1. [T6.4] Assessment of damping pressure wave inside SG Technical meeting – KIT - Karlsruhe, 22/11/2012 A. Del Nevo, A. Ciampichetti Presented by Mariano Tarantino LEADER Project Working Package 6

2. List of contents  Introductory remarks: LIFUS 5  Objectives and status of deliverables and milestones  Outline of Task 6.4  Status of deliverables and milestones  Refurbishment of LIFUS5: LIFUS5/Mod2  Design of the test section - (Task 3.2)  Test section layout and instrumentation  Preliminary TM specifications  Conclusive remarks, issues & new plan schedule 2/15 LEADER Project Working Package 6 Task 4 - Technical meeting – KIT - Karlsruhe, 22/11/2012

3. Introductory remarks: LIFUS 5  Experimental facility for HLM/water interaction investigations (i.e. PbLi, LBE, Pb)  Designed to operate in a wide range of conditions: up to 200 bar and 500 °C  Operated for supporting LFR and ADS technology development  Suitable for code validation, models development, safety analysis studies, testing engineering solutions, …  Reaction vessel S1  Pressurised water vessel S2  Safety vessel S3  Liquid metal storage tank LEADER Project Working Package 6 Task 4 - Technical meeting – KIT - Karlsruhe, 22/11/2012 3/15

4. Objectives and status of deliverables and milestones With reference LFR and ETDR configurations  Investigate and asses the damping of pressure waves by SGTR event (3 tests planned).  Cooperation (exchange of knowledge and joint technological efforts) with the ROSATOM project in specific topics MILESTONES (T 0 = April 2010)  M06 - SG test facility commissioned (T 0 + 24)  Delay of 10 months DELIVERABLES (T 0 = April 2010)  D23 - Tests report on the performance of the proposed pressure wave damping system (T 0 +36)  Delay of 6 months LEADER Project Working Package 6 Task 4 - Technical meeting – KIT - Karlsruhe, 22/11/2012 4/15

5. Outline of Task 6.4  Definition of an experimental configuration representative of the SG of LFR reference configuration in conjunction with Task 3.2  Execution of the experimental campaign in LIFUS 5 test facility The tests will be performed in LBE on a mock up representative (mainly diameter and pitch of the tubes and their support) of the bundle of the SG of LFR reference configuration with perforated outer thin and main shells, immersed in a vessel. Pressure evolution inside and outside the bundle at different elevation will be measured, as well the final deformation, if any, of the bundle.  Connection with Working Package 3 – Task 3.2 “Conceptual design: SG damping pressure waves system design”  Connection with Working Package 6 – Task 6.5 “Scientific and technology collaboration with ROSATOM institutions”  Comparison with Russian design and the connected experimental work LEADER Project Working Package 6 Task 4 - Technical meeting – KIT - Karlsruhe, 22/11/2012 5/15

6. Refurbishment of LIFUS-5 LIFUS-5/Mod2 for LFR and ADS technology development  New support frame  New injection line  New test procedure  New control room  New DAS and I&CS  New instrumentation Objectives:  Procedure for preparing and operating the facility simplified  Reliable and controlled boundary and initial conditions (repeatability)  Reliable and highly instrumented for detailed experimental data LEADER Project Working Package 6 Task 4 - Technical meeting – KIT - Karlsruhe, 22/11/2012 6/15

7. Refurbishment of LIFUS5: new DACS & instrumentation Instrumentation available for DAS (installed in…):  up to 15 strain gauges (LBE system)  70 TCs for fast acquisition (LBE and water systems)  8 fast pressure transducers (LBE and water systems)  1 Coriolis flowmeter (water system)  1 Level gauge (water system) Acquisition @ 1 kHz High temperature strain gauge Level gauge LEADER Project Working Package 6 Task 4 - Technical meeting – KIT - Karlsruhe, 22/11/2012 7/15 NEW DACS available

8. Refurbishment of LIFUS-5  LIFUS5/Mod2 is a new facility, set up at ENEA CR Brasimone: 4 main vessels and few components have been recycled from LIFUS5 LEADER Project Working Package 6 Task 4 - Technical meeting – KIT - Karlsruhe, 22/11/2012 Water flow meter Workshop activities on S1 8/15

9. Design of the test section - (Task 3.2)  Ref. design of ELSY SG  22.22 mm OD tube, 3 mm thick, axial and radial pitch of 24 mm.  Max flow rate is 15 kg/s, about 1 kg in 0.1s and 3,4 kg in 1s  LIFUS 5 limits  Small dimension and geometrical shape (scaled down test section required)  Achievable operating conditions of the tube to be ruptured (max flow rate, duration of the test, water in the tube is stagnant etc…)  Design of a test section in order to reproduce the velocity field of the displaced molten lead in the very first moments after tube rupture  Max. flow rate estimated 50-60% of the reference flow rate  Tests relevant for code validation LEADER Project Working Package 6 Task 4 - Technical meeting – KIT - Karlsruhe, 22/11/2012 9/15

10. Design of the test section - (Task 3.2)  Proposed layout of the tube bundle in LIFUS5 involves tube to tube gap dimension scaled down consistently with the tube dimension ELSYLIFUS5  Tube OD = 17.2mm  Tube thickness TBD in order to achieve valuable information about mechanical loading on the tubes during the transient at different locations  No plastic deformation of the tubes during the 10% flow rate test  Plastic deformations of tubes during 100% flow rate test  Measurements of plastic deformations will provide information about the pressure evolution across the test section LEADER Project Working Package 6 Task 4 - Technical meeting – KIT - Karlsruhe, 22/11/2012 10/15

11. Design of the test section - (Task 3.2)  The test section consists of  Straight-tube bundle arranged in 13 tube rows by 8 columns  Dimensions and description are provided as preliminary information (Draft report of Task 3.2 in preparation)  The plates provide the path to the pressure surge buffering S3 dump tank.  The tubes are fixed to the tube sheets by means of rod caps at both ends  The tube prepared to be ruptured is the 7 th row-4 th column-tube, LEADER Project Working Package 6 Task 4 - Technical meeting – KIT - Karlsruhe, 22/11/2012 11/15

12. Test section layout and instrumentation Perforated shell  The test section layout: placed in vertical position with the injector in the center in order to  To simplify the construction and to speed up the activities  To keep the axi-symmetry (code validation)  To increase the tube length  No influence on the objectives LEADER Project Working Package 6 Task 4 - Technical meeting – KIT - Karlsruhe, 22/11/2012  Planned instrumentation for LEADER campaign inside the reaction vessel (S1):  Up to 70 TCs for fast acquisition  Inside and outside the perforated shell  Up to 8 fast pressure transducers  Inside and outside the perforated shell  Up to 15 strain gauges  6 on the vessel wall (5 inside and 1 outside)  3 planned on the test section 12/15

13. Preliminary TM specifications #ParameterT#1T#2T#3 1Reaction systemS1 (+S3) 2LBE temp. [°C]400 3Water pressure [bar]180 4Water temp. [°C]330 5Argon vol./LBE vol. [%]TBD 6 Lasting time of the injection valve on [s] TBD 7Injector orifice diam. [mm]TBD  Three tests planned  10%, 50%, 100% of reference flow rate  Test section design supported by MERIVUS  Pre-test calculations (NPP and LIFUS5) by SIMMER code by CIRTEN  Support calculations for evaluating the tube thickness by CIRTEN  Support calculations for the design of the new water injection line by ANSALDO LEADER Project Working Package 6 Task 4 - Technical meeting – KIT - Karlsruhe, 22/11/2012 13/15

14. Conclusive remarks, issues & new plan schedule  LIFUS5/Mod2 is a new facility set up at ENEA CR. Brasimone)  Delays accumulated  certification issues (activities stopped from Feb. to June 2012 )  The layout of the facility, the instrumentation and the performances of the acquisition system are consistent with the specifications  February 2012. [ Problem ] The safety office of ENEA raised the issue that LIFUS5 facility (constructed in 1998) was not in accordance with the PED.  March 2012. [ Corrective actions ] Actions started to solve the issue: i.e. review of the design, new documentation of the facility components, of the facility as system, qualification of all welding processes, check (RX and PT) of all weldings including those already existing, verification of all RX weldings by a certified external body, risk assessment and installation of safety valves, etc.  June 2012. [ Problem solved ] Construction of the facility, design and realization of the new I&C system and DAS restarted  Sept. 2012. Construction of LIFUS5/Mod2 completed. New control system available  October 2012. Checking heating wires, sensors, etc. Insulation placed. Fast aqcquisition system available. Commissioning tests on overall system (procedure tests, pressure tests, instrumentation and control tests) LEADER Project Working Package 6 Task 4 - Technical meeting – KIT - Karlsruhe, 22/11/2012 14/15

15. Conclusive remarks, issues & new plan schedule  New plan schedule  discussed in Madrid 10/05/2012 and according with the letter ENEA/2012/39527/UTIS sent 30 July 2012  Certification of the experimental facility  in progress  LIFUS5/Mod2 LEADER test section construction  in progress  Performing the LEADER experimental campaign  According with the new time schedule LEADER Project Working Package 6 Task 4 - Technical meeting – KIT - Karlsruhe, 22/11/2012 15/15

16. 16 Support to the Steam Generator Tube Rupture (SGTR) Experimental activity in LIFUS 5 CIRTEN Interuniversity Consortium for Technological Nuclear Research Rosa Lo Frano INTRODUCTION LIFUS 5 EXPERIMENTAL ACTIVITY BUCKLING ANALYSIS BUCKLING ANALYSIS RESULTS CONCLUSIONS

17. 17 Introduction The intent of this study is to provide a contribution to the development of a LIFUS 5 mock up to be developed to the evaluation of the SGTR. In particular in agreement with the proposed experimental configuration, it was analyzed the conditions for which the rupture of SG tube could occur. Scheme of two spiral tubes arrangement (Alemberti et al., 2012) The reference design of SG features a 22,22 mm OD tube, 3 mm thick with axial and radial pitch of 24 mm

18. 18 LIFUS 5 EXPERIMENTAL ACTIVITY The LIFUS 5 test rig has been designed to investigate the SGTR dynamical interaction involving molten heavy metal and water injected into it, influenced by the temperature of the interacting coolants and the pressure of the secondary coolant, of about 190 bar. Considering the limits of LIFUS facility, related to the small dimensions of the test vessel, the geometrical shape and achievable operating conditions, a full scale testing is not possible. Therefore, a simplified scaled mock up with tube 17,2 OD and 2 mm thick with bore cross section of about 60% of that of the ELFR-Option A reference SG will be used.

19. 19 The test section consists of a 17.2 mm OD straight-tube bundle arranged in 13 tube rows by 8 columns, and of its enclosure. The tube is about 220 mm long (in literature classified as short tube) and hanged between two perforated plates, which serve as the inner and outer shell of the steam generator makeup. The vertical plates are 18,5 mm apart from each other, and of section tapered from the base edge of 17.2 mm to a thin top edge of 5 mm. How to foresee the tube to be ruptured ?? Buckling analysis LIFUS 5 EXPERIMENTAL ACTIVITY

20. 20 Buckling Analysis The buckling is influenced not only by the pressure load but mainly by the nature and magnitude of the imperfections invariably caused by various manufacturing processes (strongly dependent on that). The load carrying capacity is recognized to be strongly influenced by the yield load. tube 17,2 OD and 2 mm thick

21. 21 Hypotheses: Cylindrical/spiral shell with radius R, length L and thickness t; Homogeneous and Isotropic material;. Uniform internal/external pressure p The shell is assumed to be “thin” so that the buckling occurs below yield. For short-moderate length isotropic cylindrical shells pressure buckling loads a simply supported boundary condition may be considered: w = 0, M = 0, N = 0, v = 0 In practice, a clamped boundary is used, represented by: Buckling Analysis

22. 22 1) Material is homogeneous, isotropic and elasto-plastic A 304L/316. 2) The model consists of solid 3-D finite elements. The mesh involves five elements on the thickness and 160 over the tube circumference; a suitable elements number capable to assure the convergence of results. FEM model characteristics: Size of model: 8800 Elements 3-D Solid Element Brick type: Hex 8 Nonlinear analyses as function of the first change in the slope (i.e. stiffness) in the load deflection curve were performed adopting the Lanczos method. Buckling Analysis

23. 23 l/Dt/Dt (mm) l (mm) P cr (MPa) 12.790.11222066.37 25.810.11244015.85 38.370.1126603.16 The load carrying capacity is also dependent by D/l and t/D ratio. Buckling value under external pressure The obtained values referred to perfect shell. The real buckling value, if a real shape of the tube is considered (eccentricity, ovality, etc.), would be 10- 15% lower than numerical P cr. l/Dt/Dt (mm) l (mm) P cr (MPa) 12.790.06122052.68 25.810.0614404.5 38.370.0616601.12 Buckling value under external pressure Buckling Analysis Results

24. 24 t (mm) l (mm) P cr (MPa) 1.522062.5 122052.68 0.7522041.4 0.522035.77 0.252205.02 Buckling load vs. reduced thickness Buckling Analysis Results

25. 25 Conclusions The 1st buckling mode was m = 1 (bending mode along the longitudinal direction): the tube is influenced by the edge effects, its wavy form is not damped out and contribute to the magnitude of the critical load. As for as the proposed simplified scaled mock up concerned, the conditions for which the rupture of SG tube could occur is obtained at very small thickness of tube that is very difficult to obtain by means of mechanical machinery treatment. To reach the failure condition it is therefore suggested to intentionally reduce the thickness of the short tube (reduced strength) in order to attain low buckling values