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 Garching – 25th April 2006

Summary report of the ORE Summary report of the ORE study; methods and principlesstudy; methods and principles

EFDA Task TW4 TSS SEA2.1 AEFDA Task TW4 TSS SEA2.1 A

Revision of the ORE assessment for the Port-Interfacing Revision of the ORE assessment for the Port-Interfacing systems (WBS 5.0)systems (WBS 5.0)

M. T. Porfiri, A. NatalizioM. T. Porfiri, A. Natalizio

EFDA Garching 25 April 2006EFDA Garching 25 April 2006

ENTE PER LE NUOVE TECNOLOGIE, L'ENERGIA E L'AMBIENTEAssociazione ENEA-EURATOM sulla Fusione

FUSION UNIT


Outlines

1. Task’s requests2. Documentation used3. Methodology4. Example of application5. Intrinsic limits


Review & Documentation of Past AnalysisThe 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, and5. Test Blankets

Task’s requests (1)



Port Interfacing Systems (WBS 5.0) WBS Worker Dose

(p-mSv/a)

Reference

Ion Cyclotron Heating And Current Drive (Ic H&Cd) System

5.1 31.0 [SAN01]

Electron Cyclotron Heating And Current Drive (Ec H&Cd) System

5.2 125.9 [SAN01]

Neutral Beam Heating And Current Drive (Nb H&Cd) System

5.3 0.0

[MOS00b]

Lower Hybrid Heating And Current Drive (Lh H&Cd) System

5.4 0.0

[SAN01]

Diagnostics 5.5 80.0 [MOS00a] Test Blankets 5.6 13.0 [SAN01] TOTAL 5.0 249.9

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).



First ORE assessment for LHH&CD and NBI&CDThe 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 ENEAreport tr132_05 “Worker Dose Estimates for NB & LH Heating & Current Drive Systems” (Nov 05).

WBS SYSTEM Earlier Estimated Dose [NAT05] (p-mSv/a)

5.3 Neutral Beam Heating and Current Drive 8.1 5.4 Lower Hybrid Heating and Current Drive 1.22


Task’s requests (4)New ORE AnalysisThe third milestone of the task (originally defined to performsensitivity analysis) involves a reanalysis of thefive 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 assessmentfor the Port-Interfacing Systems (WBS5.0)” (December 2005)documents the results, listed below.

WBS SYSTEM Current Estimated Dose

(p-mSv/a)

Earlier Estimated Dose

(p-mSv/a) 5.1 Ion-Cyclotron Heating and Current Drive 10.0 20.6 5.2 Electron-Cyclotron Heating and Current Drive 43.7 40.2 5.3 Neutral Beam Heating and Current Drive 16.5 0.0 5.4 Lower Hybrid Heating and Current Drive 6.3 0.0 5.5 Diagnostics 84.5 58.5 5.6 Test Blanket Modules 22.4 13.0 TOTAL 183.4 132.3


Task’s requests (5)It is important the comparison of the present ORE results with those obtained in the first assessment of the LHH&CDnd 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 thebeam 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

WBS SYSTEM Current Estimated Dose

(p-mSv/a)

Earlier Estimated Dose [NAT05] (p-mSv/a)

5.3 Neutral Beam Heating and Current Drive 16.5 8.1 5.4 Lower Hybrid Heating and Current Drive 6.3 1.22


Documentation used for the new ORE1. DDD23 Remote Handling Equipment - N 23 DDD 66 R0.3 –

ITER JWS Garching, July 20042. DDD 5.1 Ion Cyclotron Heating and Current Drive System

WBS5.1- 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 4. 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, ITER7. 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 20049. E. Polunovskiy, Private Communications, EFDA, October 2005.


Methodology for the ORE Methodology for the ORE assessment (1)assessment (1)

To build the ORE evaluations the steps were,for each system:

1. Description of the main components to be maintained2. 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 activity4. Description of the minor activities.Their sequence forms the major activity5. Description of the elementary activities. Their sequence forms the minor activities



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.



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.


Procedures in maintenanceProcedures 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.


What are the elementary activitiesWhat 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.


One example: LHH ORE One example: LHH ORE assessementassessement1. Maintenance of Launcher

Assembly

2. Maintenance of VTL Assembly

3. Maintenance of I&C Components

Shielding block

The activities 1,2 and 3 arethe main activities identified for LHH&CD system


LH Launcher replacement: major LH Launcher replacement: major activitiesactivities

•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.


LH: Launcher LH: Launcher replacement 2replacement 2

Port Cell Components Removed



Port Cell Bioshield Plug Removed



VTL Components Removed


Major Activity

Description Minor Activity Description Work Effort

(p-h)

1.1 perform radiation survey inside port cell 1.1.1 perform radiation survey inside port cell 0.25

1.2 remove sections of MTL 1.2.1 remove section of MTL1 10.65 1.2.2 remove section of MTL2 6.45 1.2.3…1.2.22 remove section of MTL3………22 6.45*19 1.2.23 remove section of MTL23 6.45 1.2.24 remove section of MTL24 11.65 1.3 clear port cell of all debris 1.5.1 clear port cell of all debris 4.00 TOTAL 168.45

LH – LH – Work effort for port cell Work effort for port cell clearanceclearance• 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.


LH - LH - List of elementary activities for List of elementary activities for MTL section removalMTL section removal

Work-Effort Estimates for Launcher Replacement Minor Activity 1.2.1 :Remove Section of MTL1

ELEMENTARY ACTIVITY NOTEs WE (p-h)

make visual inspection 0.25

set-up work platform to proper height above head level 4.00

set-up temporary supports for MTL1 1.00

transport tools to work location by trolley 0.20

cut cooling water inlet tube to MTL1 small pipe <5 cm dia. 1.50

cut cooling water outlet tube to MTL1 small pipe <5 cm dia. 1.50

unbolt first flange of waveguide section small flange <5 cm dia. 1.00

unbolt second flange of waveguide section 1.00

transport section of waveguide to temporary storage by trolley 0.20

transport tools back to tool room by trolley 0.00

remove temporary supports 0.00

remove work platform 0.00

TOTAL 10.65


Step Description Work Effort (p-h)

1 Clear Port Cell 191

2 Remove Bio-shield Blocks 70

3 Clear Port Interspace 382

4 Prepare Port Flange 63

5 Remote Operation (Replace Launcher) 0

6 Reestablish Port-Flange Connections 64

7 Reinstall Port-Interspace Components 381

8 Reinstall Bio-Shield Blocks 50

9 Reinstall Port-Cell Components 197

TOTAL 1,398

LH: Work effort for launcher LH: Work effort for launcher replacementreplacement


LH: maintenance frequency

Maintenance Type Maintenance Frequency Launcher Replacement Bi-annual (every 2 years) Primary Window Replacement Bi-annual (every 2 years) Secondary Window Replacement Bi-annual (every 2 years) VTL Dummy Loads Bi-annual (every 2 years) I&C Components Annual

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


LH: Radiation LH: Radiation FieldsFields

Location Dose Rate (μSv/h) inside port-cell with all shielding in place 5 inside port-cell with biological shield plug removed 10 inside interspace with vacuum vessel port plug in place 10


LH: worker dose

Activity Annual Worker Dose per

component (p-mSv/a)

Annual Worker Dose

(p-mSv/a) Launcher replacement 5.8 5.8 Primary window replacement 5.7 - Secondary window replacement 1.6 - VTL dummy load replacement 1.6 - I&C Component Maintenance 0.5 0.5 Hot-Cell repairs Not Estimated Not Estimated

TOTAL 6.3

•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.


Intrinsic limits of this ORE assessment1. The design of the systems is not frozen2. The maintenance procedures are not yet established

and they will be well known only after some period of the ITER

operation3. 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.

4. 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

5. 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 to conclude the analysis in the due time, including the updating.


Conclusions

• What was important for the scope of the work was toprepare a methodology that, if it obtains the consensus ofthe 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.

Documents

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