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Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 1
Safety issues review of the EU HCLL ITER TBM
I. HCLL main features
II. Safety issues
III. Occupational exposure
IV. Conclusion
Christian Girard (CEA/Cadarache – France)
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 2
I - HCLL TBM main features
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 3
The HCLL (He-PbLi) DEMO blanket
Stiffeninggrid
Module box(container & surface heatextraction) Breeder
cooling unit (heat extraction from PbLi)
He collector system (back plates)
PbLi slowly re-circulating (10/50 rec/day)90 % 6Li in Pb-15.7Li
Large modulesRAFM steel (EUROFER)
TBR = 1.15 with 550mm Breeder radial depth
Lifetime 7.5 MWy/m2
Liquid Pb-15.7Li (eutectic) as breeder and multiplier
He (8 MPa, 300-500°C)
DEMO HCLLMain features
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 4
The HCLL TBM to be tested in ITER
TBMs have to be DEMO-relevant � TBMs proposal are derived from DEMO programsFirst TBMs have to be installed since the first day of the H-H operation(to check interfaces & main operations, compatibility with ITER operations and to support to licensing and safety dossier)TBM design (mainly Breeder Units) will be specifically optimized for each ITER phase (at least 4 different TBMs could be tested in ITER)
Top cover
Stiffening grid
BUs
PbLi distribution box
FW/SW
Stiffening rod
BUs back platesBUs He collectors
PbLi feeding pipe
PbLi feeding pipe
BP1BP2BP3BP4
He inlet pipe
He outlet pipe
PbLi outlet pipe
PbLi inlet pipe
Vertical shear key-way
Vertical shear key-way
Horizontal shear key-way
Back collector
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety »
HeliumHelium--CooledCooled LithiumLithium--Lead Lead (HCLL) (HCLL) ITER TBM descriptionITER TBM description
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 6
HCLL main design features
Box layout common with HCPB– FW– Stiffening plates (SPs)– Back collectors
radial cells delimited by stiffeningplates (SPs) for box resistance under faulted conditionsbreeder units inside cellsAll flow connections located at the rear of the module
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 7
HCLL blanket design
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 8
First Wall – Toroidal He cooling
He out
He in
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 9
Horizontal/vertical Stiffening Plates (He cooled)
He in/out
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 10
He flow in horizontal/vertical Stiffening Plates (SPs)
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 11
Breeder units are inserted inside cells
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 12
Breeder units inserted inside SPs (view from back)
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 13
HCLL breeder unit design
Cooling Plates (CPs)
He in/out unit manifolds
Front
He unit inlet
He unit outletUnit backplate
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 14
He flow scheme in cooling plates
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 15
Design of a 3-levels collector
Main inlet He
Level # 1:-Main inlet He spreadout-FW/SP/Covers inlet
Level # 2:- FW/SP/Covers return- Breeder unit inlet
Level # 3:-Breeder unit return
Main outlet He
(Module top view)
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety »
HCLL breeding blanket
He flow scheme
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 17
He flow scheme – I
Main He inlet
80% He in FW
(Module top view)
20% He in SPs
Stage # 1:-Main inlet He spreadout-FW/SP/Covers inlet
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 18
He flow scheme – II
Main He inlet
80% He in FW
(Module top view)
20% He in SPs
100% He in BUs
Stage # 2:- FW/SP/Covers return- Breeder unit inlet
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 19
He flow scheme – III
Main He inlet
80% He in FW
(Module top view)
20% He in SPs
100% He in BUs
Main He outlet
Stage # 3:-Breeder unit return-Main He outlet
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 20
He thermalhydraulic performances
300°C1.3 kg/s300°C
1.3 kg/sFW
1.3 kg/sFWFW
1.3 kg/s1.3 kg/s 369°C369°C
SP0.286 kg/s
SPSP0.286 kg/s0.286 kg/s
CP0.286 kg/s
CPCP0.286 kg/s0.286 kg/s
By-pass1.014 kg/sByBy--passpass
1.014 kg/s1.014 kg/s 369°C369°C
457°C457°C 500°C500°C
398°C398°C
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety »
HCLL breeding blanket
PbLi flow scheme
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 22
PbLi feeding through back collector
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 23
Stiffening plates (SPs) frontier
PbLi
FW frontier(FW not shown here)
PbLi flowing inside Breeder Unit
tor
polrad
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 24
PbLi general flow scheme
LiPb inlet
Horizontal stiffening plate
Breeding zone cell
Breeding zone column
LiPb distribution box
LiPb outlet
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 25
Tritium extractionfromLiPb
ΦFWΦ
Φ5
He purificationGHe
ηLiPb
ηHe
mHe
GPbLi
Φ1
Φ2
Φ4
Steamgenerator
Secondary
HCLL
LiPbpurification Pump
air purification
QHe
mLiPb
Tritium extractionfromLiPb
ΦFW 3
Φ5
He purificationGHe
ηLiPb
ηHe
mHe
GPbLi
Φ1
Φ2
Φ4
Steamgenerator
Secondary circuit
HCLL Blanketmodules
LiPbpurification Pump
air purification
QHe
mLiPb
Φ1 = tritium production rateΦ2 = extraction rate from LiPbΦ3 = permeation rate towards HeΦ4 = extraction rate from HeΦ5 = potential release rate
to the environment
Main Tritium flows
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety »
The HCLL TBM system integrationHe circuit in vault
PbLi circuit in port cell
TBM in port frame
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 27
II - Safety issues
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 28
Safety approach for HCLL-TBM integration
� Safety requirements presented in § 8 of the TBWG report are or will be fulfilled,� Respect and application of ITER basic safety guidelines (AAG, AAS, SADL),� Establishment of a list of potential new hazards brought by the integration of the TBM� The identification of the SF assigned to TBM and the Safety Important Components of the whole experimental device,� The review of the normal and abnormal operating conditions of ITER including the HCLL-TBM,� The selection, from the operating conditions and events, of those relevant for definition of the studies either on safety, dimensioning or operation.
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 29
Coupling aspects of the approach
A general approach, both for initiating the TBM safety analysis and defining safety design requirements, can be split into two sub-approaches :
� Investigating the influence of TBM integration on ITER operation, availability and safety,
� Investigating the impact of ITER system and operation on TBM design, operation and safety.
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 30
Identification of new radioactive inventories and new sources of hazards for the HCLL TBM
� Radioactive inventory� T production in the TBM has to be quantified and Tritium outputs
have to be assessed (extraction, permeation, release)� New hazard
� Exothermic chemical reaction between Pb-Li and possible released steam (from an ITER FW failure),
� New “condition”� He when spilt in the VV acts as a non-condensable gas which may
alter VVPSS performance (if triggered in case of combination of a large FW leak and He leak).
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 31
HCLL-TBM SAFETY RELATED FUNCTIONS
� TBM safety requirements indicate that:
� This implies that many TBM components must be safety classified:� Safety classified barriers to prevent fluid leakage or chemical interaction,� Safety classified cooling system, if failure of heat removal can threaten barriers
integrity.
Component Safety function andrationale for classification
Ex-vessel part of Test Blanket components
Part of confinement barrier
Test Blanket cells The another (second) confinement barrier
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 33
ABNORMAL OPERATING CONDITIONS AND EVENTS
Two complementary approaches:
1. ITER events impacting the HCLL-TBMA re a R e fe re n c e e v e n ts C a t . O ff -s ite R *
P la sm a Los s o f p la sm a con tro l/e x c ep tio na l p la sm a beha v io r I, A X P ow e r Los s o f o ff-s ite pow e r fo r u p to 1 h I X In -v e s s e l L o s s o f va cuum th rou gh a v a cuum ves se l p en e tra tio n lin e A X E x -ve s se l H T S H ea t e x ch ang e r tu b e rup tu re A X M a in ten anc e S tu c k d ive r to r c a s se tte in tra n sp o r t c a s k
M a in te n ance a c c ide n t o n v a cuum ves s e l A A
X X
T r it ium p lan t, F ue l c yc le
T r itium p ro ce s s lin e le a k age Is o tope sepa ra tio n s ys tem fa ilu re F ue llin g lin e w ith im pa ired c on fin em en t
I A A
X X
X
M agn e t N o t re le v a n t fo r re le a s e s , a n d n o t fo r H C L L -T B M s tu d ie s C ryo s ta t W a te r /a ir /h e l ium ing re s s A X H o t C e ll F a ilu re o f c o n fin em en t A X
I : In c ide n t A : A c c id e n t O ff-s ite : re le va n t fo r en v ironm en ta l re le a ses R * : re le va n t fo r T BM -H C LL s tud ie s
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 34
OFF-NORMAL OPERATING CONDITIONS AND EVENTS
1.2. HCLL-TBM events with self-impact or impacting ITER
The following methodology was developed in order to define a list of events. Its outlines are :� Define the Initiating Event (IE), a priori equivalent to a loss of
barrier: direct (leakage) or indirect one (resulting from overheating) for a confinement barrier (for radioactive material) or a separating barrier (separation of 2 reactive media that could threaten confinement barriers).� Check completeness by comparing to WCLL I.E. list (set by an
FMEA) for Pb-Li faults and to HCPB list for He faults.� Define aggravating condition that shall be combined with the PIE.
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 35
OFF-NORMAL OPERATING CONDITIONS AND EVENTS
Internal faults :AOC Loss of He pressure
He overpressureHe inventory changeFault of He purification systemPbLi inventory changeFault of PbLi purification systemPbLi flow changeHeating circuit fault (PbLi freezing)
LOF He flow decreaseHe circulator tripHe circulator seizurePbLi pump seizurePartial blockage of CP channel(s)Partial blockage of SP channel(s)Partial blockage of FW channel(s)
LOHS LOF of secondary circuitLoss of final heat sink(s)
LOSP Loss of one supply fileTotal LOSP
LOC Leak of cooling plate(s)Leak of stiffening plate(s)Inner LOC of FWRupture of HX tube(s)
Faults impacting the 1st confinement :LOC In-vessel He leakage
In-vessel PbLi leakageSmall FW break (He+PbLi)Large FW break (He+PbLi)
Faults impacting the 2nd confinement :LOC In-cryostat PbLi leakage
In cryostat He leakageIn-cryostat (He+PbLi) leakageEx-cryostat He leakageBreaking of PbLi detritiation systemBreaking of PbLi purification systemBreakingof He detritiation systemBreaking of He purification systemLeak of secondary coolantLeak of primary + secondary fluids
Required rationale for compatibility with the ITER project selected PIE
PIE Assessment of1) Loss of
coolant into VV
• small pressurisation of the first confinement (i.e.VV)
• passive removal of decay heat• Limited chemical reactions and hydrogen
formation2) Loss of
coolant into breeder/ multiplier zone
• pressurisation of the module and purge gas sysstem.
• Limited chemical reactions and hydrogen formation
• subsequent in-vessel leakage3) Ex-vessel loss
of coolant into port cell (vault)
• pressurisation of the port cell, vault, assembly cask
• Limited chemical reactions and hydrogen formation
rationale
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 36
HCLL TBM safety issues status
In progressRationale for PIE selectionIn progressFMEA studies to confirm I.E. list
OK for in TBM volume, provisions for outside volume have TBD
PbLi limited to 0.28 m3
In progress (see next slides)Passive decay heat removal
When accurate He circuit volume will be determined
In progress (see next slides)
Pressurization in: � vault� Port Cell� CCWS� TBM box (breeder)
HCLL TBM statusParameters to be assessed (asked by ITER-IT )
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 37
TBM thermal-mechanical results
1. Decay heat removal2. In-TBM LOCA and box pressurization3. LOFA
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 38
Decay heat removal by thermal radiation (1/3)
TBM-HCLL : Thermal loads
Heat flux / Be layer : 0.5 MW.m-2
Power density profile versus distance from the plasma (NWL 0.78) :• Be : 5.2 MW.m-3
• FW : 5.4 MW.m-3 (0.69 kW.kg-1)• SW : red curve• CP : blue curve• SPV : green curve• PbLi : pink curve (10 MW.m-3 0.98 kW.kg-1)
Thermal emissivity Be layer : 0.61Thermal emissivity ITER wall : 0.3Temperature ITER wall : 413 K
Be layer : boundary conditions
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 39
Decay heat removal by thermal radiation (2/3)
TBM decay heat
Several hypothesis :• decay heat Eurofer no impurities• decay heat Eurofer impurities• decay heat LiPb no impurities• decay heat LiPb impurities (with or without Tritium)
Lipb
1,E-121,E-111,E-101,E-091,E-081,E-071,E-061,E-051,E-041,E-031,E-021,E-011,E+00
1,E+00 1,E+02 1,E+04 1,E+06 1,E+08 1,E+10
time after shutdown (s)
deca
y hea
t kW
/kg
frontmidrear
1,E-111,E-101,E-091,E-081,E-071,E-061,E-051,E-041,E-031,E-021,E-011,E+00
1,E+00 1,E+03 1,E+06 1,E+09 1,E+12
time (seconds)
heat
deca
y kW/
kg
frontmidrear
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 40
Decay heat removal by thermal radiation (3/3)
He in-vessel LOCA- Helium leak stops immediately the plasma so that the surface heat flux and the nuclear power density drop to zero,- There is no cooling by He.
t1 : T max. = 563°C
t1
t1 + 1 sec. :T max. = 541°C
t2 : T max. = 426°C
t2
FW temp.
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 41
TBM box pressurization (in TBM LOCA)
Thermomechanical calculation of the moduleat 8.0 MPa .
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 42
Loss of Flow Accidents
555 °C ≤ T ≤ 1100 °C
Plasmaside
Beginning of LOFAt = 0 sec. – T max. = 559 °C
End of simulationt = 135 sec. – T max. = 692 °C
Automatic shut-downt = 35 sec. – T max. = 1100 °C
Under some conditions LOFAs could avoid to end up in a LOCA.
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 43
III - Occupational exposure
The contribution of the TBM to occupational exposure during operation was estimated taking into account the ALARA principle, with the objective of minimizing such exposure:
• Dose rate was estimated for TBM structural material (EUROFER) and for Liquid Breeder (Pb-Li).
• Dose rate was estimated with and without bioshield protection – the attenuation is quite significant (926 mSv/hr at 1 year without shield and 1.26E-09 mSv/hr with shield).
• Review of this analysis has to be performed considering the new operating scenarios and design (new neutronics data).
• Dose rate during maintenance activities still to be done.
Ch. Girard - 8th IAEA Technical Meeting on « Fusion Power Plant Safety » 44
IV – Conclusion
HCLL TBM safety does not show any critical issue,All TBM events are covered by ITER accidental situations,He inventory is small and not able to pressurize ITER confinement volumes,Pb-Li inventory is limited and reaction with steam in hypothetical situations cannot produce more than 2.5 kg of hydrogen,Combined ITER + TBM sequences have to be assessed in order to estimate safety systems performance with mixed medias as: steam, He, Pb-Li.