- Email: [email protected]
Radwaste management aspects of the test blanket systems in ITER
G Model
ARTICLE IN PRESS
FUSION-8643; No. of Pages 5
Fusion Engineering and Design xxx (2016) xxx–xxx
Contents lists available at ScienceDirect
Fusion Engineering and Design journal homepage: www.elsevier.com/locate/fusengdes
Radwaste management aspects of the test blanket systems in ITER J.G. van der Laan a,∗ , D. Canas b , V. Chaudhari c , M. Iseli a , Y. Kawamura d , D.W. Lee e , P. Petit f , C.S. Pitcher a , D. Torcy a , D. Ugolini g , H. Zhang h a
ITER Organization, Route de Vinon sur Verdon, F-13067 Saint Paul Lez Durance, France CEA, DEN/DADN, centre de Saclay, F-91191 Gif-sur-Yvette cedex, France Institute for Plasma Research, Bhat, Gandhinagar 382428, India d Japan Atomic Energy Agency, Naka-shi, Ibaraki-ken 311-0193, Japan e Korea Atomic Energy Research Institute, Daejeon, Republic of Korea f European Commission, DG ENER, Brussels, Belgium g Fusion for Energy, Barcelona, Spain h China Nuclear Energy Industry Corporation, Beijing 100032, China b c
h i g h l i g h t s • • • • •
Test Blanket Systems are operated in ITER to test tritium breeding technologies. The in-vessel parts of TBS become radio-active during the ITER nuclear phase. For each TBM campaign the TBM, its shield and the Pipe Forests are removed. High tritium contents and novel materials are specific TBS radwaste features. A preliminary assessment confirmed RW routing, provided its proper conditioning.
a r t i c l e
i n f o
Article history: Received 31 August 2015 Received in revised form 28 February 2016 Accepted 2 March 2016 Available online xxx Keywords: ITER Nuclear Waste Characterization Decommissioning Test Blanket Systems
a b s t r a c t Test Blanket Systems (TBS) will be operated in ITER in order to prepare the next steps towards fusion power generation. After the initial operation in H/He plasmas, the introduction of D and T in ITER will mark the transition to nuclear operation. The significant fusion neutron production will give rise to nuclear heating and tritium breeding in the in-vessel part of the TBS. The management of the activated and tritiated structures of the TBS from operation in ITER is described. The TBS specific features like tritium breeding and power conversion at elevated temperatures, and the use of novel materials require a dedicated approach, which could be different to that needed for the other ITER equipment. © 2016 Published by Elsevier B.V.
1. Introduction Test Blanket Systems (TBS) will be operated in ITER in order to prepare the next steps towards fusion power generation, in particular the breeding of 3 H (or T) fuel from lithium compounds, see the overview by Giancarli et al. [1]. After the initial operation in H/He plasmas, the introduction of D and T in ITER will mark the transition to nuclear operation. ITER is an international research project
located in France and registered as ‘Installation nucléaire de base’ (INB-174) under French legislation. The fusion neutron production in ITER will allow tritium breeding in the Test Blanket Module (TBM) by neutron-capture in lithium compounds, but it will also lead to strongly activated structures. Depending on the materials composition short-lived and/or long lived radionuclides are formed, and the resulting radiation field limits human access for short term inspections and maintenance, but also causes the TBS components to be contaminated, and in the long term they need to be treated as radioactive waste (radwaste) requiring disposal in a suitable repository.
∗ Corresponding author. E-mail address: [email protected] (J.G. van der Laan). http://dx.doi.org/10.1016/j.fusengdes.2016.03.022 0920-3796/© 2016 Published by Elsevier B.V.
Please cite this article in press as: J.G. van der Laan, et al., Radwaste management aspects of the test blanket systems in ITER, Fusion Eng. Des. (2016), http://dx.doi.org/10.1016/j.fusengdes.2016.03.022
G Model FUSION-8643; No. of Pages 5 2
ARTICLE IN PRESS J.G. van der Laan et al. / Fusion Engineering and Design xxx (2016) xxx–xxx
Fig. 1. Simplified schematic diagram of a Test Blanket System integrated in the ITER facility. The TBSs are located in various rooms in the Tokamak and adjacent buildings, as visualized in Fig. 2.
each Long Term Maintenance period, the Port Plugs with TBMs are removed, and replaced by new sets. In the same period the AEU is refurbished. In case a specific TBM will not be operated for a certain campaign, its place can be filled by a “dummy-TBM”, which is a water-cooled stainless steel structure, as described by Kim et al. [2]. The TBS specific features like tritium breeding and power conversion at elevated temperatures, and the use of novel materials require a dedicated radwaste management approach, which could be different to that needed for the other ITER equipment, as reported by Rosanvallon et al. [3]. Most of the TBS (e.g. port plug, tritium extraction/removal system, liquid metal loop) are Protection Important Components (PIC). TBSs have components classified as Safety Important Class PIC/SIC1 and -2, as well as some Safety-Relevant and other non-PIC. Therefore the subject of most of this paper is a Protection Important Activity (PIA).
2. Management of the TBS radwaste
Fig. 2. Overall lay-out of the 6 Test Blanket Systems to be installed and operated in ITER.
Fig. 3. Simplified schedule of TBM Program in ITER (status 2014).
Each TBS is comprised of a TBM-Set and various ancillary equipment and systems, see the general overview [1], which is summarized as follows, see also Figs. 1 and 2: 1. A TBM-Set consists of the TBM and the TBM shield. Two TBMsets are placed in the TBM Frame, and form the TBM Port Plug (PP). 2. The Ancillary equipment and systems, depending on the specific TBS design [1], may consist of: 3. Ancillary Equipment Unit (AEU) 4. Primary Cooling System (PCS) (e.g. Helium or Water) 5. Lithium–Lead Cooling System (LLCS) 6. Helium Purge System (HPS) 7. Coolant Purification System (CPS) (linked to PCS) 8. Tritium Extraction/Removal System (TES) The TBM program preliminary foresees TBMs being operated in 4 campaigns over a 10 years period, starting from “2nd assembly phase”, conforming to the ITER Research Plan, see Fig. 3. At
The TBM Program is established in the framework of the ITER Project and is therefore part of the ITER project objectives, but the radwaste generated from the TBS operations has to be separately assessed and managed as the TBM Program was established as an additional program to the ITER Project. Indeed it was established by the ITER Council as an additional activity necessary to achieve the purpose of the ITER Organization pursuant to Article 3.1.d of the ITER Agreement established after the ITER Agreement. According to Article 14 of the ITER Agreement the ITER Organization shall observe applicable laws and regulations of the Host State in the fields of public and occupational health and safety, nuclear safety, radiation protection, licensing nuclear substances, environmental protection and protection from acts of malevolence. Consequently, the Host State has participated in the definition of the conditions of temporary storage and disposal of the TBS radwaste in France. The entity responsible for the disposals in France is Andra (French National Agency for the Radioactive Waste Management). Therefore the TBM-Program Committee has charged a Working Group (WG) to address technical, strategic and legal issues for the TBS radwaste management. The charges of this WG, involving the ITER Organization, the ITER Members (IMs) and the Agence ITER France (AIF), are: • Generation and homogenization of the data for the six TBSs needed to define the radwaste classification, and temporary storage conditions, and/or additional treatments; • Definition of models adopted to perform the estimation of the components tritium inventory and outgassing behavior; • Definition of the actions required from the disassembly of TBM and TBS up to the disposal; • Identification of the interfaces with other ITER systems such as the Hot Cell Facility, and ensure full compliance with the ITER license; • Identification of cost drivers for TBMs temporary storage and shipment to external facilities for Post-Irradiation Examinations, TBS rad-waste temporary storage, transportations and disposal; • Development of a detailed approach addressing detritiation and chemical treatments, and assessment of the impact on cost drivers, in support of TBM development.
Four categories of radwaste are considered in the ITER Project, see the more detailed descriptions of their routings up to disposal by Andra as given by Rosanvallon et al. [3], and Canas et al. [4]:
Please cite this article in press as: J.G. van der Laan, et al., Radwaste management aspects of the test blanket systems in ITER, Fusion Eng. Des. (2016), http://dx.doi.org/10.1016/j.fusengdes.2016.03.022
G Model
ARTICLE IN PRESS
FUSION-8643; No. of Pages 5
J.G. van der Laan et al. / Fusion Engineering and Design xxx (2016) xxx–xxx
3
1. Very Low-Level Waste (TFA). Solid TFA waste is managed in the PACB (Personnel access and control building). 2. Low and Intermediate-Level Short-Lived or type A waste (FMAVC). Solid FMA-VC waste is managed in the RWB (Radwaste building). 3. Intermediate-Level Long-Lived or type-B waste (MA-VL). Solid MA-VL waste is handled in the HCB (hot-cell building). 4. Purely Tritiated or PT-Waste (additional to the ANDRA categories 1–3). Solid PT-waste is managed in the Tritium Building and in the HCB. 3. Radwaste resulting from the TBM program 3.1. TBS activation and contamination sources The operation of the TBS will lead to activation of the structures facing the plasma: the 3 TBM Port-Plugs containing two TBM-sets each. Surface contamination of by deposited plasma facing materials (mainly Be, with some W) is to be anticipated. Though the TBM-shields are designed to minimize the neutron-flux at the portinterspace, the activation of the Pipe-Forest (PF), the Bio-Shield Plug (BSP), and other structures cannot be prevented. By circulation of the coolants, operation of the breeder purge line and TES, and circulation of Pb16Li, the tritium and activated corrosion products (ACP) will be distributed through the entire loops. Since the TES and CPS have a finite efficiency, there will be a gradual build-up of a radioactive inventory in nearly all of the TBS subsystems. At the same time tritium permeates through the structures of all subsystems and their connection lines. Since parts of the TBS are operated at temperatures up to ∼500 ◦ C, a small fraction of tritium permeates to the hosting rooms, which requires room ventilation. Consequently other equipment in the rooms will absorb tritium from the room atmosphere. Therefore, a significant fraction of the TBS radwaste is highly tritiated, and clearly necessitates an enhanced tritium removal from systems and hosting rooms. 3.2. TBS specific components and materials By their very nature the TBSs have specific components and materials, not used in any other ITER system, for example: • Ternary lithium oxide ceramics, used as solid 3 H breeder in the form of pebble-beds. Li4 SiO4 and Li2 TiO3 appear the favored compositions. • Beryllium as solid neutron multiplier in the form of pebble-beds. • Pb16Li eutectic alloy (liquid 3 H breeder and neutron multiplier), with melting temperature around 235 ◦ C. • Reduced Activation Ferritic-Martensitic (RAFM) steel, a 9Cr base steel with a “reduced activation” profile tailored to fusion environment and minimization of long term waste streams. • Graphite, a neutron reflector shaped as blocks or pebble-bed. • Lead for gamma-shielding, mainly in the BSP. • Boron Carbide for thermal neutron shielding either integrated in the TBM-shield or in the BSP. • Thermal insulator materials, for all TBS pipes and parts operated at high temperature, up to ∼500 ◦ C. • Getter & Storage beds for tritium in various molecular forms and concentrations, including molecular sieves. • Reductor and oxidation beds, or catalyzer columns, for chemical processing of tritiated gas flows. • Instrumentation and various types of sensors used to measure the TBS performance in high radiation field and tritiated environment. • Tritiated water: lowly tritiated water coolant, and highly tritiated water formed by oxidation process in the TES.
Fig. 4. Major activities during ITER Long Term Maintenance periods on TBSs, and their associated radwaste. For the port plugs, the TBM or parts of the TBM are shipped to the IMs facilities for PIE, and supposed to be disposed of by the IMs.
3.3. TBS RadWaste streams A preliminary inventory of the TBS radwaste stream has been established, based on detailed nuclear analyses for the 6 TBSs, their operational scheme, and the routing and classification given for the ITER Radwaste [3,4]. Every TBM campaign is followed by an exchange of the TBMSets, an action performed in the HCB. The TBMs are separated from their shield, and subsequently their shipment or partial shipment is prepared to export the parts to the IM’s domestic hot cell facilities for Post-Irradiation Examinations (PIE). For that purpose the “TBM cutting station” to be installed in the HCB allows the cutting of TBMs, and reduce the size and activity of the objects to be shipped. In addition a process for jacketing the transport object needs to be implemented, in order to prevent contamination of the HCB export function, the transport package and the import function at the Domestic PIE facility. The primary option is to have a stainless steel jacket which can be sealed by welding, or by means of a mechanical seal to be developed. Analyses are ongoing for the case where the remains of a cut TBM would be prepared for disposal at the Host State. Waste disposal schemes for objects composed of TBM structure and functional zones (breeder and beryllium beds) need to be developed. During the Long Term Maintenance (LTM) the AEU is maintained in the AEU Maintenance Area in the HCB. The resulting operational waste consists of replaced parts like filters, valves and sensors. All this waste is considered “operational waste”. Summarizing the resulting waste from each TBM campaign for each of the 3 ports is (see Fig. 4): 1. TBM-Shields, 1 Pipe Forest, and 1 Bio Shield Plug (current baseline), 2. the waste resulting from the TBM PP refurbishment operations and TBM shipment operations, and the non-shipped parts of TBMs, 3. the waste from refurbishing the AEU For the TBSs operating Pb16Li-loops it is an option to have the Pb16Li replaced by fresh material, and dispose of the Pb16Li used up to the previous test campaign. This waste would be considered “operational waste”. The generic waste routing for the Pb16Li is under development, and will most likely be managed though drainage into smaller stainless steel packages, and applying appropriate passivation measures, in order to be compatible with long term storage conditions at the Andra repositories. After the end of ITER lifetime the TBM frames are prepared for disposal, and also the Dummy-TBMs, except those not used. These
Please cite this article in press as: J.G. van der Laan, et al., Radwaste management aspects of the test blanket systems in ITER, Fusion Eng. Des. (2016), http://dx.doi.org/10.1016/j.fusengdes.2016.03.022
G Model FUSION-8643; No. of Pages 5
ARTICLE IN PRESS J.G. van der Laan et al. / Fusion Engineering and Design xxx (2016) xxx–xxx
4
parts are included in the declared ITER waste, as “Decommissioning Waste”. This waste stream also includes the common maintenance structures, and the various TBS supports fixed to the buildings. TBS decommissioning waste results from dismantling of all the ancillary systems, including • AEU & structure. • All Equipment outside of Port Cell (HCS/WCS, CPS, TES, and supporting structures). • Connection Pipes & Mountable Supports (TBS-CP). • Waste from Handling and Maintenance Operations, Refurbishments, Material Exports, Disassembly. • All I&C and other servicing equipment and components. Further working assumptions for the radwaste management considerations are that additional TBM’s, even of different designs, may be tested after the first 10 year period of the TBM Program. All the subsystems of the 6 TBSs will be dismantled after completion of the ITER operation: TBS Cooling Systems, PbLi-loops, TESs, AEU’s, and all the TBS Connection Pipes. The proper timing of the deactivation and dismantling of the TBS is being detailed. All TBS parts need to be compatible with confirmed routings for waste disposal in France [3,4]. For TBS specific waste such compatibility should be demonstrated prior to TBS/TBM operations, or be enabled with specific on-site treatments. Specific exchanges are on-going between the Host State, the IO, and the concerned IMs, in order to prepare for tri-lateral TBS RadWaste agreements. These exchanges should enable to agree on the predicted quantities of waste, the expected classification, required treatments, and the acceptance conditions in the final disposal. These values could still change as the design of the TBMs is conceptual today, and the TBS experimental campaigns in ITER will need being defined and detailed. For a large part of the TBS waste (a minimal 30% of the waste amount), tritium contamination and outgassing rate deserve particular attention. Specific additional treatments could be necessary. These elements are being consolidated between IO, IMs and the Host State on the basis of achieving common model calculations. Some TBS operational waste will probably require additional treatments, in particular in the hot cell building, taking into account the waste specificities (such as LiPb-alloy, Be contamination) and the Andra acceptance criteria. Be contamination is a common issue with ITER In-vessel components. During the licensing process, the waste inventories are assessed to demonstrate that all the waste produced by the facility are manageable from the production (on-site treatments and interim storage) to the off-site treatments, if any, and final disposal. 4. Integrated strategy For the development an integrated strategy for the future TBS radwaste management, the Working Group identified the following elements: • The list of TBS components forms the basis of the IMs declaration for the generation of radwaste, starting from the CATIA Bill-of-Material for the TBS Design. It results in a full list of components that will match with the structure of the ITER Plant Life Management system, the equipment locations (rooms) and their configuration towards the ITER plasma as neutron source. • Radioactive Inventory Estimate: nuclear analyses are performed to derive the components activation spectra, accounting for all isotopes, and adding the estimated 3 H inventories. • RadWaste Classification: the radwaste will be classified according to the guidelines for radwaste classification and segregation
by producers, as agreed between the IO and Host State, meeting the Andra acceptance criteria. • The RadWaste routing/logistics in the ITER facility can subsequently be detailed. The provisional radwaste declaration and classification forms the basis of the tri-lateral radwaste agreements. This allows estimation of funds for TBS nuclear operations in ITER. • Tracking of radioactive inventory build-up: after delivery and acceptance of the TBS, the component & Materials certificates will form the basis for further tracking of the TBSs radioactive inventory. It is foreseen that this inventory is periodically updated, based on actuals from ITER operations (feedback from neutronics measurements, actual activation measurements, feedback from tritium accountancy measurements and analyses, room monitors, etc.). This will allow a periodical review of the radwaste management plan and an update of the classifications, treatments, and routings (in particular the acceptance by the IO RadWaste process). • TBS RadWaste Acceptance: before the IO RW process accepts the TBS radwaste, it will have to be pre-characterized. Based on these measurements the IO will process the waste and prepare the packaging for transfer to Host State (to Andra sites or first to Intermed). The IO can then declare the type and quantity of waste accordingly. 5. Future activities The ITER facilities relevant for the radwaste management, like the hot cell, the radwaste and the personnel access and control buildings, are described in more detail by Rosanvallon et al. [3]. Related studies are found in [4–6]. The various TBS maintenance and refurbishment operations are described by Giancarli et al. [1]. It is evident that quite a number of TBS components may require a detritiation treatment. This will reduce the outgassing of the waste in the interim storage and disposal, which effluents are strictly limited in their licenses. Various options are considered to reduce the tritium inventories: • In-Tokamak: it is considered to keep the TBM as long as possible at operational (at least elevated) temperature after plasma shutdown, and keep extracting tritium from the loops. A dedicated Operational State “Outgassing” has been defined for the TBSs. It should be used any time prior to outages for inspections and maintenance. • Ex-Tokamak: currently ITER foresees a detritiation process for type B waste with a target of 95% efficiency, which for few TBS materials is still insufficient. For the other waste categories suitable detritiation treatments need to be explored. The process of TBS disassembly and dismantling needs to be more detailed, not only in safety and technical terms, but also in project management terms and phasing. During the deactivation phase the activated and contaminated TBS subsystems & parts will be disassembled, using the (RH) tools designed, and transferred to the RadWaste Process.
6. Conclusion The radwaste management aspects of the Test Blanket Systems to be tested in ITER have been identified and described by the dedicated Working Group of the ITER TBM Program Committee. A preliminary radwaste inventory has been established, based on detailed nuclear analyses for the 6 TBSs, their operational scheme, and the routing and classification available for the ITER Radwaste.
Please cite this article in press as: J.G. van der Laan, et al., Radwaste management aspects of the test blanket systems in ITER, Fusion Eng. Des. (2016), http://dx.doi.org/10.1016/j.fusengdes.2016.03.022
G Model FUSION-8643; No. of Pages 5
ARTICLE IN PRESS J.G. van der Laan et al. / Fusion Engineering and Design xxx (2016) xxx–xxx
TBS specific materials and issues for their disposal as radwaste have been identified, and a provisional declaration has been discussed with the Andra, the responsible entity for the final disposal in France, the ITER Host State. No showstoppers have been identified for this final disposal, provided that appropriate treatments are performed, including detritiation and/or passivation, and that additional shielding, and suitable packaging is ensured. The TBS radwaste that cannot be sent directly to the final disposal, because of tritium content or outgassing rates, may be sent after appropriate treatments if required, including detritiation to an interim storage developed by the Host State. A structure for the TBS radwaste declaration, validation, monitoring, routing and acceptance has been developed, which will form the basis for the TBS radwaste agreements to be established between the five ITER Members being the TBS owners, the IO as the nuclear operator and France as Host State for the ITER project.
5
Acknowledgments The views and opinions expressed herein do not necessarily reflect those of the ITER Organization, those of the ITER Members, and the Host State. References [1] L.M. Giancarli, et al., Progress and Challenges of the ITER TBM Program from the I O-CT Perspective, this conference. [2] B.Y. Kim, et al., Design and Manufacture Feasibility of ITER TBM Frame and Dummy TBMs, this conference. [3] S. Rosanvallon, et al., Waste Management Plans for ITER, this conference. [4] D. Canas, et al., Classification methodology for tritiated waste requiring interim storage, Fusion Sci. Technol. 67 (2015) 290–295. [5] C. Decanis, K. Liger, J. Pamela, D. Canas, Methodology to prepare the decommissioning and the radwaste management of the ITER Test Blanket Systems Decommissioning and Remote Systems Meeting, Reno, US (2014). [6] J. Pamela, et al., ITER tritiated waste management by the Host state and first lessons learned for fusion development, Fusion Eng. Des. 89 (2014) 2001–2007.
Please cite this article in press as: J.G. van der Laan, et al., Radwaste management aspects of the test blanket systems in ITER, Fusion Eng. Des. (2016), http://dx.doi.org/10.1016/j.fusengdes.2016.03.022
ARTICLE IN PRESS
FUSION-8643; No. of Pages 5
Fusion Engineering and Design xxx (2016) xxx–xxx
Contents lists available at ScienceDirect
Fusion Engineering and Design journal homepage: www.elsevier.com/locate/fusengdes
Radwaste management aspects of the test blanket systems in ITER J.G. van der Laan a,∗ , D. Canas b , V. Chaudhari c , M. Iseli a , Y. Kawamura d , D.W. Lee e , P. Petit f , C.S. Pitcher a , D. Torcy a , D. Ugolini g , H. Zhang h a
ITER Organization, Route de Vinon sur Verdon, F-13067 Saint Paul Lez Durance, France CEA, DEN/DADN, centre de Saclay, F-91191 Gif-sur-Yvette cedex, France Institute for Plasma Research, Bhat, Gandhinagar 382428, India d Japan Atomic Energy Agency, Naka-shi, Ibaraki-ken 311-0193, Japan e Korea Atomic Energy Research Institute, Daejeon, Republic of Korea f European Commission, DG ENER, Brussels, Belgium g Fusion for Energy, Barcelona, Spain h China Nuclear Energy Industry Corporation, Beijing 100032, China b c
h i g h l i g h t s • • • • •
Test Blanket Systems are operated in ITER to test tritium breeding technologies. The in-vessel parts of TBS become radio-active during the ITER nuclear phase. For each TBM campaign the TBM, its shield and the Pipe Forests are removed. High tritium contents and novel materials are specific TBS radwaste features. A preliminary assessment confirmed RW routing, provided its proper conditioning.
a r t i c l e
i n f o
Article history: Received 31 August 2015 Received in revised form 28 February 2016 Accepted 2 March 2016 Available online xxx Keywords: ITER Nuclear Waste Characterization Decommissioning Test Blanket Systems
a b s t r a c t Test Blanket Systems (TBS) will be operated in ITER in order to prepare the next steps towards fusion power generation. After the initial operation in H/He plasmas, the introduction of D and T in ITER will mark the transition to nuclear operation. The significant fusion neutron production will give rise to nuclear heating and tritium breeding in the in-vessel part of the TBS. The management of the activated and tritiated structures of the TBS from operation in ITER is described. The TBS specific features like tritium breeding and power conversion at elevated temperatures, and the use of novel materials require a dedicated approach, which could be different to that needed for the other ITER equipment. © 2016 Published by Elsevier B.V.
1. Introduction Test Blanket Systems (TBS) will be operated in ITER in order to prepare the next steps towards fusion power generation, in particular the breeding of 3 H (or T) fuel from lithium compounds, see the overview by Giancarli et al. [1]. After the initial operation in H/He plasmas, the introduction of D and T in ITER will mark the transition to nuclear operation. ITER is an international research project
located in France and registered as ‘Installation nucléaire de base’ (INB-174) under French legislation. The fusion neutron production in ITER will allow tritium breeding in the Test Blanket Module (TBM) by neutron-capture in lithium compounds, but it will also lead to strongly activated structures. Depending on the materials composition short-lived and/or long lived radionuclides are formed, and the resulting radiation field limits human access for short term inspections and maintenance, but also causes the TBS components to be contaminated, and in the long term they need to be treated as radioactive waste (radwaste) requiring disposal in a suitable repository.
∗ Corresponding author. E-mail address: [email protected] (J.G. van der Laan). http://dx.doi.org/10.1016/j.fusengdes.2016.03.022 0920-3796/© 2016 Published by Elsevier B.V.
Please cite this article in press as: J.G. van der Laan, et al., Radwaste management aspects of the test blanket systems in ITER, Fusion Eng. Des. (2016), http://dx.doi.org/10.1016/j.fusengdes.2016.03.022
G Model FUSION-8643; No. of Pages 5 2
ARTICLE IN PRESS J.G. van der Laan et al. / Fusion Engineering and Design xxx (2016) xxx–xxx
Fig. 1. Simplified schematic diagram of a Test Blanket System integrated in the ITER facility. The TBSs are located in various rooms in the Tokamak and adjacent buildings, as visualized in Fig. 2.
each Long Term Maintenance period, the Port Plugs with TBMs are removed, and replaced by new sets. In the same period the AEU is refurbished. In case a specific TBM will not be operated for a certain campaign, its place can be filled by a “dummy-TBM”, which is a water-cooled stainless steel structure, as described by Kim et al. [2]. The TBS specific features like tritium breeding and power conversion at elevated temperatures, and the use of novel materials require a dedicated radwaste management approach, which could be different to that needed for the other ITER equipment, as reported by Rosanvallon et al. [3]. Most of the TBS (e.g. port plug, tritium extraction/removal system, liquid metal loop) are Protection Important Components (PIC). TBSs have components classified as Safety Important Class PIC/SIC1 and -2, as well as some Safety-Relevant and other non-PIC. Therefore the subject of most of this paper is a Protection Important Activity (PIA).
2. Management of the TBS radwaste
Fig. 2. Overall lay-out of the 6 Test Blanket Systems to be installed and operated in ITER.
Fig. 3. Simplified schedule of TBM Program in ITER (status 2014).
Each TBS is comprised of a TBM-Set and various ancillary equipment and systems, see the general overview [1], which is summarized as follows, see also Figs. 1 and 2: 1. A TBM-Set consists of the TBM and the TBM shield. Two TBMsets are placed in the TBM Frame, and form the TBM Port Plug (PP). 2. The Ancillary equipment and systems, depending on the specific TBS design [1], may consist of: 3. Ancillary Equipment Unit (AEU) 4. Primary Cooling System (PCS) (e.g. Helium or Water) 5. Lithium–Lead Cooling System (LLCS) 6. Helium Purge System (HPS) 7. Coolant Purification System (CPS) (linked to PCS) 8. Tritium Extraction/Removal System (TES) The TBM program preliminary foresees TBMs being operated in 4 campaigns over a 10 years period, starting from “2nd assembly phase”, conforming to the ITER Research Plan, see Fig. 3. At
The TBM Program is established in the framework of the ITER Project and is therefore part of the ITER project objectives, but the radwaste generated from the TBS operations has to be separately assessed and managed as the TBM Program was established as an additional program to the ITER Project. Indeed it was established by the ITER Council as an additional activity necessary to achieve the purpose of the ITER Organization pursuant to Article 3.1.d of the ITER Agreement established after the ITER Agreement. According to Article 14 of the ITER Agreement the ITER Organization shall observe applicable laws and regulations of the Host State in the fields of public and occupational health and safety, nuclear safety, radiation protection, licensing nuclear substances, environmental protection and protection from acts of malevolence. Consequently, the Host State has participated in the definition of the conditions of temporary storage and disposal of the TBS radwaste in France. The entity responsible for the disposals in France is Andra (French National Agency for the Radioactive Waste Management). Therefore the TBM-Program Committee has charged a Working Group (WG) to address technical, strategic and legal issues for the TBS radwaste management. The charges of this WG, involving the ITER Organization, the ITER Members (IMs) and the Agence ITER France (AIF), are: • Generation and homogenization of the data for the six TBSs needed to define the radwaste classification, and temporary storage conditions, and/or additional treatments; • Definition of models adopted to perform the estimation of the components tritium inventory and outgassing behavior; • Definition of the actions required from the disassembly of TBM and TBS up to the disposal; • Identification of the interfaces with other ITER systems such as the Hot Cell Facility, and ensure full compliance with the ITER license; • Identification of cost drivers for TBMs temporary storage and shipment to external facilities for Post-Irradiation Examinations, TBS rad-waste temporary storage, transportations and disposal; • Development of a detailed approach addressing detritiation and chemical treatments, and assessment of the impact on cost drivers, in support of TBM development.
Four categories of radwaste are considered in the ITER Project, see the more detailed descriptions of their routings up to disposal by Andra as given by Rosanvallon et al. [3], and Canas et al. [4]:
Please cite this article in press as: J.G. van der Laan, et al., Radwaste management aspects of the test blanket systems in ITER, Fusion Eng. Des. (2016), http://dx.doi.org/10.1016/j.fusengdes.2016.03.022
G Model
ARTICLE IN PRESS
FUSION-8643; No. of Pages 5
J.G. van der Laan et al. / Fusion Engineering and Design xxx (2016) xxx–xxx
3
1. Very Low-Level Waste (TFA). Solid TFA waste is managed in the PACB (Personnel access and control building). 2. Low and Intermediate-Level Short-Lived or type A waste (FMAVC). Solid FMA-VC waste is managed in the RWB (Radwaste building). 3. Intermediate-Level Long-Lived or type-B waste (MA-VL). Solid MA-VL waste is handled in the HCB (hot-cell building). 4. Purely Tritiated or PT-Waste (additional to the ANDRA categories 1–3). Solid PT-waste is managed in the Tritium Building and in the HCB. 3. Radwaste resulting from the TBM program 3.1. TBS activation and contamination sources The operation of the TBS will lead to activation of the structures facing the plasma: the 3 TBM Port-Plugs containing two TBM-sets each. Surface contamination of by deposited plasma facing materials (mainly Be, with some W) is to be anticipated. Though the TBM-shields are designed to minimize the neutron-flux at the portinterspace, the activation of the Pipe-Forest (PF), the Bio-Shield Plug (BSP), and other structures cannot be prevented. By circulation of the coolants, operation of the breeder purge line and TES, and circulation of Pb16Li, the tritium and activated corrosion products (ACP) will be distributed through the entire loops. Since the TES and CPS have a finite efficiency, there will be a gradual build-up of a radioactive inventory in nearly all of the TBS subsystems. At the same time tritium permeates through the structures of all subsystems and their connection lines. Since parts of the TBS are operated at temperatures up to ∼500 ◦ C, a small fraction of tritium permeates to the hosting rooms, which requires room ventilation. Consequently other equipment in the rooms will absorb tritium from the room atmosphere. Therefore, a significant fraction of the TBS radwaste is highly tritiated, and clearly necessitates an enhanced tritium removal from systems and hosting rooms. 3.2. TBS specific components and materials By their very nature the TBSs have specific components and materials, not used in any other ITER system, for example: • Ternary lithium oxide ceramics, used as solid 3 H breeder in the form of pebble-beds. Li4 SiO4 and Li2 TiO3 appear the favored compositions. • Beryllium as solid neutron multiplier in the form of pebble-beds. • Pb16Li eutectic alloy (liquid 3 H breeder and neutron multiplier), with melting temperature around 235 ◦ C. • Reduced Activation Ferritic-Martensitic (RAFM) steel, a 9Cr base steel with a “reduced activation” profile tailored to fusion environment and minimization of long term waste streams. • Graphite, a neutron reflector shaped as blocks or pebble-bed. • Lead for gamma-shielding, mainly in the BSP. • Boron Carbide for thermal neutron shielding either integrated in the TBM-shield or in the BSP. • Thermal insulator materials, for all TBS pipes and parts operated at high temperature, up to ∼500 ◦ C. • Getter & Storage beds for tritium in various molecular forms and concentrations, including molecular sieves. • Reductor and oxidation beds, or catalyzer columns, for chemical processing of tritiated gas flows. • Instrumentation and various types of sensors used to measure the TBS performance in high radiation field and tritiated environment. • Tritiated water: lowly tritiated water coolant, and highly tritiated water formed by oxidation process in the TES.
Fig. 4. Major activities during ITER Long Term Maintenance periods on TBSs, and their associated radwaste. For the port plugs, the TBM or parts of the TBM are shipped to the IMs facilities for PIE, and supposed to be disposed of by the IMs.
3.3. TBS RadWaste streams A preliminary inventory of the TBS radwaste stream has been established, based on detailed nuclear analyses for the 6 TBSs, their operational scheme, and the routing and classification given for the ITER Radwaste [3,4]. Every TBM campaign is followed by an exchange of the TBMSets, an action performed in the HCB. The TBMs are separated from their shield, and subsequently their shipment or partial shipment is prepared to export the parts to the IM’s domestic hot cell facilities for Post-Irradiation Examinations (PIE). For that purpose the “TBM cutting station” to be installed in the HCB allows the cutting of TBMs, and reduce the size and activity of the objects to be shipped. In addition a process for jacketing the transport object needs to be implemented, in order to prevent contamination of the HCB export function, the transport package and the import function at the Domestic PIE facility. The primary option is to have a stainless steel jacket which can be sealed by welding, or by means of a mechanical seal to be developed. Analyses are ongoing for the case where the remains of a cut TBM would be prepared for disposal at the Host State. Waste disposal schemes for objects composed of TBM structure and functional zones (breeder and beryllium beds) need to be developed. During the Long Term Maintenance (LTM) the AEU is maintained in the AEU Maintenance Area in the HCB. The resulting operational waste consists of replaced parts like filters, valves and sensors. All this waste is considered “operational waste”. Summarizing the resulting waste from each TBM campaign for each of the 3 ports is (see Fig. 4): 1. TBM-Shields, 1 Pipe Forest, and 1 Bio Shield Plug (current baseline), 2. the waste resulting from the TBM PP refurbishment operations and TBM shipment operations, and the non-shipped parts of TBMs, 3. the waste from refurbishing the AEU For the TBSs operating Pb16Li-loops it is an option to have the Pb16Li replaced by fresh material, and dispose of the Pb16Li used up to the previous test campaign. This waste would be considered “operational waste”. The generic waste routing for the Pb16Li is under development, and will most likely be managed though drainage into smaller stainless steel packages, and applying appropriate passivation measures, in order to be compatible with long term storage conditions at the Andra repositories. After the end of ITER lifetime the TBM frames are prepared for disposal, and also the Dummy-TBMs, except those not used. These
Please cite this article in press as: J.G. van der Laan, et al., Radwaste management aspects of the test blanket systems in ITER, Fusion Eng. Des. (2016), http://dx.doi.org/10.1016/j.fusengdes.2016.03.022
G Model FUSION-8643; No. of Pages 5
ARTICLE IN PRESS J.G. van der Laan et al. / Fusion Engineering and Design xxx (2016) xxx–xxx
4
parts are included in the declared ITER waste, as “Decommissioning Waste”. This waste stream also includes the common maintenance structures, and the various TBS supports fixed to the buildings. TBS decommissioning waste results from dismantling of all the ancillary systems, including • AEU & structure. • All Equipment outside of Port Cell (HCS/WCS, CPS, TES, and supporting structures). • Connection Pipes & Mountable Supports (TBS-CP). • Waste from Handling and Maintenance Operations, Refurbishments, Material Exports, Disassembly. • All I&C and other servicing equipment and components. Further working assumptions for the radwaste management considerations are that additional TBM’s, even of different designs, may be tested after the first 10 year period of the TBM Program. All the subsystems of the 6 TBSs will be dismantled after completion of the ITER operation: TBS Cooling Systems, PbLi-loops, TESs, AEU’s, and all the TBS Connection Pipes. The proper timing of the deactivation and dismantling of the TBS is being detailed. All TBS parts need to be compatible with confirmed routings for waste disposal in France [3,4]. For TBS specific waste such compatibility should be demonstrated prior to TBS/TBM operations, or be enabled with specific on-site treatments. Specific exchanges are on-going between the Host State, the IO, and the concerned IMs, in order to prepare for tri-lateral TBS RadWaste agreements. These exchanges should enable to agree on the predicted quantities of waste, the expected classification, required treatments, and the acceptance conditions in the final disposal. These values could still change as the design of the TBMs is conceptual today, and the TBS experimental campaigns in ITER will need being defined and detailed. For a large part of the TBS waste (a minimal 30% of the waste amount), tritium contamination and outgassing rate deserve particular attention. Specific additional treatments could be necessary. These elements are being consolidated between IO, IMs and the Host State on the basis of achieving common model calculations. Some TBS operational waste will probably require additional treatments, in particular in the hot cell building, taking into account the waste specificities (such as LiPb-alloy, Be contamination) and the Andra acceptance criteria. Be contamination is a common issue with ITER In-vessel components. During the licensing process, the waste inventories are assessed to demonstrate that all the waste produced by the facility are manageable from the production (on-site treatments and interim storage) to the off-site treatments, if any, and final disposal. 4. Integrated strategy For the development an integrated strategy for the future TBS radwaste management, the Working Group identified the following elements: • The list of TBS components forms the basis of the IMs declaration for the generation of radwaste, starting from the CATIA Bill-of-Material for the TBS Design. It results in a full list of components that will match with the structure of the ITER Plant Life Management system, the equipment locations (rooms) and their configuration towards the ITER plasma as neutron source. • Radioactive Inventory Estimate: nuclear analyses are performed to derive the components activation spectra, accounting for all isotopes, and adding the estimated 3 H inventories. • RadWaste Classification: the radwaste will be classified according to the guidelines for radwaste classification and segregation
by producers, as agreed between the IO and Host State, meeting the Andra acceptance criteria. • The RadWaste routing/logistics in the ITER facility can subsequently be detailed. The provisional radwaste declaration and classification forms the basis of the tri-lateral radwaste agreements. This allows estimation of funds for TBS nuclear operations in ITER. • Tracking of radioactive inventory build-up: after delivery and acceptance of the TBS, the component & Materials certificates will form the basis for further tracking of the TBSs radioactive inventory. It is foreseen that this inventory is periodically updated, based on actuals from ITER operations (feedback from neutronics measurements, actual activation measurements, feedback from tritium accountancy measurements and analyses, room monitors, etc.). This will allow a periodical review of the radwaste management plan and an update of the classifications, treatments, and routings (in particular the acceptance by the IO RadWaste process). • TBS RadWaste Acceptance: before the IO RW process accepts the TBS radwaste, it will have to be pre-characterized. Based on these measurements the IO will process the waste and prepare the packaging for transfer to Host State (to Andra sites or first to Intermed). The IO can then declare the type and quantity of waste accordingly. 5. Future activities The ITER facilities relevant for the radwaste management, like the hot cell, the radwaste and the personnel access and control buildings, are described in more detail by Rosanvallon et al. [3]. Related studies are found in [4–6]. The various TBS maintenance and refurbishment operations are described by Giancarli et al. [1]. It is evident that quite a number of TBS components may require a detritiation treatment. This will reduce the outgassing of the waste in the interim storage and disposal, which effluents are strictly limited in their licenses. Various options are considered to reduce the tritium inventories: • In-Tokamak: it is considered to keep the TBM as long as possible at operational (at least elevated) temperature after plasma shutdown, and keep extracting tritium from the loops. A dedicated Operational State “Outgassing” has been defined for the TBSs. It should be used any time prior to outages for inspections and maintenance. • Ex-Tokamak: currently ITER foresees a detritiation process for type B waste with a target of 95% efficiency, which for few TBS materials is still insufficient. For the other waste categories suitable detritiation treatments need to be explored. The process of TBS disassembly and dismantling needs to be more detailed, not only in safety and technical terms, but also in project management terms and phasing. During the deactivation phase the activated and contaminated TBS subsystems & parts will be disassembled, using the (RH) tools designed, and transferred to the RadWaste Process.
6. Conclusion The radwaste management aspects of the Test Blanket Systems to be tested in ITER have been identified and described by the dedicated Working Group of the ITER TBM Program Committee. A preliminary radwaste inventory has been established, based on detailed nuclear analyses for the 6 TBSs, their operational scheme, and the routing and classification available for the ITER Radwaste.
Please cite this article in press as: J.G. van der Laan, et al., Radwaste management aspects of the test blanket systems in ITER, Fusion Eng. Des. (2016), http://dx.doi.org/10.1016/j.fusengdes.2016.03.022
G Model FUSION-8643; No. of Pages 5
ARTICLE IN PRESS J.G. van der Laan et al. / Fusion Engineering and Design xxx (2016) xxx–xxx
TBS specific materials and issues for their disposal as radwaste have been identified, and a provisional declaration has been discussed with the Andra, the responsible entity for the final disposal in France, the ITER Host State. No showstoppers have been identified for this final disposal, provided that appropriate treatments are performed, including detritiation and/or passivation, and that additional shielding, and suitable packaging is ensured. The TBS radwaste that cannot be sent directly to the final disposal, because of tritium content or outgassing rates, may be sent after appropriate treatments if required, including detritiation to an interim storage developed by the Host State. A structure for the TBS radwaste declaration, validation, monitoring, routing and acceptance has been developed, which will form the basis for the TBS radwaste agreements to be established between the five ITER Members being the TBS owners, the IO as the nuclear operator and France as Host State for the ITER project.
5
Acknowledgments The views and opinions expressed herein do not necessarily reflect those of the ITER Organization, those of the ITER Members, and the Host State. References [1] L.M. Giancarli, et al., Progress and Challenges of the ITER TBM Program from the I O-CT Perspective, this conference. [2] B.Y. Kim, et al., Design and Manufacture Feasibility of ITER TBM Frame and Dummy TBMs, this conference. [3] S. Rosanvallon, et al., Waste Management Plans for ITER, this conference. [4] D. Canas, et al., Classification methodology for tritiated waste requiring interim storage, Fusion Sci. Technol. 67 (2015) 290–295. [5] C. Decanis, K. Liger, J. Pamela, D. Canas, Methodology to prepare the decommissioning and the radwaste management of the ITER Test Blanket Systems Decommissioning and Remote Systems Meeting, Reno, US (2014). [6] J. Pamela, et al., ITER tritiated waste management by the Host state and first lessons learned for fusion development, Fusion Eng. Des. 89 (2014) 2001–2007.
Please cite this article in press as: J.G. van der Laan, et al., Radwaste management aspects of the test blanket systems in ITER, Fusion Eng. Des. (2016), http://dx.doi.org/10.1016/j.fusengdes.2016.03.022