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B. J. Merrill 1 , L.C. Cadwallader 1 , C. Wong 2

Status of DCLL TBM Safety Documentation Containing RPrS Information. Presented at: FNST Meeting UCLA, August 18 th -20 th. 1. 2. B. J. Merrill 1 , L.C. Cadwallader 1 , C. Wong 2. Overview. Describe RPrS information available in existing DCLL TBS safety documentation

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B. J. Merrill 1 , L.C. Cadwallader 1 , C. Wong 2

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  1. Status of DCLL TBM Safety Documentation Containing RPrS Information Presented at: FNST Meeting UCLA, August 18th -20th 1 2 B. J. Merrill1, L.C. Cadwallader1, C. Wong2

  2. Overview • Describe RPrS information available in existing DCLL TBS safety documentation • Present ITER IO RPrS input request and comment on if this information is available for the DCLL TBS. • Discuss issues related to giving the required data in a format and at a level of detail that fits ITER IO requirements and schedule • Present conclusions

  3. DCLL Safety Documents Containing RPrS Information *The DDD has not been updated, and an update is not planned prior to February 2010 • Safety section of the Dual Coolant Pb-17Li (DCLL) TBM Design Description Document (DDD) – GA-C25027 Rev. 3, Nov. 15, 2005,* contains: System description, operational tritium releases, tritium inventory, breeder material radioactive inventory, structural material radioactive inventory, chemical energy and hydrogen sources, nuclear energy sources, accident analyses, evaluation of accidental radiological releases (all in GSSR format) • Failure Modes and Effects Analysis (FMEA) for the US DCLL TBM – INL/EXT-07-13115, Aug., 2007, contains: Identifies components of the DCLL Test Blanket Systems, estimates component failure rates, identifies and classifies postulated initiating events (PIEs), gives estimates of component repair times • Occupational Radiation Exposure Analysis of the US DCLL TBM, INL/EXT-07-13073, Aug., 2007, contains: Anticipated maintenance activities, radioactive source terms, predicted worker dose rates, and annual occupation radiation exposure estimates

  4. TBM Program Contributions to RPrS Urgent information to be delivered in September 2009 (preliminary level): a) The maximum expected operational releases have to be identified qualitatively and quantitatively for T, ACP and chemicals. Expected coolant and chemical releases have to be identified. – T2 operational release in DDD. ACP or chemical releases do not occur during operation, but may happen during maintenance or accident conditions. • List of all TBS components (to be available as soon as possible, even before September) and their preliminary (SIC, seismic, etc.) classification (to be confirmed later). (SIC – safety importance class – component is one that the performs a safety function, such as radioactive confinement, radioactive monitoring, plasma power termination, chemical or nuclear heat removal, fire suppression, etc)– Component listing in TBM DDD (Section 2.2.3) and FMEA report, but neither a safety (SIC), or seismic (functional) analysis has been performed to date. • Definition of the main interfaces with other relevant ITER systems (e.g., Tritium Plant)– Available in Interface Panel Report (A. Ying), and Appendix A of DCLL TBM DDD d) Maximum expected Tritium inventories in all systems and components (e.g., cooling systems, purge gas systems, liquid metal systems,…) - Available in TBM DDD e) Maximum expected Activation Inventories in all systems and components – Available in TBM DDD and ORE report

  5. TBM Program Contributions to RPrS (cont.) f) Maximum expected dose rates in the various locations of the TBS components (port cell, CCs locations, Hot Cell,…) – Available in TBM ORE (except Hot Cell), Hot cell dose rate estimate available in TBM Post Irradiation Study (A. Ying). • Waste management: all new elements (compared to the elements listed for ITER) shall be identified and their management outline has to be described in chapter 11 of the RPrS A Waste Management Plan has not been developed for the DCLL TBS Further required information needed by the end of October 2009: 1) TBS conceptual design (“envelope design” for components not fully defined yet) - Available in DCLL TBM DDD 2) Description of the operational status of the various TBS components with relation with the status of ITER (pulses, short and long shutdowns, stand-by, …) Operation of DCLL TBS appears throughout the DDD (Section 2.2.2.5&6), but has not been written coherently. The FMEA also has an overview of the DCLL TBS operation for typical ITER pulses. • Results of the main safety analyses. Most of the analyses are probably available but, for each TBS, they need to be collected in a unique coherent set and checked. Available in DCLL TBM DDD. • Identification of the TBSs components that have to be classified “SIC for confinement”. SIC or any other functional analyses have not been performed for the DCLL TBS

  6. Equatorial Port DCLL TBM General Arrangement Pipe well TBM frame Assembly AEU AEU Components Equatorial Port Inner Space Area Bio-Shield Plug Shielding TBM Assembly Vacuum Vessel

  7. DCLL Helium Loops (AEU) Layout Vault TBM Helium AEU Not optimized and not all piping thermal Insulations are indicated

  8. DCLL TBM Nuclear Parameters from Detailed 3-D Calculations • Tritium generation rate in the PbLi is 4.19x10-7 g/sduring a 500 MW D-T pulse • For the planned 3000 pulses per year annual tritium production in TBM is 0.53 g/year • Tritium production in the Be PFC is 1.04x10-3 g/year • Peak cumulative end-of-life (after 0.3 MWa/m2)damage in FW is3.67 dpaand He production is50.9 He appm Total TBM thermal power is 0.614 MW (0.24 MW surface heat + 0.374 MW volumetric nuclear heating) This is recent information not available in DCLL DDD.

  9. TBM Decay Heat from DCLL DDD • At shutdown, the total TBM decay heat is ~22 kW • Contributions are: 4 kW from the F82H structure, 15 kW from Pb-17Li (primarily from Pb-207m), and 3 kW from SiC insert • The decay heat levels after 1 hour, 1 day, 1 year are: 3.5 kW, 1 kW, 0.1 kW, respectively.

  10. TBM Activation Inventories from DCLL DDD • At shutdown, the total TBM activity is 2.44 MCi (3.1 MCi including PbLi AES) • Contribution is 0.75 MCi from the structure, 1.54 MCi from Pb-17Li (2.2 MCi including PbLi AES), and 0.15 MCi from SiC insert • PbLi and SiC isotopes rapidly decay resulting in a total of 0.74 MCi after 60 s • The TBM waste disposal rating (WDR, a function of the level long-term activation) is << 1 • The main contributors in F82H structure: Nb-94, Mn-53, Ni-59, and Nb-91 • In Pb-17Li the main contributor is the Pb-205 • C-14 and Be-10 are the main contributors in the SiC insert.

  11. Tritium Release and Inventory Predictions • For a tritium generation rate in the PbLi of 2.33 g/year (larger TBM, 1-D neutronics => conservative numbers) • For a FS permeator extraction system, of the annual tritium production (at equilibrium – after 50 pulses PbLi AES, 3000 pulses for He AES) • 1.63 g removed and stored in-situ or transferred to T2 building • 0.47 g permeates into the reactor confinement building (operational release) • 0.14 g permeates into ITER VV • 0.09 g remains in TBS, with 0.002 g in the PbLi and ~ same in helium (inventory) • Because the tritium release is into building areas that have air detritiation systems, the release to the environment will only be 4.7 mg/year

  12. 6 3 4 5 1 2 DCLL Ancillary System Components General Arrangement • Drain tank • PbLi/helium heat exchanger • PbLi pump • PbLi Surge tank • PbLi Cold trap • Permeator

  13. Occupational Radiation Exposure Predicted Dose Rates for Various Locations and Components • Occupational dose estimates for the DCLL TBS have been made with the QADMOD-GP point kernel gamma-ray shielding code • The annual worker dose for maintenance activities is 5.2 p-mSv (this dose could drop to ~3.4 p-mSv if EU transport/tube forest is adopted – approach uncertain) • Plans to update this calculation by using the Attila discrete ordinates code are progressing • Generated Po-210 and Hg-203 do not appear to be a public release concern but may pose a worker risk

  14. Initial Thoughts Regarding DCLL TBS Safety Importance Component (SIC) Classification • The ITER IO has requested an SIC analysis of TBS components for the RPrS (also asking for all designated ESPN components to be listed > 370 MBq (0.01 Ci) requires ESPN or comparable standards) • SIC components mitigate safety hazards associated with (internal or external to) the TBS, by taking into account the safety function of components (radioactive confinement, heat removal, plasma termination, etc) and the possibility of internal faults, fires, explosions (e.g., H2-air), floods, load drop, earthquake, support system faults (we’ve asked for guidance from the ITER IO but haven’t received any yet, but some exists in Section 7.7.3 of ITER Project Requirements Document, ITER_D_27ZRW8) • The designation of a SIC translates into a very high design standard, design certification, demonstration of operation during accident conditions, acceptance testing, and in service inspection and testing. Our goal is to minimize the number of components classified as SIC components • Based on preliminary discussion with various team members, initial conclusions are: • The TBM in-vessel module will not be an SIC

  15. Initial Thoughts Regarding DCLL TBS Safety Importance Component (SIC) Classification (cont.) • Based on preliminary discussion (cont.): • Because the two TBM primary coolant loops (helium and PbLi) are extensions of the VV boundary these loops would be considered SICs based on the radioactivity confinement function of the VV • Should redundant isolation valves be placed on helium loop piping leaving the VV, making only these valves and run of pipes up to the valves SIC in this loop with regards to radioactive confinement? This loop will contain a small amount of T2 (<0.3g) in the piping that can only be liberated slowly (i.e., by diffusion) – There has been no guidance from the IO on lower radioactive limit that would exclude components from SIC consideration; however if approved the issue may become convincing the regulators that we know how to monitor this inventory • Because the DCLL TBM can not survive an entire power pulse without helium cooling, loop coolant flow, temperature, and pressure sensors that actuate ITER’s Fast Plasma Termination System are required and must be classified as SICs. • Most components (some experimental) of the PbLi cooling system will have a SIC radioactive confinement function, not only with regards to the radioactive inventories within the ITER VV, but also regarding the activated PbLi (total is 0.014 MCi (520 TBq) at 60 s – Pb-203) and TBM FS corrosion products (~180 g, or ~1.7 Ci (63,000 MBq) Fe-55) in this cooling loop. (>370 MBq (0.01 Ci) requires ESPN or comparable standards)

  16. Initial Thoughts Regarding DCLL TBS Safety Importance Component (SIC) Classification (cont.) • Based on preliminary discussion (cont.): • Conservative estimates of Po-210 and Hg-203 inventories are 1.8 Ci and 36 Ci, respectively. (low dose at site boundary if stacked but is a maintenance issue) • Radiation monitors for Po-210 and Hg-203 isotopes may be required for maintenance activities. • The PbLi TBS transporter could be designed to protect the TBS against load drops and if necessary earthquakes, making the transporter an SIC. • Because PbLi reacts with water to produce H2, and with air to produce some chemical heating, the design options of metal walls, catch trays, and guard pipes should be considered for the PbLi TBS to minimize the possibility of fires and explosions by confining any spills, preventing impacts from pipe whip, or external impact events. These components will be SICs. A hydrogen monitor (SIC) may be required if the port cell doesn’t have one. • The ITER IO requires discussion of protection of SICs, especially for fires • Cables will reside in conduits and sensors in enclosures for fire protection. Design of SICs will use US DOE standards and US best practice standards (ASME, IEEE, NFPA), or comparable international standards, to provide safety margins and robustness. • A non-water fire suppression system may be needed

  17. Conclusions • Safety documentation for the DCLL TBM exists and a significant portion of the requested RPrS information is already available • So far the ITER IO has not relayed a format for transferring this information (The IO is working their way through this process just as we are) • Additional information will have to be generated, for example SIC designations • Guidelines and guidance for generating this information needs to be issued • So far the ITER IO has not given guidance, but there may already be enough information in Section 7.7.3 of the ITER Project Requirements Document (ITER_D_27ZRW8) to perform an initial assessment, especially given the level of radioactivty in the PbLi system • At this time, the purpose of presenting this information is to alert the design team to what will be coming our way during the final design activity

  18. ESP and ESPN classification for RPrS* • Numerous files about C&S and ESP-ESPN application and official guidelines are available in IDM • IO can provide some help for the issue of list of ESPN equipments, and in any case IO will check (ITER_D_2LNRY7 ) Will a SIC in this column suffice? *Slide from presentation by Pascal Garin, ITER Organisation at PMG-18-01 Meeting, 15 July 2009

  19. Or Will This be the Desired SIC Declaration Format?

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