Occupational Radiation Exposure (ORE) Dose Rate for TBM Replacement/Maintenance and Improving Estimates by 3-D Calculations

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1 Occupational Radiation Exposure (ORE) Dose Rate for TBM Replacement/Maintenance and Improving Estimates by 3-D Calculations Mahmoud Youssef Mohamed Dagher UCLA With input from Brad Merrill (INL) FNST Meeting, August 18-20, 2009, UCLA

2 Outlines Comparing ORE dose rate for replacing/maintaining DCLL TBM to other recent assessment for Generic TBM Can we reach ITER goal of ~1.2 p-sv/a per TBM? Outline procedures for 3-D dose rate calculations Report on status and follow up Supporting Documents B. Merrill, L. Cadwallader,M. Dagher, Occupational Radiation Exposure Analysis of US ITER DCLL TBM, INL/EXT , August, 2007 Natalizio, M.T. Porfiri, Revision of the ORE assessment for the Port-Interfacing Systems (WBS5.0), FUS-TN-SA-SE-R-140, Dec M.T. Porfiri, ITER ORE: Status of art and summary of the studies at 2007, FUS- TN-SA-SE-R-178, May 2008 ITER GSSR (Generic Site Safety Report), Vol VI, G 84 RI 5 R 02, July 2004

3 Layout of the TBM Frame Assembly and the AEU inside the Port Cell and Port Inter-space Area Port Cell TBM Frame Assembly AEU components Port Inter space Area Bio Shield Plug

Dose Rate Calculation Model of the AEU components of the US DCLL TBM (see Merrill, et al)* Calculation: QADMOD-GP point-kernel code (results calibrated with the MicroShields code) Activation sources

4 Dose Rate Calculation Model of the AEU components of the US DCLL TBM (see Merrill, et al)* Calculation: QADMOD-GP point-kernel code (results calibrated with the MicroShields code) Activation sources (1) ~ 45 mg/cm2 PbLi film on of pipes inner surface (activity after 1 w dominated by Pb-203). (2) ~1.8 μm activated corrosion product (ACP) layer on pipes inner surface (activation 1 w dominated by Fe-55 and Mn-54) B. Merrill, L. Cadwallader,M. Dagher, Occupational Radiation Exposure Analysis of US ITER DCLL TBM, INL/EXT , August, 2007

5 Predicted maintenance doses for replacing the TBM Description Time Required (p-hr) Dose Rate (msv/hr) Dose (p-msv) ORE DCLL Generic DCLL Generic DCLL Generic Activities in the Port Cell Remove AEU from Port cell Area Bio-Shield Plug removal Activities in the Port Interspace Equatorial Port Interspace Pipe removal Port Flange Preparation Port plug Assembly removal, transportation RH RH and insertion into hot cell. Port plug testing, and assembly Installation. RH RH Port Interspace Pipe and service equipment Installation. Activities in the Port Cell Bio-Shield Plug Installation AEU Installation TOTAL (1) AEU removal and installation required the longest time followed by EP interspace pipe removal installation. (2) AEU time removal/installation in the Generic TBM is ~2-3 factor more than DCLL TBM.

6 Annual ORE Dose Estimates for Replacing/Maintaining the TBM DCLL TBM Generic TBM * Dose due to replacement, p-msv * Frequency of replacement Once in 2 years Once in 3 years * Annual replacement dose, p-msv/a * Annual dose due to repair/maintenance 1.5(a) * Annual dose due to I&C component activities Inspection and instrumentation calibration are not Hot cell repairs are not considered 0.17(b) * Total Annual ORE Dose, p-msv/a ~5.2 ~7.5 (a) Assumed to be performed under AEU radiation environment in the Port Cell (b) Assuming 34 p-h repair time per TBM at Port Cell radiation field of 5 μsv/h

7 We will assess the background dose rates by performing 3-D dose rate analysis using ATTILA CAD-based discrete Ordinates Code Improving ORE Dose Rate Estimates Dose Rate Inside Port Cell Generic TBM assessment (5 μsv/h) < dose rates in the DCLL TBM case (~35 μsv/h) Dose Rate Inside Port Inter-space Area DCLL TBM assessment (~12 μsv/h) < dose rates in the Generic TBM case (50 μsv/h) Background Dose Rate from activated TBM/Shield Assembly Not accounted for in DCLL TBM assessment.. Is assumed in the Generic TBM assessment. It does not account for contribution from ACP.

8 Reduction in the DCLL TBM by Proposed Design of Bioshield/AEU Transporter The EU is proposing a concept of combining unit of the bioshield/ interspace pipes /AEU transporter making one complete unit. ORE dose for the DCLL TBM replacement would be reduced by nearly a factor of 2. Annual ORE dose 1.9 p-msv/a. Combined annual dose 3.4 p-msv/a. ITER ORE goal for TBM maintenance is ~1% of the annual maintenance dose for the ITER device (367p-mSv/a Goal for DCLL TBM maintenance ~3.67/3=1.2 p-msv/a. Current ORE dose estimate should be reduced by a factor 2.8

Limit for ITER 500 msv/a--margin= 26.7% of 500= 133.7 msv/a Calculated so far=367 msv/a--1% for TBM=3.7 msv/a ORE/port=3.

9 Limit for ITER 500 msv/a--margin= 26.7% of 500= msv/a Calculated so far=367 msv/a--1% for TBM=3.7 msv/a ORE/port=3.7/3=1.23 msv/a W. Gulden, Fusion for Energy, IAEA, 9-th Technical Meeting on Fusion Power Plant Safety, July 2009, Vienna

11 THE DCLL Assembly, the AEU Unit and Connecting Pipes were Implemented in the 40-degree Brad Model For Neutronics Calculation

12 THE DCLL Assembly, the AEU Unit and Connecting Pipes were Implemented in the 40-degree Brad Model For Neutronics Calculation

13 BSM Details of the DCLL TBM VV TBM Port Inter space Area TBM Shield

14 40o Model of ITER is meshed with ATTILA Total number of generated tetrahedral meshes ~1M Plasma Zone: Meshed for accurate source specification

15 40 o Model of ITER is meshed with ATTILA DCLL TBM Total number of generated tetrahedral meshes ~1M

16 Meshed DCLL TBM Shield PFC (Be) DCLL TBM

ATTILA Results Benchmarked Favorably with DAG-MCNP Results Total Neutron Flux in the Dummy Blanket Shield Modules (BSM) and the Dummy Shield Layers Placed at the Equatorial Port ) 10 15 10 14 BSM

17 ATTILA Results Benchmarked Favorably with DAG-MCNP Results Total Neutron Flux in the Dummy Blanket Shield Modules (BSM) and the Dummy Shield Layers Placed at the Equatorial Port ) BSM Total Neutron Flux Dummy Shield Layers ATTIAL (Sn40-Sn16) ATTILA (Sn16) MCNP (UW) 8 Locations Behind the Shield Radial Distance at the Equatorial Port M. Z. YOUSSEF, R. FEDER, AND, I. M. DAVIS, Neutronics Analysis of the International Thermonuclear Experimental Reactor (ITER) MCNP Benchmark CAD Model with the ATTILA Discrete Ordinates Code, presented at the 8th International Symposium on Fusion Nuclear Technology, ISFNT-8, Heidelberg, Germany, Sept. 30-Oct. 5 (2007).

ATTILA Results (green) Benchmarked Favorably with Experimental Data and MCNP Results (red) Dose Rate Experiment at FNG Facility (Italy) Mock-up assembly Lateral side plug 14 MeV Source M.Z.

18 ATTILA Results (green) Benchmarked Favorably with Experimental Data and MCNP Results (red) Dose Rate Experiment at FNG Facility (Italy) Mock-up assembly Lateral side plug 14 MeV Source M.Z.Youssef, et Al, Benchmarking the three-dimensional cad-based discrete ordinates code ATTILA using integral dose-rate experiments and comparison to MCNP results, 18 th Topical Meeting on The Technology of Fusion Energy, San Francisco, Sep 28-Oct 2, 2008

19 Dose Rate Calculation Procedures (Entire ITER Model with TBM inside Test Port) Step 1 Step 2 Step 3 Neutron transport calculation Terminal Restart File Gamma Source Calculation Input File Dose Rate Calculation Neutron only calculation. gammas could optionally be run. Decay gamma source computed in each tetrahedral element of ITER and TBM. Option to specify which mesh regions to activate Multiple time steps after irradiation can be specified. Irradiation history (pulse on, pulse off, etc) is specified Decay gamma transport calculation inside the TBM and, shield, and in the service area. Use conversion factors of gamma flux to dose rate everywhere (e.g. ANSI/ANS )

Assessment of Dose Rates in the Diagnostics Upper Port Plug Was Completed using 20

Vessel And Shielding Layers Boundary Condition: Albedo Divertor Blanket Shield Modules

YOUSSEF Nuclear Heating And Interspace Dose Rates For The Generic ITER Diagnostic Upper

20 Assessment of Dose Rates in the Diagnostics Upper Port Plug Was Completed using 20 Truncated ITER Model TF Coil PF Coil Cryostat Bio-Shield Upper Port Plug PF Coil Vacuum Vessel And Shielding Layers Boundary Condition: Albedo Divertor Blanket Shield Modules Boundary Condition: Reflecting R.E. FEDER, M.Z. YOUSSEF Nuclear Heating And Interspace Dose Rates For The Generic ITER Diagnostic Upper Port Plugs, to be presented at the 23rd Symposium on Fusion Engineering, SOFE-09, May 31-June 5, 2009, San Diego, CA, USA (2009).

21 M. Youssef-June 24, 09 Three Step ATTILA Dose Rate Solution Process

22 Status and Follow Up SolidWorks CAD model of the TBM/shield Assembly, the AEU and connecting pipes were implemented in the ITER 40 0 Model. Most assemblies were successfully meshed. Step-1 (neutron transport calculation) is underway. Results on TBR, heating rates, etc. will be compared to DAG-MCNP 3-D calculations for confirmation. Dose rate assessment is expected to be completed in few weeks input to RPrS

23 Additional Backup Slides

24 Detailed Maintenance Dose for Replacing the DCLL TBM (1) Task No. Description Time Required (p-hr) Dose Rate (msv/hr) Dose (p-msv) ORE DCLL Generic DCLL Generic DCLL Generic 1 Remove AEU from Port cell Area Prepare AEU for system separation and relocation to storage and maintenance area including tools. 1.2 Cut and remove primary and secondary He coolant lines between AEU and Pipe chase area. 1.3 Cut and remove primary and secondary He coolant lines between AEU and Bio-Shield Plug Cut and separate Concentric Pb-Li pipe assembly Transfer AEU to maintenance area Bio-Shield Plug removal Equatorial Port Interspace Pipe removal Interspace Preparation process Pipe Hanger removal Concentric pipe removal He Pipe removal Port Flange Preparation Position special tooling for Port Flange cutting and 4 Un-Bolting. 4.2 Perform Lip Seal cutting operation, clean and remove all debris. 4.3 Un-Bolt all Port flange nuts and store. 3 5 Port plug Assembly removal, transportation RH RH and insertion into hot cell. 6 Port plug testing, and assembly Installation. RH RH 6 7 Port Interspace Pipe and service equipment Installation. 7.1 Port Preparation Port Interspace Pipe Installation Remove all temporary supports, tooling, equipment and clean Port Interspace area, and remove storage container from Port cell area

25 Detailed Maintenance Dose for Replacing the DCLL TBM (Cont.d) Task No. Description Time Required (p-hr) Dose Rate (msv/hr) Dose (p-msv) 8 Bio-Shield Plug Installation Position tooling and supports around Bio-shield door opening. 8.2 position Bio-Shield Plug transporter in port cell area Open transporter and install Bio-Shield Plug Install seals around pipe penetrations through the 5 Bio-Shield Plug. 8.5 Remove Bio-Shield Transporter, all tooling, supports and equipment from Port Cell area. 3 9 AEU Installation Port cell preparation. Temporary supports, equipment, tools and saftey equipment. 9.2 Position AEU in Port Cell Area, connect to building power check equipment status inside the transporter TBM/AEU Service connections AEU/Pipe chase area connections Pressure testing, leak testing and full system test and inspection including service qualification. 9.6 Remove all equipment, tooling, temporary supports, and testing equipment from port cell area. ORE DCLL Generic DCLL Generic DCLL Generic TOTAL TBM Maintenance Dose DCLL TBM Generic TBM 7.4 person-msv 21.9 person-msv

26 Annual ORE Dose for AEU Component Repair activities (DCLL-TBM) Component Types included: Motor controller, pumps, level/temperature and pressure sensors, rupture disc, drain tank electric heater, erc (active repair time, hr) X (Probability of a component failure/yr) X (Dose rate, msv/h) Annual Dose (p-msv/yr) per failure ADD ALL POSSIBLE COMPONENT Failures Annual ORE Dose for all AEU components repair ~1.5 p-msv/yr

27 Annual ORE Dose Estimates for replacing/maintaining the TBM DCLL TBM: Total dose estimate for replacing the DCLL TBM is 7.4 p-msv. TBM would be replaced once every two years. Annual dose 3.7 p-msv/a. Add ~1.5 p-msv/a for repair/maintenance activities Total Annual ORE Dose ~5.2 p-msv/a * Routine inspection and instrument calibration are not considered. * A time and motion study should be conducted to give better estimates. Generic TBM: Total dose estimate for replacing the TBM is 21.9 p-msv TBM would be replaced once every three years. Annual dose 7.3 p-msv/a. Add ~0.17 p-msv/a for I&C maintenance activities (34 p-h at 5 μsv/h) Total Annual ORE Dose ~7.5 p-msv/a * Hot cell repairs are not considered

28 THE DCLL Assembly, the AEU Unit and Connecting Pipes were Implemented in the 40-degree Brad Model For Neutronics Calculation

29 The DCLL TBM Assembly and the AEU in the 40 o ITER BRAND Model

Proliferation Risks of Magnetic Fusion Energy

Proliferation Risks of Magnetic Fusion Energy Alexander Glaser* Department of Mechanical and Aerospace Engineering and Woodrow Wilson School of Public and International Affairs Princeton University International