kick off meeting efda task tw6-tsl-002 garching 9th/10/2006 enea overview of the task and...

Kick off meeting EFDA Task TW6-TSL-002 Garching 9th/10/2006

ENEA

Overview of the task and Overview of the task and coordination: refined description of coordination: refined description of the accident sequences, reference the accident sequences, reference

data (AAS), data (AAS), work planwork plan

M. T. Porfiri, T. PinnaM. T. Porfiri, T. Pinna

Garching 9th October 2006 Meeting Safety assessment for EU TBM to support ITER Licensing Process


OutlineOutline Coordination task scopeCoordination task scope FMEA and postulated initiating eventsFMEA and postulated initiating events Finished description of the accident Finished description of the accident sequencessequences Reference data Reference data ScheduleSchedule


Coordination task scope (1)Coordination task scope (1) 1. Study and analyses of all the existing design TBM 1. Study and analyses of all the existing design TBM documentsdocuments DoneDone

2.2. Revision of the existing accident analyses Revision of the existing accident analyses

DoneDone

3. Documentation of the inherent limitations and lacunas3. Documentation of the inherent limitations and lacunas

Within two months (December 06) from the kick off meeting Within two months (December 06) from the kick off meeting including also the main outcomes of the FMEA, in order to justify including also the main outcomes of the FMEA, in order to justify the choice of the sequences selected for the accident analyses the choice of the sequences selected for the accident analyses proposedproposed

4.4. Discussion together with the Associations involved in the safety Discussion together with the Associations involved in the safety analyses for the refinement of the accidents to be analyzedanalyses for the refinement of the accidents to be analyzedKick off meetingKick off meeting


Coordination task scope (2)Coordination task scope (2)5. Verifications of the tools used (codes) for the analyses and a 5. Verifications of the tools used (codes) for the analyses and a

quality assurance procedure for the reproducibility of the resultsquality assurance procedure for the reproducibility of the results

Decision during the kick off meetingDecision during the kick off meeting

6. Preparation of a data base pulled out from the design to 6. Preparation of a data base pulled out from the design to support the accident analyses, in order to avoid misleading in support the accident analyses, in order to avoid misleading in the data interpretation;the data interpretation;

In preparation, to be completed within November 2006In preparation, to be completed within November 2006

7.7. Technical review of the results of the accident analyses Technical review of the results of the accident analyses performed in the frame of the current task.performed in the frame of the current task.

First results: January 07First results: January 07

Final results:Final results: April 07April 07


HCPB: failure mode and effect analysisHCPB: failure mode and effect analysisThe components of the TBM are on going to be analyzed with the

FMEA methodology. For each one of them, the possible failure modes that could occur

in the different operating phases will evaluated. For each failure mode will be pointed out: failure causes and possible actions to prevent the failure, consequences and actions to prevent and mitigate the

consequences, identification of the Postulated Initiating Events (PIEs) which

include the failure. This last attribute will be useful to individuate the set of PIEs to

be taken into account in the deterministic transient analyses.At present only the FMEA for HCPB is quite completed, while the

HCLL FMEA is still on going.


HCPB: postulated initiating events HCPB: postulated initiating events (1)(1)PIEs Description

FB1 Loss of flow in a TBM cooling circuit because of circulator/pump seizureFB2 Partial flow blockage in a TBM cooling circuit because filter cloggingHB1 Loss of heat sink in TBM cooling circuitLBB1 Loss of TBM cooling circuit inside breeder blanket box: Rupture of a sealing

weldLBB2 Loss of TBM cooling circuit inside breeder blanket box: Leak of a sealing

weldLBO1 LOCA Out-VV because large rupture of TBM cooling circuit pipe inside TWCS

RoomLBO2 LOCA Out-VV because small rupture of TBM cooling circuit pipe inside

TWCS RoomLBO3 LOCA Out-VV because rupture of tubes in a primary TBM-HCS HXLBP1 LOCA Out-VV because rupture of a TBM cooling circuit pipe inside Port CellLBP2 LOCA Out-VV because small rupture of TBM cooling circuit pipe inside Port

CellLBV1 Loss of TBM cooling circuit inside VV: Rupture of TBM-FSWLBV2 Loss of TBM cooling circuit inside VV: Leak from TBM-FSW


PIE DescriptionLFP2 LOCA Out-VV because small rupture of PFW/BLK cooling circuit pipe inside Port

CellLFV2 Small PFW/BLK in vessel LOCA. Equivalent break size: a few cm2LVP2 Small rupture of VV cooling circuit pipe inside Port CellLVV2 Small rupture in the internal VV shell - equivalent break size: a few cm2TBP2 Leak of TBM - Tritium Extraction System process line inside Port CellTBL2 Leak of TBM - Tritium Extraction System process line inside Glove Box

containmentVBG1 Loss of vacuum in VV: break inside the VV of TBM purge gas systemVBG2 Loss of vacuum in VV: leak inside VV from TBM purge gas systemVVA2 Ingress of air in the VV - small leakage

N/S Not Safety Relevant

HCPB: postulated initiating events HCPB: postulated initiating events (2)(2)


Choice of accident analyses Choice of accident analyses The accident analyses selected for the two models The accident analyses selected for the two models

that are:that are: Ex-vessel LOCA+in-vessel LOVAEx-vessel LOCA+in-vessel LOVA for for HCPBHCPB and and ex-vessel LOCA+in-vessel He, LiPb and water LOCAex-vessel LOCA+in-vessel He, LiPb and water LOCA

for for HCLLHCLL

have the scope to include the PIE detected by the have the scope to include the PIE detected by the Failure Mode and Effect Analysis.Failure Mode and Effect Analysis.

As example the PIE As example the PIE LBO1LBO1

LOCA Out-VV because large rupture of TBM cooling LOCA Out-VV because large rupture of TBM cooling circuit pipe inside TWCS Roomcircuit pipe inside TWCS Room

can be used.can be used.


From FMEA HCPB: LB01 description From FMEA HCPB: LB01 description (1)(1)

A large A large LOCA out-vesselLOCA out-vessel from the TBM HCS could be determined by a from the TBM HCS could be determined by a significant rupture in the cooling circuit from components located in the significant rupture in the cooling circuit from components located in the HCS room or in the piping running from the Port Cell to the HCS room (i.e.: HCS room or in the piping running from the Port Cell to the HCS room (i.e.: service shaft and TWCS Room). The representative event here selected service shaft and TWCS Room). The representative event here selected has been the break of a cooling pipe inside the TWCS Room (HCS zone).has been the break of a cooling pipe inside the TWCS Room (HCS zone).

The following chain of consequences could follow the initiator:The following chain of consequences could follow the initiator: Loss of He coolant into VaultLoss of He coolant into Vault Pressurization of VaultPressurization of Vault Release of Tritium contained in He coolant into VaultRelease of Tritium contained in He coolant into Vault Emptying of the TBM cooling loop and loss of heat removal capabilityEmptying of the TBM cooling loop and loss of heat removal capability Overheating of TBM if the plasma is not promptly shutdownOverheating of TBM if the plasma is not promptly shutdown Swelling of Ceramic Breeder and Be pebblesSwelling of Ceramic Breeder and Be pebbles Over thermo-mechanical stress on BU, Grid, Caps and FSW structuresOver thermo-mechanical stress on BU, Grid, Caps and FSW structures



Ingress of air in TBM box cooling channels when the pressure in Ingress of air in TBM box cooling channels when the pressure in cooling circuit gets room pressurecooling circuit gets room pressure

Be-air and Be-water (moisture contained in air) reactions if coolant Be-air and Be-water (moisture contained in air) reactions if coolant channels inside the box lost their integrity because thermo-channels inside the box lost their integrity because thermo-mechanical stress, particularly, if the plasma is not shutdown. In mechanical stress, particularly, if the plasma is not shutdown. In such a case, the following aggravating failures could follow:such a case, the following aggravating failures could follow:

- H2 production- H2 production - Possible H2 explosion inside the box- Possible H2 explosion inside the box Possible break of TBM boxPossible break of TBM box Ingress of He (i.e.: some coolant not yet discharged from the loop Ingress of He (i.e.: some coolant not yet discharged from the loop

and purge gas) and air (from the external break) into VVand purge gas) and air (from the external break) into VV Plasma disruption if it has not been actively or passively (plasma Plasma disruption if it has not been actively or passively (plasma

poisoning due to armour material evaporation) shutdownpoisoning due to armour material evaporation) shutdown VV pressurisationVV pressurisation



Opening of bleed lines towards VVPSS when VV pressure gets 80 kPa Opening of bleed lines towards VVPSS when VV pressure gets 80 kPa and opening of lines to drain tank when p>110kPaand opening of lines to drain tank when p>110kPa

Release of radioactive products contained in VV (tritium & dusts) to Release of radioactive products contained in VV (tritium & dusts) to VVPSSVVPSS

Release of radioactive products contained in VV (tritium & dusts) to Release of radioactive products contained in VV (tritium & dusts) to TWCS Room if VV pressure overcomes room pressureTWCS Room if VV pressure overcomes room pressure

Loss of Be pebbles into VV due to dynamic effects (e.g. VV suction, He Loss of Be pebbles into VV due to dynamic effects (e.g. VV suction, He flowing) caused by the FW rupture. In this case, it is also worthwhile flowing) caused by the FW rupture. In this case, it is also worthwhile to remark that the loosing of pebbles inside the VV makes more to remark that the loosing of pebbles inside the VV makes more complicated recovery actions inside the VV to clean vacuum chamber complicated recovery actions inside the VV to clean vacuum chamber before restart. Consequences that could reduce plant availabilitybefore restart. Consequences that could reduce plant availability

Aggravating consequences could occur in case of rupture in other Aggravating consequences could occur in case of rupture in other water cooled PFCs due to disruptionwater cooled PFCs due to disruption

Increase of ORE for recovery actions.Increase of ORE for recovery actions.


Finished description of the accident Finished description of the accident sequencessequences

The AAS document used for GSSR has been adopted as a template The AAS document used for GSSR has been adopted as a template to describe the accident sequences and all the connected to describe the accident sequences and all the connected information as:information as:

Event SequenceEvent Sequence System AssumptionsSystem Assumptions Confinement assumptionsConfinement assumptions Analysis MethodologyAnalysis Methodology ResultsResults

They are in the linked documentsThey are in the linked documents::

HCPB HCPB accidentaccident - - AAS.docAAS.doc, , HCLL HCLL accidentaccident - - AAS.docAAS.doc


Accident description for HCLL TBMAccident description for HCLL TBM E Ex-vessel LOCA+in-vessel He, LiPB and water x-vessel LOCA+in-vessel He, LiPB and water

LOCALOCA1.1. The detection of the ex-vessel LOCA The detection of the ex-vessel LOCA

fails to trigger the Fusion Power fails to trigger the Fusion Power Shutdown System (FPSS) Shutdown System (FPSS) Modest Modest inventories of radioactive materialinventories of radioactive material

2.2. Consequent Consequent melting of the TBM wall melting of the TBM wall structure and LiPb spreading in VVstructure and LiPb spreading in VV

3.3. Water and steam enter the VV from Water and steam enter the VV from the FW cooling loopthe FW cooling loop

0. Initiating event: break in the ex-vessel He cooling loop


HCLL TBMHCLL TBM general scheme for ex-vessel LOCA+in-vessel He, general scheme for ex-vessel LOCA+in-vessel He,

LiPB and water LOCALiPB and water LOCA

4.4. VV pressurizes and the reaction between lithium lead and VV pressurizes and the reaction between lithium lead and water produces hydrogen.water produces hydrogen.

5.5. The release of tritium and aerosols from the VV and the TBM The release of tritium and aerosols from the VV and the TBM box can occur through the TBM cooling loop bypass box can occur through the TBM cooling loop bypass generated between VV and external zone (TCWS vault). generated between VV and external zone (TCWS vault).

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6.6. Either because the exit of Either because the exit of H2 in the cooling room H2 in the cooling room through the by bypass or, through the by bypass or, the ingress of air in the VV the ingress of air in the VV after differential pressure after differential pressure inversion, hydrogen/oxygen inversion, hydrogen/oxygen explosion can be possible. explosion can be possible.


1.1. The detection of the ex-vessel The detection of the ex-vessel LOCA fails to trigger the Fusion LOCA fails to trigger the Fusion Power Shutdown System (FPSS) Power Shutdown System (FPSS)

2.2. Melting and/or thermal-Melting and/or thermal-mechanical stresses on the box mechanical stresses on the box structure occursstructure occurs

3.3. He ingress in the VV will cause He ingress in the VV will cause the plasma disruptionthe plasma disruption

4.4. Box structures containing lithium Box structures containing lithium orthosilicate and beryllium orthosilicate and beryllium pebbles can loose their integritypebbles can loose their integrity

Accident description for HCPBAccident description for HCPB Ex-vessel LOCA+in-vessel LOVAEx-vessel LOCA+in-vessel LOVA

0. Initiating event: break in the ex-vessel He cooling loop

5.5. After differential pressure inversion the gases (air, He) in the After differential pressure inversion the gases (air, He) in the VV and in TBM flow towards outside through the TBM cooling loop VV and in TBM flow towards outside through the TBM cooling loop bypass and tritium and dust can be transported from the gas stream bypass and tritium and dust can be transported from the gas stream and released in the external zones. and released in the external zones.


Reference data Reference data The base documents for the safety analysis are:The base documents for the safety analysis are:- sadl.pdfsadl.pdf- TBM DDDsTBM DDDs

In addition data necessary for the selected accidents are:In addition data necessary for the selected accidents are:1.1. section of the pipesection of the pipe for the double ended break in the TBM for the double ended break in the TBM

cooling loop cooling loop 2.2. melting temperaturemelting temperature for the TBM wall towards plasma and/or for the TBM wall towards plasma and/or

embrittlement temperatureembrittlement temperature for TBM box for TBM box 3.3. Section of the Section of the break in TBM boxbreak in TBM box towards plasma to simulate in- towards plasma to simulate in-

vessel LOVA for HCPB and in-vessel LOCA for HCLLvessel LOVA for HCPB and in-vessel LOCA for HCLL4.4. Be dustBe dust inventory to be mobilized in TBM box for HCPB inventory to be mobilized in TBM box for HCPB


HCPB: section of the break ex-vessel HCPB: section of the break ex-vessel

At the inlet of the circulator a pipe DN 100 is designed. The section At the inlet of the circulator a pipe DN 100 is designed. The section of the break is 8119.17 mmof the break is 8119.17 mm22


Reference DDD:The number of the TBM pipes leaving the TBM from the rear has been fixed to four, two for the cooling helium (inlet pipe having ∅in = 60mm, outlet pipe having ∅in = 70 mm)

It is not specified if the pipe at the compressor inlet has the same section.

HCLL: section of the break ex-vessel HCLL: section of the break ex-vessel


ActionAction When/WhoWhen/Who1. The work plan, outcome of 1. The work plan, outcome of this meeting, will be supplied this meeting, will be supplied to EFDAto EFDA

One week after kick off One week after kick off meeting / meeting / CC

2. Finishing of a data base 2. Finishing of a data base for the accident analysesfor the accident analyses

One monthOne month after kick off after kick off meeting (11/06) / meeting (11/06) / C+FZK+CEAC+FZK+CEA

3. Status of the work and 3. Status of the work and difficulties met difficulties met

2 months after kick off 2 months after kick off meeting (12/6) / meeting (12/6) / FZK+VR+CFZK+VR+C

4. Phone meeting for the 4. Phone meeting for the discussion of the first resultsdiscussion of the first results

3 months after kick off 3 months after kick off meeting (1/07)/ meeting (1/07)/ C&AA&EFDA&ITERC&AA&EFDA&ITER

5. Meeting for the 5. Meeting for the presentation and discussion presentation and discussion of the final resultsof the final results

6 months after kick off 6 months after kick off meeting (4/07)/ meeting (4/07)/ C&AA&EFDA&ITERC&AA&EFDA&ITER

ScheduleSchedule

C = coordinator, AA = Associations

kick off meeting efda task tw6-tsl-002 garching 9th/10/2006 enea overview of the task and...

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