1 Assessment of previous ORE evaluation by comparison with 3D exposure analysis. Analysis of the main difference contributors and optimisation of the calculation F.Vermeersch SCKCEN “Occupational Radiation Exposure – ALARA in ITER: further refinement”, Garching 10 October 2006

2  A 3D exposure analysis is proposed for the ORE results that were assessed earlier.  A comparison and analysis will be performed of the main difference between the earlier results and the ones obtained using 3D simulation.  The impact of local differences in the radiation fields will be examined. Task description

3 Dose assessment Dose optimisation Dose assessment is currently based on average dose rates in an area. 3D simulation could be used to evaluate  The effect of non-uniform dose distributions  The introduction of shielding  The effect of design changes  The dose distribution in a changing environment (maintenance, decommissioning)

4 3D dose modeling and planning tool Based on: 3D model including material, geometry and sources Point-kernel dose calculation, with build- up correction Allows: Dose assessment for tasks, trajectories and scenarios Individual and collective dose assessment Source strength calculation from measured dose rate sets. Source Sensitivity Analysis Heat exchangers BR2 and their VISIPLAN model. Dose pattern 120 cm above the floor.

5 VISIPLAN General methodology Model building stage General analysis stage Detailed planning stage The follow up stage Prediction Measurement

6 Detailed planning tools

7 VISIPLAN Scenario Comparison Scenario Comparison Results Collective dose (man.Sv) Max individual dose (mSv) Intervention time (h) Collective time (man.h) If you want to optimise you need to compare different scenarios.

8 Simplified Model of Eq.Port 1 Simplified source structure for demonstration Sources include nose section beam line and port flange and port section

9 Dose uptake by the workers Unshielded nose section

10 Deliverables The Occupational Radiation Exposure results obtained earlier, using average dose rates for a room or area, will be revisited using a 3D simulation tool. The assessment will be based on the information available in the earlier ORE documents and supplementary information from the ITER technical web-site. Where necessary a more detailed modeling will be proposed to re-examine the occupational exposure. The results will be compared and the main contributors to the differences will be described. Suggestions for dose reduction will be made where possible.