i. hcll main features ii. safety issues iii. occupational ......ch. girard - 8thiaea technical...

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)


I - HCLL TBM main features


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


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


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


HCLL blanket design


First Wall – Toroidal He cooling

He out

He in


Horizontal/vertical Stiffening Plates (He cooled)

He in/out


He flow in horizontal/vertical Stiffening Plates (SPs)


Breeder units are inserted inside cells


Breeder units inserted inside SPs (view from back)


HCLL breeder unit design

Cooling Plates (CPs)

He in/out unit manifolds

Front

He unit inlet

He unit outletUnit backplate


He flow scheme in cooling plates


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)


HCLL breeding blanket

He flow scheme


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


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


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


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


HCLL breeding blanket

PbLi flow scheme


PbLi feeding through back collector


Stiffening plates (SPs) frontier

PbLi

FW frontier(FW not shown here)

PbLi flowing inside Breeder Unit

tor

polrad


PbLi general flow scheme

LiPb inlet

Horizontal stiffening plate

Breeding zone cell

Breeding zone column

LiPb distribution box

LiPb outlet


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


The HCLL TBM system integrationHe circuit in vault

PbLi circuit in port cell

TBM in port frame


II - Safety issues


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.


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.


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).


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


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


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.


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


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 )


TBM thermal-mechanical results

1. Decay heat removal2. In-TBM LOCA and box pressurization3. LOFA


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



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



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.


TBM box pressurization (in TBM LOCA)

Thermomechanical calculation of the moduleat 8.0 MPa .


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.


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.


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.

i. hcll main features ii. safety issues iii. occupational ......ch. girard - 8thiaea technical...

Documents