Progress Report by ITER Test Blanket Working Group (TBWG)

(covering the period “February 2005 – December 2005” )

February 2006



·
Introduction

The ITER Test Blanket Working Group (TBWG) was re-established in September 2003 for the duration of the ITER Transitional Arrangements (ITA) phase with a revised charter and it is now including seven delegations, one from the ITER Team and one from each of the six ITER parties.
Work from the initial period, including the first four meetings (TBWG-11, 12, 13 and 14), was reported on two previous TBWG Progress Report released respectively in June 2004 and March 2005. In the present reporting period, two other meetings have been held: TBWG-15, held in the ITER-JWS Garching on July 12-13, 2005, and TBWG-16, held in Beijing (PRC) on November 15-17, 2005.

· Summary of the Activities during the reporting period

The main achievements during the reporting period concern the following aspects:

A) Preparation and edition of the TBWG Report for the period of the ITER Transitional Arrangements;

B) Preparation and edition of TBMs Detailed Description Document (DDD);

C) Improvement of frame design, associated TBM replacement strategy, and shield penetrations issue;

D) Preliminary Parties R&D planning prior the TBM installation in ITER;

E) Establishment of a procedure for TBM licensing;

F) Preliminary assessment of the Parties TBM proposals;

G) Identification of TBM needs in term of codes and standards and Quality Assurance (QA);

H) Identification of required Post-Irradiation Examinations (PIE) and of limitations in present ITER Hot Cell design;

I) Further identification of space issues related with the various ITER/TBM systems interfaces.

All these aspects are discussed in more details in the chapters below.

Moreover, further preliminary proposals/requests of collaboration on specific R&D items (e.g., structural materials, He-coolant systems) have been made from all the Parties, although if no specific agreements between Parties have yet been identified. In order to officially establish collaboration, existing International Agreements can be used; however, the TBWG also strongly supports the establishment of direct official collaboration agreements between two (or more) Parties on specific R&D items as soon as possible.

A) Preparation and edition of the TBWG Report for the period of the ITER Transitional Arrangements
As foreseen in the TBWG Working Plan, the TBWG has prepared and edited in September 2005 a report concerning the present view of a coordinated Tests Blanket Program in ITER and covering the work performed by the present TBWG since its creation in September 2003.
The TBWG report has been distributed in October 2005 and is available on the “TBWG ftp server”. The writing of the report has been performed in the first half of 2005, the various chapters have been discussed and approved by TBWG during the TBWG-15 meeting and finalized in the following month.
The main contents of the report are the following: i) ITER boundary conditions & testing parameters; ii) ITER testing capabilities and testing objectives; iii) blanket development and corresponding TBMs proposed by Parties; iv) testing program by blanket concept (5 concepts having common R&D); v) test port cell boundary conditions and operations; vi) remote handling and Hot Cell issues; vii) general safety consideration; viii) technical specifications, QA and acceptance tests for TBMs, ix) preliminary view on licensing process; x) TBWG recommendations and future work proposals.
It is recalled that all Parties have identified, at least, two kinds of DEMO-relevant blanket for testing them in ITER in support of their breeding blankets development programs. Most of them are proposed for testing on day_one. The TBWG strategy is to have a selection of six TBMs (half-port size) among these proposals in the next few years based on future R&D results and Parties commitments.

B) Preparation and edition of TBMs Detailed Description Document (DDD)
In support to the TBM proposals summarized in the TBWG report, the Parties have prepared a DDD for each TBM that is candidate to installation in ITER on day_one. The TBWG has recommended the DDD structure, however the amount of information included in the DDD depends on their availability and therefore the choice has been left to the Parties. Typically, DDDs include TBM design and analyses, description of TBM associated systems, R&D results and planning, materials characteristics, fabrication and mounting procedure, etc…
Typically, for each TBM type, there is a series of TBMs (4 or more) to be used in the different ITER phases. In the DDDs, Parties have mostly addressed the Integral-TBM, whose installation is expected at the end of the first 10 years of ITER operation, with some preliminary description of the TBM to be installed on day_one.
All DDDs are available on the “TBWG ftp server” with the exception of the DDD of the Korea He-cooled Molten Lithium TBM that is not yet available. As a general comment, it can be said that the amount of information available in the various DDDs is quite different, reflecting the different levels of the various TBMs development. It is expected that DDDs will be continuously improved in the next few years until all needed information will be available.

C) Improvement of frame design, associated TBM replacement strategy, and shield penetrations issue
It is recalled that the port frames procurement is missing from the released ITER packaging. Responsibilities sharing between ITER Organization and Parties have not yet been defined. This point has to be clarified as soon as possible because it is an essential element for allowing the installation of TBMs at the beginning of ITER operation.
To avoid impact on ITER availability, TBMs replacements should occur during ITER scheduled shutdowns. TBWG has assumed to have a one-month shutdown each year of operation and a three-month shutdown between the D-D phase and the D-T phase. The available replacement time appears very low especially if all TBM need to be replaced at the same time.
Two maintenance strategies are possible, implying the procurement of either 1 or 2 frames per port. The 2-frames-per-port strategy (replacement of the whole port plug with a new one) could be interesting for quick TBM replacement. However, the storage capability in the ITER HC has to be checked. The drawback of the 2-frames-per-port strategy is that the 2 TBMs present in the port have to be replaced at the same time.
In case of the single-frame strategy, two design options are possible: i) replacement of the TBMs in the hot cell (initial reference option); ii) replacement of TBMs together with the back shield in the Hot Cell. The option with removable back shield needs a dismountable attachment of the shield to the frame (fastening bolt + lip seal). It reduces the replacement time compared to the first option but also reduces the available space for pipe penetrations and increases the amount of radio-waste.
In general, the “removable” backshield option is preferred because it offers more flexibility. However, it may be a concern for liquid-metal TBMs because the drain pipe cannot be located at the TBM bottom (as foreseen in present design), preventing the possibility of emergency draining fully performed by gravity. This point will be assessed in the near future.
Taking into account the assumption of having two half-port size TBMs per port, the layout of shield penetration was checked by ITER on the typical configuration of the EU HCLL-TBM. The conclusion is that it is acceptable, even in the case of the “removable shield” option, although it is quite tight. More detailed studies are still required. It was stressed that, in any case, the integration of any additional pipes will be very difficult. A preliminary review of penetration analysis for the different Parties proposals has also been performed by ITER on the basis of the documents prepared by the Parties for the TBWG report. Preliminary conclusions are that, for most proposals, the number of penetrations is acceptable but just at the limit of acceptability; for instance, the proposals of RF and CHN to test He-cooled ceramic breeder TBMs having a quarter-port size (in order to increase the number of tested TBMs) lead to too high shielding penetrations and become acceptable only if common feeding pipes are used (and then common coolant systems). The same considerations may apply to the proposals of having independent TBM sub-components.
This assessment clearly shows that the limitation to two TBMs per Test Port is also preferable from the point of view of the minimization of the number of penetrations through the shield.

D) Preliminary Parties R&D planning prior the TBM installation in ITER
Starting from the TBMs proposals described in the TBWG report, the Parties have made a preliminary assessment of the required R&D work program for each proposed TBMs up to installation in ITER on day_one, including some cost evaluations, comments on QA, and collaboration proposals.
China has confirmed the proposal of installing a Helium-Cooled Ceramic Breeder (HCCB) TBM (1/4 port size) and a Dual-Functional Lithium-Lead (DFLL) TBM (half-port size) and associated systems. The R&D for the two TBMs will be performed in parallel. For DFLL TBM, tests in EAST tokamak are planned. A cost of 100/200 MYuan has been estimated per each TBM type until TBM installation in ITER, including TBMs procurement and tests (but not special R&D referring to the corresponding DEMO).
EU has confirmed the proposal of installing a HCCB TBM (half-port size) and a He-Cooled Lithium-Lead (HCLL) TBM (half-port size) and associated systems. The R&D for the two TBMs will be performed in parallel. Several small-size TBM mock-ups have already been fabricated and will be tested in a near future. A cost assessment per each TBM type up to ITER installation, including TBMs procurement and test facilities, is planned for spring 2006.
Japan has confirmed the proposal of installing a Water-Cooled Ceramic Breeder (WCCB) TBM (half-port size) and a HCCB TBM (half-port size) and associated systems. The R&D for the two TBMs will be performed in parallel. TBMs fabrication are planned to start in 2010. No cost assessment has yet been performed.
Korea
has confirmed the proposal of installing a HCCB sub-component in another Party TBM (within the framework of a bilateral collaborative action that has not yet been discussed) and a He-Cooled Molten Lithium (HCML) TBM (half-port size) and associated systems. The required R&D will be started in 2006 and planned until installation in ITER on day_one. No cost assessment has yet been performed.
RF has confirmed the proposal of installing a HCCB TBM (half-port size) and a Self-Cooled Lithium (SCLi) TBM (half-port size) and associated systems. The R&D for the two TBMs will be performed in parallel. Small-size TBM mock-ups fabrication has already been started, the TBMs fabrication is planned to start 3 years before day_one. For SCLi TBM, validation of electrical insulating coating should be achieved within three years. A cost of about 50 M $ has been estimated for both TBMs until TBM installation in ITER. TBMs manufacturing is expected to be performed by RF Institutes.
US has confirmed the proposal of installing a HCCB sub-component in another Party TBM (within the framework of a bilateral collaborative action that has not yet been discussed) and a Dual-Coolant Lithium-Lead (DCLL) TBM (half-port size) and associated systems. Cost assessment and Work Program Breakdown are planned for spring 2006. US strongly promote collaboration between Parties in priority on He-technology, T-management issues and Be-coating of TBM first wall.
It has to be stressed that some Parties have indicated that they intend to use a structural material that is being developed by another Party (for instance, F82H by Japan and EUROFER by EU). In principle, such an assumption requires several official bilateral agreements between concerned Parties, for which the corresponding discussions have not yet been started.
For each proposed TBM, detailed R&D programs milestones and corresponding Work Program Breakdown will be defined in the next few months.
Finally, the TBWG recalled that a QA procedure has to be fully operational at least from the beginning of the design phase of the TBMs that have to be installed in ITER on day_one (which means in about 3-4 years).

E) Establishment of a procedure for TBM licensing
There are different possible routes to link TBM experiments to the ITER licensing process. Three cases have been identified:
- Case 1: the experiment is already extensively included in the ITER Preliminary Safety Report (RPrS); therefore, when the TBM will be installed in ITER, its licensing requires just a conformity review process; this case requires the largest analyses effort in the short term;
- Case 2: an intermediate case is when the TBM is included in the RPrS but with little details. The main characteristics of the TBM are however supposed to be anticipated. In this case, the licensing process will be specific for TBMs and the Safety Authority will review the safety dossier before installation of the TBM;
- Case 3: this case is when the TBM experiment has not been included in the RPrS; if a limited impact by this new experiment can be demonstrated, then this case will become the same as the second case; however, if there is a significant increase in safety impact, then a complete licensing process has to be performed again for the whole ITER machine before TBM installation.
For starting TBMs licensing process, it is required to identify as soon as possible who are the people involved in the TBM program and who is responsible for delivering documents and the final TBMs (both from ITER and from the Parties sides). The ITER Organization will be the operator of the facility and therefore the “legal” responsible entity (including TBM operations). CEA acts as IO representative before Parties signature and ratification of the ITER Agreement (expected mid-2007 at the earliest).
The TBWG agreed on the importance to include the TBMs in the RPrS and the ITER licensing process, if possible as “case  1” . Parties not able to furnish on time the required information could be included either as case 2 (Experiments with no extensive description in the RPrS) or, at a later stage, as case 3 (Unforeseen experiments).
To be included as “case  1” , the following roadmap has been defined:

i)             Establishment of a TBM Safety Working Group (performed in December 2005) including a contact person from each Party;

ii)            ITER Safety Group (ISG) will send to Contact Persons by January 2006 a preliminary document (revision of existing ITER document) including more details about which TBM-specific documents are required to the Parties (in line with requirements of other ITER components);

iii)           ISG will send templates to the Contact Persons by the end of February 2006 and will organize a meeting/workshop in Spring 2006;

iv)          Preliminary documents from Parties are expected to be available by July 2006.

TBWG noted that ITER Interim Project Leader (IPL) has to receive official delegation from Parties to include the TBMs in the ITER RPrS and therefore in a common licensing process with ITER.
Therefore, the TBWG proposed that the Parties willing to include their TBMs in the ITER licensing process, either as “case  1” or “case 2” , should ask it to IPL by writing a letter through the corresponding Participant Team Leader by March 15th, 2006.
The IPL agreed with the procedure proposed by the TBWG and presented it to the ITER Preparatory Committee. The procedure has then been endorsed by the IPC during its December 2005 meeting.

F) Preliminary assessment of the Parties TBM proposals
Based on the Parties proposals described in the TBWG report, the TBWG has launched a preliminary assessment of the various TBMs and DEMO studies. The objectives are to find the main differences between the various proposals and the main reasons of the performed choices. The assessment should allow identifying common issues between the proposals in view of evaluating potential common TBM testing (aiming to reduce the number of TBMs options).
Two groups have performed the work, one charged of solid breeder proposals and the other one of liquid breeders proposals. Extensive lists of parameters and characteristics have been produced by both groups.
Direct comparison of solid breeder proposals has shown that many similarities exist between them and that most issues on ceramic breeders and beryllium multiplier are common. In this case, the main difference concern structural materials and the corresponding design choices.
Liquid breeder proposals indicate common issues on Tritium management especially for proposals based on Lithium-Lead. MHD issues are common to most concepts and could allow common experiments.
The assessment is expected to continue in the next few months.

G) Identification of TBM needs in term of Codes and Standards and Quality Assurance
Structural Design Criteria (SDC) have been developed for structural design of ITER components. TBMs will have to refer to SDC-IC (In-vessel Components).
The ITER Code & Standard (C&S) will be based on SDC and additional requirements for fabrication, operation and maintenance. The ITER C&S will cover all processes such as material, design, fabrication, examination, testing, repairing, transportation, etc. The level of reliability to be reached is equivalent to ASME Sec. VIII or Sec. III Class-3. About 18 criteria are included in QA (organization, procurement, fabrication, testing, etc.). The question of conformity assessment is presently under discussion within IT. Concerning the specific case of TBM Systems, it is considered that TBMs are experimental components with no safety credit imposed. However, high reliability standard have to be imposed on TBM.
It was recalled that each Party is supposed to prepare Technical Specification Documents (TDS), however the IO will also participate to the definition of some specifications. It was noted that the preparation of the Procurement Specification Document (PSD) for the ITER VV has been very time consuming (more than 2 years).
ITER Team is preparing SDC for VV. The basis is existing design codes (e.g. RCC-MR for VV). In addition, code cases have to be considered for instance for material not described in the RCC-MR or new welds design. Concerning the time schedule for TBM R&D, it appears to be tight, especially considering the qualification procedure. It is expected that the TBWG will assess this point in detail. In any case, the same quality standard and reliability is asked for TBMs as for other ITER components. One shall note, in particular, that acceptance test (before and after installation) are performed before ITER day-1 and should take a time of about 1 year after TBM systems fabrication.

H) Identification of required Post-Irradiation Examinations (PIE) and of limitations in present ITER Hot Cell design.
The TBWG believes that PIE of the TBMs are an important part of the testing program. This kind of investigation will be mostly a complementary part of experiments of ITER testing. It provides additional information to validate TBM performance, optimize operating parameters, assess the condition of the TBM, evaluate the root causes of unanticipated failures (if any), reconstruct the tritium balance in conjunction with the results of direct measurements of T in the TBM materials, etc.
At present, no space is available in the Hot Cell for adding all the required PIE instrumentation. Current ITER Hot Cell scheme considers the irradiated TBMs as a waste object that has to be evacuated in a few months (limited storage space available).
It is commonly assumed that the transport of an activated full-size TBM back to the country of origin will be extremely difficult and expensive (although if, in any case, the final waste have to be recovered by the owner Party). One solution could be to include an Annex to the ITER Hot Cell for performing specific TBM PIE and/or samples preparation. It is also assumed that the owner Party can do PIE of miniature specimens and/or small TBM sub-components. Then, the main function of the TBM PIE Hot Cell should be to perform optical and other non-destructive examinations, extraction of specimen cassettes, and sectioning the TBMs into smaller, more manageable pieces and preparation of samples for shipment. In any case, the corresponding Remote Handling equipment is not available in the Hot Cell.
The TBWG has highlighted that such an enterprise can be a collaborative effort between the Parties and encouraged a prior agreement and official framework concerning the items of intellectual property to be established.
The presence of hot-cell facilities close to the ITER site could partially help to solve the PIE issues.

I) Further identification of the space issues related with the various ITER/TBM systems interfaces
As indicated in previous Progress Report, the TBWG has identified several interface issues between TBMs systems and ITER machine and buildings. These issues have been confirmed in more details in the present reporting period, in particular concerning the space availability. The main ones are the following:
w Test Port Cells: the impact of the confinement strategy for Port Cell has to be checked and, if necessary, countermeasures have to be taken. In fact, Port Cells are located out of the cryostat safety boundaries, and therefore need to be protected against excessive pressurization in case of failure of piping and circuit’s components located there. The consequences could be the need of double-wall piping and/or additional barriers that could require the availability of additional space. Moreover, the proliferation of component casks and large permanent devices in the port cell is in any case of concern for ITER. In fact, they will require temporary parking space during port plug removal and may affect the number of ports that can be maintained simultaneously.
w TWCS vault: According to the proposed layout of the 3 Port Cells, Coolant Systems (CSs) should be located in TCWS to feed the lines foreseen for each Port Cell. Taking into account the different strategy proposed by TBWG, at least five coolant systems could be present simultaneously in the TWCS vault. The assumed available area has a footprint of ( 16.6m x 7.3m ) with a height of 5m available for the integration of the CSs in the TCWS (space for access should be integrated as well). This place is sufficient for locating, at the most, four independent CSs. Moreover, in the recent TWCS-vault design the space for the installation of the components of the HCS is limited in vertical direction by pipes of the Heat Rejection System (HRS) and there are additional space restrictions caused by the requirement to have an emergency escape at the sidewalls of the vault. In particular, the envisaged possibility to use a crane for the assembly and maintenance operations of the CSs is precluded by the presence of the HRS piping.
It can be concluded that the place available in the TCWS is largely insufficient for the needs of the present Test-Blanket testing program.
w ITER Hot Cell port: TBMs replacement has to be performed during the ITER shutdown periods (assumed to be one month per year); in principle, one should ensure the possibility to replace all the six TBMs present in the three test ports. At present, only one port is foreseen in the Hot Cell to perform the dismantling operation, therefore the replacement of all TBMs in the same shutdown period (one month) appears unfeasible. One possible solution is to increase from one to three the number of the Hot Cell ports dedicated to TBMs maintenance (at least, one per each Test Port ).
Another solution is to replace the whole port plugs for entering directly in the Hot Cell (see above). The drawback is that this option requires more parking spaces in the Hot Cell and more powerful RH equipment. Moreover, the ITER Hot Cell may be used to replace irradiated TBMs, but, at present, it is not designed to allow TBM repair and/or Post-Irradiation Examinations (PIE). An increase of the available space in the Hot Cell appears compulsory (see PIE issue above).

·Main Conclusions and Future Plan

A very important and outstanding step has been achieved during the present reporting period, consisting in the preparation and distribution from Parties and ITER Team of the TBWG Report in October 2005. Parties have also prepared a Detailed Description Document for each TBM proposed for installation on day_one.
Although still incomplete, these documents have permitted to start proper discussions between Parties based on sound and defined proposals in order to identify still pending R&D issues, to make preliminary assessment of TBM/Interfaces with identification of some issues requiring immediate action on the ITER project, and to launch safety studies with the aim to include most of TBMs in the ITER licensing process (in particular, in the RPrS).
These documents will also be used to identify specific activities in the next few years in order to achieve detailed and complete DDDs before starting the final design of the TBMs to be installed in ITER on day_one.
On the basis of the TBWG Report, the ITER Interim Team Leader, with the endorsement of the IPC, has proposed to the TBWG to continue its activities until the establishment of a new framework for the Test Blanket Program at the end of 2006. During 2006, it was suggested to work especially on TBM Safety analyses and assessment of the necessary resources for TBM/ITER interfaces.
Based on the above recommendations, the TBWG has launched a procedure that should allow to include most of TBMs in the ITER licensing procedure, in particular in the ITER RPrS (as envelop cases). The procedure foresees to have available the most important TBM safety-related data (results from main safety analysis, TBM activation, waste) by July 2006. In order to apply such a procedure, Parties have to explicitly ask to ITER IPL the addition of their TBMs in the ITER RPrS. This request has to be received by Marc 15th, 2006.
The resources required for the different activities which must be performed by ITER Organization at all stages of testing, starting from quality control of the TBMs design and fabrication and finishing at the handling of the irradiated TBMs, are not currently included in the ITER budget. ITER costs associated with the TBM testing program must be recognized and addressed by Parties. The TBWG will address this item in the next few months.
Requirements of improvements and/or modifications of the ITER/TBM interfaces should be defined in details as soon as possible in order to be discussed in the framework of the ITER Design Review which is expected to start sometime in 2006.
 

 

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