the laser head. The ease of change of thesetools allows to store them in a small tool rack inside the PCV. Collection heads can be designed for any fueldebris processing tools
To increase the durability of collection heads, they are coated with a non adhesive material

4 – Filtration system (tentative)
The filtration system is composed by a cyclonic filter, a self-cleaning filter and a vacuum pump.
The implementation of the filtration system takes into account the priority to cutting operations:• The on-site filtration system should be composed by one cyclonic filter and three fine
filtration filters. Two of them operate in series and the third one is used in replacement of oneof the two others (in case of problems or maintenance). Number of filters shall be determinedwith specific studies• Sets of cartridges for the fine filtration system could be integrated into the rack for
replacement whenclogging appears.
These features should be sufficient to allow a full cutting step without changing filters.

Dust filtered by the cyclonic filter and self-cleaning system and full cartridges of fine filtration system can be put into cans designed to becompatible with unit cans and storage canisters.
All filtration components are gathered in a specific rack and they are easily manipulated by the robotic arm.
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4. FINAL OUTCOMESITEM #3 – APPLICATION ON SITE
[1] – Study on applicability
5 – Filtration system (tentative) implementation
Two implementations are considered for the side access :• A rack with filtration component inside the PCV and compressed air tank and vacuum pump outside the PCV. The arm is used to do all filter
replacement operations (left side).
• All components outside the PCV. Remote controlled equipment is needed to do filter replacement operations and a specific conveyor isneeded to evacuate cans fill of dust (right side).

CaptionCompressed
air tank
Vacuum pump
Ventilation
exhaust
Filtration
system81

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #3 – APPLICATION ON SITE
[1] – Study on applicability
5 – Filtration system (tentative) implementation
Two implementations are considered for the top access :• A rack with filtration component on the top of the moving platform and compressed air tank and vacuum pump on the top of the PCV. The
arm is used to do all filter replacement operations (left side).
• All components on the top of the PCV. The arm can be used to do filter replacement operations but remote controlled equipment could be
used to not lift up the platform (right side).
Filtration system

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4. FINAL OUTCOMESITEM #3 – APPLICATION ON SITE
[1] – Study on applicability
6 – Spraying system
The spraying system is divided in two different systems:• The global system used to cover a maximal volume of the pedestal volume. The nozzles can be disposed on a spreader on the robotic arm.
Several nozzles spread water toward the bottom of the pedestal. They cover a large surface . Others kind of nozzles create spread water
toward the top in order to create a fog.
• The local system includes several nozzles disposed on the laser cutting head.
In addition, a water tank is proposed to provide half an hour of spray scrubbing in case of loss of water supply.

Spread toward the top
Spread toward the bottom

Water tank and spray scrubbing
equipment rack
Global spray scrubbing83

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4. FINAL OUTCOMESITEM #3 – APPLICATION ON SITE
[1] – Study on applicability
7 – Cutting scenario and maintenance operations
Past achievements• Cutting scenario for the lower part of the PCV including CRD cutting and fuel debris cutting in the pedestal.
• Cutting scenario for the upper part of the PCV including all identified component (from steam dryer to bottom of RPV)
• Analysis of the fuel debris retrieval method in the bottom of the pedestal (retrieval speed, aerosol production per hour)

Remainder of constraints take into account• Keep an atmosphere inside the PCV as clean as possible• Optimize the system to be adjustable and compatible with IRID’s deployment solutions• Optimize the system to have no maintenance during the cutting process (few hours)• Maintenance operations have to be fast and easily done with a remote controlled arm• Equipment weight inferior to 100 Kg and compatible with PCV robotic arm entrance• All components have to be compatible with storage canister size or they can be easily cut or dismantling84

DEVELOPMENT OF DUST COLLECTION SYSTEM FOR FUEL DEBRIS – PERFORMANCE REPORT – SUPPLEMENTARY BUDGET FY2018

4. FINAL OUTCOMESITEM #3 – APPLICATION ON SITE
[1] – Study on applicability
7 – Cutting scenario and maintenance operations
Study focused on operability and maintenance operations.
The rack of the filtration system is made to be assembling by the robotic arm and all components are easily catch by a clamp. To lower spreadcontamination, the size of cans that receive dust and filters from pulsejet are compatible with storage canister. There is no need to cut highly
contaminated waste for size reduction. Images below show handling operation of cans.

Tools (cutting tools, collection heads, suction tools) are disposed in a rack. Compatibility with existing cutting scenarios was checked.

Rack for side access

Rack for top access(under the plateform)

Changing tool operation

Changing tool operation

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4. FINAL OUTCOMESITEM #3 – APPLICATION ON SITE[2] – Safety analysis assessment
1 – General safety analysis
Definition of principle and safety functions:Two main functions were identified :• Contain and limit radioactive material in the PCV• Maintain subcriticality
Definition of general prevention measures and constraints
A Preliminary safety analysis has been made about the general laser cutting technology :Safety related events or operations

Risk(s) and potential
consequences
All activity

Suggested provisions
Any opening of a containment barrier should be compensatedby a reproduction of this barrier, as close as possible to theradioactive materials.

Activities on utilities
Loss of coolant for the laser source and/or the coupler

Optical fiber path

Automatic stop of the source if gaps identified on a
Laser source or coupler
temperature measure.
overheating, resulting in a risk
Inflammable materials in the surroundings of the fiber areof fire departure.
identified and relocated if necessary.
The path of the optical fiber is studied and labeled and/or
Damaging optical fiber,leading to the creation of a physically protected if necessary.
"hot spot" resulting in a risk Inflammable materials in the surroundings of the fiber areof fire departure.
identified and relocated if necessary.
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4. FINAL OUTCOMESITEM #3 – APPLICATION ON SITE[2] – Safety analysis assessment
1 – General safety analysis
Safety related events or operations

Risk(s) and potential
consequences
Preparation of tools, material, maintenance

Suggested provisions

The design of the safe zone for maintenance and evacuation of retrieveddebris/induced waste shall take into account human intervention according to thetechnical and physical options available for this area. For example, filters are clogged
quite quickly which means they have to be replaced on a regular basis.

Maintenance of the arm andcutting/collecting tools (replacement offilters…)

Human intervention on theequipment can be requested, Shielding and containment parameters are to be set according to:
implying a risk of internal
Dose rates in the area
exposure to radioactive
Contamination on the equipment
material and external exposure
The ALARA ("As Low AS Reasonably Achievable") approach
to radiations.

The type of extraction chosen (to the general HVAC system or in close cycle inside the
PCV)
Induced nuclear waste is limited to the minimum requested.

The rail passage into the PCV does not present containment requirements since
Breach of PCV containment
containment is assured by the safe zone.
Passage of the umbilical (power, fluids, etc.)
and release of aerosols outside
through the PCV
However aerosols collection is implemented as close as possible to the cutting
the PCV.
process.

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4. FINAL OUTCOMESITEM #3 – APPLICATION ON SITE[2] – Safety analysis assessment
1 – General safety analysis
Safety related eventsor operations

Risk(s) and potential consequences

Suggested provisions

Collect and cutting activities
Operations inside the control room
The laser beam is not effective unless triggered by the operator. If theSince the laser beam is very powerful and has a long range, an error in its operator stops moving for too long, a mechanism could automaticallyControl of thepiloting may result in cutting walls or structures that are important for detect it and stop the beam.
laser headsafety (walls of RPV). The end result could be a loss of containment of
Before the cutting operation, a double check shall be performed by aradioactive materials.
person who is not the operator.
Power delivered by the laser source shall be periodically checked.
Operations inside the PCV
Criticality event due to remaining fissionable radionuclides (U235, Pu239,
Geometry and mass of corium retrieved pieces adapted to thePu241, Cm244, Am 244…) in the corium and due the enveloping
operation to ensure non criticality.
moderating water.
Laser shot in stationary position implying damage on parts located
Shutdown of the laser after X seconds passed in stationary position.
behind the target.
“Safeguards” included in the operational software
Laser shot on prohibited/ weak area implying damage on parts, structure- Laser can shot only on authorized areaand equipment.
Cutting pieces of- Laser can shot during a limited duration in stationary position
fuel debris(in air) Fire due to the presence of ignition source (laser, heat,
The flexible collection system or cables (pipes…) materials should beincandescent particles…) and inflammable materials (Flexible collection
fire retardantsystem, flexible cables...).
A regulation system could be linked to the PCV exhaust ventilation.
Pressure increase inside the PCV due to laser air supply.
In case of a closed cycle collection system, the impact on the aeraulicof the PCV is to be studied.
Inert gas injected in the PCV is polluted by oxygen brought by the laser
Air is replaced by nitrogen for laser cutting.
cutting process, increasing the risk of fire departure.
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4. FINAL OUTCOMESITEM #3 – APPLICATION ON SITE[2] – Safety analysis assessment
1 – General safety analysis
Safety related
events oroperations

Risk(s) and potential consequences

Suggested provisions

Operations inside the PCV
Criticality is to be studied regarding foreseen geometry/compositionof the collection systems and dust spectra/composition.
Criticality event due to the contained fissionable material in theFilters are to be chosen adequately with the risk of criticality theycollection box and/or HEPA filter.
present. Especially, they must be sized to take into account thecriticality risk.
Collecting dust in
The flow rate and hoses path is to be implemented to limit
the collection box
accumulation.
and/or HEPA filter
Criticality event in hoses due to an accumulation of fissionable material. The hoses’ diameters are chosen so that in case of accumulation,
there is a guaranty of not reaching critical mass.
Control of dose rate along the hoses on a regular basis.
Too high quantity of particles collected in the pre-filter system resulting Prefilter system clogging is to be checked on a regular basis andin a leakage of radioactive materials
replaced accordingly.
The number (redundancy) and strength of provisions for this case are
to be adapted in the frame of the acceptable risk in the PCV and in theFall of an equipment resulting :frame of PCV ventilation systems. Especially, the necessity for aseismic behavior study of on-site installed equipment (aspersion
All operations
system, robotic arms...) should be reviewed.
- in suspending radioactive dust,
A video surveillance system is an example of provisions for detecting- in potentially modifying the corium structure (sub-critical in initial
the risk.
state).
Loss of functionality or integrity of equipment due to irradiation fluence Maintenance processes or design specifications should take these
All operations
or corrosion leading to a fall.
physical phenomena into account.
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4. FINAL OUTCOMESITEM #3 – APPLICATION ON SITE[2] – Safety analysis assessment
1 – General safety analysis
Safety related
events oroperations

Risk(s) and potential consequences

Suggested provisions

Operations inside the PCV
The number (redundancy) and strength of provisions for this case(redundancy, limitation) are to be adapted in the frame of the
Loss of functionality during underwater cutting resulting in an
acceptable risk in the PCV and in the frame of PCV ventilation systems.
accumulation of fumes in the PCV.
Set up of theA video surveillance system and/or measures of water flow rate areaspersion system
example of provisions for detecting the risk.
Fall of equipment/materials on the aspersion system from above.
Same as above.
Water level increase due to the spray system.
Spray regulation according to the global water level
Alarm or on low flow rate level inside the hoses.
Loss of collecting No collecting of dust and fumes implying a dispersion of radioactive
Laser power shutdown.
capability
material during in-air cutting activities.
The current state of the reactor being in an initial degraded mode, theaim is to not degrade even more this state.

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4. FINAL OUTCOMESITEM #3 – APPLICATION ON SITE[2] – Safety analysis assessment
2 – Safety analysis applied to the dust extraction system with laser
The following countermeasures and constraints do not include general safety measures about laser cutting technology
previously presented
Risk

OriginCutting operation

Radionuclides
Dispersion

Drop of load and shock on thefiltration system

Earthquake

Criticality

Countermeasures / Constraints• Use collection head and spray scrubbing system. The fraction of aerosols that remains non-collected
is about a few percent (see task 3.4)
• Provide a water tank to ensure water supply for half an hour in case of problem• Keep the full system of filtration in depression• Use an inert gas for outlet gas of the laser cutting head (N2 environment lower the radionuclides
dispersion)• After filtration, release the air inside the PCV to use the global ventilation
External measures :• The PCV global ventilation must take into account the air supply of the laser head
• Inert the PCV (N2 environment lower the radionuclides dispersion)• Protect cans that receive dust from shock and drop of load by using a rack and by disposing cansbelow filters.
• Stop cutting operations and reduce dispersion while cutting by using associated countermeasures.
• Use a rack to stabilize the filtration system and to protect cans receiving dust.

Fissile material in the fuel debris •(the critical mass is 46 kg)•

The size of each element of the system is limited to forbid an accumulation of 23 kg of dust
The cans used to receive dust is a unit can or a smaller can
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4. FINAL OUTCOMESITEM #3 – APPLICATION ON SITE[2] – Safety analysis assessment
2 – Safety analysis applied to the dust extraction system with laser
Risk

OriginFire

Cutting operation

Hydrogen explosion

Accumulation of fueldebris in the filtration
systemCountermeasures / Constraints•

Fire proof material for equipment in contact with sparks or incandescent particles :- Collection head in stainless steel- First part of the collection hose in stainless steel- Cyclonic filter in stainless steel- Pulsejet filter in stainless steel••

No volume that could lead to a gas retention in the filtration system
Limited the mass of fuel debris in the filtration system (especially in cans that receive dust)

92