Fp7 - LEADER Slide 1 ALFRED C&S rods mechanical design C&S_Rods_ ppt Task Primary system conceptual design of ALFRED Control rods & Safety rods (mech. Design) The LEADER project ALFRED core layout Basic concepts C/R design S/R concept Status TOC F. Manni (S.R.S.) D. Vitale Di Maio (S.R.S.) LEADER Technical Meeting November , 2012 Karlsruhe Institut of Technology

Fp7 - LEADER Slide 2 ALFRED C&S rods mechanical design C&S_Rods_ ppt 171 Fuel Assembly 12 Control Rods 4 Safety Rods 108 Dummy Element ALFRED Core Layout Ø 158

Fp7 - LEADER Slide 3 ALFRED C&S rods mechanical design C&S_Rods_ ppt 600 Fully extracted Fully inserted 680 Lead free level (in operation) 3730 Basic Concepts Fully extracted Fully inserted Diagrid top plane Control RodSafety Rod Core middle plane Scram: buoyancy Tuning: stepper motor Scram: gravity + booster F/A

Fp7 - LEADER Slide 4 ALFRED C&S rods mechanical design C&S_Rods_ ppt Lead Free Level (during operation) Core Active zone C/R S/R Diagrid F/A Drag Ballast Weight Buoyancy ±20% Refueling Operation Preloaded Spring counteracting buoyancy effects.. ±20% Ballast Preloaded Springs Top Grid Basic Concepts

Fp7 - LEADER Slide 5 ALFRED C&S rods mechanical design C&S_Rods_ ppt Control Rod design Both Control and Scram purposes Control: absorber pin bundle actuated by stepper motor driven worm gear Scram: buoyancy driven (upward insertion) Only electrical connections required features: notes: The very large gas plenum implies a big buoyancy force and the need for additional ballast which does not fit in the "standard" ballast housing (room found anyway on the top) Spring press re-designed in order to host worm gear (for actuation) and additional ballast (unification of F/A spring presses required)

Fp7 - LEADER Slide 6 ALFRED C&S rods mechanical design C&S_Rods_ ppt Gas plenum Reflector Absorber C/R design Lower half Reflector Float Spike Absorber pin bundle

Fp7 - LEADER Slide 7 ALFRED C&S rods mechanical design C&S_Rods_ ppt Absorber Reflector Gas plenum (very large!) 1340 Reflector 30 6 C/R design Absorber Bundle layout (from MYRRAH to ALFRED) Increased peripheral gap

Fp7 - LEADER Slide 8 ALFRED C&S rods mechanical design C&S_Rods_ ppt nut solenoid worm Control Scram C/R design Stepper Motor Float Actuation

Fp7 - LEADER Slide 9 ALFRED C&S rods mechanical design C&S_Rods_ ppt Ballast Standard (282 kg) Additional (83 kg) C/R: 623 kg C/R design Due to the very large gas plenum additional ballast is needed to counteract buoyancy Total mass 365 kg

Fp7 - LEADER Slide 10 ALFRED C&S rods mechanical design C&S_Rods_ ppt C/R design Spring Press Top Grid Belleville washers Stepper Motor

Fp7 - LEADER Slide 11 ALFRED C&S rods mechanical design C&S_Rods_ ppt Preliminary evaluation of the insertion transient Lead flow and stopping time impacts on the insertion time are not considered in the preliminary evaluation. A preliminary insertion time of about 0.85 s has been estimated; considering the negative acceleration for the arrest, the insertion time is longer but should be shorter than 1 s. C/R design

Fp7 - LEADER Slide 12 ALFRED C&S rods mechanical design C&S_Rods_ ppt Safety Rod concept Just scram, not regulation Scram: gravity driven (downward insertion) pneumatic booster system needed to speed up insertion Electrical and Pneumatic connections (Hi and Lo pressure lines) required features: notes: Very small gas plenum (reduced buoyancy problems) Structural design and interfaces similar to C/R and F/A

Fp7 - LEADER Slide 13 ALFRED C&S rods mechanical design C&S_Rods_ ppt Absorber Reflector 60 Reflector S/R Concept Very small Gas plenum (not necessary) Reduced buoyancy Provisional Layout!

Fp7 - LEADER Slide 14 ALFRED C&S rods mechanical design C&S_Rods_ ppt A1 A2 << > A1' A2 D d F1 < F2 (P1 A1 < P2 A1) F1 >> F2 (P1 A1 >> P2 A1) P1 P2 F1 F2 F1 F2 Low pressure chamber High pressure chamber Metering pin Thrust piston Thrust column Housing Orifice Booster Adaptation of a proven concept used for automotive safety tests (HyGe  sled)

Fp7 - LEADER Slide 15 ALFRED C&S rods mechanical design C&S_Rods_ ppt P1 P2 By playing with inner diameter and pressures, a wide range of performance can be attained. D d P1P2 The shape of the metering pin determine the acceleration profile. burst ramplong ramp Booster

Fp7 - LEADER Slide 16 ALFRED C&S rods mechanical design C&S_Rods_ ppt P1P2 B C D A Active mode: Solenoid "A", valves "A" and "B" (both normally open) are electrically actuated. De-energizing any (or all) of them will cause depressurization (i.e. "shot" initiation) Passive mode: Loss of electrical supply  see above Low pressure line break  see above High pressure line break causes the mechanical actuation of the Valve "C" low chamber depressurization is the basic event (but not the only one) which can trigger the device The system does not relay on the efficiency of the gas reservoirs or of the feeding lines. due to the small diameter of the high pressure line, in case of rupture, a significant depressurization of the high pressure chamber occurs after a very long time, therefore enough boosting force is available for scram (caused by automatic actuation of valve "C") Low pressure line High pressure line Booster

Fp7 - LEADER Slide 17 ALFRED C&S rods mechanical design C&S_Rods_ ppt Booster

Fp7 - LEADER Slide 18 ALFRED C&S rods mechanical design C&S_Rods_ ppt Status C/R mechanical design reports (some amendments needed) S/R concept Unification of F/A, C/R and S/R interfaces C/R drawings S/R mechanical design & drawings done to do 1 month completion time