2CNRS-ICARE, UPR 3021, 1C, avenue de la recherche scientifique, 45071 Orléans Cedex 2, France - SNETP
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Contribution of recent R&D
programs to hydrogen management
improvement
A. Bentaïb1, N. Chaumeix2
1 Institut de Radioprotection et de sûreté nucléaire, BP 17, 92262Fontenay Aux Roses, France
2CNRS-ICARE, UPR 3021, 1C, avenue de la recherche scientifique, 45071 Orléans Cedex 2, France
Severe accident and hydrogen explosion in NPP
Three Mile Island Nuclear Power Plant
Hydrogen explosion during
Fukushima accident
SNETP FORUM, TS1-Long Term Operation & Construction, Onine, February 3rd 2021 2/40
Hydrogen risk mitigation strategies
Strategy adopted for
Limiting oxygen concentration Using inert gas BWRs (Fukushima NPPs)
Limiting hydrogen concentration Ignition Strategy adopted for
both BWRs and LWRs
Recombination
Strategy adopted for
Dilution using French PWRs
large volume
SNETP FORUM, TS1-Long Term Operation & Construction, Onine, February 3rd 2021 3/40
H2 control system implementation
Distribution
Structure PARs
response operation
Combustion
SNETP FORUM, TS1-Long Term Operation & Construction, Onine, February 3rd 2021 4/40
Combustion
Flammable mixture conditions
Potential Ignition sources
Characterization of flame propagation
from early stage to accelerate regime
Perspectives:
Hydrogen monitoring system
development
Enhancement of SAMG
SNETP FORUM, TS1-Long Term Operation & Construction, Onine, February 3rd 2021 5/40
5/20
identification of flammable mixtures
H2/Air flammability limits – quiescent conditions, Spherical bomb method at ICARE CNRS
Volume= 56 L, i.d.= 476 mm No Ignition
Ignition
Pressure (bar)
Pressure (bar)
Time (s)
Time (s)
1.2
for LFL
high speed
of Ignition
camera
screen
distribution
0.8
knife Pin = 1bar; Tin = 296K
thermocouple tungsten
electrode Logistic Function
Ignition
Probability
mirror mirror
No Ignition
0.4 LFL(H2)
Probability
P=0.1
LFL(H2)
P=0.5
pin hole pressure sensor LFL(H2)
P=0.9
focus lens
white light 0
4 4.4 4.8
Hydrogen molar percent
K. N’Guessan, A. Commandini, M. Idir, J. Pavageau, T. Cuvillier, N. Chaumeix, Evaluation of flammability limits of H2/O2 mixtures in conditions relevant to nuclear waste
transportation: Pressure and nitrogen effects, ICDERS 2017, Paper 1032, 2017
SNETP FORUM, TS1-Long Term Operation & Construction, Onine, February 3rd 2021 6/40
H2/Air flammability limits – quiescent conditions
6% H2 8% H2 9% H2 10 % H2
35 ms
52 ms 31 ms 25 ms
104 ms 71 ms 153 ms 49 ms
156 ms 106 ms 400 ms 74 ms
208 ms 141 ms 1200 ms 98 ms
2000 ms
260 ms 176 ms 122 ms
Cheikhravat, H., Chaumeix, N. , Bentaib, A., Paillard, C.-E., Flammability limits of hydrogen-Air mixtures, Nuclear Technology 178 (1), 2012, p. 5-16
SNETP FORUM, TS1-Long Term Operation & Construction, Onine, February 3rd 2021 7/40
H2/Air/H2Ovap flammability limits – quiescent
conditions
0.40 H20 + 0.30H2
Pini = 0.987 bar
Tini = 100.0 °C
•
Incomplete Combustion •
0.50 H20 + 0.11H2
Pini = 0.987 bar
A
Tini = 101 °C
Cheikhravat, H., Chaumeix, N. , Bentaib, A., Paillard, C.-E., Flammability limits of hydrogen-Air mixtures, Nuclear Technology 178 (1), 2012, p. 5-16
SNETP FORUM, TS1-Long Term Operation & Construction, Onine, February 3rd 2021 8/40
Question :
" if there is a certain gas motion in the vessel
which can be represented by a given turbulence
level, will it significantly affect the lower
flammability limit?"
SNETP FORUM, TS1-Long Term Operation & Construction, Onine, February 3rd 2021 9/40
17/10/2019
Flammability limits-turbulent conditions
Spherical bomb method at ICARE-CNRS
Volume= 93 L
Tmax= 300 °C
Pmax= 200 bar
i.d.= 563 mm
∅ visualization= 200 mm
8 fans
2 pressure transducers (Kistler 601A&6001)
high speed
camera
Schlieren Visualization
screen
knife
thermocouple tungsten
electrode
mirror mirror
pin hole pressure sensor
focus lens
white light
10
SNETP FORUM, TS1-Long Term Operation & Construction, Onine, February 3rd 2021FLAMMABILITY LIMIT: initial turbulence effect
0.06
6
Ignition
No ignition
Overpressure (bar)
0.04
5.6
5.0 %
0.02
4.9 %
0
5.2
2
xH
-0.02
0 0.5 1
time (s)
1.5 2 2.5 4.8
4.4
of Ignition
for LFL
1
Distribution
0.75
Pini = 1 bar; Tini = 296 K 4
Probability
0.5 No ignition
Ignition
0 1 2 3
u' (m.s-1)
Probability
95% Confidence Interval
0.25
0 LFL increases linearly with the
4 4.4
Hydrogen molar percent
4.8
speed fluctuation
Goulier J., Chaumeix N., Meynet N. & Bentaïb A., Hydrogen Safety: Laminar and Turbulent Flame Speed of Spherical Flame in a Fanned-Stirred Closed Vessel, The
16th International Topical Meeting on Nuclear Reactor Thermal-hydraulics (NURETH-16), Chicago, Illinois, USA, 30 août au 4 septembre 2015
SNETP FORUM, TS1-Long Term Operation & Construction, Onine, February 3rd 2021 11/40Question :
“In case of spray actuation, could we ignite gas-
water droplets mixture and what could be the
effect of spray on flammability limit?”
SNETP FORUM, TS1-Long Term Operation & Construction, Onine, February 3rd 2021 12/40Spray flame interaction: Summary of PhD thesis
Could we ignite a gas-water droplet mixture ?
Step 1:
Flammability Limits of H2/air+ Mist of
liquid Water (droplets)
Step 2:
Initial non-combustible mixture of
H2/air/H2Ovap
Activation of Water Spray
Spark ignition activation
SNETP FORUM, TS1-Long Term Operation & Construction, Onine, February 3rd 2021 13/40
13 / 14Results step 1 : Influence of water mist on
flammability limits Injection of water in a dry H /Air mixture 2
Bi-fluid nozzle
T = 298 K
P = 1 bar Dmean = 5 µm
H. Cheikhravat, J. Goulier, A. Bentaib, N. Meynet, N. Chaumeix, C.-E. Paillard, Effects of water sprays on flame propagation in hydrogen/air/steam mixtures,
Proceedings of the Combustion Institute, Volume 35, Issue 3, 2015, Pages 2715-2722
SNETP FORUM, TS1-Long Term Operation & Construction, Onine, February 3rd 2021Results step 2 : Mixture made flammable
by water spray T = 383 K - P = 1 bar
XH2O = 0.55, XH2 = 0.15, Xair = 0.30
SMD = 75 µm
Domain of mixtures potentially
ignitable by cooling from the
spray
A
H. Cheikhravat, J. Goulier, A. Bentaib, N. Meynet, N. Chaumeix, C.-E. Paillard, Effects of water sprays on flame propagation in hydrogen/air/steam mixtures,
Proceedings of the Combustion Institute, Volume 35, Issue 3, 2015, Pages 2715-2722
SNETP FORUM, TS1-Long Term Operation & Construction, Onine, February 3rd 2021Flame propagation regimes
Flame acceleration Transition from Deflagration
(turbulence, instabilities…) to detonation regimes
Slow Deflagration Fast Deflagration Detonation
SNETP FORUM, TS1-Long Term Operation & Construction, Onine, February 3rd 2021 16/40TURBULENT COMBUSTION REGIME
Green : laminar
flames
Flame diameter
Ø = 120 mm
Blue : wrinkled
flamelets
Black : wrinkled
flames with
pockets
Red : thickened
wrinkled flames
GOULIER J., CHAUMEIX N., MEYNET N. & BENTAIB A., Hydrogen Safety: Laminar and Turbulent Flame Speed of Spherical Flame in a Fanned-Stirred Closed
Vessel, The 16th International Topical Meeting on Nuclear Reactor Thermal-hydraulics (NURETH-16), Chicago, Illinois, USA, 30 août au 4 septembre 2015
SNETP FORUM, TS1-Long Term Operation & Construction, Onine, February 3rd 2021 17/40On going Work
French National Program MITHYGENE
New Facility (8m high, 230 mm i.d.)
Tini = 20 – 150°C ; Pini = 1 to 3 bar
Pmax @ 20°C = 240 bar
Highly instrumented to investigate
• Flame speed, High speed Imaging
• Flow velocity induced by the flame (HS-PIV
• Effect of water vapor/spray
• Initial T & P relevant to severe accidents
SNETP FORUM, TS1-Long Term Operation & Construction, Onine, February 3rd 2021 18/40flame acceleration & flame-choc interaction
K Endwall
SD 26 PM27
SD 25 PM26
SD 24 PM25
K17 – 4.667 m K20 – 5.527 m K23 – 6.377 m
PM24
PM23
PM22
PM21
PM20
PM19
PM18
PM17
PM16
PM15
PM14
PM13
K11 – 2.977 m
PM12
PM11
PM10
Effect of initial temperature, Obstacle 9
2.48m
Obstacle 8 PM9
PM8
Obstacle 7 PM7
Effect of initial gas composition Obstacle 6
K5 – 1.277 m
Obstacle 5
PM6
Obstacle 4 PM5
Obstacle 3 PM4
Obstacle 2
Obstacle 1
BENTAIB A. & al, ETSON-MITHYGENE benchmark on simulations of upward flame propagation 0.64m PM3
PM2
experiment in the ENACCEF2 experimental facility, The 12th International Topical Meeting on Nuclear PM1
Reactor Thermal-Hydraulics, Operation and Safety (NUTHOS-12) Qingdao, China, October 14-18, 2018 Ignition
SNETP FORUM, TS1-Long Term Operation & Construction, Onine, February 3rd 2021 19/40Towards the reactor application SNETP FORUM, TS1-Long Term Operation & Construction, Onine, February 3rd 2021 20/40
PAR and flame behavior in Ex-vessel
conditions
SAMHYCO-NET PROJECT (2017-2020)
Academic: ICARE, University Shanghai, NUT, UCSN
Research Institutes, TSO, Safety Authorities: IRSN, CEA, CIEMAT, LEI, SSTC-NRS, KAERI,
KINS, PSI, IJS, NRG, JULICH, KIT, CNSC, JAEA, INRNE, SEC-NRS, SNERDI, CNL
Industrials: General Electric, EDF, AIR LIQUIDE, FRAMATOME
SNETP FORUM, TS1-Long Term Operation & Construction, Onine, February 3rd 2021 21/23Main objectives
Objective 1: Review and critical assessment regarding :
- PARs experimental data and modeling
- H2 and CO combustion experimental data and modeling
Objective 2: Experimental and analytical investigation of PARs behavior under
ex-vessel conditions including the combined effect of oxygen starvation,
steam, carbon monoxide and iodine
Objective 3: Experimental and analytical investigation of H2/CO/H2O
combustion under representative ex-vessel conditions
Objective 4: Improving the predictability of the numerical tools used for
explosion hazard evaluation inside the reactor containment
SNETP FORUM, TS1-Long Term Operation & Construction, Onine, February 3rd 2021 22/40Conclusion
▌ Flammable mixtures identification
▌ PARs ignition limits identification
▌ Flame propagation characterization
Assessment of the self-acceleration flame due to thermo-diffusive
instabilities
Flame acceleration to initial turbulence
▌ Improvement of combustion modeling based on new well
instrumented data
▌ Application to reactor Scale
▌ Perspectives
SNETP FORUM, TS1-Long Term Operation & Construction, Onine, February 3rd 2021 23/40AMHYCO PROJECT
SNETP FORUM, TS1-Long Term Operation & Construction, Onine, February 3rd 2021
24AMHYCO general data
• Full Project Name: Towards An Enhanced Accident
Management Of The Hydrogen/CO Combustion Risk
• EURATOM Work Programme 2019 “NFRP-02: Safety
assessments for Long Term Operation (LTO) upgrades
of Generation II and III reactors”
• Project No: 945057
• Start Date: 01/10/2020
• Project Duration: 48 months
• EU contribution: 3 974 402.50 €
25
SNETP FORUM, TS1-Long Term Operation & Construction, Onine, February 3rd 2021AMHYCO partners
# Participant organisation name Country
1 Universidad Politécnica de Madrid (UPM) Spain
(Coordi
nator)
2 Centro de Investigaciones Energéticas, Medioambientales y Spain
Tecnológicas (CIEMAT)
3 L'Institut de Radioprotection et de Sûreté Nucléaire (IRSN) France
4 Centre National de la Recherche Scientifique -Orleans France
(CNRS)
5 Forschungszentrum Jülich (FZJ) Germany
6 Framatome GmbH (FRG) Germany
7 Ruhr-Universität Bochum (RUB) Germany
8 Jožef Stefan Institute (JSI) Slovenia
9 Energorisk, Ltd. (ER) Ukraine
10 Nuclear Research and Consultancy Group (NRG) Netherlan
ds
11 Canadian Nuclear Laboratories (CNL) Canada
12 LGI Consulting (LGI) France
26
SNETP FORUM, TS1-Long Term Operation & Construction, Onine, February 3rd 2021AMHYCO objectives
The AMHYCO project main objective is to propose innovative enhancements on the way
combustible gases are managed in case of a severe accident in currently operating
reactors.
To reach this main objective, the AMHYCO project has three main specific objectives:
Objective 1: To experimentally investigate phenomena that are difficult to predict
theoretically: H2/CO combustion and PARs (Passive Autocatalytic Recombiners)
behavior under realistic accidental conditions, taking into account their interaction with
safety systems. Reducing the uncertainties in the phenomena is a remarkable way of
enhancing the severe accident safety.
Objective 2: To improve the predictability of analysis tools - Lumped Parameter (LP),
3D and Computational Fluid Dynamic (CFD) codes - used for explosion hazard
evaluation inside the reactor containment and providing support to SAMGs design and
development.
Objective 3: To improve the Severe Accident Management Guidelines for both in-
vessel and ex-vessel phases with respect to combustible gases risk management, using
theoretical, simulation and experimental results.
27
SNETP FORUM, TS1-Long Term Operation & Construction, Onine, February 3rd 2021AMHYCO workflow
WP1
Critical review
- SAMGs
- Equipment and
instrumentation - Existing combustion correlations
WP6: Dissemination, comunication E&T
surveillance - PAR behaviour under SA conditions
Reference
conditions
for the WP3
WP2 experimen
ts Experiments
WP7 - Coordination
Selection of sequences (Combustion, mitigation
- SAMGs systems)
WP8 - Ethics
- Equipment and
instrumentation
- Limiting sequences surveillance
input for containment
analysis
Experimental results:
- Combustion interaction
WP4 with spray, FCVS
Full containment analysis - PAR efficiency under SA
Simulation results
WP5
SAMGs
28
SNETP FORUM, TS1-Long Term Operation & Construction, Onine, February 3rd 2021SNETP FORUM, TS1-Long Term Operation & Construction, Onine, February 3rd 2021
Thank you for your attention!
For any questions or further information,
please contact:
ahmed.bentaib@irsn.fr
chaumeix@cnrs-orleans.fr
SNETP FORUM, TS1-Long Term Operation & Construction, Onine, February 3rd 2021 30/40You can also read
