[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 ProjectWorking Package 6

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

2/15LEADER Project Working Package 6 Task 4 - Technical meeting – KIT - Karlsruhe, 22/11/2012

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

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 (T0 = April 2010)

M06 - SG test facility commissioned (T0 + 24) Delay of 10 months

DELIVERABLES (T0 = April 2010)

D23 - Tests report on the performance of the proposed pressure wave damping system (T0 +36) Delay of 6 months

LEADER Project Working Package 6 Task 4 - Technical meeting – KIT - Karlsruhe, 22/11/2012 4/15

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

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

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

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

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

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 providedas preliminary information (Draft report of Task 3.2 in preparation)

The plates provide the path to thepressure 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 7th row-4th column-tube,

LEADER Project Working Package 6 Task 4 - Technical meeting – KIT - Karlsruhe, 22/11/2012 11/15

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

Preliminary TM specifications

# Parameter T#1 T#2 T#3

1 Reaction system S1 (+S3) S1 (+S3) S1 (+S3)2 LBE temp. [°C] 400 400 4003 Water pressure [bar] 180 180 1804 Water temp. [°C] 330 330 3305 Argon vol./LBE vol. [%] TBD TBD TBD

6Lasting time of the injection valve on [s]

TBD TBD TBD

7 Injector orifice diam. [mm] TBD TBD 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

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

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 scheduleLEADER Project Working Package 6 Task 4 - Technical meeting – KIT - Karlsruhe, 22/11/2012 15/15

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Support to the Steam Generator Tube Rupture (SGTR) Experimental activity in LIFUS 5

CIRTENInteruniversity Consortium for Technological Nuclear Research

Rosa Lo Frano

INTRODUCTION

LIFUS 5 EXPERIMENTAL ACTIVITY

BUCKLING ANALYSIS

BUCKLING ANALYSIS RESULTS

CONCLUSIONS

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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

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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.

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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

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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

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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: 0 ; 0

0' ; 0

N

ww

Buckling Analysis

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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

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l/D t/D t (mm) l (mm) Pcr (MPa)

12.79 0.11 2 220 66.37

25.81 0.11 2 440 15.85

38.37 0.11 2 660 3.16

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 Pcr.

l/D t/D t (mm) l (mm) Pcr (MPa)

12.79 0.06 1 220 52.68

25.81 0.06 1 440 4.5

38.37 0.06 1 660 1.12

Buckling value under external pressure

Buckling Analysis Results

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t (mm) l (mm) Pcr (MPa)

1.5 220 62.5

1 220 52.68

0.75 220 41.4

0.5 220 35.77

0.25 220 5.02

Buckling load vs. reduced thickness

Buckling Analysis Results

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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