Summary report of the ORE study; methods and principles EFDA Task TW4 TSS SEA2.1 A

1. ENTE PER LE NUOVE TECNOLOGIE, L'ENERGIA E L'AMBIENTE Associazione ENEA-EURATOM sulla Fusione FUSION UNIT Summary report of the ORE study; methods and principles EFDA Task TW4 TSS SEA2.1 A Revision of the ORE assessment for the Port-Interfacing systems (WBS 5.0) M. T. Porfiri, A. Natalizio EFDA Garching 25 April 2006

2. Outlines • Task’s requests • Documentation used • Methodology • Example of application • Intrinsic limits

3. Task’s requests (1) Review & Documentation of Past Analysis The first milestone of the task involved a review and documentation of the past analysis assumptions/parameters and results for the following five systems: 1. Ion Cyclotron Heating and Current Drive System, 2. Electron Cyclotron Heating and Current Drive System, 3. Neutral Beam Heating and Current Drive System, 4. Diagnostics, and 5. Test Blankets

4. Task’s requests (2) The outputs of the first milestone are summarized in the table and the assumptions, limits and updating necessary have been discussed in the ENEA report tr125_05 “Review and documentation of the past ORE analysis on port interfacing systems (WBS 5.0)” (April 2005).

5. Task’s requests (3) First ORE assessment for LHH&CD and NBI&CD The second milestone of the task, that originally was defined as a new ORE assessment for the five systems lested before, was changed to perform an ex-novo evaluation of the Occupational radiation exposure that did not existed in the past for the LHH&CD and NBI&CD The results of this analysis is documented in the ENEA report tr132_05 “Worker Dose Estimates for NB & LH Heating & Current Drive Systems” (Nov 05).

6. Task’s requests (4) New ORE Analysis The third milestone of the task (originally defined to perform sensitivity analysis) involves a reanalysis of the five systems, on the basis of the current design and operating information, and documentation of the analysis assumptions/parameters and results. The ENEA report tr140_06 “Revision of the ORE assessment for the Port-Interfacing Systems (WBS5.0)” (December 2005) documents the results, listed below.

7. Task’s requests (5) It is important the comparison of the present ORE results with those obtained in the first assessment of the LHH&CD nd NBI&CD. For the NBI&CD the first dose evaluation has been modified adding a small hands-on contribution from opening and closing RH ports to perform maintenance on the beam ducts, using the in-vessel remote-handling system, which needs to be deployed for in-vessel interventions. The worker dose associated with such RH operations, estimated to be 8.4 p-mSv/a for all 3 injectors. For the LHH&CD system the first evaluation was based on a general working procedure, not divided step by step and standardized

8. Documentation used for the new ORE • 1. DDD23 Remote Handling Equipment - N 23 DDD 66 R0.3 – • ITER JWS Garching, July 2004 • DDD 5.1 Ion Cyclotron Heating and Current Drive System WBS • 5.1- G 51 DDD 4 01-07-19 W 0.2, July 2001, ITER • 3. DDD 5.2 Electron Cyclotron Heating and Current Drive System – • G 52 DDD 5 01-05-29 W 0.1, July 2001, ITER • DDD 5.3 Neutral Beam Heating & Current Drive (NB H&CD) • System - N 53 DDD 29 01-07-03 R 0.1, July 2001, ITER • 5. DDD 5.4 Lower Hybrid Heating and Current Drive System - • G 54 DDD 2 01-07-19 W 0.2, July 2001, ITER • 6. DDD 5.5 Overview of ITER Diagnostic System– • N 55 DDD 13 W0.1, July 2004, ITER • 7. DDD 5.6, Chap I3 Connections to the Ports and Supply Lines, • July 2001, ITER • 8. Nuclear Analysis Report, ITER G 73 DDD 2 W 0.2, July 2004 • 9. E. Polunovskiy, Private Communications, EFDA, October 2005.

9. Methodology for the ORE assessment (1) • To build the ORE evaluations the steps were, • for each system: • Description of the main components to be maintained • Description of the main maintenance activities (es. • launcher replacement, primary window replacement for • LH&CD, etc.) • 3. Description of the major activities. Their sequence forms • the main activity • 4. Description of the minoractivities.Their sequence • forms the major activity • 5. Description of the elementary activities. Their sequence • forms the minor activities

10. Methodology for the ORE assessment (2) 6. A work effort is assigned to each elementary activity 7. The maintenance frequency for each system is selected on the basis of the design documents (DDD) 8. In each zone the radiation field is settled. In general it is the maximum value calculated in the maintenance zone. The radiation field values have been based on the “Nuclear data report 2004” for the main part of the work. Instead for NBI more recent calculations (E. Polunovskiy) have been used.

11. Methodology for the ORE assessment (3) 9. The internal dose has not been taken into account in this study, because its contribution to the total dose should be scarce if the ADS (air detritiation system) is effective. Moreover the information about the tritium concentration is not available at this time.

12. Procedures in maintenance One of the main difficulty to perform an ORE assessment, when the facility is not built yet, is to establish a procedure in the maintenance activities enough general to be applied for several components and at the same time, enough detailed to replicate correctly all the operations requested for each system.

13. What are the elementary activities We tried to overcome this difficulty having as basis of the procedures the so called “elementary activities”,developed in the context of ORE assessments of port-interfacing systems (ENEA report TR137_05, “Occupational radiation exposure software tool and hands-on activities for remote handling assessment” Pinna, December 2005). Due to the scope of the current the elementary activities reflect only those conducted in a port-cell environment. It is important to note that the work effort may not be reflective of the entire activity, but only the portion performed inside the known radiation field.

14. One example: LHH ORE assessement • 1.Maintenance of Launcher Assembly • 2. Maintenance of VTL Assembly • 3. Maintenance of I&C Components The activities 1,2 and 3 are the main activities identified for LHH&CD system

15. LH Launcher replacement: major activities •Clearing the port cell of encumbrances to allow cask access (e.g., removal of splitting network); •Removal of bioshield plug; •Clearing the interspace of encumbrances to allow cask access (e.g., removal of VTL); •Docking/undocking of cask removal/replacement of launcher (RH task); •Reinstallation of VTL; •Reinstallation of bioshield plug; and •Reinstallation of port cell components.

16. LH: Launcher replacement 2 Port Cell Components Removed

17. LH: Launcher replacement 3 Port Cell Bioshield Plug Removed

18. LH: Launcher replacement 4 VTL Components Removed

19. LH – Work effort for port cell clearance • The first major activity for the launcher replacement is the port cell clearance. In the following table the list of the minor activities and the relating work effort is listed.

20. LH - List of elementary activities for MTL section removal Work-Effort Estimates for Launcher Replacement Minor Activity 1.2.1 :Remove Section of MTL1

21. LH: Work effort for launcher replacement

22. LH: maintenance frequency •The replacement of primary and secondary windows and dummy loads can be performed in hot cell, in coincidence with the launcher replacement.

23. LH: Radiation Fields

24. LH: worker dose •The worker doses are not additive because the replacement of primary and secondary windows and dummy load can be performed in coincidence with the launcher replacement and inside the hot cell. The only exception is the I&C maintenance that would be performed during each annual shutdown period and is independent of the others.

25. Intrinsic limits of this ORE assessment • The design of the systems is not frozen • The maintenance procedures are not yet established and they will be well known only after some period of the ITER • operation • Some of the components to be maintained are traditional and it is not difficult to assess the work effort for maintenance, but in part they are not completely known. • Meetings and discussions with the designers have been done, but, due to the complexity of the systems and the continuous evolution of the design, it was not easy to follow all the suggestions and indications • We assumed the responsibility to do not include some design documentation (ECRH upper launcher, for example) because the work was in the final phase and it was impossible to • toconclude the analysis in the due time, including the updating.

26. Conclusions • What was important for the scope of the work was to • prepare a methodology that, if it obtains the consensus of • the concerned people, can be utilized during the evolution • of the ITER systems design to re-assess the ORE in a • fast and confident way. • To revise the current report the corrections of the • wrong assumptions or misunderstanding in the design • can be implemented. The updating to more recent • designs is to be avoided, because it does not add value • to the methodology and it can be post-poned to the • next phases of ALARA assessment.