1. 2006-12-11 accident deformation – doyle 1/12 Phase II Collimator - Accident Deformation Simulation December 11, 2006

2. 2006-12-11 accident deformation – doyle 2/12 Overview New medium resolution 3-D ANSYS & FLUKA models.27 MJ deposited in 200 ns Molten material removed, remaining material allowed to cool Result: permanent deformation of about 50 um after cooling –Jaw ends deflect toward beam

3. 2006-12-11 accident deformation – doyle 3/12 Accident Deformation Simulation Modeling –Original ANSYS model modified – refined mesh near beam Elements @ O.D.: 2.5 x 2.5 x 50mm (r, ,z) – were 2.5 x 8.0 x 50 Jaw length 95cm, ends not tapered –Temperature dependent stress-strain (bilinear isotropic hardening) Other properties independent of temperature –FLUKA accident simulation for refined mesh model Element-to-element mapping.27 MJ in 200 ns Axial distribution very similar to ultra-fine model (reported 3/28/06) r,  distribution more diffuse –Quasi-steady state analysis of stresses –After 200 ns energy deposit, all elements containing any node with temperature > 1100C melting point “killed” As if melted and drained from system –Model allowed to cool for 60 sec to ~ steady temperature –Permanent deformation noted –Model checked – scaled accident data to represent SS heat load

4. 2006-12-11 accident deformation – doyle 4/12 Jaw-hub-shaft – Hollow Mo Shaft Glidcop Jaw Hollow Mo Shaft Simple supports at both shaft ends Hub region - mech & thermal contact

5. 2006-12-11 accident deformation – doyle 5/12 Refined Mesh and High Resolution Models Permanent deformation simulation: Refined mesh accident model, elements 2.5 x 2.5 x 50 mm (r, ,z). About 3x finer in  than previous model. Energy density is well represented in z, coarsely in r & . Similarity of power distribution in z of medium model and fine model. High Res Accident model, elements.16 x.2 x 50mm (r, ,z), molten zone in gray: 3 x 5.2 mm (r,  ) at shower max. 2-D in ANSYS due to large number of elements.

6. 2006-12-11 accident deformation – doyle 6/12 Accident Deformation Simulation Results –Jaw deforms plastically ends of jaw move ~60 um toward beam Sagitta ~ 50 um –Jaw surfaces at 90 o usable “Flat” within 10 um

7. 2006-12-11 accident deformation – doyle 7/12 Refined Mesh Model Underestimates Peak Temperature 5mm melt 2.5mm Tmax = 57 e3 Tmax = 7195 Original ANSYS model gave Tmax ~ 2000C. The refined mesh shown above improves the simulation, but remaining factor of 8 difference is due to peak temperature dilution in excessively coarse elements. Each refined mesh element corresponds to ~ 16 x 12 high resolution elements.

8. 2006-12-11 accident deformation – doyle 8/12 Melted elements deactivated After 200 ns, elements with any nodes above melting point deactivated. Limitation of the coarse model: The logic used removes excessive energy from the system. The inverse, removing only elements with all nodes above m.p. would leave some excess energy in the model. No molten material remains. Model allowed to cool normally from this point. This simulation does not apply to jaw orientations in which some molten material may remain in the system. Note that peak temperature exceeds boiling point. Therefore, case where all melted material is retained is also unrealistic.

9. 2006-12-11 accident deformation – doyle 9/12 Cool-down After 60 sec, axial temperature gradient remains but bending gradient is minimal. Temperature history on far side over 60 sec. Decay of temperature near edge of molten region over 1 sec.

10. 2006-12-11 accident deformation – doyle 10/12 Permanent Deformation, ux, uy In plane deformation, ux ~ 60 um Normal deformation uy ~5 um Therefore, after hit, rotate jaw 90 o uy 50 um -50 um bottom top ~5 um ux uy beam side far side 100 um -100 um ux ~60 um Normal, uy In-plane, ux

11. 2006-12-11 accident deformation – doyle 11/12 Concluding Remarks We have a problem, but magnitude uncertain Model checked by rescaling accident data to equal steady state energy deposit –Refined model => temperatures 30% higher –Deflections within 5% (ss) and 6% - 25% (10 sec transient) Model not necessarily the worst case –Try case where melted material is retained? What do we do differently in view of this result? –Test to confirm –User stronger Glidcop –Limit jaw to ~ three hits –Other?

12. 2006-12-11 accident deformation – doyle 12/12 Reference: High Resolution Model Used for simulating peak temperature at shower max